Co-reporter:Qingxin Zeng, Kai Wang, and Bo Zou
Journal of the American Chemical Society November 8, 2017 Volume 139(Issue 44) pp:15648-15648
Publication Date(Web):October 25, 2017
DOI:10.1021/jacs.7b10292
Materials with negative linear compressibility (NLC) counterintuitively expand along one specific direction coupled to the volume reduction when compressed uniformly. NLC with a large value is desired for compression and materials science. However, NLC is generally smaller than −20 TPa–1. High-pressure X-ray diffraction experiments reveal that the β-quartz-like InH(BDC)2 generates an extreme NLC (−62.4 TPa–1) by framework hinging. InH(BDC)2 is much safer and lower-cost than Au+/Ag+ and CN–-containing materials that dominated the fields of large NLC. This work reconfirms that a negative thermal expansion flexible framework could likely exhibit large NLC. Moreover, a large NLC could be anticipated to arise from β-quartz-like or related frameworks composed of rigid linear ligands and flexible framework angles.
Co-reporter:Chao Wang, Yongming Sui, Man Xu, Chuang Liu, Guanjun Xiao, and Bo Zou
ACS Sustainable Chemistry & Engineering November 6, 2017 Volume 5(Issue 11) pp:9787-9787
Publication Date(Web):September 24, 2017
DOI:10.1021/acssuschemeng.7b01628
Design and fabrication of inexpensive and efficient oxygen evolution reaction (OER) catalysts are of great importance for polymer electrolyte membrane water electrolyzers (PEMWEs). Although the best electrocatalyst is IrO2 for OER in the PEMWEs, the practical application of Ir has been impeded because of its high cost and limited activity. Herein, a galvanic replacement reaction mechanism was developed for the preparation of polycrystalline Ni–Ir nanocages (NCs) by using Ni nanoparticles as templates. The formation of Ni–Ir NCs achieves the enhancement of OER catalytic performance, accompanied by the reduction of Ir loading but significantly increasing the efficiency of Ir atoms. The as-prepared Ni2.53Ir NCs exhibit improved catalytic activity toward OER in acid solution, which requires only an overpotential of 302 mV to deliver a current density of 10 mA/cm2. At an overpotential of 300 mV, the Ir-based mass activity of Ni2.53Ir catalysts reaches 114.7 mA/mgIr, which is 2.1 times higher than that of commercial Ir black. The obtained Ni2.53Ir NCs could be potentially applied for industrial scale PEMWE systems.Keywords: Electrocatalyst; Hollow porous nanostructure; Ni−Ir nanocages; Oxygen evolution reaction; Water splitting;
Co-reporter:Qian Li, Xiaojing Sha, Shourui Li, Kai Wang, Zewei Quan, Yue Meng, and Bo Zou
The Journal of Physical Chemistry Letters June 15, 2017 Volume 8(Issue 12) pp:2745-2745
Publication Date(Web):June 5, 2017
DOI:10.1021/acs.jpclett.7b01057
The search for effective methods to accurately control host–guest relationship is the central theme of host–guest chemistry. In this work, high pressure successfully promotes guest release in the Hofmann-type clathrate of [Ni(NH3)2Ni(CN)4]·2C6H6 (Ni–Bz) and restricts guest insertion into Ni(NH3)2Ni(CN)4 (Ni–Ni). Because of the weak host–guest interactions of Ni–Bz, external force gradually removes guest benzene from the host framework, leading to puckered layers. Further theoretical calculations reveal the positive pressure contribution to breaking the energy barrier between Ni–Bz and Ni–Ni, explaining guest release from an energy standpoint. Inversely, guest insertion is restricted in the synthesized host of Ni–Ni because of the steric hindrance effect at high pressure. This study not only reveals structural effects on host–guest behaviors but also proves the role of pressure in controlling host–guest interactions. This unique observation is also crucial for the further application of host–guest materials in sustained and intelligent drug release, molecular separation, and transportation.
Co-reporter:Kai Wang;Lingrui Wang
The Journal of Physical Chemistry Letters July 7, 2016 Volume 7(Issue 13) pp:2556-2562
Publication Date(Web):June 20, 2016
DOI:10.1021/acs.jpclett.6b00999
Organometal halide perovskites (OMHPs) are attracting an ever-growing scientific interest as photovoltaic materials with moderate cost and compelling properties. In this Letter, pressure-induced optical and structural changes of OMHP-based formamidinium lead bromide (FAPbBr3) were systematically investigated. We studied the pressure dependence of optical absorption and photoluminescence, both of which showed piezochromism. Synchrotron X-ray diffraction indicated that FAPbBr3 underwent two phase transitions and subsequent amorphization, leading directly to the bandgap evolution with redshift followed by blueshift during compression. Raman experiments illustrated the high pressure behavior of organic cation and the surrounding inorganic octahedra. Additionally, the effect of cation size and the different intermolecular interactions between organic cation and inorganic octahedra result in the fact that FAPbBr3 is less compressible than the reported methylammonium lead bromide (MAPbBr3). High pressure studies of the structural evolution and optical properties of OMHPs provide important clues in optimizing photovoltaic performance and help to design novel OMHPs with higher stimuli-resistant ability.
Co-reporter:Guanjun Xiao, Ye Cao, Guangyu Qi, Lingrui Wang, Chuang Liu, Zhiwei Ma, Xinyi Yang, Yongming Sui, Weitao Zheng, and Bo Zou
Journal of the American Chemical Society July 26, 2017 Volume 139(Issue 29) pp:10087-10087
Publication Date(Web):July 6, 2017
DOI:10.1021/jacs.7b05260
Metal halide perovskites (MHPs) are gaining increasing interest because of their extraordinary performance in optoelectronic devices and solar cells. However, developing an effective strategy for achieving the band-gap engineering of MHPs that will satisfy the practical applications remains a great challenge. In this study, high pressure is introduced to tailor the optical and structural properties of MHP-based cesium lead bromide nanocrystals (CsPbBr3 NCs), which exhibit excellent thermodynamic stability. Both the pressure-dependent steady-state photoluminescence and absorption spectra experience a stark discontinuity at ∼1.2 GPa, where an isostructural phase transformation regarding the Pbnm space group occurs. The physical origin points to the repulsive force impact due to the overlap between the valence electron charge clouds of neighboring layers. Simultaneous band-gap narrowing and carrier-lifetime prolongation of CsPbBr3 trihalide perovskite NCs were also achieved as expected, which facilitates the broader solar spectrum absorption for photovoltaic applications. Note that the values of the phase change interval and band-gap red-shift of CsPbBr3 nanowires are between those for CsPbBr3 nanocubes and the corresponding bulk counterparts, which results from the unique geometrical morphology effect. First-principles calculations unravel that the band-gap engineering is governed by orbital interactions within the inorganic Pb–Br frame through structural modification. Changes of band structures are attributed to the synergistic effect of pressure-induced modulations of the Br–Pb bond length and Pb–Br–Pb bond angle for the PbBr6 octahedral framework. Furthermore, the significant distortion of the lead–bromide octahedron to accommodate the Jahn–Teller effect at much higher pressure would eventually lead to a direct to indirect band-gap electronic transition. This study enables high pressure as a robust tool to control the structure and band gap of CsPbBr3 NCs, thus providing insight into the microscopic physiochemical mechanism of these compressed MHP nanosystems.
Co-reporter:Qian Li;Shourui Li;Kai Wang;Yuanyuan Zhou;Zewei Quan;Yue Meng;Yanming Ma
The Journal of Physical Chemistry C January 26, 2017 Volume 121(Issue 3) pp:1870-1875
Publication Date(Web):January 11, 2017
DOI:10.1021/acs.jpcc.6b11435
As an essential thermodynamic variable, pressure has a powerful ability to accurately control molecular structures and properties by modulating the noncovalent interactions therein. Based on this point, we utilized pressure to tune the structure and properties of trithiocyanuric acid (C3H3N3S3, TTCA), gaining deeper insight into its structural nature and structure–property relationships. During compression, layered TTCA undergoes molecular distortion and relative slippage between interlayers, as well as anisotropic and stepwise shrinkage of intralayer six-molecule rings. Importantly, these structural variations have a great influence on the luminescence properties of TTCA. Piezoluminescence is observed above ∼4 GPa, acompanied by the calculated shifting of valence-band top. In experiments, detailed stepwise compression of the intralayer structure was captured directly. The observations combine the microscopic structure and macroscopic properties together and are beneficial for the further design of luminescence materials, as well as pressure sensors and pressure switches.
Co-reporter:Lingrui Wang;Kai Wang;Guanjun Xiao;Qiaoshi Zeng
The Journal of Physical Chemistry Letters December 15, 2016 Volume 7(Issue 24) pp:5273-5279
Publication Date(Web):December 5, 2016
DOI:10.1021/acs.jpclett.6b02420
Organometal halide perovskites are promising materials for optoelectronic devices. Further development of these devices requires a deep understanding of their fundamental structure–property relationships. The effect of pressure on the structural evolution and band gap shifts of methylammonium lead chloride (MAPbCl3) was investigated systematically. Synchrotron X-ray diffraction and Raman experiments provided structural information on the shrinkage, tilting distortion, and amorphization of the primitive cubic unit cell. In situ high pressure optical absorption and photoluminescence spectra manifested that the band gap of MAPbCl3 could be fine-tuned to the ultraviolet region by pressure. The optical changes are correlated with pressure-induced structural evolution of MAPbCl3, as evidenced by band gap shifts. Comparisons between Pb-hybrid perovskites and inorganic octahedra provided insights on the effects of halogens on pressure-induced transition sequences of these compounds. Our results improve the understanding of the structural and optical properties of organometal halide perovskites.
Co-reporter:Qingxin Zeng, Kai Wang, Yuancun Qiao, Xiaodong Li, and Bo Zou
The Journal of Physical Chemistry Letters April 6, 2017 Volume 8(Issue 7) pp:1436-1436
Publication Date(Web):March 15, 2017
DOI:10.1021/acs.jpclett.7b00121
Negative linear compressibility (NLC) is a rare and counterintuitive phenomenon because materials with this property would expand along one specific direction when uniformly compressed. NLC materials have a broad range of potential applications in designing pressure sensors, artificial muscles, and so on. Designing and searching for systems with NLC is desired and crucial for material and compression science. Herein, with the help of high-pressure X-ray diffraction measurements and density functional theory calculations, we find that the 2D layered Co(SCN)2(pyrazine)2 exhibits NLC with a new mechanism: layer sliding. When compressed, the ab planes slide along the a axis, leading to the decrease of lattice parameter β, which results in the NLC effect along principal axis X3 (≈ −0.84a – 0.55c). The layer sliding mechanism opens exciting opportunities for seeking, designing, and synthesizing new classes of materials with anomalous mechanical properties in monoclinic layered or other related systems.
Co-reporter:Yuxiang Dai, Shitong Zhang, Haichao Liu, Kai WangFangfei Li, Bo HanBing Yang, Bo Zou
The Journal of Physical Chemistry C 2017 Volume 121(Issue 9) pp:
Publication Date(Web):February 13, 2017
DOI:10.1021/acs.jpcc.7b00709
The intramolecular charge-transfer (ICT) emission band in the dual fluorescence of the 4-(N,N-dimethylamino)benzonitrile (DMABN) molecular crystal exhibits increase in response to compression up to 10 GPa. On the basis of Raman and angle-dispersive X-ray diffraction (ADXRD) experiments combining with computational studies, the mechanism of this phenomenon could be assigned to the change of the intramolecular geometrical conformation, especially for the decrease of the dihedral angle between the dimethylamino (NMe2) and phenyl moieties. Meanwhile the reduction of excited-state energies and the HOMO–LUMO band gap leads to the redshifts of photoluminescence (PL) spectra and the absorption edge, respectively. Competing with the aggregation caused quenching (ACQ) effect, the planarity of molecular conformation and the slight rotation of the NMe2 group under high pressure both could enhance the ICT process, which will contribute to the revelation of the ICT mechanism and designs of new piezochromic luminescent materials.
Co-reporter:Guangxia Wang;Yongming Sui;Meina Zhang;Man Xu;Qingxin Zeng;Chuang Liu;Xinmei Liu;Fei Du
Journal of Materials Chemistry A 2017 vol. 5(Issue 35) pp:18577-18584
Publication Date(Web):2017/09/12
DOI:10.1039/C7TA03565A
Unique Cu2O–CuO–TiO2 hollow nanocages are synthesized by a facile self-template hydrothermal method without any surfactants and additional templates. In the synthesis process, Cu2O serves as the self-template to induce the morphology control of hollow nanocages. As the precursor to fabricate the TiO2 layer, TiF4 also etches the Cu2O template to form a hollow structure by releasing HF during the hydrothermal treatment. The design of combining copper oxides with the TiO2 layer in a hollow nanocage structure is favorable for Li-ion batteries (LIBs). Because it is beneficial to fully utilize the respective advantages of different components and solve the critical volume expansion issue that exists in almost every metal oxide electrode. As anode materials of LIBs, the as-prepared hollow nanocages of ternary metal oxides exhibit a superior reversible capacity of 700 mA h g−1 at 50 mA g−1 for over 85 cycles, which is much higher than the theoretical capacity of the compounds and any of their compositions. The capacity of the anode materials still deliver a negligible decay when restart charging/discharging after stopped more than one month. The outstanding electrochemical performance can be attributed to the synergetic effects of individual components and the special structure, namely, higher theoretical capacity of copper oxides, the well-designed hollow structure, and good structural stability and cycling stability of TiO2.
Co-reporter:Dr. Qian Li;Dr. Yonggang Wang;Weicheng Pan; Wenge Yang; Bo Zou; Jiang Tang; Zewei Quan
Angewandte Chemie 2017 Volume 129(Issue 50) pp:16185-16189
Publication Date(Web):2017/12/11
DOI:10.1002/ange.201708684
AbstractNovel inorganic lead-free double perovskites with improved stability are regarded as alternatives to state-of-art hybrid lead halide perovskites in photovoltaic devices. The recently discovered Cs2AgBiBr6 double perovskite exhibits attractive optical and electronic features, making it promising for various optoelectronic applications. However, its practical performance is hampered by the large band gap. In this work, remarkable band gap narrowing of Cs2AgBiBr6 is, for the first time, achieved on inorganic photovoltaic double perovskites through high pressure treatments. Moreover, the narrowed band gap is partially retainable after releasing pressure, promoting its optoelectronic applications. This work not only provides novel insights into the structure–property relationship in lead-free double perovskites, but also offers new strategies for further development of advanced perovskite devices.
Co-reporter:Dr. Siyu Lu;Dr. Guanjun Xiao;Dr. Laizhi Sui;Dr. Tanglue Feng;Dr. Xue Yong;Dr. Shoujun Zhu;Dr. Baojun Li; Dr. Zhongyi Liu; Dr. Bo Zou; Dr. Mingxing Jin; Dr. John S. Tse; Dr. Hu Yan; Dr. Bai Yang
Angewandte Chemie 2017 Volume 129(Issue 22) pp:6283-6287
Publication Date(Web):2017/05/22
DOI:10.1002/ange.201700757
AbstractPiezochromic materials, which show color changes resulting from mechanical grinding or external pressure, can be used as mechanosensors, indicators of mechano-history, security papers, optoelectronic devices, and data storage systems. A class of piezochromic materials with unprecedented two-photon absorptive and yellow emissive carbon dots (CDs) was developed for the first time. Applied pressure from 0–22.84 GPa caused a noticeable color change in the luminescence of yellow emissive CDs, shifting from yellow (557 nm) to blue-green (491 nm). Moreover, first-principles calculations support transformation of the sp2 domains into sp3-hybridized domains under high pressure. The structured CDs generated were captured by quenching the high-pressure phase to ambient conditions, thus greatly increasing the choice of materials available for a variety of applications.
Co-reporter:Qian Li, Shourui Li, Kai Wang, Zewei Quan, Yue Meng, and Bo Zou
The Journal of Physical Chemistry Letters 2017 Volume 8(Issue 2) pp:
Publication Date(Web):January 10, 2017
DOI:10.1021/acs.jpclett.6b02786
Searching for nontoxic and stable perovskite-like alternatives to lead-based halide perovskites for photovoltaic application is one urgent issue in photoelectricity science. Such exploration inevitably requires an effective method to accurately control both the crystalline and electronic structures. This work applies high pressure to narrow the band gap of perovskite-like organometal halide, [NH3-(CH2)4-NH3]CuCl4 (DABCuCl4), through the crystalline-structure tuning. The band gap keeps decreasing below ∼12 GPa, involving the shrinkage and distortion of CuCl42–. Inorganic distortion determines both band-gap narrowing and phase transition between 6.4 and 10.5 GPa, and organic chains function as the spring cushion, evidenced by the structural transition at ∼0.8 GPa. The supporting function of organic chains protects DABCuCl4 from phase transition and amorphization, which also contributes to the sustaining band-gap narrowing. This work combines crystal structure and macroscopic property together and offers new strategies for the further design and synthesis of hybrid perovskite-like alternatives.
Co-reporter:Dr. Zhao Gao;Dr. Kai Wang;Dr. Fangming Liu;Dr. Cunfang Feng;Dr. Xin He;Dr. Jinyu Li; Bing Yang; Bo Zou; Ping Lu
Chemistry - A European Journal 2017 Volume 23(Issue 4) pp:773-777
Publication Date(Web):2017/01/18
DOI:10.1002/chem.201604923
AbstractTwo piezochromic materials containing phenanthro[9,10-d]imidazole and tetraphenylethylene (M1 and M2) were developed. A supra-amplification piezochromic effect originating from their various long-to-short axis ratios was discovered in high-pressure experiments. Based on the linear relationship between applied pressure and emission-peak wavelength during pressurizing and depressurizing cycles, quantitative sensitivity for piezochromism could be denoted. M2 displayed higher piezochromic contrast (102 nm) and better sensitivity (11.19 nm GPa−1) than M1 (69 nm and 6.12 nm GPa−1), which helps to develop a more comprehensive general strategy to evaluate pressure-responsive performance.
Co-reporter:Zhe Zhang, Yu Gao, He Liu, Qing Bai, Jinyu Li, Liqun Liu, Changfeng Wu, Bing Yang, Kai Wang, Bo Zou, Yan Wang, Ping Lu
Dyes and Pigments 2017 Volume 145(Volume 145) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.dyepig.2017.06.025
•Dual fluorescence induced by polymorph is investigated in crystals.•The single-crystal study reveals that dual fluorescence is caused by different twist angle, which gives a direct observation that supported the twisted intramolecular charge transfer states (TICT) model.•The external pressure was applied to adjust the fluorescence behavior from a dual emission to a LE emission by changing the twist angel.Organic fluorescence molecules have attracted great interest in the last decades, due to their adjustable fluorescence properties and broad applications in organic electroluminescence display, fluorescence labelling, biological imaging, and so on. Conformation is one of the most important factors that determines organic molecular fluorescence properties. Herein, a compound, DBTO-PTZ, with five polymorphs was demonstrated. Distinctive polymorph-dependent optical characteristics were observed in these polymorphs, which gives an ideal model for the investigation of relationship between conformation and fluorescence property. Three of them display distinct dual fluorescence which is not observed in solution or the other two crystals. It is found that the twist angle between DBTO and PTZ units is a critical factor to determine the polymorphs of DBTO-PTZ and corresponding fluorescence behaviors. This result provides a direct proof to support the TICT model. Moreover, the external pressure was applied to adjust the fluorescence behavior from a dual emission to a single LE emission, which further proves the mechanism of TICT. This work will contribute to the understanding between conformation and optical characteristics. It also sheds light on a new strategy to fine-tune the fluorescence property.Download high-res image (304KB)Download full-size image
Co-reporter:Guanjun Xiao;Ye Cao;Guangyu Qi;Lingrui Wang;Qingxin Zeng;Chuang Liu;Zhiwei Ma;Kai Wang;Xinyi Yang;Yongming Sui;Weitao Zheng
Nanoscale (2009-Present) 2017 vol. 9(Issue 30) pp:10741-10749
Publication Date(Web):2017/08/03
DOI:10.1039/C7NR03367B
The high-pressure response of few-layer black phosphorus (BP) nanosheets remains elusive, despite the special interest in it particularly after the achievement of an exotic few-layer BP based field effect transistor. Here, we identified a pressure-induced reversible phase transition on few-layer BP nanosheets by performing in situ ADXRD and Raman spectroscopy with the assistance of DAC apparatus. The few-layer BP nanosheets transformed from orthorhombic semiconductors to simple cubic metal with increasing pressure, which is well interpreted using the pressure-induced inverse Peierls distortion. The obtained simple cubic BP nanosheets exhibited an enhanced isothermal bulk modulus of 147.0(2) GPa, and negative Grüneisen parameters that were attributed to the pressure-driven softening of phonon energies. Note that the simple cubic BP nanosheets adopted the highest symmetry which is in stark contrast to the general phase transformation under high pressure. First-principles calculations indicated that the metallic BP was significantly related to the band overlapped metallization, resulting from the traversing of density of states across the Fermi level at high pressure. Such findings paved a potential pathway to design targeted BP nanostructures with functional properties at extremes, and opened up possibilities for conceptually new devices.
Co-reporter:Man Xu;Yongming Sui;Guanjun Xiao;Xinyi Yang;Yingjin Wei
Nanoscale (2009-Present) 2017 vol. 9(Issue 7) pp:2514-2520
Publication Date(Web):2017/02/16
DOI:10.1039/C6NR08518K
Nanoporous gold (NPG) structures, which possess abundant high-index facets, kinks, and steps, have been demonstrated as effective catalysts for the glucose electrooxidation in biofuel cells. Herein, we designed surface-clean NPG structures with high-index facets by a trisodium citrate (Na3Cit) self-initiated reduction of chloroauric acid (HAuCl4) in a water–ice bath followed by a kinetically controlled self-assembly manner. This strategy breaks through the traditional trisodium citrate thermal-reducing chloroauric acid approach where solutions are required to heat to a certain temperature for the reaction to initiate. However, herein, the surface-clean NPG structures yielded highly enhanced catalytic activity in glucose electrooxidation with approximately 9 A cm−2 mg−1 current density, which is over 20 times higher than that of Au nanoparticles devised by Turkevich (Turkevich-Au NPs) under the same conditions. This remarkable electrocatalytic activity could be ascribed to the large electrochemically active surface area, clean surface, and high-index facets or highly active sites of the porous structure. The employment of the surface-clean NPG with high-index facets for glucose electrooxidation promises a substantial improvement in the current biofuel cell technology and indicates the potential of biofuel cells in practical applications.
Co-reporter:Xinyi Yang;Bo Zhou;Yingjin Wei
CrystEngComm (1999-Present) 2017 vol. 19(Issue 24) pp:3331-3337
Publication Date(Web):2017/06/20
DOI:10.1039/C7CE00491E
We report for the first time one-dimensional (1D) wurtzite (WZ) MnSe nanoconveyors with a single-crystalline configuration fabricated by a solution-processed colloidal method. High-resolution transmission electron microscopy (HRTEM) measurements show that the stem of MnSe nanoconveyors grows along the [100] direction, while the teeth grow along the [0001] direction. We find that the initial WZ nanobelts with the [100] growth direction are crucial to the formation of nanoconveyors, whereas the teeth are a result of a self-catalyzed growth process induced by the Mn-terminated (0001) surface. The magnetic measurements suggest that 1D WZ MnSe nanoconveyors consist of an antiferromagnetic core and a ferromagnetic shell below the blocking temperature. Furthermore, the hysteresis measurements indicate that these nanoconveyors have 300 Oe coercive fields, which is attributed to the high surface-to-volume ratio of the nanoconveyors. This facile solution-based strategy can be anticipated to synthesize WZ metal chalcogenide nanomaterials with 1D hierarchical structures, for potential applications from spintronics to photocatalysis.
Co-reporter:Jie Wu, Yangyang Cheng, Jingbo Lan, Di Wu, Shengyou Qian, Lipeng Yan, Zhen He, Xiaoyu Li, Kai Wang, Bo Zou, and Jingsong You
Journal of the American Chemical Society 2016 Volume 138(Issue 39) pp:12803-12812
Publication Date(Web):September 7, 2016
DOI:10.1021/jacs.6b03890
The development of facile methods for screening organic functional molecules through C–H bond activation is a revolutionary trend in materials research. The prediction of mechanochromism as well as mechanochromic trends of luminogens is an appealing yet challenging puzzle. Here, we present a strategy for the design of mechanochromic luminogens based on the dipole moment of donor–acceptor molecules. For this purpose, a highly efficient route to 2,7-diaryl-[1,2,4]triazolo[1,5-a]pyrimidines (2,7-diaryl-TAPs) has been established through programmed C–H arylation, which unlocks a great opportunity to rapidly assemble a library of fluorophores for the discovery of mechanochromic regularity. Molecular dipole moment can be employed to explain and further predict the mechanochromic trends. The 2,7-diaryl-TAPs with electron-donating groups on the 2-aryl and electron-withdrawing groups on the 7-aryl possess a relatively small dipole moment and exhibit a red-shifted mechanochromism. When the two aryls are interchanged, the resulting luminogens have a relatively large dipole moment and display a blue-shifted mechanochromism. Seven pairs of isomers with opposite mechanochromic trends are presented as illustrative examples. The aryl-interchanged congeners with a bidirectional emission shift are structurally similar, which provides an avenue for understanding in-depth the mechanochromic mechanism.
Co-reporter:Yuanxiang Xu, Kai Wang, Yujian Zhang, Zengqi Xie, Bo Zou and Yuguang Ma
Journal of Materials Chemistry A 2016 vol. 4(Issue 6) pp:1257-1262
Publication Date(Web):04 Jan 2016
DOI:10.1039/C5TC03745J
Two thermodynamically stable crystalline phases (B- and G-phases) were found for a twistable π-conjugated molecule, CN-DSB, condensed from its solution. We investigated the structural evolution at the molecular and supramolecular levels as the crystalline phase transforms from the B-phase to G-phase under varied temperature or pressure. The intermolecular interactions were undermined before phase transition as the B-phase crystal was stimulated with an external energy. Heating the B-phase crystal up to 175 °C or applying stress up to its critical pressure (0.75 GPa) initially resulted in mixture phases or disordered state. At this stage, the molecules slightly adjust from a twisting configuration to a planar configuration, corresponding to the gradual red shift of the fluorescence spectra. Above the phase transition point, the initial intermolecular interaction of the B-phase is broken down, and the CN-DSB molecules re-assemble to the new phase—a new thermodynamic equilibrium state—corresponding to the sudden change of the emission color. Furthermore, the property of thermal-induced phase transition can be used to fabricate patterns on the CN-DSB crystal surface, and a uniform raster has been prepared by femtosecond laser direct writing (FsLDW) on the B-phase. The investigations provide new insight and understanding for the crystal phase transition and may contribute to process innovation in optical devices.
Co-reporter:Bo Zhou, Xinyi Yang, Yongming Sui, Guanjun Xiao, Yingjin Wei and Bo Zou
Nanoscale 2016 vol. 8(Issue 16) pp:8784-8790
Publication Date(Web):29 Mar 2016
DOI:10.1039/C6NR00446F
The manipulated synthesis of high-quality semiconductor nanocrystals (NCs) is of high significance with respect to the exploration of their properties and their corresponding applications. Nevertheless, the preparation of metastable-phase NCs still remains a great challenge due to their high kinetic barriers and harsh synthetic conditions. Herein, we demonstrated the fabrication of high-quality MnSe nanorods with a metastable wurtzite structure via a subtle sulfur-doping strategy. Based on the UV–vis absorption spectra, manganese polysulfide clusters were formed by mixing oleylamine–sulfur and oleylamine–manganese solutions at room temperature. The existence of manganese polysulfide clusters with polymeric sulfur structures makes the system more reactive, inducing fast wurtzite-phase nucleation. This can overcome the natural kinetic barrier of wurtzite MnSe and lead to subsequent growth of targeted NCs. On the other hand, no sulfur doping would produce MnSe NCs in a thermodynamically favorable rock-salt phase. As expected, different doping contents and sulfur sources also resulted in the formation of high-quality wurtzite MnSe nanorods. This success establishes that a facile strategy can be anticipated to synthesize high-quality metal chalcogenide NCs with a metastable phase, especially wurtzite nanorods, for potential applications from spintronics to solar cells.
Co-reporter:Cunfang Feng, Kai Wang, Yuanxiang Xu, Liqun Liu, Bo Zou and Ping Lu
Chemical Communications 2016 vol. 52(Issue 19) pp:3836-3839
Publication Date(Web):03 Feb 2016
DOI:10.1039/C5CC09152G
CzCNDSB with a highly twisted conformation in the solid state is constructed. Single crystal measurements prove that it possesses an inside pore with a diameter of 8 Å and further forms a long-range orderly arrayed channel. CzCNDSB can sense external pressure from 1.0 atm to 9.21 GPa, accompanied by color changes from green to red with excellent reversibility and reproducibility.
Co-reporter:Xinmei Liu, Yongming Sui, Xinyi Yang, Yingjin Wei, and Bo Zou
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 40) pp:26886
Publication Date(Web):September 22, 2016
DOI:10.1021/acsami.6b09717
Low activity and high cost of electrocatalysts are the major challenge for the commercialization of the direct fuel cells (DFCs) and biofuel cells. In this work, we demonstrate the desirable “clean surfaces” effect of Cu nanocrystals in electrocatalysis. By a new reaction route of Cu2O nanospheres (Cu2O NSs), Cu nanowires (Cu NWs) with high purity and “clean surfaces” are first obtained under mild conditions. Benefiting from the path directing effects and abundant (100) facets, the as-prepared Cu NWs exhibit a lower overpotential to achieve the methanol electro-oxidation reaction (MOR) than that of analogous Cu nanoparticles (Cu NPs). Moreover, the “clean surfaces” provide more available active sites for the efficient transfer of electrons, enabling the Cu NWs to show their enhanced electrocatalytic activity. In the MOR, forward peak current density for the surface-cleaned Cu NWs is 2839 μA cm–2, which is ca. 6.45-fold higher than that of the Cu NWs with residual capping molecules on their surface. The “clean surfaces” effect can also be extended to the glucose electro-oxidation reaction (GOR), and the enhancement in specific surface area activity for the Cu NWs is 11.3-fold. This work enhances the electrocatalytic performance of Cu nanocrystals without the need for additional noble metals, which opens up new avenues for utilizing non-noble metals in the DFC or biofuel cell applications.Keywords: 1D metal nanostructures; catalyst; Cu nanocrystals; glucose electro-oxidation reaction; methanol electro-oxidation reaction
Co-reporter:Qingxin Zeng, Tingting Yan, Kai Wang, Yinyan Gong, Yong Zhou, Yongli Huang, Chang Q. Sun and Bo Zou
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 20) pp:14046-14054
Publication Date(Web):25 Apr 2016
DOI:10.1039/C6CP00648E
In situ Raman spectroscopy revealed that transiting H2O/NaX (∼64) solutions into an ice VI phase and then into an ice VII phase at a temperature of 298 K requires excessive pressures with respect to pure water. The increase of the critical pressures varies with the solute type in the Hofmeister series order: X = I > Br > Cl > F ∼ 0. The results suggest that the solute hydration creates electric fields that lengthen and soften the O:H nonbond and meanwhile shorten and stiffen the H–O bond through O–O Coulomb repulsion. Compression, however, does the opposite to solute electrification upon the O:H–O bond relaxation. Therefore, compression of the aqueous solutions recovers the electrification-deformed O:H–O bond first and then proceeds to the phase transitions, which requires excessive energy for the same sequence of phase transitions. Ice exclusion of solute disperses the frequencies of characteristic phonons and the critical pressures with unlikely new bond formation.
Co-reporter:Yuxiang Dai
The Journal of Physical Chemistry C 2016 Volume 120(Issue 10) pp:5340-5346
Publication Date(Web):February 24, 2016
DOI:10.1021/acs.jpcc.5b12341
Organic chain molecules have considerable importance because of their conformational stability, which is fundamental to their chemical stability. The phase behaviors and conformational equilibrium of simple hydrocarbons and their derivatives under extreme conditions are of interest to research because of their applications. In situ high-pressure Raman spectroscopy studies on succinonitrile up to 24 GPa at ambient temperature have been conducted to investigate its structural properties and conformational equilibria. Succinonitrile has undergone a plastic-to-crystal phase transition around 0.7 GPa. A simultaneous conversion of gauche to trans conformation has been observed. A crystal-to-crystal phase transition has subsequently occurred around 2.9 GPa. The second high-pressure phase has remained stable up to 24 GPa. These two crystal structural transitions have also been confirmed by in situ high-pressure angle-dispersive X-ray diffraction experiments. Compared with the reported low-temperature phase, the new phases under high pressure have different molecular conformations and higher densities, which can provide better understanding of the paths of conformational transitions under different extreme conditions.
Co-reporter:Guangyu Qi
The Journal of Physical Chemistry C 2016 Volume 120(Issue 25) pp:13414-13420
Publication Date(Web):June 7, 2016
DOI:10.1021/acs.jpcc.6b04154
A combination of synchrotron powder angle-dispersive X-ray diffraction (ADXRD) and Raman spectroscopy has been utilized to study high pressure behavior of the chemical hydrogen storage material guanidinium borohydride (GBH) [C(NH2)3]+[BH4]−. A reversible structural phase transition was observed at approximately 0.4 GPa, evidenced by the obvious changes in ADXRD patterns and Raman spectra. Both Raman spectra and the first-principles calculation revealed that new dihydrogen bonds generated under high pressure, which was proposed to be the reason for the observed phase transition. This research explored the pressure induced changes of GBH and studied the evolution of dihydrogen bonds, which can give insight into the improvement of the hydrogen release properties.
Co-reporter:Lei Kang
The Journal of Physical Chemistry C 2016 Volume 120(Issue 27) pp:14758-14766
Publication Date(Web):June 28, 2016
DOI:10.1021/acs.jpcc.6b05001
The structural stability of benzoic acid (C6H5COOH, BA), a hydrogen-bonded molecular crystal, has been investigated by Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) up to ∼18 GPa at room temperature. Under ambient conditions, benzoic acid molecules are arranged in two sets of parallel planes and held together by hydrogen bonding and van der Waals interactions. Small changes (e.g., emergence of new peaks, splitting of original peaks) can be observed in the Raman spectra at high pressures. However, no obvious changes can be observed in the X-ray diffraction measurements, which rules out any symmetry/structure changes within this pressure range. The pressure dependence of lattice parameters is presented, which shows monotonously decrease without any anomalies. The experimental isothermal pressure–volume data are well fitted by the third-order Birch–Murnaghan equation of state, yielding bulk modulus B0 = 41.7(6) GPa and a first pressure derivative B0′ = 4.5(4). Axial compressibility shows obvious anisotropy, the a axis is more compressible than b and c axes. Moreover, the near symmetrization limit of hydrogen bonds at high pressures is proposed from the first-principles calculations. Based on the Raman, XRD, and the first-principles calculations analysis, we propose that the high pressure structural stability of benzoic acid is associated with the special hydrogen-bonded dimer structure.
Co-reporter:Yuxiang Dai, Kai Wang, Xiaodong Li, and Bo Zou
The Journal of Physical Chemistry C 2016 Volume 120(Issue 33) pp:18503-18509
Publication Date(Web):August 4, 2016
DOI:10.1021/acs.jpcc.6b06351
Maleic anhydride, an industrially important chemical, was investigated by conducting in situ high-pressure Raman scattering and synchrotron angle-dispersive X-ray diffraction (ADXRD) experiments at a pressure of up to 1.0 GPa. Drastic discontinuities of Raman modes at 0.5 GPa indicated that a phase transition occurred when pressure was elevated. This transformation is further discussed by analysis of the ADXRD results. The Raman spectra and X-ray diffraction patterns of the recovered samples indicated that this pressure-induced transformation is reversible. The calculated results by the first-principle method indicated that the pressure-induced planarity of molecular arrangement is the mechanism of this transition. This study shows that the pressure-induced phase transition of maleic anhydride at 0.5 GPa is derived from supramolecular rearrangements.
Co-reporter:Guangyu Qi, Kai Wang, Ke Yang, and Bo Zou
The Journal of Physical Chemistry C 2016 Volume 120(Issue 38) pp:21293-21298
Publication Date(Web):September 1, 2016
DOI:10.1021/acs.jpcc.6b07278
We report the high-pressure behavior of dihydrogen-bonded hydrogen storage material hydrazine bisborane (BH3N2H4BH3, HBB) via in situ angle-dispersive X-ray diffraction (ADXRD) and Raman spectroscopy in a diamond anvil cell up to 2.0 GPa. A reversible phase transition at 0.4 GPa was confirmed by ADXRD experiments. The Rietveld refinement showed the high-pressure phase was consistent with the crystal structure of α′-phase (low-temperature phase). Through the analysis of structure changes, Raman spectroscopy, and the Hirshfeld surface, we studied the evolution of dihydrogen bonds under high pressure and attributed the pressure-induced phase transition to the distortion and rotation of the NH2–NH2 group. This work will further the understanding of the characteristics of dihydrogen bonds and provide some contribution to future hydrogen storage applications of HBB.
Co-reporter:Lu Wang;Kai Wang;Kaiqi Ye;Hongyu Zhang;Yue Wang
Advanced Materials 2015 Volume 27( Issue 18) pp:2918-2922
Publication Date(Web):
DOI:10.1002/adma.201500589
Co-reporter:Guanjun Xiao; Xinyi Yang; Xinxin Zhang; Kai Wang; Xiaoli Huang; Zhanhui Ding; Yanming Ma; Guangtian Zou
Journal of the American Chemical Society 2015 Volume 137(Issue 32) pp:10297-10303
Publication Date(Web):August 5, 2015
DOI:10.1021/jacs.5b05629
Synthesis of nanomaterials with target crystal structures, especially those new structures that cannot be crystallized in their bulk counterparts, is of considerable interest owing to their strongly structure-dependent properties. Here, we have successfully synthesized and identified new-phase nanocrystals (NCs) associated with orthorhombic MnP-type (B31) MnS by utilizing an effective high-pressure technique. It is particularly worth noting that the generated new structured MnS NCs were captured as expected by quenching the high-pressure phase to the ambient conditions at room temperature. Likewise, the commercially available bulk rocksalt (RS) MnS material underwent unambiguously a reversible phase transition when the pressure was released completely. First-principles calculations further supported that the B31-MnS was more energetically preferable than the RS one under high pressure, which can be plausibly interpreted by the structural buckling with respect to zigzagged arrangements within B31 unit cell. Our findings represent a significant step forward in a deeper understanding of the high-pressure phase diagram of MnS and even provide a promising strategy to prepare desired nanomaterials with new structures that do not exist in their bulk counterparts, thus greatly increasing the choice of materials for a variety of applications.
Co-reporter:Yujian Zhang, Qingbao Song, Kai Wang, Wengang Mao, Feng Cao, Jingwei Sun, Lingling Zhan, Yaokang Lv, Yuguang Ma, Bo Zou and Cheng Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 13) pp:3049-3054
Publication Date(Web):06 Feb 2015
DOI:10.1039/C4TC02826K
For piezo-, vapo-, and thermochromic materials, it remains a challenge to figure out the underlying reason for fluorescence color changes upon external stimulation and determine why only some fluorophores reveal emission switching. A novel triphenylacrylonitrile derivative (TPAN-MeO) with remarkably twisted conformations has been carefully prepared via the Suzuki coupling reaction. The fluorescence of TPAN-MeO in the aggregate state depends on the polymorphic forms: three crystalline forms BCrys, SCrys and YCrys exhibit bright blue, sky-blue and yellow emission, respectively; meanwhile the amorphous powders are also strongly fluorescent with green emission. The crystals BCrys and SCrys exhibit mechano- and piezochromism in that grinding and high pressure could alter the emission colour, respectively. In addition, the amorphous film exhibits vapo- and thermochromic behaviour in that organic vapour and heating could change the green colour into sky-blue. Interestingly, the solvent vapour and heating stimuli can trigger a crystal-to-crystal transformation between SCrys form and YCrys form.
Co-reporter:Man Xu, Yongming Sui, Chao Wang, Bo Zhou, Yingjin Wei and Bo Zou
Journal of Materials Chemistry A 2015 vol. 3(Issue 44) pp:22339-22346
Publication Date(Web):23 Sep 2015
DOI:10.1039/C5TA07027A
Porous Ag structures have recently attracted great interest due to their unique characteristics, relatively low cost and good biocompatibility. Shape-, size-, porosity-, and crystallinity-controlled and surface defect tailored synthesis of porous metal materials is of scientific significance yet greatly underdeveloped because of the lack of rational design strategies. Here, a low cost and facile synthetic route is presented to produce regular porous Ag platelet structures with controlled size, porosity, crystallinity and surface defects by a two-step process. Initially, size-tailored regular Ag platelet precursors from 2.5 μm to 36 μm are obtained by merely adjusting the solution pH value; meanwhile D-glucose is introduced as a structure-directing agent. Subsequently, thermal treatment is performed to afford the porous Ag platelet structures. Simply by optimizing the annealing time, temperature and heating rate, porous Ag platelets with effectively tunable porosity, crystallinity and surface defects can be achieved. The porous Ag platelet structures could catalyze the reduction of p-nitrophenol and dyes quite effectively at room temperature, which is attributed to their regular morphologies, porosity, high surface-to-volume ratio, short diffusion length and good permeability. Moreover, these porous Ag platelet structures because of their unique morphology and network characteristics will exhibit excellent electrochemical catalytic activity, or act as outstanding electrodes, sensors, actuators, etc.
Co-reporter:Chao Wang, Yongming Sui, Guanjun Xiao, Xinyi Yang, Yingjin Wei, Guangtian Zou and Bo Zou
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:19669-19673
Publication Date(Web):03 Sep 2015
DOI:10.1039/C5TA05384F
Iridium (Ir) is widely used as a catalyst in polymer electrolyte membrane water electrolyzers (PEMWEs). However, high cost and limited catalytic performance of Ir hamper its large-scale industrial application. Here, based on a modified galvanic replacement, we introduce Cu nanoparticles as a template to prepare single-crystalline Cu–Ir polyhedral nanocages (NCs). Alloying Ir with 3d transition metal Cu not only significantly reduces the loading of Ir but also remarkably enhances its catalytic activity by forming a unique NC structure and tuning the d-band structure of Ir. The as-prepared single-crystalline Cu1.11Ir NCs exhibit enhanced catalytic activity toward the oxygen evolution reaction (OER) in 0.05 M H2SO4, with a smaller overpotential (286 mV) required for a current density of 10 mA cm−2 and a Tafel slope of 43.8 mV per decade. The mass activity can reach 73 mA mgIr−1 at an overpotential of 0.28 V for Cu1.11Ir NCs. Hence, the obtained Cu1.11Ir NCs would be a promising electrocatalyst for practical electrocatalytic water splitting systems.
Co-reporter:Xiao Meng, Guangyu Qi, Chen Zhang, Kai Wang, Bo Zou and Yuguo Ma
Chemical Communications 2015 vol. 51(Issue 45) pp:9320-9323
Publication Date(Web):27 Apr 2015
DOI:10.1039/C5CC01064K
The isomerization of spiropyrans in crystals was realized under high pressure, and the corresponding mechanochromic response could be observed by the naked eye. In situ UV-Vis spectroscopy study demonstrated that the equilibrium constant increases with the increasing pressure, from which we proposed that the negative volume of reaction determined the isomerization under high pressure.
Co-reporter:Lu Wang, Kai Wang, Houyu Zhang, Chuanjun Jiao, Bo Zou, Kaiqi Ye, Hongyu Zhang and Yue Wang
Chemical Communications 2015 vol. 51(Issue 36) pp:7701-7704
Publication Date(Web):30 Mar 2015
DOI:10.1039/C5CC01113B
The orange emissive powders of a boron-containing compound generate red, green, and blue luminescence after compressing, heating, and volatile acid fuming, respectively. Thus, stimulus-induced RGB emissions have been facilely realized based on one organic π-conjugated material for the first time, to the best of our knowledge.
Co-reporter:Xinmei Liu, Yongming Sui, Xinyi Yang, Lina Jiang, Fei Wang, Yingjin Wei and Bo Zou
RSC Advances 2015 vol. 5(Issue 73) pp:59099-59105
Publication Date(Web):29 Jun 2015
DOI:10.1039/C5RA08586A
We have introduced potassium bromide (KBr) as an additive to synthesize cuprous oxide (Cu2O) microcrystals with various well-defined shapes. Here, the bromide ions play a pivotal role in controlling the shape of the Cu2O microcrystals, from concave cubic into short hexapod shapes. As a typical representative, the obtained Cu2O microcrystals were further utilized in a non-enzymatic amperometric glucose sensor. And the sensor constructed by the extended hexapod Cu2O microcrystals show the best performance, exhibiting remarkable sensitivity (97 μA mM−1 cm−2), significant selectivity and a wide linear response (up to 14.3 mM) towards glucose detection. Compared with the previous sensors that were constructed by the Cu-based materials, this detection range is much closer to the glucose range in human serum. The wide range can be ascribed to the “clean surface” (with no organic capping agent adsorbed on the surface) and more rich {111} facets exposed for the extended hexapod structure, which maximize the accessible electroactive surface for the efficient transfer of electrons, as well as the product molecules. This work provides a green and feasible approach to enhance the Cu2O sensor performance, which can be extended to other applications such as solar-energy conversion and catalysis.
Co-reporter:Lei Kang, Kai Wang, Shourui Li, Xiaodong Li and Bo Zou
RSC Advances 2015 vol. 5(Issue 103) pp:84703-84710
Publication Date(Web):29 Sep 2015
DOI:10.1039/C5RA17223C
The structural and vibrational properties of acetamide under high pressure were probed by in situ synchrotron X-ray diffraction (XRD) and Raman scattering up to ∼10 GPa. Two structural phase transitions are observed at 0.9 and 3.2 GPa, evidenced by the obvious changes in the Raman spectra as well as the discontinuities of peak positions versus pressure. The phase transitions are further confirmed by the significant changes in the XRD patterns. The two phase transitions are proposed to originate from the rearrangements of hydrogen-bonded networks, deduced by the redistribution of intensities and positions of N–H vibrations. Detailed analysis of the XRD patterns indicates that the first high-pressure phase (phase II) possesses a monoclinic structure with a possible space group of C2/c. Moreover, the phase transitions are reversible since the diffraction pattern returns to its initial state upon total decompression. The detailed mechanisms for these phase transitions, the cooperativity of different intermolecular interactions, as well as the high-pressure behaviors of hydrogen bonds are presented and discussed.
Co-reporter:Yuancun Qiao; Kai Wang; Hongsheng Yuan; Ke Yang
The Journal of Physical Chemistry Letters 2015 Volume 6(Issue 14) pp:2755-2760
Publication Date(Web):June 28, 2015
DOI:10.1021/acs.jpclett.5b01129
Negative linear compressibility (NLC) is a relatively uncommon phenomenon and rarely studied in organic systems. Here we provide the direct evidence of the persistent NLC in organic mineral ammonium oxalate monohydrate under high pressure using synchrotron X-ray powder diffraction, Raman spectroscopy and density functional theory (DFT) calculation. Synchrotron X-ray powder diffraction measurement reveals that ammonium oxalate monohydrate shows both positive and negative linear compressibility along b-axis before 11.5 GPa. The red shift of the external Raman modes and abnormal changes of several selected internal modes in high-pressure Raman spectra further confirmed the NLC. DFT calculations demonstrate that the N—H···O hydrogen bonding “wine-rack” motifs result in the NLC along b-axis in ammonium oxalate monohydrate. We anticipate the high-pressure study of ammonium oxalate monohydrate may represent a promising strategy for accelerating the pace of exploitation and improvement of NLC materials especially in organic systems.
Co-reporter:Dr. Yujian Zhang;Dr. Kai Wang;Guilin Zhuang; Zengqi Xie; Cheng Zhang; Feng Cao; Guoxiang Pan;Haifeng Chen; Bo Zou; Yuguang Ma
Chemistry - A European Journal 2015 Volume 21( Issue 6) pp:2474-2479
Publication Date(Web):
DOI:10.1002/chem.201405348
Abstract
A donor–acceptor-type fluorophore containing a twisted diphenylacrylonitrile and triphenylamine has been developed by using the Suzuki reaction. The system indicates typical intramolecular charge-transfer properties. Upon mechanical grinding or hydrostatic pressure, the fluorophore reveals a multicolored fluorescence switching. Interestingly, a fluorescence color transition from green to red was clearly observed, and the change of photoluminescent (PL) wavelength gets close to 111 nm. The mechanisms of high-contrast mechanochromic behavior are fully investigated by techniques including powder XRD, PL lifetime, high-pressure PL lifetime, and Raman spectra analysis. The tremendous PL wavelength shift is attributed to gradual transition of excited states from the local excited state to the charge-transfer state.
Co-reporter:Guanjun Xiao
The Journal of Physical Chemistry C 2015 Volume 119(Issue 7) pp:3843-3848
Publication Date(Web):January 26, 2015
DOI:10.1021/jp512565b
High-pressure research on nanostructured materials has been of considerable interest owing to the quantum confinement effect and intrinsic defects in the nanocrystals. Here, we report a pressure-induced reversible structural phase transition in nanostructured Bi2Te3 hierarchical architectures (HAs) that were prepared via a facile solution-phase method. Therein, distinct phases I–IV by respectively adopting crystal structures of rhombohedral (I), monoclinic (II, III), and cubic (IV) were experimentally identified with increasing pressure up to 20.2 GPa in a diamond anvil cell (DAC). It is worthwhile to notice that nanostructured Bi2Te3 HAs ultimately evolved into a fascinating Bi–Te substitutional nonmetallic alloy at pressure even as low as 15.0 GPa, approximately 10 GPa lower than that of the corresponding bulk counterpart. The synergistic effect involving large volume collapse and the unique one-dimensional nanostructures with intrinsic antisite defects was proposed to be responsible for the reduction of transition pressure that is contrary to the general model for most nanomaterials. Our findings may pave a potential pathway for developing future multifunctional nanoalloys that are composed of nonmetallic elements.
Co-reporter:Hongsheng Yuan
The Journal of Physical Chemistry C 2015 Volume 119(Issue 15) pp:8364-8372
Publication Date(Web):March 26, 2015
DOI:10.1021/acs.jpcc.5b01007
A combination of synchrotron powder X-ray diffraction (XRD) and Raman spectroscopy has been used to study high-pressure behavior of the zircon-type LaVO4 nanorods. In situ high-pressure XRD results identified an irreversible zircon-to-monazite phase transition at ∼5 GPa and a reversible transition to an undetermined second high-pressure phase (phase III) at ∼12.9 GPa. Through Le Bail refinements of the XRD patterns with zircon-type structure, we show that the zircon-type LaVO4 nanorods possess the smallest bulk modulus among zircon-type rare-earth orthovanadates. Furthermore, negative pressure coefficients of external translational T(Eg) and internal υ2(B2g) bending modes have been observed in Raman measurements. The Raman spectra of phase III with distinctive features have been fully recorded for the first time, and a related structure associated with a coordination increase for V is suggested in terms of the postmonazite phase in LaVO4 nanorods. Finally, analysis of the transmission electron microscopy both before and after compression indicates that a large number of nanorods can be recovered in the quenched samples, allowing us to verify the orientation relationship for zircon-to-monazite phase transformation.
Co-reporter:Xiao Tan
The Journal of Physical Chemistry C 2015 Volume 119(Issue 19) pp:10178-10188
Publication Date(Web):April 21, 2015
DOI:10.1021/jp512035s
The variation of pressure is an effective experimental technique to explore new polymorphs of organic crystals. At ambient condition, oxalyl dihydrazide (C2N4O2H6, ODH) exhibits five polymorphs: α, β, δ, γ, and ε. Here we report the high-pressure response of the existed five forms of ODH by in situ Raman spectroscopy and synchrotron X-ray diffraction techniques with a pressure of about 20 GPa. High-pressure experimental results show that all five polymorphs undergo phase transitions to new phases at different pressures, respectively. We propose that the special molecular conformation yields several geometric constructions for hydrogen-bonding arrangements. The detailed mechanisms of the phase transition and the high-pressure behaviors of the polymorphs are analyzed by considering molecular stacking.
Co-reporter:Yuxiang Dai
The Journal of Physical Chemistry C 2015 Volume 119(Issue 23) pp:12801-12807
Publication Date(Web):May 19, 2015
DOI:10.1021/acs.jpcc.5b01105
We studied high-pressure reaction of solid cyanamide in a diamond anvil cell up to a pressure of 21.7 GPa. The results of in situ high-pressure Raman spectroscopy and angle-dispersive X-ray diffraction experiments indicated the occurrence of pressure-induced oligomerization in cyanamide over 13 GPa. The Raman, NMR, and UV absorption spectra of recovered samples confirmed that the chemical reaction was irreversible and that the high-pressure products contained C═N bonds. Subsequently, results of kinetic studies showed the relation between pressure and the reaction rate. Meanwhile dependence of activation volume with pressure indicated that the steric factors affected the reaction. Additionally, the increase in the amount of C–C bonds of recovered samples was attributed to the change of reactive sites of adjacent C≡N groups. These results suggest that the application of pressure can tune both the reactive sites and the reaction rate to affect oligomerization and even other chemical reactions.
Co-reporter:Yi Wang; Xiao Tan; Yu-Mo Zhang; Shaoyin Zhu; Ivan Zhang; Binhong Yu; Kai Wang; Bing Yang; Minjie Li; Bo Zou;Sean Xiao-An Zhang
Journal of the American Chemical Society 2014 Volume 137(Issue 2) pp:931-939
Publication Date(Web):December 22, 2014
DOI:10.1021/ja511499p
Molecular switches have attracted increasing interest in the past decades, due to their broad applications in data storage, optical gating, smart windows, and so on. However, up till now, most of the molecular switches are operated in solutions or polymer blends with the stimuli of light, heat, and electric fields. Herein, we demonstrate the first pressure-controllable molecular switch of a benzo[1,3]oxazine OX-1 in crystal. Distinct from the light-triggered tautomerization between two optical states, applying hydrostatic pressure on the OX-1 crystal results in large-scale and continuous states across the whole visible light range (from ∼430 to ∼700 nm), which has not been achieved with other stimuli. Based on detailed and systematic control experiments and theoretical calculation, the preliminary requirements and mechanism of pressure-dependent tautomerization are fully discussed. The contributions of molecular tautomerization to the large-scale optical modulation are also stressed. Finally, the importance of studying pressure-responsive materials on understanding tactile sensing is also discussed and a possible mechanotransduction mode is proposed.
Co-reporter:Chao Wang, Guanjun Xiao, Yongming Sui, Xinyi Yang, Gang Liu, Mingjun Jia, Wei Han, Bingbing Liu and Bo Zou
Nanoscale 2014 vol. 6(Issue 24) pp:15059-15065
Publication Date(Web):15 Oct 2014
DOI:10.1039/C4NR04072D
Branched iridium nanodendrites (Ir NDs) have been synthesized by a simple method based on the oriented attachment mechanism. Transmission electron microscopy images reveal the temporal growth process from small particles to NDs. Precursor concentrations and reaction temperatures have a limited effect on the morphology of Ir NDs. Metal oxide and hydroxide-supported Ir NDs exhibit enhanced activity for catalytic CO oxidation. Particularly, the Fe(OH)x-supported Ir NDs catalyst with a 4 wt% Ir loading show superior CO oxidation catalytic activity with a full conversion of CO at 120 °C. Furthermore, compared with Ir NPs and commercial Ir black, Ir NDs exhibit higher activity and stability for ammonia oxidation. The specific activity and mass activity of Ir NDs for ammonia oxidation are 1.7 and 7 times higher than that of Ir NPs. The improved catalytic activities of Ir NDs are attributed not only to their large specific surface area, but also to their considerably high index facets and rich edge and corner atoms. Hence, the obtained Ir NDs provide a promising alternative for direct ammonia fuel cells and proton-exchange membrane fuel cells.
Co-reporter:Pinhua Zhang, Yongming Sui, Chao Wang, Yingnan Wang, Guangliang Cui, Chunzhong Wang, Bingbing Liu and Bo Zou
Nanoscale 2014 vol. 6(Issue 10) pp:5343-5350
Publication Date(Web):04 Mar 2014
DOI:10.1039/C4NR00412D
A nontoxic, simple, inexpensive, and reproducible strategy, which meets the standard of green chemistry, is introduced for the synthesis of copper nanocrystals (Cu NCs) with olive oil as both reducing agent and capping agent. By changing the reaction parameters, the shape, size and surface structure of the Cu NCs can be well controlled. The obtained Cu nanocubes show excellent catalytic properties for the catalytic reduction of dyes and CO oxidation. Moreover, the prepared Cu nanocubes as substrates exhibit surface enhanced Raman scattering (SERS) activity for 4-mercaptopyridine (4-Mpy). Therefore, this facile route provides a useful platform for the fabrication of Cu NCs which have the potential to replace noble metals for certain applications.
Co-reporter:Mi Zhou, Kai Wang, Zhiwei Men, Chenglin Sun, Zhanlong Li, Bingbing Liu, Guangtian Zou and Bo Zou
CrystEngComm 2014 vol. 16(Issue 20) pp:4084-4087
Publication Date(Web):19 Feb 2014
DOI:10.1039/C3CE42607F
Based on the 4,4′-bipyridine organic linker, metal–organic frameworks of Co2(4,4′-bpy)3(NO3)4·xH2O (CB-MOF) have been prepared. The pressure-dependent structure evolution of CB-MOF has been investigated up to 11 GPa. An isostructural phase transition was observed at about 6 GPa followed by negative compressibility along the b axis.
Co-reporter:Tingting Yan, Kai Wang, Defang Duan, Xiao Tan, Bingbing Liu and Bo Zou
RSC Advances 2014 vol. 4(Issue 30) pp:15534-15541
Publication Date(Web):18 Mar 2014
DOI:10.1039/C4RA00247D
The effect of high pressure on two forms (α, β) of p-aminobenzoic acids (PABA) is studied in a diamond anvil cell using in situ Raman spectroscopy. Previous research showed that α-PABA undergoes a phase transition, and β-PABA is transformed to α-PABA at high temperatures. In the present study, we investigate whether a new polymorph or a transformation between the two polymorphs occurs upon the application of pressure. Experimental results reveal that the two forms remain stable up to ∼13 GPa. Ab initio calculations are performed to account for the changes in unit cell parameters, molecular arrangements, and hydrogen bonds. Polymerization is observed in type B molecules of α-PABA through the calculated geometric parameters of hydrogen bonds. Based on a systematic comparison of the subtle structural changes, anisotropic characteristic, and various interactions of the two polymorphs, we propose that the stability of α-form crystals is associated with the special dimer structure. The stability of the β-form is attributed to hydrogen-bonded networks with four-membered ring construction.
Co-reporter:Kai Wang ; Jing Liu ; Ke Yang ; Bingbing Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 15) pp:8122-8127
Publication Date(Web):March 24, 2014
DOI:10.1021/jp500689w
Maleic hydrazide, a unique example of polymorphic structures, was analyzed at pressure up to 5 GPa using in situ high-pressure Raman scattering and synchrotron X-ray diffraction techniques. Changes in the Raman spectra at 2 GPa indicate that a pressure-induced phase transition is occurring. The transition was further analyzed with angle dispersive X-ray diffraction, which demonstrated that maleic hydrazide underwent a polymorphic transformation from the form III to the form II. Moreover, the observed transformation was partially reversible when the system was brought back to ambient pressure. This work suggests that the high-pressure polymorphic transformation is caused by changes in the hydrogen-bonded ribbons which lead to supramolecular rearrangements in the crystal structure.
Co-reporter:Tingting Yan ; Kai Wang ; Xiao Tan ; Ke Yang ; Bingbing Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 28) pp:15162-15168
Publication Date(Web):June 26, 2014
DOI:10.1021/jp503803n
The response of biurea to high pressures is investigated by in situ Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell up to ∼5 GPa. Raman scattering measurements indicate a phase transition occurring over the pressure range of 0.6–1.5 GPa. Phase transition is confirmed by changes in the ADXRD spectra with symmetry transformation from C2/c to a possible space group P2/n. Upon total release of pressure, the diffraction spectrum returns to its initial state, which implies that the transition observed is reversible. We discuss variations in the Raman spectra, including splitting of modes, appearance of new modes, and abrupt changes in the slope of the frequency shift curves at several pressures. We propose that the phase transition observed in this study is attributed to rearrangement of the hydrogen-bonded networks.
Co-reporter:Hongsheng Yuan, Kai Wang, Ke Yang, Bingbing Liu, and Bo Zou
The Journal of Physical Chemistry Letters 2014 Volume 5(Issue 17) pp:2968-2973
Publication Date(Web):August 18, 2014
DOI:10.1021/jz501371k
Mechanochromic materials with aggregation-induced enhanced emission (AIEE) characteristic have been intensively expanded in the past few years. In general, intermolecular interactions invariably alter photophysical processes, while their role in the luminescence properties of these AIEE-active molecules is difficult to fully recognize because the pressurized samples possess amorphous nature in many cases. We now report the high-pressure studies on a prototype AIEE-active molecule, tetraphenylethene, using diamond anvil cell technique with associated spectroscopic measurements. An unusual pressure-dependent color, intensity, and lifetime change in tetraphenylethene has been detected by steady-state photoluminescence and time-resolved emission decay measurements. The flexible role of the aromatic C–H···π and C–H···C contacts in structural recovery, conformational modification, and emission efficiency modulation upon compression is demonstrated through structure and infrared analysis.Keywords: aggregation-induced enhanced emission (AIEE); conformational analysis; fluorescence; high pressure; intermolecular interactions; ring-opening reaction;
Co-reporter:Qian Li ; Shourui Li ; Kai Wang ; Jing Liu ; Bingbing Liu ; Ke Yang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 14) pp:7562-7568
Publication Date(Web):March 18, 2014
DOI:10.1021/jp412366y
We have performed in situ high-pressure synchrotron X-ray diffraction (XRD) and photoluminescence (PL) measurements to explore the behaviors of europium fluoride (EuF3). At ambient conditions, EuF3 consists of two representative phases of the rare earth trifluorides family. The orthorhombic phase (α-EuF3) evolves into its hexagonal phase (β-EuF3) in the pressure range 2.7–7.8 GPa, which involves the variations of europium positions in one layer and changes in the coordination number of europium from nine to eleven. The existence of pure β-EuF3 at high pressure allows solving detailed structural information of β-EuF3 for the first time. In comparison with the excellent hydrostatic condition in methanol–ethanol–water, a somewhat poor pressure condition in silicon oil contributes to the sluggishness of the phase transition, restrains the compression of lattice constants, and controls the phase content ratio of the quenched sample. Significantly, the PL measurements show that the pressure-induced purity of EuF3 is a benefit to the enhancement of its luminescence intensity. This work provides precise structural and PL information on β-EuF3, getting a deeper insight into the nature of these two typical structures with respect to rare-earth trifluorides.
Co-reporter:Kai Wang;Shourui Li;Xiao Tan;Guanjun Xiao;Bingbing Liu
Science Bulletin 2014 Volume 59( Issue 36) pp:5258-5268
Publication Date(Web):2014 December
DOI:10.1007/s11434-014-0615-9
High pressure supramolecular chemistry is a developing interdisciplinary field. The use of high pressure for the study and fabrication of supramolecular systems has been explored only in the past few years. Such studies would shed light on the nature of the structures and functions of the complex supramolecular architectures. In this review, systematic progress made in this field is introduced based on the recent achievements. Special attention is paid to pressure-driven novel properties and functions of supramolecular assemblies resulting from the changes of molecular conformations, intermolecular interactions and supramolecular arrangements under high pressure.
Co-reporter:Dr. Guanjun Xiao;Dr. Chunye Zhu; Yanming Ma; Bingbing Liu; Guangtian Zou ; Bo Zou
Angewandte Chemie International Edition 2014 Volume 53( Issue 3) pp:729-733
Publication Date(Web):
DOI:10.1002/anie.201309416
Abstract
There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room-temperature ferromagnetism was identified. First-principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment. Such a mechanism, which is different from that of a vacancy defect, provides new insights into the origins of magnetism. Our findings may pave the way for developing future Bi2Te3-based dissipationless spintronics and fault-tolerant quantum computation.
Co-reporter:Dr. Guanjun Xiao;Dr. Chunye Zhu; Yanming Ma; Bingbing Liu; Guangtian Zou ; Bo Zou
Angewandte Chemie 2014 Volume 126( Issue 3) pp:748-752
Publication Date(Web):
DOI:10.1002/ange.201309416
Abstract
There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room-temperature ferromagnetism was identified. First-principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment. Such a mechanism, which is different from that of a vacancy defect, provides new insights into the origins of magnetism. Our findings may pave the way for developing future Bi2Te3-based dissipationless spintronics and fault-tolerant quantum computation.
Co-reporter:Lei Kang ; Kai Wang ; Shourui Li ; Jing Liu ; Ke Yang ; Bingbing Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 16) pp:8521-8530
Publication Date(Web):March 26, 2014
DOI:10.1021/jp412112g
High-pressure behaviors of hydrogen-bonded supramolecular structure, ammonium formate (NH4+COOH–, AF), have been investigated under pressure by in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy up to 20 GPa. Under ambient conditions, AF exhibits three-dimensional hydrogen-bonded networks with two molecules crystallize in a monoclinic unit cell of space group Pc. A structural phase transition can be identified at around 1.8 GPa, as indicated by the abrupt changes in Raman spectra as well as the pressure dependence of major Raman modes. Furthermore, two new N–H stretching modes emerge, indicative of the construction of new hydrogen bonds. Rearrangement of the hydrogen-bonded networks is also deduced by the obvious changes of N–H stretching modes both in position and intensity. The reversible phase transition is confirmed by in situ synchrotron XRD experiments with the emergence of a new set of diffraction pattern. The high-pressure phase is found to have a structure with a monoclinic unit cell (space group P21) containing two molecules. The structural transformation is proposed to be a result of the rearrangement of the hydrogen-bonded networks. Detailed mechanism for the phase transition, high-pressure behaviors of hydrogen bonds, as well as the cooperativity of different noncovalent interactions are presented and discussed.
Co-reporter:Kai Wang ; Jing Liu ; Ke Yang ; Bingbing Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 32) pp:18640-18645
Publication Date(Web):July 28, 2014
DOI:10.1021/jp504641z
Diamond anvil cells combined with Raman spectroscopy and synchrotron X-ray diffraction were used to analyze the compression behavior of sulfamide, a hydrogen-bonded crystal. The marked changes in the Raman spectra at approximately 5 GPa strongly suggest a structural phase transition associated with the rearrangement of hydrogen bonds. Results from angle-dispersive X-ray diffraction confirmed this pressure-induced phase transition, and the high-pressure phase was indexed and refined to a low-symmetry monoclinic structure with space group I2/m. Further phase transitions were not detected up to the maximum pressure of 10 GPa. The observed transition was completely reversible when the pressure was released to ambient conditions. The results from ab initio calculations reveal that the phase transition was mainly caused by changes in the hydrogen-bond networks in sulfamide.
Co-reporter:Tingting Yan ; Kai Wang ; Xiao Tan ; Jing Liu ; Bingbing Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 40) pp:22960-22967
Publication Date(Web):September 18, 2014
DOI:10.1021/jp507748x
We have reported the high-pressure behavior of hydrogen-bonded energetic material carbohydrazide (CON4H6, CHZ) via in situ Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell with ∼15 GPa at room temperature. Significant changes in Raman spectra provide evidence for a pressure-induced structural phase transition in the range of ∼8 to 10.5 GPa. ADXRD experiments confirm this phase transition by symmetry transformation from P21/n to a possible space group P1̅, which exhibits ∼23.1% higher density at 10.1 GPa compared to phase P21/n at ambient pressure. Moreover, the observed transition is completely reversible when the pressure is totally released. On the basis of the decreased number of hydrogen bonds, the shortened hydrogen bond lengths, and the variations in the NH and NH2 stretching Raman peaks in the high-pressure phase, we propose that this phase transition is caused by the rearrangement of the hydrogen-bonded networks.
Co-reporter:Shourui Li ; Qian Li ; Rui Li ; Jing Liu ; Ke Yang ; Bingbing Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 41) pp:23443-23450
Publication Date(Web):September 12, 2014
DOI:10.1021/jp503495k
High pressure is an essential thermodynamic parameter in exploring the performance of condensed energetic materials. Combination of high-pressure techniques and supramolecular chemistry opens a new avenue for synthesis of high energy density materials. Herein, we fabricate a new high-pressure-assisted assembly of energetic material acetamidinium nitrate (C2N2H7+·NO3–, AN) with P-1 symmetry after a 0–12 GPa–0 treatment at room temperature, which exhibits a density that is 9.8% higher than that of the initial P21/m phase. Evolution of intermolecular lattice modes in Raman spectra and synchrotron X-ray diffraction (XRD) patterns provide strong evidence for this transition in the 1.3–3.4 GPa range. The mechanism involves relative motions between ionic pairs in the hydrogen-bonded array and distortions of building blocks.
Co-reporter:Pinhua Zhang, Yongming Sui, Guanjun Xiao, Yingnan Wang, Chunzhong Wang, Bingbing Liu, Guangtian Zou and Bo Zou
Journal of Materials Chemistry A 2013 vol. 1(Issue 5) pp:1632-1638
Publication Date(Web):20 Nov 2012
DOI:10.1039/C2TA00350C
This article reports a reproducible and facile approach to synthesize faceted copper nanocrystals (Cu NCs) using an inexpensive copper oxide as a precursor. By simply prolonging the reaction time, Cu cubes and polyhedrons were successfully produced, and the mean size could be effectively controlled in the range of 9 to 21 nm. The catalytic activities of the Cu cubes and polyhedrons were investigated by photometrically monitoring the reduction of p-nitrophenol by an excess of NaBH4. The kinetics of the reduction reaction at different temperatures were investigated to determine the activation parameters. Our investigations indicate that Cu nanocubes exhibit higher catalytic activity than Cu polyhedrons, which can be ascribed to three features: the higher surface-to-volume ratio, the higher surface energy of the {100} facet, and the lower redox potential. In addition, these catalysts can be easily recycled with a slight decrease of the catalytic activities, and are stable in the air. Therefore, this facile route provides a useful platform for the fabrication of Cu catalysts which have the potential to replace noble metals for certain catalytic applications.
Co-reporter:Ben-Bo Ni, Kai Wang, Qifan Yan, Hao Chen, Yuguo Ma and Bo Zou
Chemical Communications 2013 vol. 49(Issue 86) pp:10130-10132
Publication Date(Web):02 Sep 2013
DOI:10.1039/C3CC46153J
The cycloaddition of azides and alkynes in the solid state was accelerated by high pressure. In situ Raman scattering and synchrotron X-ray diffraction were employed to study reaction kinetics at different pressures which revealed that the pressure acceleration originates from the elevated substrate energy and decreased activation energy.
Co-reporter:Jiajia Ning, Guanjun Xiao, Chunzhong Wang, Bingbing Liu, Guangtian Zou and Bo Zou
CrystEngComm 2013 vol. 15(Issue 18) pp:3734-3738
Publication Date(Web):06 Mar 2013
DOI:10.1039/C3CE26872A
Zinc blende (ZB) structure InSe nanocrystals (NCs) doped with transition metals have been synthesized via a simple and facile synthetic route. Pure ZB InSe NCs are nanosheets, while InSe:Fe are nanoparticles 6–7 nm in size and InSe:Co are 10 nm nanoworms. Doped transition metal ions have an important influence on the shape and size of produced NCs, and the influence mainly occurs at the nucleation stage for the formation of NCs. Doped ZB-InSe NCs exhibit ferromagnetism, in particular, room-temperature ferromagnetic behavior for InSe:Co NCs was observed. This is the observation of magnetism in III–VI semiconductors. The doped metal ions and the induced defects are responsible for the generated ferromagnetism in doped ZB-InSe NCs.
Co-reporter:Yingnan Wang, Xinyi Yang, Guanjun Xiao, Bo Zhou, Bingbing Liu, Guangtian Zou and Bo Zou
CrystEngComm 2013 vol. 15(Issue 27) pp:5496-5505
Publication Date(Web):01 May 2013
DOI:10.1039/C3CE40337H
The traditional concept of the synthesis of semiconductor nanocrystals (NCs) by solvent routes usually performed under high temperatures, causes the semiconductor materials to nucleate and grow into various shaped NCs in solution. Therefore, these methods are named as “solvent-thermal approachs”. In this work, we describe a simple and reproducible strategy for the synthesis of PbS NCs at temperatures even as low as −20 °C by using frozen and solidified precursors. With the aid of alkylamines, nano-sized PbS could also nucleate and grow at such low temperatures within a short time (a few seconds). The experimental results not only break people's traditional thinking but also provide a significant and novel direction in the engineering of the synthesis of NCs. In addition, we further systematically investigated the effect of two types of temperatures (the mixing temperature of the precursors and the ripening temperature of the PbS NCs). Combining this with different alkylamines, we found an obvious competition between a growth kinetic process caused by the alkylamines and a thermodynamic process induced by the temperature, which formed variously shaped monodispersed PbS NCs, including flower-, star-, sphere-, truncated octahedron-, cuboctahedron-, quasi cube-, cube-shaped and some hollow PbS NCs. Furthermore, this competition process could also provide a facile and cost-effective route to synthesize size-tunable but shape-permanent PbS NCs and their self-assembly superlattices in the same reaction systems, which is still a major challenge at present. Afterward, both the formation mechanisms of the PbS nanostructures synthesized below room temperature and the shape transformation depending on two types of temperature and alkylamines are systematically discussed.
Co-reporter:Guanjun Xiao, Yingnan Wang, Jiajia Ning, Yingjin Wei, Bingbing Liu, William W. Yu, Guangtian Zou and Bo Zou
RSC Advances 2013 vol. 3(Issue 22) pp:8104-8130
Publication Date(Web):07 Feb 2013
DOI:10.1039/C3RA23209C
This review is focused on the recent developments of the synthesis, mechanism and applications of IV–VI semiconductor nanocrystals (NCs), including germanium-, tin- and lead-based chalcogenides NCs. First of all, we systematically introduce a series of investigations on the preparation with controllable size and shape via a wide variety of methods. Corresponding growth mechanisms are also discussed. Moreover, the promising potential of IV–VI semiconductor NCs as building blocks with respect to energy, sensors and catalysis is highlighted. For the purpose of enhancing the performance to satisfy the practical applications, tailored nanocomposites by combining noble metals or graphene etc. are further developed. Finally, we present some concluding remarks and perspectives for future developments. We hope this article can provide researchers with the key snapshots of the recent advances and the future challenges, thus achieving a great progress in IV–VI semiconductor NCs.
Co-reporter:Yongming Sui, Yi Zeng, Linlin Fu, Weitao Zheng, Dongmei Li, Bingbing Liu and Bo Zou
RSC Advances 2013 vol. 3(Issue 40) pp:18651-18660
Publication Date(Web):08 Aug 2013
DOI:10.1039/C3RA42192A
In this contribution, a facile and low-temperature solution route has been developed to large-scale synthesis of Cu2O with polyhedral, porous and hollow structures by the assistance of surfactant CTAB. The morphologies (six symmetric branches, porous branches and porous-shell hollow spheres) of the Cu2O particles, which can be controlled by changing the amount of CTAB and a possible formation mechanism, is also proposed. Our results found that CTAB not only serves as a soft template to synthesize hollow and porous Cu2O structures, but also acts as a capping agent to adsorb on the {111} plane to obtain six symmetric branches of Cu2O. Moreover, the photocatalytic and gas-sensing properties of the hollow and porous structure Cu2O samples were studied in detail. Due to the special structure character, the Cu2O porous-shell hollow spheres exhibited both strong adsorption abilities and high degradation activities for methyl orange (MO) under visible light irradiation. A gas sensor was also fabricated which showed high sensitivity for ethanol.
Co-reporter:Hongsheng Yuan, Kai Wang, Shourui Li, Xiao Tan, Qian Li, Tingting Yan, Ke Yang, Jing Liu, Bingbing Liu, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry C 2013 Volume 117(Issue 36) pp:18603-18612
Publication Date(Web):August 13, 2013
DOI:10.1021/jp405405t
We probed the high-pressure response of the YV1–xPxO4:Eu3+ (x = 0, 0.5, 0.7, 1.0) solid-solution nanoparticles using angular dispersive synchrotron X-ray diffraction (XRD) and Raman techniques at room temperature. In situ diffraction results showed that the overall nanoparticles underwent an irreversible zircon-to-scheelite structural transformation. The transition pressures were ∼9.3, ∼12.1, ∼14, and ∼18.4 GPa for the YV1–xPxO4:Eu3+ (x = 0, 0.5, 0.7, 1.0) samples, respectively. Coupled with the zircon-to-scheelite transition features, it was proposed that the transition pressure was probably governed by the stiffness of VO4/PO4 units in the solid solutions. This claim was verified by further Raman measurements, which revealed that the stiffness of VO4/PO4 units was enhanced with increasing P contents. The structural refinements showed that the samples with comparable particle size (20–90 nm) became less compressible with increasing P content (x = 0 → 0.7 → 1.0). However, the compressibility of the YV0.5P0.5O4:Eu3+ sample with smaller particle size (10–30 nm) was similar to that of the YV0.3P0.7O4:Eu3+ sample. The general compressibility behavior as a function of P content was ascribed to the special packing style related to the stiffness of VO4/PO4 tetrahedra in zircon structure, and the higher surface energy contribution was responsible for the exceptional compressibility in the smaller nanoparticles.
Co-reporter:Min Zhang, Yong-Qiang Dang, Tian-Ying Liu, Hong-Wei Li, Yuqing Wu, Qian Li, Kai Wang, and Bo Zou
The Journal of Physical Chemistry C 2013 Volume 117(Issue 1) pp:639-647
Publication Date(Web):December 17, 2012
DOI:10.1021/jp309175k
We investigated the pressure-induced fluorescence enhancement of BSA-protected gold nanoclusters, AuNCs@BSA, and the corresponding conformational changes of ligand protein by in situ fluorescence and IR spectral measurements. It is documented that the fluorescence enhancement of AuNCs@BSA is essentially attributed to the conformational changes of the ligand, which undergoes substantial secondary and tertiary structural changes. Under compression BSA loses more buried α-helical structure, while it changes oppositely in the AuNCs@BSA as the protein adopts a more flexible conformational state at the boundary surface of gold nanoclusters. The present work will be helpful to understand the fundamental mechanism and to reveal the important factors of ligands in nanoclusters, which are hope to improve the luminescence efficiency of gold nanoclusters in final.
Co-reporter:Shourui Li, Qian Li, Kai Wang, Mi Zhou, Xiaoli Huang, Jing Liu, Ke Yang, Bingbing Liu, Tian Cui, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry C 2013 Volume 117(Issue 1) pp:152-159
Publication Date(Web):December 13, 2012
DOI:10.1021/jp311208c
In situ high-pressure Raman spectroscopy and synchrotron X-ray diffraction (XRD) have been employed to investigate the behavior of the energetic material urea nitrate ((NH2)2COH+·NO3–, UN) up to the pressure of ∼26 GPa. UN exhibits the typical supramolecular structure with the uronium cation and nitrate anion held together by multiple hydrogen bonds in the layer. The irreversible phase transition in the range ∼9–15 GPa has been corroborated by experimental results and is proposed to stem from rearrangements of hydrogen bonds. Further analysis of XRD patterns indicates the new phase (phase II) has Pc symmetry. The retrieved sample is ∼10.6% smaller than the ambient phase (phase I) in volume owing to the transformation from two-dimensional (2D) hydrogen-bonded networks to three-dimensional (3D) ones. The mechanism for the phase transition involves the cooperativity of noncovalent interactions under high pressure and distortions of the layered structure. This work suggests high pressure is an efficient technique to explore the performance of energetic materials, and to synthesize new phases with high density.
Co-reporter:Ningru Xiao, Li Zhu, Kai Wang, Quanqin Dai, Yingnan Wang, Shourui Li, Yongming Sui, Yanming Ma, Jing Liu, Bingbing Liu, Guangtian Zou and Bo Zou
Nanoscale 2012 vol. 4(Issue 23) pp:7443-7447
Publication Date(Web):03 Oct 2012
DOI:10.1039/C2NR31629C
The metastable wurtzite nanocrystals of CuGaS2 have been synthesized through a facile and effective one-pot solvothermal approach. Through the Rietveld refinement on experimental X-ray diffraction patterns, we have unambiguously determined the structural parameters and the disordered nature of this wurtzite phase. The metastability of wurtzite structure with respect to the stable chalcopyrite structure was testified by a precise theoretical total energy calculation. Subsequent high-pressure experiments were performed to establish the isothermal phase stability of this wurtzite phase in the pressure range of 0–15.9 GPa, above which another disordered rock salt phase crystallized and remained stable up to 30.3 GPa, the highest pressure studied. Upon release of pressure, the sample was irreversible and intriguingly converted into the energetically more favorable and ordered chalcopyrite structure as revealed by the synchrotron X-ray diffraction and the high-resolution transmission electron microscopic measurements. The observed phase transitions were rationalized by first-principles calculations. The current research surely establishes a novel phase transition sequence of disorder → disorder → order, where pressure has played a significant role in effectively tuning stabilities of these different phases.
Co-reporter:Guanjun Xiao, Jiajia Ning, Zhaoyang Liu, Yongming Sui, Yingnan Wang, Qingfeng Dong, Wenjing Tian, Bingbing Liu, Guangtian Zou and Bo Zou
CrystEngComm 2012 vol. 14(Issue 6) pp:2139-2144
Publication Date(Web):16 Jan 2012
DOI:10.1039/C2CE06270D
In this paper, we developed a one-pot solution strategy to synthesize copper selenide NCs with controllable shape and structure. By changing the precursors in the reaction, copper selenide NCs (Cu2−xSe nanoparticles, nanorods and CuSe nanoplates) with various morphologies could be achieved. We proposed a possible mechanism to explain the influence of precursors on the shape of copper selenide NCs and we found that the chemical activities of precursors played key roles in the morphologies and crystal structures of the final products. Moreover, the electrical transport properties of as-prepared products were investigated. The morphologies of copper selenide NCs have a great influence on the electrical transport properties. The copper selenide NCs with nanorods display the best electrochemical performance compared with the other two types. We believe that copper selenide NCs would be promising candidates for electrical transport materials.
Co-reporter:Pinhua Zhang, Yingnan Wang, Yongming Sui, Chunzhong Wang, Bingbing Liu, Guangtian Zou and Bo Zou
CrystEngComm 2012 vol. 14(Issue 18) pp:5937-5942
Publication Date(Web):08 Jun 2012
DOI:10.1039/C2CE25398D
In this work, we present a facile and reproducible one-pot approach to synthesize a series of nanosized metal oxides (CdO, PbO, ZnO, SnO and Ga2O3) using their corresponding bulk materials as precursors. These nanosized metal oxides were synthesized by heating the mixture of the metal oxide, oleic acid and oleylamine directly, and retained the structure of the corresponding bulk material. For lead oxide, both the original orthorhombic and the tetragonal PbO were successfully synthesized by varying the reaction temperature. The optical properties of nanosized CdO, PbO and ZnO show a significant quantum confinement effect compared with their behavior in the bulk phase. Moreover, we proposed the possible mechanism of the reaction in which the dissolution–recrystallization process provided the dominant contribution.
Co-reporter:Xinyi Yang, Yingnan Wang, Yongming Sui, Xiaoli Huang, Tian Cui, Chunzhong Wang, Bingbing Liu, Guangtian Zou and Bo Zou
CrystEngComm 2012 vol. 14(Issue 20) pp:6916-6920
Publication Date(Web):16 Jul 2012
DOI:10.1039/C2CE25741F
Manipulating the shape and size of metastable semiconductor nanocrystals (NCs) is important in various applications. In this work, anisotropic tetrapod- and waterdrop-shaped MnSe NCs with wurtzite (WZ) structure have been successfully synthesized by a one-pot solvothermal approach. The morphology, size and crystal structure have been investigated using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and powder X-ray diffraction (XRD). It was found that the shape and aspect ratio of WZ-MnSe NCs can be easily controlled by simply varying the heating rates. Furthermore, these WZ-MnSe NCs display blue–violet emission, which may find applications in full-colour display and short wavelength optoelectronic devices. The magnetic measurements indicate that the Néel temperature is found to be reduced with decreasing nanocrystal diameter. The size-dependent phase-transition behavior is attributed to the surface effect.
Co-reporter:Guanjun Xiao, Qingfeng Dong, Yingnan Wang, Yongming Sui, Jiajia Ning, Zhaoyang Liu, Wenjing Tian, Bingbing Liu, Guangtian Zou and Bo Zou
RSC Advances 2012 vol. 2(Issue 1) pp:234-240
Publication Date(Web):03 Nov 2011
DOI:10.1039/C1RA00289A
In this paper, we introduce a facile and phosphine-free one-step solution method to synthesize size- and shape-controlled bismuth sulfide (Bi2S3) with hierarchical architectures. Changing variables, such as the reaction temperature, the ratio of precursors, and the concentration of oleic acid were observed to influence the resultant shape of Bi2S3 microstructures. For the formation of Bi2S3 hierarchical architectures, the crystal splitting growth mechanism played the dominant role. The absorption spectra were recorded at room temperature, which revealed that the obtained Bi2S3 product was a direct band gap semiconductor and the band gap Eg was estimated to be about 1.9 eV. Furthermore, the I–V characteristics of the Bi2S3-based device show a significant increase by ca. 1 order of magnitude compared with the dark state, indicating an enhanced conductivity and high sensitivity. The response and decay times are estimated to be about 0.5 and 0.8 s, respectively, which are short enough for it to be an excellent candidate for high-speed and high-sensitivity photodetectors or optical switches. Thus the Bi2S3 hierarchies as building blocks may offer the potential for monolithic, low-cost and large-scale integration with CMOS electronics.
Co-reporter:Xinguang Zhao;Tingting Yan;Kai Wang;Yan Yan;Jihong Yu;Ruren Xu
European Journal of Inorganic Chemistry 2012 Volume 2012( Issue 15) pp:2527-2532
Publication Date(Web):
DOI:10.1002/ejic.201200200
Abstract
The europium germanate NaEu3(GeO4)2(OH)2 was prepared under mild hydrothermal conditions. In situ synchrotron X-ray diffraction analysis and photoluminescence spectroscopic measurement in a diamond anvil cell (DAC) under high pressure were performed to study its structural stability as well as the luminescent properties of the Eu3+ ions. The synchrotron X-ray diffraction analysis revealed that the structure of NaEu3(GeO4)2(OH)2 was stable under pressure that ranged from 1 atm to 20 GPa with only a little distortion, and the unit-cell compression occurred more readily along the a axis than along the c axis. When the pressure was reduced to ambient pressure, the distortion and the unit cell recovered to the original state. Photoluminescence spectroscopic studies under high pressure showed that the redshift of the 5D0 7FJ (J = 0, 1, 2) transitions and the pressure imposed on the sample had a good linear relationship. Also, the intensity of the red emission lines was independent of the pressure in the range from 9 to about 20 GPa.
Co-reporter:Xinguang Zhao;Kai Wang;Tingting Yan;Yan Yan;Jihong Yu;Ruren Xu
Chinese Journal of Chemistry 2012 Volume 30( Issue 9) pp:2066-2072
Publication Date(Web):
DOI:10.1002/cjoc.201200583
Abstract
The crystalline solid europium germanate NaEuGeO4 was prepared under hydrothermal conditions. The in-situ photoluminescence spectroscopic measurement and the synchrotron X-ray diffraction analysis in a diamond anvil cell (DAC) under high pressure were performed to study the pressure-induced phase transition of NaEuGeO4 as well as changes of the luminescent properties of Eu3+ ions. Photoluminescence spectroscopic studies revealed that a phase transition occurred at a pressure range of 6.5–10 GPa and the high-pressure phase of NaEuGeO4 (NaEuGeO4-HP) was still stable when the pressure raised up to about 20 GPa. As the pressure was released, the spectra returned to the original state, revealing that the pressure-induced phase transition is a completely reversible process. The synchrotron X-ray diffraction analysis demonstrated that the structure of NaEuGeO4 transformed to an unidentified phase NaEuGeO4-HP at a pressure higher than 10 GPa, and the phase transition is reversible. This result is consisted with that obtained by photoluminescence spectra analysis.
Co-reporter:Xinyi Yang, Yingnan Wang, Yongming Sui, Xiaoli Huang, Tian Cui, Chunzhong Wang, Bingbing Liu, Guangtian Zou, and Bo Zou
Langmuir 2012 Volume 28(Issue 51) pp:17811-17816
Publication Date(Web):December 4, 2012
DOI:10.1021/la304228w
Wide-band-gap rock-salt (RS) MnS nanocubes were synthesized by the one-pot solvent thermal approach. The edge length of the nanocubes can be easily controlled by prolonging the reaction time (or aging time). We systematically explored the formation of RS-MnS nanocubes and found that the present synthetic method is virtually a combination of oriented aggregation and intraparticle ripening processes. Furthermore, these RS-MnS nanocubes could spontaneously assemble into ordered superlattices via the natural cooling process. The optical and magnetic properties were investigated using measured by UV–vis absorption, photoluminescence spectra, and a magnetometer. The obtained RS-MnS nanocubes exhibit good ultraviolet optical properties depending on the size of the samples. The magnetic measurements suggest that RS-MnS nanocubes consist of an antiferromagnetic core and a ferromagnetic shell below the blocking temperatures. Furthermore, the hysteresis measurements indicate these RS-MnS nanocubes have large coercive fields (e.g., 1265 Oe for 40 nm nanocubes), which is attributed to the size and self-assembly of the samples.
Co-reporter:Yujie Dong;Dr. Bin Xu;Jibo Zhang;Xiao Tan;Lijuan Wang;Jinlong Chen;Dr. Hongguang Lv;Dr. Shanpeng Wen;Dr. Bao Li;Dr. Ling Ye;Dr. Bo Zou;Dr. Wenjing Tian
Angewandte Chemie 2012 Volume 124( Issue 43) pp:10940-10943
Publication Date(Web):
DOI:10.1002/ange.201204660
Co-reporter:Yujie Dong;Dr. Bin Xu;Jibo Zhang;Xiao Tan;Lijuan Wang;Jinlong Chen;Dr. Hongguang Lv;Dr. Shanpeng Wen;Dr. Bao Li;Dr. Ling Ye;Dr. Bo Zou;Dr. Wenjing Tian
Angewandte Chemie International Edition 2012 Volume 51( Issue 43) pp:10782-10785
Publication Date(Web):
DOI:10.1002/anie.201204660
Co-reporter:Shourui Li, Qian Li, Jing Zhou, Run Wang, Zhangmei Jiang, Kai Wang, Dapeng Xu, Jing Liu, Bingbing Liu, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry B 2012 Volume 116(Issue 10) pp:3092-3098
Publication Date(Web):February 16, 2012
DOI:10.1021/jp212349h
We report the high-pressure response of guanidinium methanesulfonate (C(NH2)3+·CH3SO3–, GMS) using in situ Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques up to the pressures of ∼11 GPa. GMS exhibits the representative supramolecular structure of two-dimensional (2D) hydrogen-bonded bilayered motifs under ambient conditions. On the basis of the experimental results, two phase transitions were identified at 0.6 and 1.5 GPa, respectively. The first phase transition, which shows the reconstructive feature, is ascribed to the rearrangements of hydrogen-bonded networks, resulting in the symmetry transformation from C2/m to Pnma. The second one proves to be associated with local distortions of methyl groups, accompanied by the symmetry transformation from Pnma to Pna21. The cooperativity of hydrogen bonding, electrostatic, and van der Waals interactions, as well as mechanisms for the phase transitions is discussed by means of the local nature of the structure.
Co-reporter:Tingting Yan, Shourui Li, Kai Wang, Xiao Tan, Zhangmei Jiang, Ke Yang, Bingbing Liu, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry B 2012 Volume 116(Issue 32) pp:9796-9802
Publication Date(Web):July 20, 2012
DOI:10.1021/jp302575k
The effect of high pressure on the structural stability of oxamide has been investigated in a diamond anvil cell by Raman spectroscopy up to ∼14.6 GPa and by angle-dispersive X-ray diffraction (ADXRD) up to ∼17.5 GPa. The discontinuity in Raman shifts around 9.6 GPa indicates a pressure-induced structural phase transition. This phase transition is confirmed by the change of ADXRD spectra with the symmetry transformation from P1̅ to P1. On total release of pressure, the diffraction pattern returns to its initial state, implying this transition is reversible. We discuss the pressure-induced variations in N–H stretching vibrations and the amide modes in Raman spectra and propose that this phase transition is attributed to the distortions of the hydrogen-bonded networks.
Co-reporter:Yong-Qiang Dang, Qian Li, Kai Wang, Yuqing Wu, Lili Lian, and Bo Zou
The Journal of Physical Chemistry B 2012 Volume 116(Issue 36) pp:11010-11016
Publication Date(Web):August 23, 2012
DOI:10.1021/jp306466j
FRET has been used as a powerful tool in biological fields as biosensors, bioimaging, protein folding/unfolding monitoring, biomolecular interactions, and so on. It is also important to applying FRET to high hydrostatic pressure studies on biosystems or biorelated systems. Herein, we construct a FRET system by labeling Cy3 on C-phycocyanin (C-PC) to investigate the effect of hydrostatic pressure on the fluorescence and FRET behavior between them. The fluorescence spectra of individual Cy3, C-PC, and integrated Cy3/C-PC system are measured separately under compression. An enhanced FRET efficiency under compression is concluded based on fluorescence behavior differences between them. To further reveal the origination of the enhanced FRET efficiency with pressure, the overlap integral between Cy3 emission and C-PC absorption is also calculated, and several possible explanations are proposed.
Co-reporter:Xinyi Yang ; Yingnan Wang ; Kai Wang ; Yongming Sui ; Meiguang Zhang ; Bing Li ; Yanming Ma ; Bingbing Liu ; Guangtian Zou
The Journal of Physical Chemistry C 2012 Volume 116(Issue 5) pp:3292-3297
Publication Date(Web):January 13, 2012
DOI:10.1021/jp209591r
Manganese sulfide (MnS) nanocrystals (NCs) with three different phases were synthesized by one-pot solvent thermal approach. The crystal structures and morphologies were investigated using powder X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. We found that the crystal structure and morphology of MnS NCs could be controlled by simply varying the reaction temperature. The detailed growth process of MnS nanobipods, including the zinc blende (ZB)-core formation and wurtzite (WZ)-arms growth, provides direct experimental evidence for the polymorphism model. Furthermore, we have studied the stability of metastable ZB- and WZ-MnS NCs under high pressure and found that ZB-nanoparticles and ZB/WZ-nanobipods are stable below their critical pressure, 5.3 and 2.9 GPa, respectively. When pressures exceed the critical point, all these metastable MnS NCs directly convert to the stable rock salt MnS.
Co-reporter:Hongsheng Yuan, Kai Wang, Shourui Li, Xiao Tan, Qian Li, Tingting Yan, Benyuan Cheng, Ke Yang, Bingbing Liu, Guangtian Zou, and Bo Zou.
The Journal of Physical Chemistry C 2012 Volume 116(Issue 46) pp:24837-24844
Publication Date(Web):November 2, 2012
DOI:10.1021/jp3088995
The high-pressure behavior of zircon-structured YPO4 (with/without Eu3+ doping) nanoparticles was examined at room temperature using in situ synchrotron X-ray diffraction (XRD) and photoluminescence (PL) measurements. In contrast with the reported XRD results of bulk YPO4 upon compression, the nanoparticles showed a distinct transition sequence: zircon phase → scheelite phase (∼18 GPa) without the metastable monazite phase. By the return to ambient pressure, both XRD and PL results revealed that the scheelite phase could be reserved. Further Raman experiments helped us to identify the valuable mode ν1(Ag) of the scheelite structure in the quenched samples. The dopants effect, quasi-hydrostatic stress, and nanoscale-induced surface energy difference are considered to explain the high-pressure behavior of the nanoparticles. It is proposed that the nanoscale-induced higher surface energy contribution plays a crucial role in the distinctive high-pressure behavior of the nanoparticles.
Co-reporter:Xiao Tan, Kai Wang, Shourui Li, Hongsheng Yuan, Tingting Yan, Jing Liu, Ke Yang, Bingbing Liu, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry B 2012 Volume 116(Issue 49) pp:14441-14450
Publication Date(Web):November 24, 2012
DOI:10.1021/jp3039219
We report the high-pressure response of three forms (α, δ, and γ) of pyrazinamide (C5H5N3O, PZA) by in situ Raman spectroscopy and synchrotron X-ray diffraction techniques with a pressure of about 14 GPa. These different forms are characterized by various intermolecular bonding schemes. High-pressure experimental results show that the γ phase undergoes phase transition to the β phase at a pressure of about 4 GPa, whereas the other two forms retain their original structures at a high pressure. We propose that the stabilities of the α and δ forms upon compression are due to the special dimer connection that these forms possess. On the other hand, the γ form, which does not have this connection, prefers to transform to the closely related β form when pressure is applied. The detailed mechanism of the phase transition together with the stability of the three polymorphs is discussed by taking molecular stacking into account.
Co-reporter:Yongming Sui, Yi Zeng, Weitao Zheng, Bingbing Liu, Bo Zou, Haibin Yang
Sensors and Actuators B: Chemical 2012 s 171–172() pp: 135-140
Publication Date(Web):
DOI:10.1016/j.snb.2012.01.069
Co-reporter:Jiajia Ning, Guanjun Xiao, Li Wang, Bo Zou, Bingbing Liu and Guangtian Zou
Nanoscale 2011 vol. 3(Issue 2) pp:741-745
Publication Date(Web):26 Nov 2010
DOI:10.1039/C0NR00684J
Magnetic metal (Mn, Fe, Co, and Ni) oxides nanocrystals with small size and uniform size distribution are synthesized via a cation-exchange reaction. Two experimental stages are included in the synthesis of metal oxides nanocrystals. Firstly, Cu(OH)2 decomposes to CuO nanocrystals, induced by free metal cations. Compared to CuO nanocrystals produced without any free metal cation, the free metal cation has an important influence on the shape and size of CuO. Secondly, free metal cations exchange with the Cu2+ cation in the CuO nanocrystals to get Mn3O4, Fe2O3, CoO and NiO nanocrystals by cation-exchange reactions. The magnetic properties of these metal oxides nanocrystals have been investigated, all the nanocrystals are superparamagnetic at room temperature.
Co-reporter:Jiajia Ning, Guanjun Xiao, Tao Jiang, Li Wang, Quanqin Dai, Bo Zou, Bingbing Liu, Yingjin Wei, Gang Chen and Guangtian Zou
CrystEngComm 2011 vol. 13(Issue 12) pp:4161-4166
Publication Date(Web):21 Apr 2011
DOI:10.1039/C1CE05083D
Colloidal IV–VI SnSe nanocrystals with small and uniform size distribution were synthesized by a facile and phosphine-free method. Simple Sn6O4(OH)4 was introduced as a tin precursor to synthesize the SnSe nanocrystals. By changing the reaction temperature and Sn/Se molar ratio, SnSe nanocrystals with different shapes and sizes were achieved. The influence of reaction temperature and Sn/Se molar ratio to the shape and size of SnSe nanocrystals has been discussed detail. Similar to other IV–VI tin chalcogenides, SnSe shows potential as energy storage material. The performance of SnSe nanocrystals as an anode material for lithium ion batteries has been investigated. A mechanism for SnSe as anode material has been proposed based on its performance. The influence of the shape and size of the SnSe nanocrystals on the performance of lithium ion batteries has been discussed in detail.
Co-reporter:Yingnan Wang, Quanqin Dai, Xinyi Yang, Bo Zou, Dongmei Li, Bingbing Liu, Michael Z. Hu and Guangtian Zou
CrystEngComm 2011 vol. 13(Issue 1) pp:199-203
Publication Date(Web):27 Aug 2010
DOI:10.1039/C004459H
In this work, we presented a facile approach for the preparation of three-dimensional PbS nanoflowers, which was attributed to the coexistence of two types of amines with different-length alkyl chains and different steric hindrance. These monodisperse PbS nanoflowers showed small particle sizes (∼35 nm) and narrow size distribution (δ ≈ 9%). On the basis of these nanoflowers, we obtained a series of single-crystal hollow PbS nanostructures with tunable morphologies (including sphere, cuboctahedron, cube, and tube/rod) through elevating reaction temperature and prolonging growth time. It was further followed by a detailed discussion of the mechanism of morphology evolution, where the recrystallization and intraparticle ripening made contributions.
Co-reporter:Kai Wang, Defang Duan, Mi Zhou, Shourui Li, Tian Cui, Bingbing Liu, Jing Liu, Bo Zou, and Guangtian Zou
The Journal of Physical Chemistry B 2011 Volume 115(Issue 16) pp:4639-4644
Publication Date(Web):March 31, 2011
DOI:10.1021/jp200966n
The effects of high pressure on cyanuric chloride (C3N3Cl3), a remarkable crystal structure dominated by halogen bonds, have been studied by synchrotron X-ray diffraction and Raman spectroscopy in a diamond anvil cell. The results of high pressure experiments revealed that there was no obvious phase transition up to 30 GPa, indicating that halogen bonding is an effective noncovalent interaction to stabilize the crystal structure. Moreover, cyanuric chloride exhibited a high compressibility and a strong anisotropic compression, which can be explained by the layered crystal packing. Ab initio calculations were also performed to account for the high pressure Raman spectra and the high pressure behavior of halogen bonding.
Co-reporter:Shourui Li, Qian Li, Kai Wang, Xiao Tan, Mi Zhou, Bing Li, Bingbing Liu, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry B 2011 Volume 115(Issue 41) pp:11816-11822
Publication Date(Web):September 12, 2011
DOI:10.1021/jp207143f
In situ Raman spectroscopy and synchrotron X-ray diffraction (XRD) experiments have been performed to investigate the response of guanidinium perchlorate (C(NH2)3+·ClO4–, GP) to high pressures of ∼11 GPa. GP exhibits a typical supramolecular structure of two-dimensional (2D) hydrogen-bonded ionic networks at ambient conditions. A subtle phase transition, accompanied by the symmetry transformation from R3m to C2, has been confirmed by obvious changes in both Raman and XRD patterns at 4.5 GPa. The phase transition is attributed to the competition between hydrogen bonds and close packing of the supramolecular structure at high pressure. Hydrogen bonds have been demonstrated to evolve into a distorted state through the phase transition, accompanied by the reduction in separation of oppositely charged ions in adjacent sheet motifs. A detailed mechanism of the phase transition, as well as the cooperativity between hydrogen bonding and electrostatic interactions, is discussed by virtue of the local nature of the structure.
Co-reporter:Shourui Li, Kai Wang, Mi Zhou, Qian Li, Bingbing Liu, Guangtian Zou, and Bo Zou
The Journal of Physical Chemistry B 2011 Volume 115(Issue 29) pp:8981-8988
Publication Date(Web):June 24, 2011
DOI:10.1021/jp202975q
We report the results of high-pressure Raman and X-ray diffraction measurements performed on ammonium squarate ((NH4)2C4O4, AS), a representative supramolecular architecture based on hydrogen bonding and π-stacking interactions, at various pressures up to 19 GPa. Two phase transitions at ∼2.7 GPa and in the pressure range of 11.1–13.6 GPa were observed. Both Raman and XRD results provide convincing evidence for these two phase transitions. The first phase transition is attributed to the rearrangements of hydrogen-bonding networks, resulting in the symmetry transformation from P21/c to P1. The second one, which is identified as an order–disorder phase transition, arises from significant modifications of squarate rings and random orientations of NH4+ cations. The cooperative effects between hydrogen-bonding and π-stacking interactions, as well as mechanisms for the phase transitions, are discussed by virtue of the local structure of AS.
Co-reporter:Jiajia Ning, Kangkang Men, Guanjun Xiao, Li Wang, Quanqin Dai, Bo Zou, Bingbing Liu and Guangtian Zou
Nanoscale 2010 vol. 2(Issue 9) pp:1699-1703
Publication Date(Web):03 Jul 2010
DOI:10.1039/C0NR00052C
SnS nanocrystals have been synthesized in a simple and facile way. Sn6O4(OH)4 is introduced to synthesize tin sulfide, which is used as tin precursor. By changing the reaction conditions (reaction temperature and Sn/S molar ratio), SnS nanocrystals with different shape and size can be produced. SnS nanoparticles and nanoflowers with orthorhombic crystal structure have uniform size distribution. The SnS nanoflowers firstly transform to polycrystalline nanoflowers, and then become amorphous nanosheets. The drive force of amorphization reduces the high free-energy of nanocrystals. The layered crystal structure of SnS is the main reason for the shape evolution and amorphization processes. The optical properties of nanoparticles are investigated by optical absorption spectra. The optical direct band gap and optical indirect band gap in SnS nanoparticles are 3.6 eV and 1.6 eV, respectively. Compared to direct band gap (1.3 eV) and indirect band gap (1.09 eV) in bulk SnS, both direct transition and indirect transition in nanoparticles show an obvious quantum-size effect.
Co-reporter:Jiajia Ning, Kangkang Men, Guanjun Xiao, Bo Zou, Li Wang, Quanqin Dai, Bingbing Liu and Guantian Zou
CrystEngComm 2010 vol. 12(Issue 12) pp:4275-4279
Publication Date(Web):09 Aug 2010
DOI:10.1039/C004098N
SnTe nanocrystals with different shapes and sizes are synthesized by a simple and facile method. The length of the fatty chain in amine has an important effect on the shape and size of SnTe nanocrystals. When oleylamine (OLA) is used as ligand, SnTe nanoparticles with size of 4 nm and high crystallinity are produced. However, when octylamine (OTA) is used as ligand, larger SnTe nanoparticles with low crystallinity are achieved, which would transform into single crystal SnTe nanowires with increasing reaction time. The driving force of shape evolution of SnTe nanocrystals is reducing the high surface free energy. An oriented attachment mechanism is proposed to explain the transition from nanoparticles to nanowires, and oriented attachment of nanoparticles to single crystal nanowires is proposed to reduce the interface energy by the greatest amount.
Co-reporter:Jiajia Ning, Kangkang Men, Guanjun Xiao, Liyan Zhao, Li Wang, Bingbing Liu, Bo Zou
Journal of Colloid and Interface Science 2010 Volume 347(Issue 2) pp:172-176
Publication Date(Web):15 July 2010
DOI:10.1016/j.jcis.2010.03.053
Cubic β-In2S3 nanoparticles (NPs) have been synthesized by a simple and facile way, which is 6 nm in size. Absorption and emission spectra of In2S3 NPs show obvious blue peak shift compared to band gap of bulk In2S3, indicating the strong quantum size confinement effect. The fluorescence quantum yield of In2S3 NPs is found to be 10%. During the synthesis process, the absorption spectra have no peak shift, which is responding to transition from valence band to the conduction band levels. This absorption spectra show that the nucleation and growth process of In2S3 NPs is very quick. The PL lifetime spectra and time resolved spectra give two emission processes in In2S3 NPs, which would be excitonic recombination and electron–hole recombination via defects levels. The blue shift of emission peaks show the emission process in In2S3 NPs is from mainly electron–holes recombination via defects levels to excitonic recombination. The Stokes shift becomes smaller which is mainly contributed by blue shift of emission and smaller contribution from the UV–Vis absorption. The absorption and emission spectra show the size and crystallinity of In2S3 NPs have no changes (HRTEM images provide enough proofs); however the surface-related defects changed greatly in the reaction process.In2S3 nanoparticles with size of 6 nm have been synthesized. The absorption and emission spectra reflect the nucleation and growth process of nanoparticles in the reaction and obvious quantum size effect in nanoparticles.
Co-reporter:Quanqin Dai ; Yu Zhang ; Yingnan Wang ; Yiding Wang ; Bo Zou ; William W. Yu ;Michael Z. Hu
The Journal of Physical Chemistry C 2010 Volume 114(Issue 39) pp:16160-16167
Publication Date(Web):September 15, 2010
DOI:10.1021/jp102660g
This paper reports the effect of ligands including oleic acid (OA), trioctylphosphine (TOP), and tributylphosphine (TBP) on the PbSe nanocrystal growth during synthesis, as well as the effect of OA ligands on the nanocrystal stability after synthesis. These ligands play important roles in the nucleation and growth mechanism of nanocrystals. We have discovered that the ligand effect on the growth of PbSe nanocrystals can differ from that on the mostly studied CdSe nanocrystals. Also, we present a method for producing relatively smaller and more monodisperse PbSe nanocrystals based on our new understanding that the use of TBP, instead of the generally reported TOP, can slow down the growth of PbSe nanocrystals. In addition, our postsynthetic investigation of OA ligand effects demonstrate the dominant desorption of OA-bonded Pb atoms, causing the shrinkage of PbSe nanocrystals. This provides some insight into stabilization strategies for labile PbSe nanocrystals.
Co-reporter:Quanqin Dai, Yu Zhang, Yingnan Wang, Michael Z. Hu, Bo Zou, Yiding Wang and William W. Yu
Langmuir 2010 Volume 26(Issue 13) pp:11435-11440
Publication Date(Web):June 15, 2010
DOI:10.1021/la101545w
An investigation show that the temperature-induced band gap (Eg) variation of PbSe nanocrystals is strongly size-dependent. The temperature coefficients (dEg/dT) evolve from negative to zero and then to positive values, with the increase of PbSe nanocrystal sizes. Such phenomena imply that PbSe nanocrystals may be the potential candidate as sensitive temperature markers. Additional analyses disclose that the molar extinction coefficients of PbSe nanocrystals remain unchanged in the investigated temperature range (25−120 °C).
Co-reporter:Kangkang Men, Jiajia Ning, Quanqin Dai, Dongmei Li, Bingbing Liu, William W. Yu, Bo Zou
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 363(1–3) pp:30-34
Publication Date(Web):20 June 2010
DOI:10.1016/j.colsurfa.2010.04.005
SnO nanoplates, nanosheets and nanorings have been synthesized by a simple and facile approach. By changing the reaction temperature, SnO nanoplates would become to individual SnO nanosheets. Complex nanostructures disassemble to its basic unit. When reaction temperature is much higher, novel SnO nanorings by assemble of nanosheets appear. Assemble processes and disassemble processes are observed in this experiment. Ligand plays a key role in the morphology evolution of nanocrystals. The ligand interaction mechanism is proposed to explain the transition from nanoplates to nanosheets, and ligand protection mechanism is used to explain the formation of nanorings. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM) images, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and Fourier transform infrared spectrometry (FTIR) are used to characterize these samples.
Co-reporter:Yingnan Wang, Quanqin Dai, Liancheng Wang, Bo Zou, Tian Cui, Bingbing Liu, William W. Yu, Michael Z. Hu and Guangtian Zou
The Journal of Physical Chemistry C 2010 Volume 114(Issue 26) pp:11425-11429
Publication Date(Web):June 14, 2010
DOI:10.1021/jp103586n
We presented a facile and efficient route to prepare single-component nanoparticle (NP) superlattices. It was demonstrated that mutual transformation between random NPs and their well-ordered superlattices could be unified by a proposed model of ligand configuration. When the ligand chains capped on NPs were disordered at room temperature, NPs existed separately in solution, which were noninteracting and thus showed random states on transmission electron microscopy (TEM) grids; comparatively, the ligand chains capped on NPs in an ordered state in solution would correspond to superlattice structures obtained on TEM grids. These experimental observations were consistent with our theoretical analysis.
Co-reporter:Yingnan Wang, Quanqin Dai, Bo Zou, William W. Yu, Bingbing Liu, and Guangtian Zou
Langmuir 2010 Volume 26(Issue 24) pp:19129-19135
Publication Date(Web):November 30, 2010
DOI:10.1021/la103444h
In comparison to the previous lengthy approaches, we described a general and simple strategy for engineering the superlattice assembly of IV−VI semiconductor nanocrystals (NCs) with tunable sizes and morphologies. Not only the well-studied spherical NCs but also some special-shaped NCs, such as the quasi-cubic, cubic, truncated octahedral, and octahedral, could self-assemble into well-ordered patterns, as demonstrated in PbS, PbSe, and PbTe. These results extended our proposed model about the configuration of ligand chains in the superlattice assembly. This powerful capability of assembling superlattices was dominated by a heat-treatment process, providing a significant and extensive direction in the engineering of morphology-tunable NC superlattices.
Co-reporter:Run Wang, Shourui Li, Kai Wang, Defang Duan, Lingyun Tang, Tian Cui, Bingbing Liu, Qiliang Cui, Jing Liu, Bo Zou and Guangtian Zou
The Journal of Physical Chemistry B 2010 Volume 114(Issue 20) pp:6765-6769
Publication Date(Web):April 30, 2010
DOI:10.1021/jp908656m
In situ Raman scattering and synchrotron X-ray diffraction have been used to investigate the effects of high pressure on the structural stability of guanidinium nitrate (C(NH2)3+·NO3−, GN), a representative two-dimensional supramolecular architecture of hydrogen-bonded rosette network. This study has confirmed a structural phase transition observed by Raman scattering and X-ray diffraction at ∼1 GPa and identified it as a space group change from C2 to P21. The high-pressure phase remained stable up to 22 GPa. We discussed the pressure-induced changes in N−H stretching vibration in Raman spectra and proposed that this phase transition is due to the rearrangements of the hydrogen-bonding networks.
Co-reporter:Kai Wang, Defang Duan, Run Wang, Aolei Lin, Qiliang Cui, Bingbing Liu, Tian Cui, Bo Zou, Xi Zhang, Jingzhu Hu, Guangtian Zou and Ho-kwang Mao
Langmuir 2009 Volume 25(Issue 8) pp:4787-4791
Publication Date(Web):2017-2-22
DOI:10.1021/la804034y
The effects of high pressure on the structural stability of the melamine−boric acid adduct (C3N6H6·2H3BO3, M·2B), a three-dimensional hydrogen-bonded supramolecular architecture, were studied by in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy. M·2B exhibited a high compressibility and a strong anisotropic compression, which can be explained by the layerlike crystal packing. Furthermore, evolution of XRD patterns and Raman spectra indicated that the M·2B crystal undergoes a reversible pressure-induced amorphization (PIA) at 18 GPa. The mechanism for the PIA was attributed to the competition between close packing and long-range order. Ab initio calculations were also performed to account for the behavior of hydrogen bonding under high pressure.
Co-reporter:Jiajia Ning, Quanqin Dai, Tao Jiang, Kangkang Men, Donghua Liu, Ningru Xiao, Chenyuan Li, Dongmei Li, Bingbing Liu, Bo Zou, Guangtian Zou and William W. Yu
Langmuir 2009 Volume 25(Issue 3) pp:1818-1821
Publication Date(Web):December 24, 2008
DOI:10.1021/la8037473
A facile and reproducible approach was reported to synthesize nanoparticle-attached SnO nanoflowers via decomposition of an intermediate product Sn6O4(OH)4. Sn6O4(OH)4 formed after introducing water into the traditional nonaqueous reaction, and then decomposed to SnO nanoflowers with the help of free metal cations, such as Sn2+, Fe2+, and Mn2+. This free cation-induced formation process was found independent of the nature of the surface ligand. It was demonstrated further that the as-prepared SnO nanoflowers could be utilized as good anode materials for lithium ion rechargeable batteries with a high capacity of around 800 mA h g−1, close to the theoretical value (875 mA h g−1).
Co-reporter:Quanqin Dai, Yingnan Wang, Yu Zhang, Xinbi Li, Ruowang Li, Bo Zou, JaeTae Seo, Yiding Wang, Manhong Liu and William W. Yu
Langmuir 2009 Volume 25(Issue 20) pp:12320-12324
Publication Date(Web):June 12, 2009
DOI:10.1021/la9015614
Infrared-emitting PbSe nanocrystals are of increasing interest in both fundamental research and technical application. However, the practical applications are greatly limited by their poor stability. In this work, absorption and photoluminescence spectra of PbSe nanocrystals were utilized to observe the stability of PbSe nanocrystals over several conventional factors, that is, particle concentration, particle size, temperature, light exposure, contacting atmosphere, and storage forms (solution or solid powder). Both absorption and luminescence spectra of PbSe nanocrystals exposed to air showed dependence on particle concentration, size, and light exposure, which caused large and quick blue-shifts in the optical spectra. This air-contacted instability arising from the destructive oxidation and subsequent collision-induced decomposition was kinetically dominated and differed from the traditional thought that smaller particles with lower concentrations shrank fast. The photoluminescence emission intensity of the PbSe nanocrystal solution under ultraviolet (UV) exposure in air increased first and then decreased slowly; without UV irradiation, the emission intensity monotonously decreased over time. However, if stored under nitrogen, no obvious changes in absorption and photoluminescence spectra of the PbSe nanocrystals were observed even under UV exposure or upon being heated up to 100 °C.
Co-reporter:Kai Wang, Defang Duan, Run Wang, Dan Liu, Lingyun Tang, Tian Cui, Bingbing Liu, Qiliang Cui, Jing Liu, Bo Zou and Guangtian Zou
The Journal of Physical Chemistry B 2009 Volume 113(Issue 44) pp:14719-14724
Publication Date(Web):October 15, 2009
DOI:10.1021/jp9067203
Single-crystal samples of the 1:1 adduct between cyanuric acid and melamine (CA·M), an outstanding case of noncovalent synthesis, have been studied by Raman spectroscopy and synchrotron X-ray diffraction in a diamond anvil cell up to pressures of 15 GPa. The abrupt changes in Raman spectra around 4.4 GPa have provided convincing evidence for pressure-induced structural phase transition. This phase transition was confirmed by angle dispersive X-ray diffraction (ADXRD) experiments to be a space group change from C2/m to its subgroup P21/m. On release of pressure, the observed transition was irreversible, and the new high-pressure phase was fully preserved at ambient conditions. We propose that this phase transition was due to supramolecular rearrangements brought about by changes in the hydrogen bonding networks.
Co-reporter:Jiajia Ning, Tao Jiang, Kangkang Men, Quanqin Dai, Dongmei Li, Yingjin Wei, Bingbing Liu, Gang Chen, Bo Zou and Guangtian Zou
The Journal of Physical Chemistry C 2009 Volume 113(Issue 32) pp:14140-14144
Publication Date(Web):July 17, 2009
DOI:10.1021/jp905668p
Hierarchical SnO nanocrystals are synthesized by a reproducible and facile way via decomposition of an intermediate product tin oxide hydroxide, Sn6O4(OH)4. By changing the amount of injecting water, layer-plate-like, nest-like, stepwise-bipyramid-like, and defective stepwise-bipyramid-like hierarchical SnO nanocrystals could be obtained. All of these hierarchical SnO nanostructures are constructed by smaller nanosheets. The driving force of aggregation is reducing the surface energy of nanocrystals. Water played a key role in the control morphologies of hierarchical SnO nanostructures. The water control decomposition (WCD) mechanism was proposed to explain the effect of water on the morphologies. On the basis of reaction kinetics, the different superfluous injected water after reaction would restrain the decomposition of Sn6O4(OH)4 to SnO nanosheets; a different amount of superfluous injected water would induce a different reaction rate. At different reaction rates, SnO nanosheets would have different sizes and different approaches to aggregation, and different hierarchical SnO nanocrystals appeared by injecting different amounts of water into the reaction. Typically, hierarchical SnO nanocrystals as an anode material for lithium ion batteries are studied. These SnO nanocrystals show good potential for lithium battery materials. Among these SnO nanostructures, the stepwise-bipyramid-like nanostructure shows the best properties.
Co-reporter:Quanqin Dai, Yingnan Wang, Xinbi Li, Yu Zhang, Donald J. Pellegrino, Muxun Zhao, Bo Zou, JaeTae Seo, Yiding Wang and William W. Yu
ACS Nano 2009 Volume 3(Issue 6) pp:1518
Publication Date(Web):May 12, 2009
DOI:10.1021/nn9001616
Atomic compositions and molar extinction coefficients of PbSe semiconductor nanocrystals were determined by atomic absorption spectrometry, UV−vis−NIR spectrophotometry, and transmission electron microscopy. The Pb/Se atomic ratio was found to be size-dependent with a systematic excess of Pb atoms in the PbSe nanocrystal system. Experimental results indicated that the individual PbSe nanocrystal was nonstoichiometric, consisting of a PbSe core and an extra layer of Pb atoms. For these nonstoichiometric PbSe semiconductor nanocrystals, we proposed a new computational approach to calculate the total number of Pb and Se atoms in different sized particles. This calculation played a key role on the accurate determination of the strongly size-dependent extinction coefficient, which followed a power law with an exponent of ∼2.5.Keywords: composition; molar extinction coefficient; PbSe; semiconductor nanocrystal; size dependence
Co-reporter:Quanqin Dai, Yingnan Wang, Xinbi Li, Yu Zhang, Donald J. Pellegrino, Muxun Zhao, Bo Zou, JaeTae Seo, Yiding Wang and William W. Yu
ACS Nano 2009 Volume 3(Issue 8) pp:2054
Publication Date(Web):August 25, 2009
DOI:10.1021/nn900611s
Co-reporter:Quanqin Dai, Ningru Xiao, Jiajia Ning, Chenyuan Li, Dongmei Li, Bo Zou, William W. Yu, Shihai Kan, Haiyong Chen, Bingbing Liu and Guangtian Zou
The Journal of Physical Chemistry C 2008 Volume 112(Issue 20) pp:7567-7571
Publication Date(Web):April 29, 2008
DOI:10.1021/jp7120559
A nontoxic, simple, cheap, and reproducible strategy, which meets the standard of green chemistry, is introduced for the synthesis of ZnSe nanoparticles and nanoflowers. The production of these green nanomaterials can be readily scaled up and performed directly at ambient condition without affecting their qualities. The experimental results show that the as-synthesized ZnSe nanoparticles and nanoflowers with a zinc blende structure have a narrow size distribution without resorting to any postsynthetic size-selective procedure. A systematic study of the nanocrystal formation process indicates the following properties. (i) The amount of precursors plays a greater role in the determination of the nanoparticle size than other reaction parameters. Variation of this parameter allows us to tune the nanoparticle size in the high-temperature annealing process. This tunability is interpreted well by the growth kinetics. (ii) The limited ligand protection mechanism cannot be employed to explain the formation of our nanoflowers. Instead, a new growth mechanism is proposed. Upon heating at high temperature, a mononuclear Zn complex converts to a polynuclear Zn complex with multiple Zn atoms. Each Zn atom grows into one ZnSe nanoparticle after the injection of Se solution. These nanoparticles closely connect and thus look like nanoflowers.
Co-reporter:Shoukun Wang, Jiajia Ning, Liyan Zhao, Bingbing Liu, Bo Zou
Journal of Crystal Growth (1 July 2010) Volume 312(Issue 14) pp:2060-2064
Publication Date(Web):1 July 2010
DOI:10.1016/j.jcrysgro.2010.03.040
Highly ordered hexagonal prism microstructures of copper sulfide (CuS) by assembling nano-flakes have been synthesized with high yield via a facile one-step route. We synthesized CuS microstructures using low cost beginning materials CuSO4·5H2O and Na2S2O3·5H2O under lower reaction temperature (60 °C). Hexamethylinetetramin (C6H12N4, HMT) was introduced into the reaction system as a capped agent. The influence of reaction time and capping agent (HMT) on the final structure of products was studied systematically. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopes (EDS), and transmission electron microscopy (TEM). The possible mechanism for the formation of the interesting highly ordered hexagonal prism microstructures CuS was also proposed.
Co-reporter:Yujian Zhang, Moge Qile, Jingwei Sun, Minhong Xu, Kai Wang, Feng Cao, Weijun Li, Qingbao Song, Bo Zou and Cheng Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 42) pp:NaN9960-9960
Publication Date(Web):2016/09/05
DOI:10.1039/C6TC03157A
Ratiometric sensors for visual monitoring of pressure environments are highly valuable in various fields, such as security inks and optoelectronic devices. However, ratiometric pressure sensors remain inadequate due to the lack of piezo-chromic luminescent materials with high-contrast color change and high emission efficiency. A donor–acceptor cyano-substituted oligo(p-phenylene vinylene) derivative mF-TPA exhibits a high luminescence efficiency (Φf = 82.6%), which is related to the hybridized local and charge-transfer (HLCT) states. Moreover, its crystalline particles can sense exact hydrostatic pressure as high as 10 GPa, accompanied by visible color changes (λPL = 146 nm, from light-green to deep-red). Interestingly, the photo-luminescence peak wavelengths have a linear relationship with the external pressure, enabling its use as a ratiometric pressure sensor. In situ Raman spectroscopy confirms that the intermolecular interaction is obviously enhanced due to the closer packing at high pressure, inducing a red-shift of the emission peak and a decrease of the fluorescence intensity.
Co-reporter:Qingxin Zeng, Tingting Yan, Kai Wang, Yinyan Gong, Yong Zhou, Yongli Huang, Chang Q. Sun and Bo Zou
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 20) pp:NaN14054-14054
Publication Date(Web):2016/04/25
DOI:10.1039/C6CP00648E
In situ Raman spectroscopy revealed that transiting H2O/NaX (∼64) solutions into an ice VI phase and then into an ice VII phase at a temperature of 298 K requires excessive pressures with respect to pure water. The increase of the critical pressures varies with the solute type in the Hofmeister series order: X = I > Br > Cl > F ∼ 0. The results suggest that the solute hydration creates electric fields that lengthen and soften the O:H nonbond and meanwhile shorten and stiffen the H–O bond through O–O Coulomb repulsion. Compression, however, does the opposite to solute electrification upon the O:H–O bond relaxation. Therefore, compression of the aqueous solutions recovers the electrification-deformed O:H–O bond first and then proceeds to the phase transitions, which requires excessive energy for the same sequence of phase transitions. Ice exclusion of solute disperses the frequencies of characteristic phonons and the critical pressures with unlikely new bond formation.
Co-reporter:Yujian Zhang, Qingbao Song, Kai Wang, Wengang Mao, Feng Cao, Jingwei Sun, Lingling Zhan, Yaokang Lv, Yuguang Ma, Bo Zou and Cheng Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 13) pp:NaN3054-3054
Publication Date(Web):2015/02/06
DOI:10.1039/C4TC02826K
For piezo-, vapo-, and thermochromic materials, it remains a challenge to figure out the underlying reason for fluorescence color changes upon external stimulation and determine why only some fluorophores reveal emission switching. A novel triphenylacrylonitrile derivative (TPAN-MeO) with remarkably twisted conformations has been carefully prepared via the Suzuki coupling reaction. The fluorescence of TPAN-MeO in the aggregate state depends on the polymorphic forms: three crystalline forms BCrys, SCrys and YCrys exhibit bright blue, sky-blue and yellow emission, respectively; meanwhile the amorphous powders are also strongly fluorescent with green emission. The crystals BCrys and SCrys exhibit mechano- and piezochromism in that grinding and high pressure could alter the emission colour, respectively. In addition, the amorphous film exhibits vapo- and thermochromic behaviour in that organic vapour and heating could change the green colour into sky-blue. Interestingly, the solvent vapour and heating stimuli can trigger a crystal-to-crystal transformation between SCrys form and YCrys form.
Co-reporter:Yuanxiang Xu, Kai Wang, Yujian Zhang, Zengqi Xie, Bo Zou and Yuguang Ma
Journal of Materials Chemistry A 2016 - vol. 4(Issue 6) pp:NaN1262-1262
Publication Date(Web):2016/01/04
DOI:10.1039/C5TC03745J
Two thermodynamically stable crystalline phases (B- and G-phases) were found for a twistable π-conjugated molecule, CN-DSB, condensed from its solution. We investigated the structural evolution at the molecular and supramolecular levels as the crystalline phase transforms from the B-phase to G-phase under varied temperature or pressure. The intermolecular interactions were undermined before phase transition as the B-phase crystal was stimulated with an external energy. Heating the B-phase crystal up to 175 °C or applying stress up to its critical pressure (0.75 GPa) initially resulted in mixture phases or disordered state. At this stage, the molecules slightly adjust from a twisting configuration to a planar configuration, corresponding to the gradual red shift of the fluorescence spectra. Above the phase transition point, the initial intermolecular interaction of the B-phase is broken down, and the CN-DSB molecules re-assemble to the new phase—a new thermodynamic equilibrium state—corresponding to the sudden change of the emission color. Furthermore, the property of thermal-induced phase transition can be used to fabricate patterns on the CN-DSB crystal surface, and a uniform raster has been prepared by femtosecond laser direct writing (FsLDW) on the B-phase. The investigations provide new insight and understanding for the crystal phase transition and may contribute to process innovation in optical devices.
Co-reporter:Pinhua Zhang, Yongming Sui, Guanjun Xiao, Yingnan Wang, Chunzhong Wang, Bingbing Liu, Guangtian Zou and Bo Zou
Journal of Materials Chemistry A 2013 - vol. 1(Issue 5) pp:NaN1638-1638
Publication Date(Web):2012/11/20
DOI:10.1039/C2TA00350C
This article reports a reproducible and facile approach to synthesize faceted copper nanocrystals (Cu NCs) using an inexpensive copper oxide as a precursor. By simply prolonging the reaction time, Cu cubes and polyhedrons were successfully produced, and the mean size could be effectively controlled in the range of 9 to 21 nm. The catalytic activities of the Cu cubes and polyhedrons were investigated by photometrically monitoring the reduction of p-nitrophenol by an excess of NaBH4. The kinetics of the reduction reaction at different temperatures were investigated to determine the activation parameters. Our investigations indicate that Cu nanocubes exhibit higher catalytic activity than Cu polyhedrons, which can be ascribed to three features: the higher surface-to-volume ratio, the higher surface energy of the {100} facet, and the lower redox potential. In addition, these catalysts can be easily recycled with a slight decrease of the catalytic activities, and are stable in the air. Therefore, this facile route provides a useful platform for the fabrication of Cu catalysts which have the potential to replace noble metals for certain catalytic applications.
Co-reporter:Chao Wang, Yongming Sui, Guanjun Xiao, Xinyi Yang, Yingjin Wei, Guangtian Zou and Bo Zou
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN19673-19673
Publication Date(Web):2015/09/03
DOI:10.1039/C5TA05384F
Iridium (Ir) is widely used as a catalyst in polymer electrolyte membrane water electrolyzers (PEMWEs). However, high cost and limited catalytic performance of Ir hamper its large-scale industrial application. Here, based on a modified galvanic replacement, we introduce Cu nanoparticles as a template to prepare single-crystalline Cu–Ir polyhedral nanocages (NCs). Alloying Ir with 3d transition metal Cu not only significantly reduces the loading of Ir but also remarkably enhances its catalytic activity by forming a unique NC structure and tuning the d-band structure of Ir. The as-prepared single-crystalline Cu1.11Ir NCs exhibit enhanced catalytic activity toward the oxygen evolution reaction (OER) in 0.05 M H2SO4, with a smaller overpotential (286 mV) required for a current density of 10 mA cm−2 and a Tafel slope of 43.8 mV per decade. The mass activity can reach 73 mA mgIr−1 at an overpotential of 0.28 V for Cu1.11Ir NCs. Hence, the obtained Cu1.11Ir NCs would be a promising electrocatalyst for practical electrocatalytic water splitting systems.
Co-reporter:Man Xu, Yongming Sui, Chao Wang, Bo Zhou, Yingjin Wei and Bo Zou
Journal of Materials Chemistry A 2015 - vol. 3(Issue 44) pp:NaN22346-22346
Publication Date(Web):2015/09/23
DOI:10.1039/C5TA07027A
Porous Ag structures have recently attracted great interest due to their unique characteristics, relatively low cost and good biocompatibility. Shape-, size-, porosity-, and crystallinity-controlled and surface defect tailored synthesis of porous metal materials is of scientific significance yet greatly underdeveloped because of the lack of rational design strategies. Here, a low cost and facile synthetic route is presented to produce regular porous Ag platelet structures with controlled size, porosity, crystallinity and surface defects by a two-step process. Initially, size-tailored regular Ag platelet precursors from 2.5 μm to 36 μm are obtained by merely adjusting the solution pH value; meanwhile D-glucose is introduced as a structure-directing agent. Subsequently, thermal treatment is performed to afford the porous Ag platelet structures. Simply by optimizing the annealing time, temperature and heating rate, porous Ag platelets with effectively tunable porosity, crystallinity and surface defects can be achieved. The porous Ag platelet structures could catalyze the reduction of p-nitrophenol and dyes quite effectively at room temperature, which is attributed to their regular morphologies, porosity, high surface-to-volume ratio, short diffusion length and good permeability. Moreover, these porous Ag platelet structures because of their unique morphology and network characteristics will exhibit excellent electrochemical catalytic activity, or act as outstanding electrodes, sensors, actuators, etc.
Co-reporter:Qian Li ; Shourui Li ; Kai Wang ; Jing Liu ; Ke Yang ; Bingbing Liu ; Guangtian Zou
The Journal of Physical Chemistry C () pp:
Publication Date(Web):February 24, 2014
DOI:10.1021/jp412105a
High-pressure guest-dependent behaviors of porous coordination polymer {[Cu(CO3)2](CH6N3)2}n (GCC) are investigated using synchrotron X-ray diffraction (XRD) and Raman techniques. In GCC, the host framework of 3D [Cu(CO3)2]2– coordination network presents a diamond-like topology, with guest guanidinium cations locating at the window of the pores through N–H···O hydrogen bonds. Above a critical pressure, the external force can squeeze the guanidinium ions into the pores, leading to the abnormal expansion of the structure. Meanwhile, the critical pressure for expansion can be effectively lowered when no pressure transmitting medium is employed. Moreover, nonhydrostatic effects can promote the insertion of guanidinium ions, along with the amorphization of the structure, and thus affect the reversibility of the structure after releasing the pressure. Our results show that pressure is an effective tool to tune the host–guest relationship and to prepare high-pressure phase host–guest materials. Meanwhile, this study broadens the understanding of host–guest chemistry and offers a new strategy for fabricating novel materials with applications of pressure switches and zero contraction material in porous coordination polymers.
Co-reporter:Cunfang Feng, Kai Wang, Yuanxiang Xu, Liqun Liu, Bo Zou and Ping Lu
Chemical Communications 2016 - vol. 52(Issue 19) pp:NaN3839-3839
Publication Date(Web):2016/02/03
DOI:10.1039/C5CC09152G
CzCNDSB with a highly twisted conformation in the solid state is constructed. Single crystal measurements prove that it possesses an inside pore with a diameter of 8 Å and further forms a long-range orderly arrayed channel. CzCNDSB can sense external pressure from 1.0 atm to 9.21 GPa, accompanied by color changes from green to red with excellent reversibility and reproducibility.
Co-reporter:Lu Wang, Kai Wang, Houyu Zhang, Chuanjun Jiao, Bo Zou, Kaiqi Ye, Hongyu Zhang and Yue Wang
Chemical Communications 2015 - vol. 51(Issue 36) pp:NaN7704-7704
Publication Date(Web):2015/03/30
DOI:10.1039/C5CC01113B
The orange emissive powders of a boron-containing compound generate red, green, and blue luminescence after compressing, heating, and volatile acid fuming, respectively. Thus, stimulus-induced RGB emissions have been facilely realized based on one organic π-conjugated material for the first time, to the best of our knowledge.
Co-reporter:Xiao Meng, Guangyu Qi, Chen Zhang, Kai Wang, Bo Zou and Yuguo Ma
Chemical Communications 2015 - vol. 51(Issue 45) pp:NaN9323-9323
Publication Date(Web):2015/04/27
DOI:10.1039/C5CC01064K
The isomerization of spiropyrans in crystals was realized under high pressure, and the corresponding mechanochromic response could be observed by the naked eye. In situ UV-Vis spectroscopy study demonstrated that the equilibrium constant increases with the increasing pressure, from which we proposed that the negative volume of reaction determined the isomerization under high pressure.
Co-reporter:Ben-Bo Ni, Kai Wang, Qifan Yan, Hao Chen, Yuguo Ma and Bo Zou
Chemical Communications 2013 - vol. 49(Issue 86) pp:NaN10132-10132
Publication Date(Web):2013/09/02
DOI:10.1039/C3CC46153J
The cycloaddition of azides and alkynes in the solid state was accelerated by high pressure. In situ Raman scattering and synchrotron X-ray diffraction were employed to study reaction kinetics at different pressures which revealed that the pressure acceleration originates from the elevated substrate energy and decreased activation energy.
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