Co-reporter:Xi-Guang Han;Hui-Zhong He;Tao Xu;Xian-Hua Zhang;Zhao-Xiong Xie;Xi Zhou;Lan-Sun Zheng
The Journal of Physical Chemistry C January 15, 2009 Volume 113(Issue 2) pp:584-589
Publication Date(Web):2017-2-22
DOI:10.1021/jp808233e
In this paper, we successfully synthesized three kinds of typical ZnO micro/nanocrystallites including flakes, columns, and pyramids by means of different facile wet chemical routes. The growth environment plays a crucial role in the morphologies of these ZnO micro/nanocrystallites. At the same time, we find that physical/chemical properties of these ZnO samples are dependent on their exposed surface, and the order of gas sensing and photocatalytic efficiency of the ZnO crystal planes is (0001) > {101̅0} > {101̅1} and (0001̅). On the basis of structural analyses of various exposed surfaces and related X-ray photoelectron spectroscopy, we deeply discussed the effect of definite surface structures on their gas sensing and photocatalytic properties.
Co-reporter:Jiawei Zhang 张嘉伟;Meishan Chen 陈梅珊;Jiayu Chen 陈佳煜;Huiqi Li 李慧齐
Science China Materials 2017 Volume 60( Issue 8) pp:685-696
Publication Date(Web):08 August 2017
DOI:10.1007/s40843-017-9073-9
The catalytic properties of noble metal nanocrystals can be tuned via engineering their structures. Nanocrystals with fractal structures are fascinating catalysts regarding their large surface area-to-volume ratios, large numbers of edges and corners, which can be tuned simultaneously by their hierarchical ordering. However, it is still a great challenge to control the hierarchical ordering of noble metal fractal nanocrystals and their formation mechanism is not fully understood. Herein, we report a facile solvothermal method for the direct preparation of a unique single-crystal Rh-hyperbranched structure, which consists of hierarchically ultrathin nanoplates with threefold symmetry, large surface area and high density of low-coordinated edge/corner sites. Importantly, the hierarchical ordering can be readily tuned by changing the composition of solvent. In addition, we found the as-prepared single-crystal hyperbranched Rh nanoplates possessed great structure stability, and exhibited better catalytic performance towards both ethanol electrooxidation and hydrogenation of styrene than the commercial Rh black, which can be attributed to the large surface area and high-dentisty of edge/corner sites.贵金属纳米晶的催化性质与其结构密切相关. 比表面积越大、配位不饱和的边角原子密度越高, 贵金属纳米晶在催化反应过程中表现出的性能往往越优异. 相比于常见的具有完整几何形貌的贵金属纳米晶, 具有多重分级结构特征的超支化贵金属纳米晶拥有更大的比表面积以及更丰富的配位不饱和的活性位点, 因此被认为是一种潜在的性能优异的催化剂. 但这种具有多重分级结构特征的超支化贵金属纳米晶无论是在生长机理研究还是可控制备上都还存在巨大的挑战. 本文通过简单的湿化学法成功制备出一种具有多重分级结构特征的超支化Rh纳米薄片. 该产物由三角形纳米片在扩散限制条件下分级生长形成, 整体呈现三次对称性的单晶特征. 研究表明, 该纳米结构不仅具有出色的结构稳定性, 而且其生长级数可通过反应溶剂比例的简单调节进行调控, 从而实现Rh纳米薄片比表面积和位于边/角活性位点的原子比例的调控. 由于拥有更大的比表面积以及更为丰富的配位不饱和的活性位点, 这种具有多重分级结构的超支化Rh纳米薄片在乙醇电催化氧化和苯乙烯催化加氢催化反应中展现出了比目前主流商业催化剂Rh黑更为优异的催化活性.
Co-reporter:Qiaoli Chen, Zhenming Cao, Guifen Du, Qin Kuang, Jin Huang, Zhaoxiong Xie, Lansun Zheng
Nano Energy 2017 Volume 39(Volume 39) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.nanoen.2017.07.041
•Excavated octahedral PtCo NCs with specific facets and large surface area were synthesized.•The surfactant and growth kinetics affects the composition and morphology of PtCo NCs.•Excavated PtCo NCs showed superior performance as multifunctional electrocatalysts.Pt-Co alloy is thought to be the best potential catalyst toward many electrocatalytic energy conversion reactions among various bimetallic alloys. To optimize the performance and reduce the usage of noble metal Pt, both the mass and surface contribution should be considered, which requires Pt-Co alloy nanocrystals (NCs) to possess large surface area and expose specific facets. Unfortunately, these requirements can hardly be met simultaneously for the NCs with normal convex polyhedral shapes. In this work, a simple cetyltrimethylammonium bromide-assisted method is proposed to controllably synthesize Pt-Co alloy NCs with a unique excavated octahedral shape. The excavated octahedral Pt-Co alloy NCs is intrinsically built with mutually perpendicular interlaced ultrathin PtCo nanosheets bound with {100} facets that are not the thermodynamically most stable for face-centered cubic metals. The electrochemically surface area of the unique excavated octahedral PtCo alloy NCs is determined to be 23.3 m2 g−1Pt, which is significantly larger than that of the normal octahedral Pt2Co alloy NCs with the same size (11.4 m2 g−1Pt). Owing to the combination of large surface area and high active {100} facets, the excavated octahedral PtCo NCs display extraordinary catalytic activity and durability towards hydrogen evolution reaction in alkaline environment. Strikingly, the overpotential of excavated PtCo NCs at the current density of 20 mA cm−2 is as low as 76.2 mV, which is much lower than that for the {111} faceted Pt2Co NCs (83.9 mV) and the commercial Pt/C (107 mV), respectively. Besides, the excavated octahedral PtCo NCs also show significantly enhanced electrocatalytic performances towards methanol oxidation reaction and oxygen reduction reaction when both considering the mass and surface contribution.Download high-res image (214KB)Download full-size image
Co-reporter:Yinyun Lü, Yating Jiang, Qi Zhou, Yunmei Li, Luning Chen, Qin Kuang, Zhaoxiong Xie, Lansun Zheng
Journal of Solid State Chemistry 2017 Volume 256(Volume 256) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.jssc.2017.08.035
•Porous Co3O4/ZnO nanocages were synthesized by a facile thermolysis route of heterometallic MOFs.•The as-prepared nanocages possessed massive pores and Co3O4/ZnO heterojunctions.•The Co3O4/ZnO ratio in the composites was easily adjusted by tuning the Co/Zn ratio in the precursors.•The composite catalysts exhibited a significantly enhanced production efficiency of glycerol carbonate in the carbonylation reaction of glycerol with urea.The efficient synthesis of glycerol carbonate (GLC) has recently received great attention due to its significance in reducing excess glycerol in biodiesel production as well as its promising applications in several industrial fields. However, the achievement of high conversion and high selectivity of GLC from glycerol in heterogeneous catalytic processes remains a challenge due to the absence of high-performance solid catalysts. Herein, highly porous nanocage catalysts composed of well-mixed Co3O4 and ZnO nanocrystals were successfully fabricated via a facile heterometallic metal-organic framework (MOF)-templated synthetic route. Benefiting from a high porosity and the synergistic effect between Co3O4 and ZnO, the as-prepared composite catalysts exhibited a significantly enhanced production efficiency of GLC in the carbonylation reaction of glycerol with urea compared to the single-component counterparts. The yield of GLC over the Co50Zn50-350 catalyst reached 85.2%, with 93.3% conversion and near 91% GLC selectivity, and this catalytic performance was superior to that over most heterogeneous catalysts. More importantly, the proposed templated synthetic strategy of heterometallic MOFs facilitates the regulation of catalyst composition and surface structure and can therefore be potentially extended in the tailoring of other metal oxide composite catalysts.Highly porous Co3O4/ZnO nanocages were fabricated via a heterometallic MOF-templated route and exhibited a significantly enhanced photocatalytic performance in the production of glycerol carbonate.Download high-res image (150KB)Download full-size image
Co-reporter:Wenwen Zhan, Yue He, Jiangbin Guo, Luning Chen, Xiangjian Kong, Haixia Zhao, Qin Kuang, Zhaoxiong Xie and Lansun Zheng
Nanoscale 2016 vol. 8(Issue 27) pp:13181-13185
Publication Date(Web):13 Jun 2016
DOI:10.1039/C6NR02257J
It is becoming a challenge to achieve simpler characterization and wider application of flexible metal organic frameworks (MOFs) exhibiting the gate-opening or breathing behavior. Herein, we designed an intelligent MOF-based system where the gate-opening or breathing behavior of MOFs can be facially visualized in solution. Two types of metal oxide@MOF core–shell heterostructures, ZnO@ZIF-7 and ZnO@ZIF-71, were prepared using ZnO nanorods as self-sacrificial templates. The structural flexibility of both the MOFs can be easily judged from the distinct molecular-size-related formation modes and photoelectrochemical performances between the two ZnO@ZIF heterostructures. Moreover, the rotational dynamics of the flexible parts of ZIF-7 were studied by analyzing the intrinsic physical properties, such as dielectric constants, of the structure. The present work reminds us to pay particular attention to the influences of the structural flexibility of MOFs on the structure and properties of MOF-involved heterostructures in future studies.
Co-reporter:Ruifeng Tong, Chang Liu, Zhenkai Xu, Qin Kuang, Zhaoxiong Xie, and Lansun Zheng
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 33) pp:21326
Publication Date(Web):August 1, 2016
DOI:10.1021/acsami.6b05563
Integrating wide bandgap semiconductor photocatalysts with visible-light-active inorganic nanoparticles (such as Au and CdS) as sensitizers is one of the most efficient methods to improve their photocatalytic activity in the visible light region. However, as for all such composite photocatalysts, a rational design and precise control over their architecture is often required to achieve optimal performance. Herein, a new TiO2-based ternary composite photocatalyst with superior visible light activity was designed and synthesized. In this composite photocatalyst, the location of the visible light sensitizers was engineered according to the intrinsic facet-induced effect of well-faceted TiO2 nanocrystals on the spatial separation of photogenerated carriers. Experimentally, core–shell structured Au@CdS nanoparticles acting as visible light sensitizers were selectively deposited onto photoreductive {101} facets of well-faceted anatase TiO2 nanocrystals through a two-step in situ photodeposition route. Because the combination of Au@CdS and specific {101} facets of TiO2 nanocrystals facilitates the transport of charges photogenerated under visible light irradiation, this well-designed ternary composite photocatalyst exhibited superior activity in visible-light-driven photocatalytic H2 evolution, as expected.Keywords: Au@CdS nanoparticles; charge separation; H2 evolution; selective deposition; TiO2; visible light photocatalytic activity
Co-reporter:Luning Chen, Huiqi Li, Wenwen Zhan, Zhenming Cao, Jiayu Chen, Qiaorong Jiang, Yaqi Jiang, Zhaoxiong Xie, Qin Kuang, and Lansun Zheng
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 45) pp:31059
Publication Date(Web):October 26, 2016
DOI:10.1021/acsami.6b11567
For new composite materials with functional nanoparticles (NPs) embedded in metal organic frameworks (MOFs), rational design and precise control over their architectures are imperative for achieving enhanced performance and novel functions. Especially in catalysis, the activity and selectivity of such composite materials are strongly determined by the encapsulation state and thickness of the MOF shell, which greatly influences the diffusion and adsorption of substance molecules onto the NP surface. In this study, MOF-74(Ni)-encapsulated Rh–Ni hierarchical heterostructures (Rh–Ni@MOF-74(Ni)) were successfully constructed using magnetic Rh–Ni-alloyed nanoflowers (NFs) as a self-sacrificial template. Strikingly, the encapsulation state and thickness of the formed MOF shell were well-tuned via template dealloying by changing the Ni content in the Rh–Ni NFs template. More interestingly, such unique Rh–Ni composites encapsulated with MOFs as catalysts could be magnetically recyclable and exhibited enhanced catalytic performance for the selective hydrogenation of alkynes to cis products, owing to the confinement effect of the MOF shell, as compared to their pristine counterparts.Keywords: composite catalyst; hydrogenation; isomerization; metal−organic framework; self-sacrificial template
Co-reporter:Yinyun Lü, Qi Zhou, Luning Chen, Wenwen Zhan, Zhaoxiong Xie, Qin Kuang and Lansun Zheng
CrystEngComm 2016 vol. 18(Issue 22) pp:4121-4126
Publication Date(Web):22 Jan 2016
DOI:10.1039/C5CE02488A
At present, the deliberate and controlled doping of transition metal ions in semiconductor hosts remains a challenge for the development of diluted magnetic semiconductors (DMSs) with room-temperature ferromagnetic properties. In this work, Co-doped ZnO (Zn1−xCoxO, x = 0.03, 0.05, and 0.10) with different Co doping concentrations were successfully prepared via a simple thermal decomposition process using Co-doped Zn-containing metal–organic frameworks as precursors. X-ray diffraction and Raman scattering studies confirmed the incorporation of Co into the ZnO lattices. X-ray photoelectron spectroscopy indicated that the substituted Co ions were in the 2+ oxidation state and were incorporated at Zn2+ sites. The as-prepared Co-doped ZnO samples displayed an extended light absorption range compared to pure ZnO and were ferromagnetic at room temperature. Given the widely tunable range of the doping concentrations used and the abundance of metal–organic framework resources, the proposed synthetic strategy is potentially applicable to the fabrication of other transition metal ion-doped DMSs.
Co-reporter:Chang Liu, Ruifeng Tong, Zhenkai Xu, Qin Kuang, Zhaoxiong Xie and Lansun Zheng
RSC Advances 2016 vol. 6(Issue 35) pp:29794-29801
Publication Date(Web):17 Mar 2016
DOI:10.1039/C6RA04552A
The loading of oxidation and/or reduction co-catalysts onto the surface of semiconductor nanomaterials is one of the most efficient methods of improving the performance of semiconductor-based photocatalysts. However, in most of cases, the enhancing effect can be weakened by a random co-catalyst loading method because the different roles of photocatalyst facets in the photocatalytic process are not simultaneously considered. In this paper, a ternary composite photocatalyst, Fe2O3–TiO2–Pt, with α-Fe2O3 and Pt nanoparticles selectively deposited onto the {001} and {101} facets of TiO2, respectively, was successfully constructed using the facet-induced photogenerated electrons and holes of well-faceted anatase TiO2 nanocrystals as natural redox agents. The overall photocatalytic activity of this well-designed composite photocatalyst in H2 production has been enhanced greatly by as much as 2.2 times and 30 times compared to the photocatalysts loaded randomly and without a co-catalyst, respectively. The enhanced photocatalytic activity of Fe2O3–TiO2–Pt was attributed to the remarkably enhanced separation of photogenerated charge carriers with the excitation of UV light.
Co-reporter:Jiawei Zhang, Qin Kuang, Yaqi Jiang, Zhaoxiong Xie
Nano Today 2016 Volume 11(Issue 5) pp:661-677
Publication Date(Web):October 2016
DOI:10.1016/j.nantod.2016.08.012
•Overview of synthesis of noble metal nanocrystals with high-energy facets.•Thermodynamic/kinetic roles of capping agents in formation of high-energy facets.•Supersaturation-controlled crystal growth explains contradictory results.•Surface structure-dependent activity and selectivity of noble metal catalysts.Tailoring of the surface structure of noble metal nanocrystals is a hot research topic because of the fascinating surface structure-dependent properties in enormous applications, such as heterogeneous catalysis. Due to high densities of atomic steps and kinks and their abundance of unsaturated coordination sites, noble metal NCs with high-energy surfaces often exhibit superior performances compared to those with low-energy surface structures. A complete understanding of the growth mechanisms of noble-metal NCs with high-energy surface structures would enable the rational design of noble metal NCs with optimized performances for specific applications. In this review, we concentrate on the growth mechanisms of noble-metal NCs with high-energy facets by summarizing the state-of-the-art progress in the surface structure-controlled synthesis of noble metal NCs with high-energy facets. By carefully considering both the thermodynamic and kinetic factors that affect the surface structures, we intentionally classify different approaches into four categories (i.e., surface-regulating-agent assisted strategies, supersaturation controlled strategies, electrochemical methods, and template directed methods), and insights into the respective growth mechanisms are demonstrated by representative examples. Especially, we highlight the role of supersaturation in the formation of the high-energy surface, which successfully explained apparent contradictory results when only taking the “capping” effect into consideration. Then several typical examples are given to demonstrate the versatility of the high-energy facets in improving both catalytic activity and selectivity. In addition, the stability of high-energy facets is also discussed. Finally, the remaining challenges and perspectives for future directions are given for this promising field of research. We hope the deep and comprehensive understanding the growth mechanism of the nanocrystals would help to guild the rational design of functional nanomaterials with desired outstanding properties.
Co-reporter:Qiaoli Chen;Yanan Yang;Zhenming Cao;Dr. Qin Kuang;Guifen Du;Dr. Yaqi Jiang; Zhaoxiong Xie; Lansun Zheng
Angewandte Chemie 2016 Volume 128( Issue 31) pp:9167-9171
Publication Date(Web):
DOI:10.1002/ange.201602592
Abstract
Excavated polyhedral noble-metal materials that were built by the orderly assembly of ultrathin nanosheets have both large surface areas and well-defined facets, and therefore could be promising candidates for diverse important applications. In this work, excavated cubic Pt–Sn alloy nanocrystals (NCs) with {110} facets were constructed from twelve nanosheets by a simple co-reduction method with the assistance of the surface regulator polyvinylpyrrolidone. The specific surface area of the excavated cubic Pt–Sn NCs is comparable to that of commercial Pt black despite their larger particle size. The excavated cubic Pt–Sn NCs exhibited superior electrocatalytic activity in terms of both the specific area current density and the mass current density towards methanol oxidation.
Co-reporter:Qiaoli Chen;Yanan Yang;Zhenming Cao;Dr. Qin Kuang;Guifen Du;Dr. Yaqi Jiang; Zhaoxiong Xie; Lansun Zheng
Angewandte Chemie International Edition 2016 Volume 55( Issue 31) pp:9021-9025
Publication Date(Web):
DOI:10.1002/anie.201602592
Abstract
Excavated polyhedral noble-metal materials that were built by the orderly assembly of ultrathin nanosheets have both large surface areas and well-defined facets, and therefore could be promising candidates for diverse important applications. In this work, excavated cubic Pt–Sn alloy nanocrystals (NCs) with {110} facets were constructed from twelve nanosheets by a simple co-reduction method with the assistance of the surface regulator polyvinylpyrrolidone. The specific surface area of the excavated cubic Pt–Sn NCs is comparable to that of commercial Pt black despite their larger particle size. The excavated cubic Pt–Sn NCs exhibited superior electrocatalytic activity in terms of both the specific area current density and the mass current density towards methanol oxidation.
Co-reporter:Yiting Wang, Yinyun Lü, Wenwen Zhan, Zhaoxiong Xie, Qin Kuang and Lansun Zheng
Journal of Materials Chemistry A 2015 vol. 3(Issue 24) pp:12796-12803
Publication Date(Web):06 May 2015
DOI:10.1039/C5TA01108F
Shape-controllable porous, hollow metal oxide cages are attracting more and more attention due to their widespread applications. In this paper, octahedral, truncated octahedral and cubic Cu2O/CuO cages were successfully fabricated by the thermal decomposition of the polyhedral crystals of Cu-based metal–organic frameworks (Cu-MOFs) as self-sacrificial templates at 300 °C. The morphology of the Cu-MOF polyhedral precursors was well tuned by using lauric acid as the growth modulator under solvothermal conditions. Gas-sensing measurements revealed that the octahedral Cu2O/CuO cages exhibited a gas-sensing performance far better than those exhibited by truncated octahedral and cubic cages, which is attributed to the cooperative effect of the large specific surface area (150.3 m2 g−1) and high capacity of surface-adsorbed oxygen of the octahedral Cu2O/CuO cages.
Co-reporter:Yinyun Lü, Yiting Wang, Hongli Li, Yuan Lin, Zhiyuan Jiang, Zhaoxiong Xie, Qin Kuang, and Lansun Zheng
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 24) pp:13604
Publication Date(Web):June 3, 2015
DOI:10.1021/acsami.5b03177
Composites incorporating ferromagnetic metal nanopartices into a highly porous carbon matrix are promising as electromagnetic wave absorption materials. Such special composite nanomaterials are potentially prepared by the thermal decomposition of metal–organic framework (MOF) materials under controlled atmospheres. In this study, using Co-based MOFs (Co-MOF, ZIF-67) as an example, the feasibility of this synthetic strategy was demonstrated by the successful fabrication of porous Co/C composite nanomaterials. The atmosphere and temperature for the thermal decomposition of MOF precursors were crucial factors for the formation of the ferromagnetic metal nanopartices and carbon matrix in the porous Co/C composites. Among the three Co/C composites obtained at different temperatures, Co/C-500 obtained at 500 °C exhibited the best performance for electromagnetic wave absorption. In particular, the maximum reflection loss (RL) of Co/C-500 reached −35.3 dB, and the effective absorption bandwidth (RL ≤ −10 dB) was 5.80 GHz (8.40 GHz–14.20 GHz) corresponding to an absorber thickness of 2.5 mm. Such excellent electromagnetic wave absorption properties are ascribed to the synergetic effects between the highly porous structure and multiple components, which significantly improved impedance matching.Keywords: Co/C composite; electromagnetic wave absorption; metal−organic frameworks; porous structure; self-sacrificial template synthesis;
Co-reporter:Chang Liu, Qin Kuang, Zhaoxiong Xie and Lansun Zheng
CrystEngComm 2015 vol. 17(Issue 33) pp:6308-6313
Publication Date(Web):06 Jul 2015
DOI:10.1039/C5CE01162K
Surface modification with noble metals is considered as an effective strategy to enhance sensitivity and selectivity of metal oxide-based gas sensors. This enhancement with noble metal decoration is generally attributed to the formation of a heterogeneous interface between the noble metal and metal oxide. However, the sensitization mechanism of noble metals on the specific facets of the metal oxide support lacks a unified understanding. In this work, three gas sensing hybrid nanostructures based on noble metal (Au, Pd and Pt) decorated {221} faceted octahedral SnO2 nanocrystals were specifically constructed. Our results showed that, on these {221} specific facets of SnO2, Au exhibited a positive effect for enhancing the sensitivity and selectivity of SnO2 sensors, while Pd and Pt played the opposite roles. It is considered that the sensitization effects of noble metals are related to their surface chemical states and interaction with the metal oxide support. The methodology demonstrated in this work is beneficial to probing into the sensitization mechanisms of noble metals in semiconductor/metal hybrid sensors.
Co-reporter:Wei Chen, Qin Kuang, Qiuxiang Wang and Zhaoxiong Xie
RSC Advances 2015 vol. 5(Issue 26) pp:20396-20409
Publication Date(Web):05 Feb 2015
DOI:10.1039/C5RA00344J
Anatase titanium dioxide (A-TiO2) is one of the most important functional materials and is widely used in various energy- and environmental related applications. Over the past decade, great efforts have been devoted to surface engineering of A-TiO2 crystals at the atomic level so as to fundamentally understand the relationship between the surface structure and their performance in practical applications. In this review, we briefly summarize recent important achievements on the control of specific surface structures of A-TiO2 crystals, focusing on facets with high surface energy (such as {001}, {100}, {101}) and their combinations. In addition, fascinating performances of A-TiO2 crystals enhanced by these high energy surfaces are examined and discussed through the perspectives of synergistic effects of different facets and surface adsorbates, with additional insights related to some contradictory results. Finally, we offer a summary and some perspectives on current challenges and promising directions in this emerging field. We believe that a comprehensive understanding of surface engineering of A-TiO2 crystals with regard to high energy facets will in the long term help us to rationally design functional nanomaterials with desired performances.
Co-reporter:Qiuxiang Wang, Qin kuang, Kunshui Wang, Xue Wang and Zhaoxiong Xie
RSC Advances 2015 vol. 5(Issue 75) pp:61421-61425
Publication Date(Web):10 Jul 2015
DOI:10.1039/C5RA08988C
Hollow nanomaterials have attracted intense attention due to their special structures and potential applications in many fields. In this paper, we report a surfactant free synthesis of hollow Cu2O nanocubes by reducing Cu2+ precursors using Cl− ions as the morphology regulator at room temperature. It is found that in the presence of Cl− ions, hollow Cu2O nanocubes can be easily synthesized by directly reducing Cu2+ precursors with ascorbic acid. Through well-designed experiments, we propose that, in this surfactant free synthetic route, the formation of hollow Cu2O nanocubes results from a reaction activated Kirkendall diffusion process of cubic CuCl intermediates, which are formed in the reaction process and act as self-sacrificial templates. The amounts of Cl− ions and NaOH are two key factors to determine whether hollow Cu2O nanocubes are formed or not.
Co-reporter:Wei Chen;Zhaoxiong Xie
Science China Materials 2015 Volume 58( Issue 4) pp:281-288
Publication Date(Web):2015 April
DOI:10.1007/s40843-015-0041-6
Surface structure control of functional nano-/micro-crystallites has attracted great attention because many important physicochemical properties depend on their surface. Guided by the supersaturation-dependent surface structure evolution strategy we proposed recently, NaTaO3 submicrometer crystals with morphologies of cubes, corner truncated cubes, edge and corner truncated cubes, and quasi-spheres can be synthesized by changing the volume ratio of ethylene glycol to water and the amount of NaOH in the composite solvent. Under low supersaturation condition, NaTaO3 cubic crystals with low energy {100} facets were obtained. As the supersaturation increases, the corners and edges of NaTaO3 cubic crystals, which possess higher surface energy, were gradually truncated. Surprisingly, quasi-sphere crystallites formed under extremely high supersaturation condition, which is difficult to be explained by the classical crystal growth theories. By analyzing the formation work of two-dimension crystal nuclei, we concluded that the crystal growth tend to be isotropic at extremely high supersaturation, which well explained the formation of the quasi-sphere crystallites.表面结构决定了晶体材料的许多重要的物理化学性质. 可控制备具有特定表面结构的微纳米晶体, 从而实现对晶体材料性能的改善, 引起了广泛的关注. 本课题组近期相关的研究表明, 晶体生长体系中, 生长单元的过饱和度决定了晶体的表面结构. 基于已有研究结果, 本文通过调节混合溶剂体系中乙二醇和水的相对体积比及NaOH的用量, 改变晶体生长体系中生长单元的过饱和度, 合成了亚微米尺寸的NaTaO3立方体、 削角立方体、 削角削棱立方体和准球体. 低过饱和度条件下, 形成的NaTaO3颗粒是低能{100}晶面裸露的立方体; 随过饱和度的增加, 立方体的角和棱逐渐削去, 裸露表面能更高的晶面; 极高过饱和度条件下, 则形成准球体NaTaO3颗粒. 这种准球体的形成难以用经典的晶体生长理论加以解释. 通过研究同样受过饱和度影响的二维晶核生成功(Whkl), 发现在极高的过饱和度的条件下, 晶体生长趋于各向同性, 合理地解释了准球体的形成机制.
Co-reporter:Junjie Ouyang, Jun Pei, Qin Kuang, Zhaoxiong Xie, and Lansun Zheng
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:12505
Publication Date(Web):July 8, 2014
DOI:10.1021/am502358g
Surface engineering of crystals at nanoscale level by precisely and rationally exposing specific facets proved to be highly effective in enhancing the performance of inorganic functional nanocrystals. To do so, a comprehensive understanding of the growth mechanism was of great importance. By using hematite (α-Fe2O3) as an example, in this paper we demonstrated high effectiveness of controlling supersaturation of growth monomers in engineering the exposed facets of nanocrystals. Under surfactant-free hydrothermal conditions, a series of morphology evolution of α-Fe2O3 nanocrystals from {012} faceted pseudocubes to {113} faceted hexagonal bipyramids and {001} faceted nanoplates were successfully activated through concentration-, reaction time-, and solvent-dependent hydrolysis of ferric acetylacetonate. High supersaturation was eventually proven to be conducive to the formation of facets with high surface energy. Furthermore, the α-Fe2O3 nanocrystals enclosed with facets of high surface energy exhibited excellent catalytic activity and gas-sensing ability. The present work will deepen our understanding of thermodynamics and kinetic control over the morphology of nanocrystals as well as our understanding of surface-related performance of inorganic functional nanocrystals.Keywords: CO catalysis; Gas sensing; Hematite; Shape evolution; Supersaturation
Co-reporter:Yinyun Lü, Wenwen Zhan, Yue He, Yiting Wang, Xiangjian Kong, Qin Kuang, Zhaoxiong Xie, and Lansun Zheng
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 6) pp:4186
Publication Date(Web):February 21, 2014
DOI:10.1021/am405858v
Porous metal oxides nanomaterials with controlled morphology have received great attention because of their promising applications in catalysis, energy storage and conversion, gas sensing, etc. In this paper, porous Co3O4 concave nanocubes with extremely high specific surface area (120.9 m2·g-1) were synthesized simply by calcining Co-based metal–organic framework (Co-MOF, ZIF-67) templates at the optimized temperature (300 °C), and the formation mechanism of such highly porous structures as well as the influence of the calcination temperature are well explained by taking into account thermal behavior and intrinsic structural features of the Co-MOF precursors. The gas-sensing properties of the as-synthesized porous Co3O4 concave nanocubes were systematically tested towards volatile organic compounds including ethanol, acetone, toluene, and benzene. Experimental results reveal that the porous Co3O4 concave nanocubes present the highest sensitivity to ethanol with fast response/recovery time (< 10 s) and a low detection limit (at least 10 ppm). Such outstanding gas sensing performance of the porous Co3O4 concave nanocubes benefits from their high porosity, large specific surface area, and remarkable capabilities of surface-adsorbed oxygen.Keywords: Co3O4; gas sensor; metal-organic frameworks; porous structure; self-sacrificial template synthesis;
Co-reporter:Dr. Shuifen Xie;Shixiong Bao;Junjie Ouyang;Dr. Xi Zhou; Qin Kuang; Zhaoxiong Xie; Lansun Zheng
Chemistry - A European Journal 2014 Volume 20( Issue 18) pp:5244-5252
Publication Date(Web):
DOI:10.1002/chem.201303927
Abstract
Surface functionalization of inorganic nanomaterials through chemical binding of organic ligands on the surface unsaturated atoms, forming unique organic–inorganic interfaces, is a powerful approach for creating special functions for inorganic nanomaterials. Herein, we report the synthesis of hierarchical MgO nanocrystal clusters (NCs) with an organic–inorganic interface induced multi-fluorescence and their application as new alternative labels for cellular imaging. The synthetic method was established by a dissolution and regrowth process with the assistance of carboxylic acid, in which the as-prepared MgO NCs were modified with carboxylic groups at the coordinatively unsaturated atoms of the surface. By introducing acetic acid to partially replace oleic acid in the reaction, the optical absorption of the produced MgO NCs was progressively engineered from the UV to the visible region. Importantly, with wider and continuous absorption profile, those MgO NCs presented bright and tunable multicolor emissions from blue-violet to green and yellow, with the highest absolute quantum yield up to (33±1) %. The overlap for the energy levels of the inorganic–organic interface and low-coordinated states stimulated a unique fluorescence resonance energy transfer phenomenon. Considering the potential application in cellular imaging, such multi-fluorescent MgO NCs were further encapsulated with a silica shell to improve the water solubility and stability. As expected, the as-formed MgO@SiO2 NCs possessed great biocompatibility and high performance in cellular imaging.
Co-reporter:Wen-wen Zhan ; Qin Kuang ; Jian-zhang Zhou ; Xiang-jian Kong ; Zhao-xiong Xie ;Lan-sun Zheng
Journal of the American Chemical Society 2013 Volume 135(Issue 5) pp:1926-1933
Publication Date(Web):January 3, 2013
DOI:10.1021/ja311085e
Metal–organic frameworks (MOFs) and related material classes are attracting considerable attention for their applications in gas storage/separation as well as catalysis. In contrast, research concerning potential uses in electronic devices (such as sensors) is in its infancy, which might be due to a great challenge in the fabrication of MOFs and semiconductor composites with well-designed structures. In this paper, we proposed a simple self-template strategy to fabricate metal oxide semiconductor@MOF core–shell heterostructures, and successfully obtained freestanding ZnO@ZIF-8 nanorods as well as vertically standing arrays (including nanorod arrays and nanotube arrays). In this synthetic process, ZnO nanorods not only act as the template but also provide Zn2+ ions for the formation of ZIF-8. In addition, we have demonstrated that solvent composition and reaction temperature are two crucial factors for successfully fabricating well-defined ZnO@ZIF-8 heterostructures. As we expect, the as-prepared ZnO@ZIF-8 nanorod arrays display distinct photoelectrochemical response to hole scavengers with different molecule sizes (e.g., H2O2 and ascorbic acid) owing to the limitation of the aperture of the ZIF-8 shell. Excitingly, such ZnO@ZIF-8 nanorod arrays were successfully applied to the detection of H2O2 in the presence of serous buffer solution. Therefore, it is reasonable to believe that the semiconductor@MOFs heterostructure potentially has promising applications in many electronic devices including sensors.
Co-reporter:Chang Liu, Qin Kuang, Ming-Shang Jin, Jia-Wei Zhang, Xi-Guang Han, Zhao-Xiong Xie and Lan-Sun Zheng
Nanoscale 2013 vol. 5(Issue 5) pp:1793-1796
Publication Date(Web):21 Jan 2013
DOI:10.1039/C3NR34203D
A dispersive scattering centers-based strategy was proposed to enhance the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes. Photocatalytic efficiencies of the photocatalyst, Degussa P25, in water splitting and photodegradation were markedly enhanced by using Ag nanosheets as dispersive scattering centers.
Co-reporter:Changping Hou, Jing Zhu, Chang Liu, Xue Wang, Qin Kuang and Lansun Zheng
CrystEngComm 2013 vol. 15(Issue 31) pp:6127-6130
Publication Date(Web):03 Jun 2013
DOI:10.1039/C3CE40837J
Ultrathin Rh nanosheets with a thickness of approximately 1 nm were synthesized via a simple surfactant-free hydrothermal route, using Rh(II) acetylacetonate as the precursor and formaldehyde as the shape controller. CO and H2 originating from the formaldehyde decomposition played key roles in the formation of ultrathin Rh nanosheets.
Co-reporter:Chang Liu;Dr. Xiguang Han;Shuifen Xie; Qin Kuang;Xue Wang;Dr. Mingshang Jin; Zhaoxiong Xie ; Lansun Zheng
Chemistry – An Asian Journal 2013 Volume 8( Issue 1) pp:282-289
Publication Date(Web):
DOI:10.1002/asia.201200886
Abstract
Recently, it has been proven that directional flow of photogenerated charge carriers occurs on specific facets of TiO2 nanocrystals. Herein, we demonstrate that the photocatalytic activity of anatase TiO2 nanocrystals in both photoreduction and photooxidation processes can be enhanced by selectively depositing Pt nanoparticles on the {101} facets, which strengthens spontaneously surface-induced separation between photogenerated electrons and holes in the photocatalysis process. An optimal ratio of the oxidative {001} facets to the reductive {101} facets exists with regard to the photocatalysis of the faceted TiO2 nanocrystals, and this is crucial for balancing the recombination and redox reaction rates of photogenerated electrons and holes. The present work might help us gain deeper insight into the relation between the specific surface of semiconductor photocatalysts and their photocatalytic activities and provides us with a new route to design photocatalysts with high photocatalytic activity.
Co-reporter:Shuifen Xie, Binjie Zheng, Qin Kuang, Xue Wang, Zhaoxiong Xie and Lansun Zheng
CrystEngComm 2012 vol. 14(Issue 22) pp:7715-7720
Publication Date(Web):
DOI:10.1039/C2CE25797A
Co-reporter:Xue Wang;Xiguang Han;Shuifen Xie;Dr. Qin Kuang;Yaqi Jiang;Subing Zhang;Xiaoliang Mu;Guangxu Chen; Zhaoxiong Xie; Lansun Zheng
Chemistry - A European Journal 2012 Volume 18( Issue 8) pp:2283-2289
Publication Date(Web):
DOI:10.1002/chem.201103280
Abstract
A morphology evolution of SnO2 nanoparticles from low-energy facets (i.e., {101} and {110}) to high-energy facets (i.e., {111}) was achieved in a basic environment. In the proposed synthetic method, octahedral SnO2 nanoparticles enclosed by high-energy {111} facets were successfully synthesized for the first time, and tetramethylammonium hydroxide was found to be crucial for the control of exposed facets. Furthermore, our experiments demonstrated that the SnO2 nanoparticles with exposed high-energy facets, such as {221} or {111}, exhibited enhanced catalytic activity for the oxidation of CO and enhanced gas-sensing properties due to their high chemical activity, which results from unsaturated coordination of surface atoms, superior to that of low-energy facets. These results effectively demonstrate the significance of research into improving the physical and chemical properties of materials by tailoring exposed facets of nanomaterials.
Co-reporter:Jiawei Zhang;Lei Zhang;Yanyan Jia;Guangxu Chen;Xue Wang
Nano Research 2012 Volume 5( Issue 9) pp:618-629
Publication Date(Web):2012 September
DOI:10.1007/s12274-012-0247-9
Co-reporter:Lei Zhang ; Jiawei Zhang ; Qin Kuang ; Shuifen Xie ; Zhiyuan Jiang ; Zhaoxiong Xie ;Lansun Zheng
Journal of the American Chemical Society 2011 Volume 133(Issue 43) pp:17114-17117
Publication Date(Web):September 6, 2011
DOI:10.1021/ja2063617
Controlled syntheses of multicomponent metal nanocrystals (NCs) and high-index surfaces have attracted increasing attention due to the specific physical and chemical properties of such NCs. Taking advantage of copper underpotential deposition as a bridge, hexoctahedral Au–Pd alloy NCs with {hkl} facets exposed were successfully synthesized, while phase separation occurred in the absence of Cu2+ ions. The as-prepared hexoctahedral Au–Pd alloy NCs exhibited very excellent performance in terms of both formic acid electro-oxidation and methanol tolerance due to synergism between the high-index facets and the alloy.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Yang Zhao, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2011 vol. 21(Issue 20) pp:7263-7268
Publication Date(Web):15 Apr 2011
DOI:10.1039/C1JM10745C
We report fancy brilliant photoluminescence (PL) from surface functionalized MgO nanocrystal clusters (NCs). Single-crystal-like MgO NCs were prepared by a simple one-pot pyrolysis method in the mixed organic solvent of octylamine (OTA) and oleic acid (OA) using magnesium acetate as a precursor. Under the chemical equilibrium of etching and re-growth with the assistance of OA, the MgO products were surface functionalized. It was found that such surface functionalized MgO NCs exhibited intense visible light PL with high PL thermal-stability, and the apparent quantum yield was as high as 19 ± 1%. In addition, through controlling the synthetic temperature and the reaction time, the functionalized surfaces of MgO NCs were facilely tuned, resulting in the tuneable wavelength of the PL from blue-violet to yellow. Different low-coordinated oxygen sites, capping OA and carbonate species on the surface of the MgO nanocrystals were thought to be the origin of PL at different wavelengths. Considering the intense PL, high PL stability at ambient conditions, low cost and low toxicity, such MgO NCs might have potential applications in medicine and biology as a new kind of fluorescent label.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Jie Fu, Lei Zhang, Zhaoxiong Xie and Lansun Zheng
Chemical Communications 2011 vol. 47(Issue 23) pp:6722-6724
Publication Date(Web):11 May 2011
DOI:10.1039/C1CC11542A
Three-dimensional, hollow, anatase TiO2 boxes, each was enclosed by six single-crystalline TiO2 plates exposed with highly reactive {001} facets, were facilely obtained by calcining a cubic TiOF2 solid precursor at 500–600 °C. The formation of such particular nanostructures is attributed to the hard self-template restriction and the adsorption of F− ions from the TiOF2.
Co-reporter:Jiawei Zhang;Lei Zhang;Shuifen Xie;Dr. Qin Kuang;Xiguang Han; Zhaoxiong Xie; Lansun Zheng
Chemistry - A European Journal 2011 Volume 17( Issue 36) pp:9915-9919
Publication Date(Web):
DOI:10.1002/chem.201100868
Co-reporter:Jin Kang ; Qin Kuang ; Zhao-Xiong Xie ;Lan-Sun Zheng
The Journal of Physical Chemistry C 2011 Volume 115(Issue 16) pp:7874-7879
Publication Date(Web):April 1, 2011
DOI:10.1021/jp111419w
A necklacelike SnO2/α-Fe2O3 hierarchical heterostructure was successfully fabricated by chemical vapor deposition method, using SnO2 nanowires with the preferential growth direction of [001] direction as template. Element mapping and transmission electron microscopy analysis proved that the hierarchical heterostructure was factually an assembly constructed with a SnO2/α-Fe2O3 nanocable and a series of pure α-Fe2O3 disks, and the interfacial orientation relationship was (100)SnO2//(110)Fe2O3 and [001]SnO2//[001]Fe2O3. Such a novel hierarchical heterostructure has been proved to present enhanced photocatalytic ability to degradation of methylene blue under visible light due to improvement of the hole−electron separation efficiency.
Co-reporter:Ming-Shang Jin, Qin Kuang, Xi-Guang Han, Shui-Fen Xie, Zhao-Xiong Xie, Lan-Sun Zheng
Journal of Solid State Chemistry 2010 Volume 183(Issue 6) pp:1354-1358
Publication Date(Web):June 2010
DOI:10.1016/j.jssc.2010.04.017
Here we proposed a synthetic method of high-purity Ag nanoplates by the reduction of aqueous Ag+ ions at the aqueous–organic interface with the reductant ferrocene. We demonstrated that the as-prepared Ag nanoplates can be widely tunable from 600 nm to 7 μm in size and from 10 to 35 nm in thickness, simply by adjusting the component of organic phase. To our knowledge, there are few methods to tailor the size and the thickness of metal nanoplates in such a large range although many efforts have been made aiming to realize it. Our proposed synthetic strategy is rapid, template-free, seed-less, and high-yield, and could be applied to synthesize analogous two-dimensional nanostructures of other noble metals, such as Pt, Au, and Pd.High-purity Ag nanoplates were synthesized by the reduction of aqueous Ag+ ions at the aqueous–organic interface with the reductant ferrocene, the size and thickness of which were widely tunable.
Co-reporter:Xi-Guang Han, Ya-Qi Jiang, Shui-Fen Xie, Qin Kuang, Xi Zhou, Dao-Ping Cai, Zhao-Xiong Xie and Lan-Sun Zheng
The Journal of Physical Chemistry C 2010 Volume 114(Issue 22) pp:10114-10118
Publication Date(Web):May 13, 2010
DOI:10.1021/jp101284p
In this article, we demonstrate successful application of a top-down strategy based on a selective wet-chemical etching technique in fabrication of nanostructures with a special morphology. Pagoda-like and hexagonal pyramidal ZnO nanostructures with the polar (0001̅) and {101̅1} planes as exposed surfaces have been synthesized by refluxing ZnO columns mainly bounded with {101̅0} nonpolar faces in the mixed solvent of oleic acid (OA) and 1-octylamine. Adequate evidence demonstrates that OA in the mixed solvent acts as the etchant in the process of morphology evolution, and the appropriate proportion of OA, reaction time, and reaction temperature are crucial for controlling the etching degree of ZnO. Through the selective wet-chemical etching, it has been confirmed that the dumbbell-like ZnO is of twinning morphologies growing along contrary direction on both sides of the (0001) twinning plane. Therefore, our present work provides a simple way to estimate the complicated twinning phenomena.
Co-reporter:Xiao-Liang Fang, Yue Li, Cheng Chen, Qin Kuang, Xiang-Zhi Gao, Zhao-Xiong Xie, Su-Yuan Xie, Rong-Bin Huang and Lan-Sun Zheng
Langmuir 2010 Volume 26(Issue 4) pp:2745-2750
Publication Date(Web):December 3, 2009
DOI:10.1021/la902765p
Higher-ordered architectures self-assembly of nanomaterials have recently attracted increasing attention. In this work, we report a spontaneous and efficient route to simultaneous synthesis and self-assembly of 3D layered β-FeOOH nanorods depending on a pH-induced strategy, in which the continuous change of pH is achieved by hydrolysis of FeCl3·6H2O in the presence of urea under hydrothermal conditions. The electron microscopy observations reveal that the square-prismic β-FeOOH nanorods are self-assembled in a side-by-side fashion to form highly oriented 2D nanorod arrays, and the 2D nanorod arrays are further stacked in a face-to-face fashion to form the final 3D layered architectures. On the basis of time-dependent experiments, a multistage reaction mechanism for the formation of the 3D layered β-FeOOH nanorods architecture is presented, involving the fast growth and synchronous self-assembly of the nanorods toward 1D, 2D, and 3D spontaneously. The experimental evidence further demonstrates that the urea-decomposition-dependent pH continuously changing in the solution, spontaneously altering the driving force competition between the electrostatic repulsive force and the attractive van der Waals force among the nanorods building blocks, is the essential factor to influence the self-assembly of the β-FeOOH nanorods from 1D to 3D.
Co-reporter:Xin Wang, Hui-Fang Wu, Qin Kuang, Rong-Bin Huang, Zhao-Xiong Xie and Lan-Sun Zheng
Langmuir 2010 Volume 26(Issue 4) pp:2774-2778
Publication Date(Web):October 9, 2009
DOI:10.1021/la9028172
Ag2O particles with different polyhedral shapes including octahedron, truncated octahedron, and cube were successfully synthesized by a simple wet-chemical method using silver nitrate, ammonia, and sodium hydroxide as raw materials at room temperature. Simply by tuning the concentration of starting materials, the shape of Ag2O particles evolved from octahedron to cube, and the size gradually decreased from 1−2 μm to 400−700 nm. As examples for promising applications, the antibacterial activities of the as-prepared Ag2O polyhedral particles were preliminarily studied. It has been found the antibacterial activity of Ag2O particles against E. coli depends on the shape of Ag2O particles, demonstrating that the surface structure of Ag2O particles affects the antibacterial activity.
Co-reporter:Xiao-Liang Fang, Cheng Chen, Ming-Shang Jin, Qin Kuang, Zhao-Xiong Xie, Su-Yuan Xie, Rong-Bin Huang and Lan-Sun Zheng
Journal of Materials Chemistry A 2009 vol. 19(Issue 34) pp:6154-6160
Publication Date(Web):06 Jul 2009
DOI:10.1039/B905034E
A facile and efficient one-pot solvothermal synthetic route based on a simplified self-assembly is proposed to fabricate spherical hematite colloidal nanocrystal clusters (CNCs) of uniform shape and size. The as-prepared hematite CNCs are composed of numerous nanocrystals of approximately 20 nm in size, and present a single-crystal-like characteristic. A possible formation process based on the nucleation–oriented aggregation–recrystallization mechanism is proposed. Our experiments demonstrated that both the surfactant and the mixed solvent play very critical roles in controlling the size of primary nanocrystals and the final morphology of single-crystal-like spherical CNCs. Compared with other hematite nanostructures, the spherical hematite CNCs show outstanding performance in gas sensing, photocatalysis and water treatment due to their large surface area and porous structure. In addition, interesting tertiary CNCs formed by further assembly of secondary spherical CNCs were observed for the first time.
Co-reporter:Jun Zheng, Zhi-Yuan Jiang, Qin Kuang, Zhao-Xiong Xie, Rong-Bin Huang, Lan-Sun Zheng
Journal of Solid State Chemistry 2009 Volume 182(Issue 1) pp:115-121
Publication Date(Web):January 2009
DOI:10.1016/j.jssc.2008.10.009
In this paper, we report a simple two-step approach to prepare porous octahedron- and rod-shaped ZnO architectures. The morphology of porous ZnO particles can be conveniently tuned by controlling morphologies of the ZnC2O4·2H2O precursor. SEM and TEM characterization results indicate that these porous ZnO architectures are built up by numerous ZnO primary nanoparticles with random attachment. Based on thermogravimetry analysis, we believe that the release of water vapor, CO and CO2 leads to the formation of high-density pores in shape-controlled particles during the calcination process. Further experimental results indicate that as-prepared porous ZnO particles exhibit good photocatalytic activity due to large surface area.In this paper, we report a simple two-step approach to prepare porous octahedron- and rod-shaped ZnO architectures. The morphology of the porous ZnO nanostructures can be conveniently tailored by controlling the morphologies of the precursor ZnC2O4·2H2O.
Co-reporter:Shuifen Xie, Xi Zhou, Xiguang Han, Qin Kuang, Mingshang Jin, Yaqi Jiang, Zhaoxiong Xie and Lansun Zheng
The Journal of Physical Chemistry C 2009 Volume 113(Issue 44) pp:19107-19111
Publication Date(Web):October 8, 2009
DOI:10.1021/jp907651d
Guided by the concept of regarding nanoparticles as superatoms or supermolecules in colloidal solution, we design a facile crystallization approach for preparation of 3D supercrystals (SCs). Dispersive states of as-prepared MnO nanocrystals (NCs) in solvents of cyclohexane and ethanol were studied to illuminate the effects of solvents. Ethanol was demonstrated to be the most appropriate solvent, and a large amount of microscale cubic SCs built by octahedral MnO NCs was created via direct crystallization. Although two types of packing structures are well-defined, the MnO SCs prefer the one with the higher packing efficiency of 88.89% for minimizing system energy. The crystallization process undergoes a dynamic attachment and exchange mechanism.
Co-reporter:Xiguang Han;Mingshang Jin;Shuifen Xie, Dr.;Zhiyuan Jiang Dr.;Yaqi Jiang;Zhaoxiong Xie ;Lansun Zheng
Angewandte Chemie 2009 Volume 121( Issue 48) pp:9344-9347
Publication Date(Web):
DOI:10.1002/ange.200903926
Co-reporter:Xiguang Han;Mingshang Jin;Shuifen Xie, Dr.;Zhiyuan Jiang Dr.;Yaqi Jiang;Zhaoxiong Xie ;Lansun Zheng
Angewandte Chemie International Edition 2009 Volume 48( Issue 48) pp:9180-9183
Publication Date(Web):
DOI:10.1002/anie.200903926
Co-reporter:Xi-Guang Han, Ming-Shang Jin, Qin Kuang, Xi Zhou, Zhao-Xiong Xie and Lan-Sun Zheng
The Journal of Physical Chemistry C 2009 Volume 113(Issue 7) pp:2867-2872
Publication Date(Web):2017-2-22
DOI:10.1021/jp8092836
In this paper, we successfully synthesized six-horn-like branched MnO nanocrystals by thermal decomposition of Mn(CH3CO2)2·4H2O in the present of 1-octylamine/oleic acid (OA) at 400 °C for 30 min. SEM and TEM observation indicate that every horn of six-horn-like MnO nanocrystals is constructed with a bundle of nanorods growing along the [100] direction. Adequate evidence provided by time- and temperature-dependent experiments demonstrates that the formation of such branched MnO can be divided into two processes, i.e., the formation of octahedron-based MnO exposed with polar surfaces and sequent directional etching. In this mechanism, the mixed solvent of organic amines and OA provides favorable circumstances for the formation of MnO octahedra, and at the same time, OA as the etching reagent is responsible for the evolution of six-horn-like MnO from octahedron-based MnO.
Co-reporter:Mingshang Jin, Qin Kuang, Zhiyuan Jiang, Tao Xu, Zhaoxiong Xie, Lansun Zheng
Journal of Solid State Chemistry 2008 Volume 181(Issue 9) pp:2359-2363
Publication Date(Web):September 2008
DOI:10.1016/j.jssc.2008.05.034
High-yield silver/polymer/carbon nanocables were synthesized via a one-step simple hydrothermal route by using silver chloride and glucose as precursors. High-resolution TEM and element mapping proved that as-prepared nanocables consist of a silver nanowire core, a polymer inner shell, and a graphitic carbon outer shell. A three-step growth mechanism was proposed to explain the growth of such three-layer nanocables, i.e. the formation of silver nanowires, the glycosidation of glucose molecules on silver nanowire surface and the carbonization of the outmost glycosidation layer. We believe that reaction temperature plays the key role in the polymerization of glucose and sequent surface-carbonization.High-yield silver/polymer/carbon coaxial nanocables were synthesized via a one-step simple hydrothermal route by using silver chloride and glucose as precursors. Our experiments indicate that such novel nanostructures formed through the growth mechanism that the silver nanowires grow first, and then glycosidation of glucose occurs on the silver nanowire surfaces, and finally the partial carbonization occurs on the outmost surface of the polymer layer.
Co-reporter:Yanyun Ma, Dr.;Zhiyuan Jiang Dr.;Zhaoxiong Xie ;Rongbin Huang ;Lansun Zheng
Angewandte Chemie International Edition 2008 Volume 47( Issue 46) pp:8901-8904
Publication Date(Web):
DOI:10.1002/anie.200802750
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Jie Fu, Lei Zhang, Zhaoxiong Xie and Lansun Zheng
Chemical Communications 2011 - vol. 47(Issue 23) pp:NaN6724-6724
Publication Date(Web):2011/05/11
DOI:10.1039/C1CC11542A
Three-dimensional, hollow, anatase TiO2 boxes, each was enclosed by six single-crystalline TiO2 plates exposed with highly reactive {001} facets, were facilely obtained by calcining a cubic TiOF2 solid precursor at 500–600 °C. The formation of such particular nanostructures is attributed to the hard self-template restriction and the adsorption of F− ions from the TiOF2.
Co-reporter:Yiting Wang, Yinyun Lü, Wenwen Zhan, Zhaoxiong Xie, Qin Kuang and Lansun Zheng
Journal of Materials Chemistry A 2015 - vol. 3(Issue 24) pp:NaN12803-12803
Publication Date(Web):2015/05/06
DOI:10.1039/C5TA01108F
Shape-controllable porous, hollow metal oxide cages are attracting more and more attention due to their widespread applications. In this paper, octahedral, truncated octahedral and cubic Cu2O/CuO cages were successfully fabricated by the thermal decomposition of the polyhedral crystals of Cu-based metal–organic frameworks (Cu-MOFs) as self-sacrificial templates at 300 °C. The morphology of the Cu-MOF polyhedral precursors was well tuned by using lauric acid as the growth modulator under solvothermal conditions. Gas-sensing measurements revealed that the octahedral Cu2O/CuO cages exhibited a gas-sensing performance far better than those exhibited by truncated octahedral and cubic cages, which is attributed to the cooperative effect of the large specific surface area (150.3 m2 g−1) and high capacity of surface-adsorbed oxygen of the octahedral Cu2O/CuO cages.
Co-reporter:Xiao-Liang Fang, Cheng Chen, Ming-Shang Jin, Qin Kuang, Zhao-Xiong Xie, Su-Yuan Xie, Rong-Bin Huang and Lan-Sun Zheng
Journal of Materials Chemistry A 2009 - vol. 19(Issue 34) pp:NaN6160-6160
Publication Date(Web):2009/07/06
DOI:10.1039/B905034E
A facile and efficient one-pot solvothermal synthetic route based on a simplified self-assembly is proposed to fabricate spherical hematite colloidal nanocrystal clusters (CNCs) of uniform shape and size. The as-prepared hematite CNCs are composed of numerous nanocrystals of approximately 20 nm in size, and present a single-crystal-like characteristic. A possible formation process based on the nucleation–oriented aggregation–recrystallization mechanism is proposed. Our experiments demonstrated that both the surfactant and the mixed solvent play very critical roles in controlling the size of primary nanocrystals and the final morphology of single-crystal-like spherical CNCs. Compared with other hematite nanostructures, the spherical hematite CNCs show outstanding performance in gas sensing, photocatalysis and water treatment due to their large surface area and porous structure. In addition, interesting tertiary CNCs formed by further assembly of secondary spherical CNCs were observed for the first time.
Co-reporter:Shuifen Xie, Xiguang Han, Qin Kuang, Yang Zhao, Zhaoxiong Xie and Lansun Zheng
Journal of Materials Chemistry A 2011 - vol. 21(Issue 20) pp:NaN7268-7268
Publication Date(Web):2011/04/15
DOI:10.1039/C1JM10745C
We report fancy brilliant photoluminescence (PL) from surface functionalized MgO nanocrystal clusters (NCs). Single-crystal-like MgO NCs were prepared by a simple one-pot pyrolysis method in the mixed organic solvent of octylamine (OTA) and oleic acid (OA) using magnesium acetate as a precursor. Under the chemical equilibrium of etching and re-growth with the assistance of OA, the MgO products were surface functionalized. It was found that such surface functionalized MgO NCs exhibited intense visible light PL with high PL thermal-stability, and the apparent quantum yield was as high as 19 ± 1%. In addition, through controlling the synthetic temperature and the reaction time, the functionalized surfaces of MgO NCs were facilely tuned, resulting in the tuneable wavelength of the PL from blue-violet to yellow. Different low-coordinated oxygen sites, capping OA and carbonate species on the surface of the MgO nanocrystals were thought to be the origin of PL at different wavelengths. Considering the intense PL, high PL stability at ambient conditions, low cost and low toxicity, such MgO NCs might have potential applications in medicine and biology as a new kind of fluorescent label.
Co-reporter:Qin Kuang, Xi Zhou and Lan-Sun Zheng
Inorganic Chemistry Frontiers 2014 - vol. 1(Issue 2) pp:NaN192-192
Publication Date(Web):2014/01/24
DOI:10.1039/C3QI00064H
In this paper, ZnO/SnO2 core–shell micropyramids were successfully prepared via a chemical vapor deposition process that is based on the epitaxial growth of SnO2 on the surface of ZnO hexagonal micropyramids. Upon controlling appropriate deposition times and flow rates of the precursor, two epitaxial growth modes of SnO2, i.e. a continuous thick film and well-arranged one-dimensional nanostructures were observed in the ZnO/SnO2 core–shell micropyramids. Taking advantages of the difference in acid resistance between ZnO and SnO2, the as-prepared ZnO/SnO2 micropyramids were further converted into SnO2 hollow micropyramids with a facile acid-etching treatment. Structural analysis revealed that the lattice mismatch degree between epitaxial planes determines the preferential growth direction of the SnO2 epitaxial layer on the ZnO surface. Compared to the pristine ZnO template, interestingly, the ZnO/SnO2 core–shell micropyramids exhibited very strong green emission around 504 nm. Such enhanced green emission should be induced by high-density structural defects generated in the interfacial area during the epitaxial growth.
