Co-reporter:Yueyao Zhong, Yongliang Shao, Fukun Ma, Yongzhong Wu, Baibiao Huang, Xiaopeng Hao
Nano Energy 2017 Volume 31() pp:84-89
Publication Date(Web):January 2017
DOI:10.1016/j.nanoen.2016.11.011
•Suitable band engineering is important in separating photoinduced electron-hole pairs.•Based on the band engineering theory and the quantum size effect, we designed a band-gap-matched photocatalyst.•This photocatalyst shows high-efficiency photocatalytic activity (14 mmol h-1) and high-stability.Suitable band engineering is required in order to develop new photocatalysts for water splitting under visible light irradiation. Based on the quantum size effect, the band gap energy varies with the size of the quantum dots (QDs) tuning. Besides, tuning the band gap energy of CdSe QDs can match well with the band gap energy of WS2 nanosheets, which is benefiting the separation of electron-hole pairs generated in CdSe QDs under irradiation. Some links exist between the photocatalytic activity and band gap energy of QDs. The highest rate of hydrogen evolution under visible light irradiation is 14 mmol h−1 with 58% quantum efficiency at wavelength λ=420 nm when the QDs size is 7–8 nm and the band gap of QDs is 1.48 eV. Designing and fabricating band gap energy matched nanocomposite photocatalysts can present potential applications in solving future clean energy problems.
Co-reporter:Fukun Ma;Changlong Sun;Yongliang Shao;Yongzhong Wu;Baibiao Huang
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 8) pp:3061-3067
Publication Date(Web):2017/04/10
DOI:10.1039/C7NJ00035A
Exfoliation and functionalisation of two-dimensional (2D) nanosheets are highly desired for the improvement of their chemical and physical properties. Herein, we propose a novel and efficient method for the preparation of fluorinated graphite carbon nitride (F-C3N4) nanosheets with enhanced photocatalytic activities. A one-step route was used to exfoliate and fluorinate the graphite carbon nitride (g-C3N4) nanosheets by using g-C3N4 powder combined with ammonium fluoride (NH4F). Through related instrumental characterisation, we confirmed that few-layered F-C3N4 nanosheets were produced successfully. Meanwhile, the enhanced hydrogen evolution rate of F-C3N4 nanosheets (477.6 µmol h−1 g−1) also confirmed the feasibility of this exfoliation method. This report not only opens up new possibilities for the rational design of metal-free F-C3N4 nanosheets with stable photochemical applications but also provides a potential method for producing functionalised 2D materials.
Co-reporter:Fukun Ma;Mengxia Wang;Yongliang Shao;Lijuan Wang;Yongzhong Wu;Zhengping Wang
Journal of Materials Chemistry C 2017 vol. 5(Issue 10) pp:2559-2565
Publication Date(Web):2017/03/09
DOI:10.1039/C7TC00131B
Boron carbon nitride (BCN) nanosheets have gained increased attention as a novel semiconductor because of their controllable band-gap and environmentally-friendly properties. This study presents a facile ‘thermal substitution’ method for preparing BCN nanosheets through substitutional C doping into hexagonal boron nitride nanosheets (BNNSs) at 850 °C. ‘Thermal substitution’ is an effective method used to tune the band-gap of BCN nanosheets by adjusting the amount of carbon atoms incorporated. After irradiation by laser pulses at 1064 and 532 nm, the as-obtained BCN nanosheets exhibit excellent nonlinear optical (NLO) performance. The NLO absorption properties of the nanosheets shift from saturable absorption to reverse saturable absorption. The corresponding NLO performance can be adjusted by controlling the carbon content in the BCN nanosheets. The developed BCN nanosheets can be utilised as a new and advanced NLO material for sensitive optical components and laser protection.
Co-reporter:Tailin Wang, Changlong Sun, Mingzhi Yang, Gang Zhao, Shouzhi Wang, Fukun Ma, Lei Zhang, Yongliang Shao, Yongzhong Wu, Baibiao Huang, Xiaopeng Hao
Journal of Alloys and Compounds 2017 Volume 716(Volume 716) pp:
Publication Date(Web):5 September 2017
DOI:10.1016/j.jallcom.2017.05.071
•The metallic phase (1T) MoS2 was induced by the incorporation of nitride element.•3D self-supporting 1T@2H MoS2@CC as flexible anode was constructed.•The phase transition of MoS2 exhibited outstanding electrochemical performance than that of pure 2H MoS2.•The energy storage mechanism of 1T@2H MoS2@CC electrode was investigated.Nanostructured MoS2 is emerging as a prospective material for lithium ion batteries. However, undesirable lattice stress results in inhomogeneous phase change and slow kinetics, which leads to rapid decay of cyclic stability. Initial phase conversion before the electrochemical intercalation can alleviate this problem. Herein, MoS2 nanosheets with partial 2H→1T phase transition under incorporative nitrogen atoms were synthesized controllably on the carbon cloth (CC). The hierarchical self-supporting three-dimensional (3D) 1T@2H MoS2@CC was confirmed and such a freestanding flexible electrode exhibited a significant improvement in the electrochemical characteristics. A strong correlation between such phase transition properties and electrochemical characteristics is established. This work provides an intriguing and effective approach on phase engineering of transition metal dichalcogenides (TMDs) for enhanced electrochemical energy storage.Download high-res image (420KB)Download full-size image
Co-reporter:Bin Chang;Gang Zhao;Yongliang Shao;Lei Zhang;Baibiao Huang;Yongzhong Wu
Journal of Materials Chemistry A 2017 vol. 5(Issue 34) pp:18038-18043
Publication Date(Web):2017/08/29
DOI:10.1039/C7TA05642G
Efficient and stable electrocatalysts for the hydrogen evolution reaction (HER) are central to the development of renewable energy. In this study, a photoresponse electrocatalyst Ni3(VO4)2 with a sea-urchin shaped structure was prepared by a facile solvothermal procedure. Numerous thin nanoflakes on the spherical surface increased active sites which play a promoting role in the photocatalytic or electrocatalytic reactions. Under visible light irradiation, the sea-urchin shaped Ni3(VO4)2 demonstrated improved HER activity without using any cocatalysts, featured by a small overpotential of −90 mV at 10 mA cm−2, a high current density, a small Tafel slope of 50 mV per decade and good stability in 0.5 M H2SO4. The results may offer a simple and mild methodology for the preparation of HER electrocatalysts exhibiting excellent photo-enhanced electrocatalytic activity.
Co-reporter:Shouzhi Wang;Lei Zhang;Changlong Sun;Yongliang Shao;Yongzhong Wu;Jiaxin Lv
Advanced Materials 2016 Volume 28( Issue 19) pp:3768-3776
Publication Date(Web):
DOI:10.1002/adma.201600725
Co-reporter:Gang Zhao, Yongzhong Wu, Yongliang Shao and Xiaopeng Hao
Nanoscale 2016 vol. 8(Issue 10) pp:5407-5411
Publication Date(Web):08 Feb 2016
DOI:10.1039/C5NR07950K
With the increasing demand for two-dimensional (2D) nanosheets, such as graphene, hexagonal boron nitride (h-BN), and MoS2 and WS2 nanosheets, finding a simple and feasible method to obtain nanosheets is crucial. Here, we present a high-efficiency exfoliation method to obtain abundant and superior graphene, h-BN, MoS2, and WS2 nanosheets in aqueous solution. The obtained 2D nanosheets are very thin, especially MoS2 and WS2 nanosheets which are below 1 nm.
Co-reporter:Gang Zhao;Fang Zhang;Yongzhong Wu;Zhengping Wang;Xinguang Xu
Advanced Optical Materials 2016 Volume 4( Issue 1) pp:141-146
Publication Date(Web):
DOI:10.1002/adom.201500415
Hexagonal boron nitride (h-BN) nanosheets are attracting increased attention because of their excellent optical properties. Inspired by the natural exfoliation of seaside rocks, we propose a “chemical weathering” concept for fabricating h-BN nanosheets from their bulk counterparts. We experimentally demonstrate that chemical weathering-assisted exfoliation is a simple and efficient method for preparing h-BN nanosheets. These nanolayers have a high solubility in water because of the hydroxylation of h-BN (OH-BNNS). Interestingly, the as-prepared OH-BNNSs exhibit excellent optical limiting properties with fascinating two-photon absorption. It is a new and advanced optical material in the application of sensitive optical components, and shield human eyes from laser-induced damage.
Co-reporter:Fukun Ma, Gang Zhao, Chen Li, Tailin Wang, Yongzhong Wu, Jiaxin Lv, Yueyao Zhong and Xiaopeng Hao
CrystEngComm 2016 vol. 18(Issue 4) pp:631-637
Publication Date(Web):21 Dec 2015
DOI:10.1039/C5CE02327K
In this study, the nanocomposites of cadmium sulfide (CdS) nanoparticles and hexagonal boron nitride nanosheets (BNNSs) were fabricated through in situ growing of CdS nanoparticles on BNNSs. The microstructure of the nanocomposites was clearly demonstrated. Compared with pure CdS nanoparticles, CdS/BNNSs nanocomposites show more efficient photocatalytic H2 production. The rate of H2 evolution can be doubled under the optimum conditions. The enhancement of photocatalytic H2 evolution is attributed to the ultrathin BNNSs. It is speculated that the BNNSs not only broaden the photo-absorption region, but also realized effective electronic communication through the connection between CdS nanoparticles and BNNSs. This new finding provides a promising way to design and fabricate more efficient photocatalysts based on BNNSs.
Co-reporter:Fukun Ma, Yongzhong Wu, Yongliang Shao, Yueyao Zhong, Jiaxin Lv, Xiaopeng Hao
Nano Energy 2016 Volume 27() pp:466-474
Publication Date(Web):September 2016
DOI:10.1016/j.nanoen.2016.07.014
•The photocorrosion of CdS is prevented in the 0D/2D CdS/MoS2 nanosheet system.•A photocorrosion-recrystallization strategy is proposed to resolve photocorrosion.•The as-obtained nanocomposite shows stable and efficient photocatalytic activity.•The recrystallization is verified by the mixtures of CdS with MoS2 or WS2 nanosheets.CdS systems represent promising photocatalysts for hydrogen generation; however, these systems are seriously restricted by inherent issues with photocorrosion. Here, the CdS photocorrosion process is prevented and a high stable and effective photocatalyst is obtained in the novel 0D/2D CdS/MoS2 nanosheet composite system. According to crystallization kinetics, the CdS photocorrosion process will be prevented if the S elements resulting from photocorrosion can be reduced back to S2− in the same photocatalytic system. So a photocorrosion-recrystallization strategy is proposed for the first time to resolve issues with photocorrosion when using CdS photocatalysts. Meanwhile, the recrystallized 0D/2D CdS/MoS2 nanocomposite produces a high quantum efficiency of 23.03% (λex=420 nm), the evolution of hydrogen presents no notable activity losses for up to 400 h. Thus, the approach demonstrated here represents a promising method of designing and fabricating more stable and efficient composite chalcogenide photocatalysts.A photocorrosion-recrystallization strategy is proposed to improve photocatalytic performances and resolve issues with photocorrosion for CdS photocatalysts. The obtained CdS/MoS2 nanocomposite shows highly efficient and stable photocatalytic activity for hydrogen generation.
Co-reporter:Gang Zhao;Shuo Han;Aizhu Wang;Yongzhong Wu;Mingwen Zhao;Zhengping Wang
Advanced Functional Materials 2015 Volume 25( Issue 33) pp:5292-5299
Publication Date(Web):
DOI:10.1002/adfm.201501972
2D transition metal dichalcogenides are attracting increased attention because of their excellent electronic and optical properties. Inspired by the natural weathering exfoliation of seaside rocks, a “chemical weathering” concept for fabricating atom-thick 2D materials from their bulk counterparts is proposed. It is experimentally demonstrated that chemical weathering-assisted exfoliation mechanism is a simple and efficient method of preparing atom-thick MoS2 and WS2 monolayers. These monolayers are difficult to prepare using other approaches. Interestingly, the as-prepared MoS2 and WS2 monolayers exhibit excellent saturable absorption and mode-locking properties in all-solid-state lasers because of intermediate states resulting from S-vacancy defects. The obtained passively Q-switched laser operation with 60 ns pulse width and ultrafast mode locking with 8.6 ps pulse width are promising for all-solid-state laser application.
Co-reporter:Lei Zhang, Xianlei Li, Yongliang Shao, Jiaoxian Yu, Yongzhong Wu, Xiaopeng Hao, Zhengmao Yin, Yuanbin Dai, Yuan Tian, Qin Huo, Yinan Shen, Zhen Hua, and Baoguo Zhang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 8) pp:4504
Publication Date(Web):February 9, 2015
DOI:10.1021/am5087775
The progress in nitrides technology is widely believed to be limited and hampered by the lack of high-quality gallium nitride wafers. Though various epitaxial techniques like epitaxial lateral overgrowth and its derivatives have been used to reduce defect density, there is still plenty of room for the improvement of gallium nitride crystal. Here, we report graphene or hexagonal boron nitride nanosheets can be used to improve the quality of GaN crystal using hydride vapor phase epitaxy methods. These nanosheets were directly deposited on the substrate that is used for the epitaxial growth of GaN crystal. Systematic characterizations of the as-obtained crystal show that quality of GaN crystal is greatly improved. The fabricated light-emitting diodes using the as-obtained GaN crystals emit strong electroluminescence under room illumination. This simple yet effective technique is believed to be applicable in metal–organic chemical vapor deposition systems and will find wide applications on other crystal growth.Keywords: boron nitride nanosheets; GaN; graphene; hydride vapor phase epitaxy; light-emitting diodes
Co-reporter:Zhiliang Xiu, Xiaopeng Hao, Yongzhong Wu, Qifang Lu, Suwen Liu
Journal of Power Sources 2015 Volume 287() pp:334-340
Publication Date(Web):1 August 2015
DOI:10.1016/j.jpowsour.2015.04.086
•Graphene-bonded and -enwrapped mesoporous TiO2 microspheres were fabricated.•An ex situ hybridization method without using any chemical reagents was developed.•The graphene modification improves the conductivity of TiO2.•The composites exhibited excellent electrochemical performances.A facile procedure are developed to fabricate graphene-bonded and -enwrapped mesoporous anatase TiO2 microspheres (GMTMs) using graphene oxide (GO) and titanium glycolate microspheres (TGMs) as precursors without using any cross-linking reagents. Highly nanoporous TiO2 spheres are generated via in situ hydrolysis of the TGMs and then wrapped by GO nanosheets over their surface through covalent linkage during a reflux process. After hydrothermal treatment and calcination in an Ar atmosphere, the crystallization of TiO2 and the reduction of GO is significantly increased simultaneously. Electrochemical performance of the mesoporous TiO2 microspheres (MTMs) enwrapped with chemically-bonded graphene is greatly improved in terms of specific capacity, rate capability and cycle stability. The composite material shows a discharge capacity of 170 mA h g−1 at the 10 C rate, which is much higher than that of the pristine TiO2 microspheres (116 mA h g−1).
Co-reporter:Gang Zhao;Jia Hou;Yongzhong Wu;Jingliang He
Advanced Optical Materials 2015 Volume 3( Issue 7) pp:937-942
Publication Date(Web):
DOI:10.1002/adom.201500012
Co-reporter:Qingqing Du, Wenpeng Wang, Yongzhong Wu, Gang Zhao, Fukun Ma and Xiaopeng Hao
RSC Advances 2015 vol. 5(Issue 39) pp:31057-31063
Publication Date(Web):26 Mar 2015
DOI:10.1039/C5RA02613J
Novel UV and visible light photocatalytic carbon dots/BiOBr nanocomposites were prepared for the first time. The structures, morphologies, optical, photoelectrochemical and photocatalytic properties were investigated. The results indicated that the carbon dots (CDs) combined well with BiOBr. An appropriate amount of introduced CDs can significantly enhance the photocatalytic activities under both UV and visible light irradiation. The enhanced activities were mainly attributed to the enhanced light absorption and the interfacial transfer of photogenerated electrons. The corresponding photocatalytic mechanism was proposed based on the results.
Co-reporter:Wenbin Jia, Peng Yang, Junjie Li, Zhengmao Yin, Lin Kong, Hongbo Lu, Zhishen Ge, Yongzhong Wu, Xiaopeng Hao and Jiaxiang Yang
Polymer Chemistry 2014 vol. 5(Issue 7) pp:2282-2292
Publication Date(Web):27 Nov 2013
DOI:10.1039/C3PY01550E
A novel cyanostilbene derivative (I) is synthesized and sufficiently characterized, which is also utilized as the initiator to prepare poly(ε-caprolactone) (I-PCL) and poly(D,L-lactide) (I-PLA) via ring-opening polymerization (ROP). Notably, molecule I exhibits superior aggregation-induced enhanced emission (AIEE) behavior in the mixed solvent of THF and water. The bulky cyano groups are linked to vinylene moieties in molecule (I) generating intramolecular coplanarity and preventing π–π stacking, which leads to enhanced emission in the aggregated state. Crystallographic data of I confirm that the existence of multiple intermolecular interactions among adjacent molecules restricts intramolecular vibration and rotation. In addition, molecule I can self-organize into ordered microtubes in appropriate THF/water mixtures exhibiting significant optical waveguide properties. Furthermore, the polymers, I-PCL and I-PLA, also show AIEE behaviors since the single chromophore I is anchored on the polymer chains. As compared with the corresponding small molecule I, the target polymers possess not only preferable thermostabilities but also the property of easy fabrication. The luminogen aggregation of the initiator is well-realized and even enlarged after polymerization, due to the linkage of polymer chains. In the end, the polymer I-PLA has a great prospect in white light-emitting diode (LED) application, which emits daylight white light.
Co-reporter:Yuan Tian, Lei Zhang, Yongzhong Wu, Yongliang Shao, Yuanbin Dai, Haodong Zhang, Rusheng Wei and Xiaopeng Hao
CrystEngComm 2014 vol. 16(Issue 11) pp:2317-2322
Publication Date(Web):10 Jan 2014
DOI:10.1039/C3CE41404C
In this paper, a high temperature annealing (HTA) method is proposed to characterize dislocations in GaN prepared by metal–organic chemical vapor deposition (MOCVD) on c-plane (0001) sapphire. The templates were each annealed at different temperatures for 5 min. Molten KOH–NaOH eutectic (E) etching was also applied (at 500 °C for 30 min) to test and verify this new method. A comparison between the HTA template and the E etching template was made. The morphology and distribution of HTA pits and E etching pits were examined using scanning electron microscopy (SEM). Atomic force microscopy (AFM) was employed to study the shape of the HTA pits. Transmission electron microscopy (TEM) and cathodoluminescence (CL) investigation were used to further confirm the origin and density of the dislocations.
Co-reporter:Lei Zhang, Yuanbin Dai, Yongzhong Wu, Yongliang Shao, Yuan Tian, Qin Huo, Xiaopeng Hao, Yinan Shen and Zhen Hua
CrystEngComm 2014 vol. 16(Issue 38) pp:9063-9068
Publication Date(Web):05 Aug 2014
DOI:10.1039/C4CE01188K
In this paper, a MOCVD-GaN/Al2O3 (MGA) template was annealed under appropriate annealing conditions and N2 flow to form a porous template. The porous template was used for growing GaN by HVPE. The GaN crystal was easily separated from the porous template with the assistance of the microporous structure. The self-separated GaN crystal grown on the porous template showed a smaller full width at half maximum (FWHM) for (002) and (102) reflections in the HRXRD measurement than that grown on the MGA template. The PL results indicate that the optical quality of the GaN crystal on the porous template was improved and the dislocation density decreased. The Raman results showed that the stress in the GaN crystal grown on the porous template is much smaller than that on the MGA template. These results show that the crystalline quality of GaN crystals was improved by using the porous template.
Co-reporter:Xue Zhao, Shengjiang Wang, Weijia Zhang, Jichuan Qiu, Yongzhong Wu, Hongzhi Liu, Chengwei Xu and Xiaopeng Hao
RSC Advances 2014 vol. 4(Issue 2) pp:598-604
Publication Date(Web):31 Oct 2013
DOI:10.1039/C3RA45873C
The CdTe QDs coated by octa-mercaptopropyl polyhedral oligomeric silsesquioxane (OM-POSS) were successfully applied in cell labeling as a fluorescent probe. SiHa cells and mouse preosteoblast cells MC3T3-E1 were employed to evaluate the cell toxicity of the POSS-CdTe QDs and CdTe QDs. The cells incubated with POSS-CdTe QDs show higher viability than those with CdTe QDs under the same conditions. More POSS-CdTe QDs are internalized into cells via endocytosis than CdTe QDs during the same incubation time, which is vividly exhibited in laser confocal images. The highly biocompatible CdTe QDs with amphiphilic OM-POSS coating allow rapid intracellular uptake, enabling the use of lower concentrations of QDs for an overall reduced toxicity. The as-prepared POSS-CdTe QDs have enormous potential for long-term live cell and in vivo imaging applications.
Co-reporter:Zhiliang Xiu, Hai Bo, Yongzhong Wu, Xiaopeng Hao
Applied Surface Science 2014 Volume 289() pp:394-399
Publication Date(Web):15 January 2014
DOI:10.1016/j.apsusc.2013.10.175
Highlights
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C3N4 modified Ag3PO4 nanoparticles were prepared by a chemisorption method.
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The coupled photocatalysts exhibited highly enhanced photocatalytic performance.
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The matching band potentials led to an improved separation efficiency.
Co-reporter:Yuanbin Dai, Yongzhong Wu, Lei Zhang, Yongliang Shao, Yuan Tian, Qin Huo, Peng Zhang, Xingzhong Cao and Xiaopeng Hao
RSC Advances 2014 vol. 4(Issue 66) pp:35106-35111
Publication Date(Web):30 Jul 2014
DOI:10.1039/C4RA04637D
An original high temperature annealing (HTA) technology has been established to fabricate a porous substrate with a layer of inverted pyramid structures. The details about the formation of the porous substrate and the related mechanism were discussed. It was proved that the porous structures were formed through an etching-like mechanism assisted by SiO2 patterned masks. High-quality GaN crystals have been prepared using the as-prepared porous substrate. The growth experiments demonstrated that such porous substrates were mechanically fragile. The porous structures are suitable to be used as a release layer for the growth of GaN crystals with low stress and defect density.
Co-reporter:Yuanbin Dai, Yongliang Shao, Yongzhong Wu, Xiaopeng Hao, Peng Zhang, Xingzhong Cao, Lei Zhang, Yuan Tian and Haodong Zhang
RSC Advances 2014 vol. 4(Issue 41) pp:21504-21509
Publication Date(Web):23 Apr 2014
DOI:10.1039/C3RA46940A
GaN crystals were grown on MOCVD-GaN/Al2O3 templates (MGA) and MOCVD-GaN/6H–SiC templates (MGS) in a hydride vapour phase epitaxy (HVPE) process where the V/III ratio was controlled. The tensile stress that exists in MGS was controlled by an increasing V/III ratio. The compressive stress that appears in MGA was controlled by a decreasing V/III ratio. The mechanism of stress control using the V/III ratio is discussed in terms of the interrelation of the stress, the V/III ratio and the crystal growth. The stress in these two kinds of substrates causes differences in atomic mobility which may be compensated by varying the V/III ratio. It is found that a larger V/III ratio results in a higher atomic mobility. Thus, atomic mobility is retarded by compressive stress and increased by tensile stress. This method of stress control has been shown to provide worthwhile guidance for GaN growth on different templates, and under different conditions in other investigations.
Co-reporter:Xue Zhao, Weijia Zhang, Yongzhong Wu, Hongzhi Liu and Xiaopeng Hao
New Journal of Chemistry 2014 vol. 38(Issue 7) pp:3242-3249
Publication Date(Web):07 May 2014
DOI:10.1039/C4NJ00322E
Highly biocompatible near-infrared-emitting CdSeTe alloyed quantum dots (QDs) were fabricated in aqueous medium with octa-aminopropyl polyhedral oligomeric silsesquioxane (OA-POSS) as the capping agent. By changing the size and composition of CdSeTe alloyed QDs the fluorescence emission peak reached the near infrared (NIR) region (681 nm) with a photoluminescent quantum yield (QY) of 26.4%. POSS–CdSeTe QDs were prepared by conjugating OA-POSS to CdSeTe QDs through condensation reaction utilizing EDC. And the optical properties of CdSeTe QDs were retained with improved biocompatibility. Furthermore, the as-prepared NIR-emitting POSS–CdSeTe alloyed QDs have been successfully applied to SiHa cell imaging, which demonstrates their promising applications in the biomedical field.
Co-reporter:Miao Du;Xianlei Li;Aizhu Wang; Yongzhong Wu; Xiaopeng Hao; Mingwen Zhao
Angewandte Chemie International Edition 2014 Volume 53( Issue 14) pp:3645-3649
Publication Date(Web):
DOI:10.1002/anie.201308294
Abstract
A novel, simple, and efficient method for the preparation of the fluorinated hexagonal boron nitride nanosheets (F-BNNSs) and the corresponding magnetic properties is presented. A one-step route is used to exfoliate and fluorinate the BNNSs by ammonium fluoride (NH4F) from hexagonal boron nitride (h-BN) powder. Through related instrument characterizations and theoretical calculations, we confirm that large-area and few-layer F-BNNSs were successfully produced by this method, which can be attributed to a fluorination-assisted exfoliation mechanism from the bulk h-BN in NH4F. More intriguingly, we initially verified that the as-prepared F-BNNSs exhibit ferromagnetic characteristics, which would have good potential applications in spintronic devices.
Co-reporter:Miao Du;Xianlei Li;Aizhu Wang; Yongzhong Wu; Xiaopeng Hao; Mingwen Zhao
Angewandte Chemie 2014 Volume 126( Issue 14) pp:3719-3723
Publication Date(Web):
DOI:10.1002/ange.201308294
Abstract
A novel, simple, and efficient method for the preparation of the fluorinated hexagonal boron nitride nanosheets (F-BNNSs) and the corresponding magnetic properties is presented. A one-step route is used to exfoliate and fluorinate the BNNSs by ammonium fluoride (NH4F) from hexagonal boron nitride (h-BN) powder. Through related instrument characterizations and theoretical calculations, we confirm that large-area and few-layer F-BNNSs were successfully produced by this method, which can be attributed to a fluorination-assisted exfoliation mechanism from the bulk h-BN in NH4F. More intriguingly, we initially verified that the as-prepared F-BNNSs exhibit ferromagnetic characteristics, which would have good potential applications in spintronic devices.
Co-reporter:Zhiliang Xiu, Yongzhong Wu, Xiaopeng Hao, Qifang Lu, Suwen Liu
Materials Research Bulletin 2014 59() pp: 192-198
Publication Date(Web):
DOI:10.1016/j.materresbull.2014.07.020
Co-reporter:Xianlei Li;Mingwen Zhao;Yongzhong Wu;Jiaxiang Yang;Yupeng Tian;Guodong Qian
Advanced Materials 2013 Volume 25( Issue 15) pp:2200-2204
Publication Date(Web):
DOI:10.1002/adma.201204031
Co-reporter:Xue Zhao, Jie Du, Yongzhong Wu, Hongzhi Liu and Xiaopeng Hao
Journal of Materials Chemistry A 2013 vol. 1(Issue 38) pp:11748-11753
Publication Date(Web):24 Jul 2013
DOI:10.1039/C3TA12335A
CdTe quantum dots coated by octamercaptopropyl polyhedral oligomeric silsesquioxane (OM-POSS) were applied to detect trace Cu2+. This detection method is based on selectively quenching the fluorescence originating from the CdTe QDs in the presence of Cu2+. The research showed a low interference response of the POSS-coated CdTe QDs towards other metal ions. The POSS-coated CdTe QDs obtained a higher sensitivity than NAC-coated CdTe QDs. The quenching mechanism is discussed on the basis of the competitive binding of the thiol groups of the OM-POSS between the CdTe QDs and the metal ions. The Stern–Volmer plots at different temperatures show that the fluorescence of the POSS-coated CdTe QDs was quenched by Cu2+ through a static quenching mechanism. The response of the QDs fluorescence intensity is linearly proportional to the Cu2+ concentration ranging from 1 × 10−8 to 1 × 10−6 mol L−1 with a detection limit of 2.3 × 10−9 mol L−1. Furthermore, the method has been successfully applied to the detection of Cu2+ in water samples.
Co-reporter:Yongliang Shao, Yuanbin Dai, Xiaopeng Hao, Yongzhong Wu, Lei Zhang, Haodong Zhang and Yuan Tian
CrystEngComm 2013 vol. 15(Issue 39) pp:7965-7969
Publication Date(Web):07 Aug 2013
DOI:10.1039/C3CE40802G
A GaN crystal was grown by hydride vapor phase epitaxy (HVPE) on a substrate with patterned SiO2 masks. The growth mode of HVPE-GaN was analysed, and the crystallographic orientation relationship between GaN and the sapphire substrate was identified by electron backscatter diffraction (EBSD) Kikuchi diffraction patterns and pole figures. The lattice mismatch was calculated from the crystallographic orientation relationship of the heteroepitaxial structure and the lattice parameters. EBSD mapping was employed to investigate the disorientation distribution of GaN along the [001] direction. The GaN strain in the heteroepitaxial structure was identified from the crystallographic orientation information. Raman spectrum results demonstrated that the residual stress in GaN was beneficially reduced in this growth mode.
Co-reporter:Miao Du, Yongzhong Wu and Xiaopeng Hao
CrystEngComm 2013 vol. 15(Issue 9) pp:1782-1786
Publication Date(Web):19 Dec 2012
DOI:10.1039/C2CE26446C
Owning many peculiar properties, hexagonal boron nitride nanosheets (BNNSs) have lots of potential applications, such as electronic devices and deep ultraviolet emitters. In this article, a chemical exfoliation method to prepare few-layer and large size BNNSs is reported. Through related instrument characterizations, we demonstrated that this preparation method can allow the exfoliation of BNNSs from bulk BN powder successfully. From CL spectra, the as-prepared BNNSs were proved to show stronger CL emission ability than BN powder. Based on the experiment results analysis, we proposed an exfoliation mechanism and verified it through in situ SEM detection.
Co-reporter:Xiaoyan Liu, Zhengmao Yin, Yongzhong Wu, Xiaopeng Hao, Xiangang Xu
Optics Communications 2013 Volume 291() pp:376-379
Publication Date(Web):15 March 2013
DOI:10.1016/j.optcom.2012.11.018
A low cost and simple route was presented to fabricate large-scale ordered microlens arrays on gallium phosphide light emitting diodes with enhanced extraction efficiency. The different morphological microlens arrays were simply fabricated by controlling heat treatment temperature. Light extraction efficiency and light output power of gallium phosphide light emitting diodes were enhanced by different array structures of the polystyrene microlens. Compared to conventional gallium phosphide light emitting diodes, light intensity of the light emitting diodes covered by hemispherical polystyrene microlens shows 1.32 times enhancement under the forward current of 20 mA. The mechanism of enhanced light output with microlens arrays is discussed in detail.
Co-reporter:Jie Du, Xianlei Li, Shengjiang Wang, Yongzhong Wu, Xiaopeng Hao, Chengwei Xu and Xian Zhao
Journal of Materials Chemistry A 2012 vol. 22(Issue 22) pp:11390-11395
Publication Date(Web):13 Apr 2012
DOI:10.1039/C2JM30882G
In this paper, a microwave-assisted synthesis method has been used to prepare highly luminescent GSH-capped Zn1−xCdxTe alloyed quantum dots, with pollutant-free sodium tellurite (Na2TeO3) as the Te source. The size and composition-dependent absorption and photoluminescence spectra of the as-prepared alloyed QDs can be tuned from 500 nm to 610 nm, and the photoluminescent quantum yield of our synthesized alloyed QDs can reach up to 90%. The in vitro cytotoxicity studies (MTT-assay) demonstrate that the cytotoxicity of the GSH-capped Zn1−xCdxTe alloyed QDs can be reduced to a small extent due to the incorporation of the Zn ions. Green emitting GSH-capped Zn1−xCdxTe alloyed QDs are successfully used for A549 cellular imaging on a laser scanning confocal microscopy. Our systematic investigation clearly shows that these high-performance Zn1−xCdxTe alloyed QDs are highly promising biological fluorescent labels in biological applications.
Co-reporter:Xiaoyan Liu, Weijia Zhou, Zhengmao Yin, Xiaopeng Hao, Yongzhong Wu and Xiangang Xu
Journal of Materials Chemistry A 2012 vol. 22(Issue 9) pp:3916-3921
Publication Date(Web):24 Jan 2012
DOI:10.1039/C2JM14369K
TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells and photocatalysis. In this paper, single-crystalline rutileTiO2 nanorod arrays were fabricated on the GaN based light emitting diodes (LEDs) with a TiO2 seed layer by an acid hydrothermal process. The morphologies and the crystallinity of the rutileTiO2 nanorod arrays on GaN wafer were characterized by scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction. The optical properties of surface-textured TiO2/GaN were measured and analyzed by photoluminescence. The influence and dependence of the TiO2 nanorod array with the different densities and diameters on the light output of the fabricated GaN wafers were investigated. The light extraction efficiency of GaN LEDs was enhanced by the single-crystalline rutileTiO2 nanorod array, which showed an eight-fold increase in photoluminescence intensity compared to the normal planar surface. The mechanisms for the enhanced light output of GaN LEDs by the single-crystalline rutileTiO2 nanorod arrays were discussed.
Co-reporter:Haodong Zhang, Yongliang Shao, Lei Zhang, Xiaopeng Hao, Yongzhong Wu, Xiaoyan Liu, Yuanbin Dai and Yuan Tian
CrystEngComm 2012 vol. 14(Issue 14) pp:4777-4780
Publication Date(Web):24 Apr 2012
DOI:10.1039/C2CE25363A
In this paper, GaN films were grown on a novel designed template via hydride vapour phase epitaxy (HVPE). The template was fabricated by bonding a thinned MOCVD-GaN/sapphire template to a Si wafer (BTMG). Both the lattice deformation and thermal mismatch stress in the film can be decreased. The GaN film grown on the BTMG template displayed a smaller full width at half maximum (FWHM) for the (002) and (102) reflections than the film grown on the MOCVD-GaN/sapphire template (MG), characterized by high-resolution X-ray diffraction (HRXRD). The Raman measurements showed that the residual stress of the HVPE GaN film grown on the BTMG template was greatly released. The better optical quality of the GaN film grown on the BTMG template was detected in comparison to the film grown on the MG template by photoluminescence (PL) spectra. These results indicated that high quality GaN films can be obtained by using the new template.
Co-reporter:Chao Zhang, Xiaopeng Hao, Yongzhong Wu, Miao Du
Materials Research Bulletin 2012 47(9) pp: 2277-2281
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.05.042
Co-reporter:Zhiliang Xiu, Yongzhong Wu, Xiaopeng Hao, Xianlei Li, Lei Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 401() pp:68-73
Publication Date(Web):5 May 2012
DOI:10.1016/j.colsurfa.2012.03.021
Uniform and well-dispersed Y2O3:Eu/YVO4:Eu composite microspheres were prepared by hydrothermal chemical corrosion Y2O3:Eu microspheres with Na3VO4 solution. Effects of pH, molar ratio of Na3VO4 to the Y2O3:Eu precursor (R), and reaction time (t) on the morphology and the crystal structure of the composite were investigated in detail. The photoluminescence intensity of the products synthesized under the optimum condition was much higher than that of the YVO4:Eu nanocrystals prepared by direct hydrothermal method and comparable to that of the bulk YVO4:Eu.Graphical abstractUniform and well-dispersed Y2O3:Eu/YVO4:Eu composite microspheres were prepared by hydrothermal chemical corrosion Y2O3:Eu precursor with Na3VO4 solution. The luminescence intensity of the composite is much higher than that of YVO4:Eu nanocrystals prepared by direct hydrothermal method and closed to that of the bulk YVO4:Eu.Highlights► Y2O3:Eu microspheres acted as precursor. ► Y2O3:Eu/YVO4:Eu microspheres were prepared by chemical corrosion approach. ► The composite microspheres exhibited much high luminescence intensity.
Co-reporter:Lei Zhang, Yongliang Shao, Xiaopeng Hao, Yongzhong Wu, Haodong Zhang, Shuang Qu, Xiufang Chen and Xiangang Xu
CrystEngComm 2011 vol. 13(Issue 15) pp:5001-5004
Publication Date(Web):13 Jun 2011
DOI:10.1039/C1CE05147D
In this paper, GaN films were grown on an H3PO4 etched MOCVD-GaN/Al2O3 template (EMGA) by hydride vapor phase epitaxy (HVPE). The GaN film grown on the EMAG template showed a smaller full width at half maximum (FWHM) of the (002) and (102) reflections in the XRD measurement than that grown on the MOCVD-GaN/Al2O3 (MGA) template. A stronger PL band edge emission was observed for the GaN grown on the EMGA template compared to the MGA template. Defect related yellow luminescence was observed for GaN grown on the MGA template, which did not appear for the EMGA template. The Raman results showed that the stress of the GaN grown on the EMGA is much smaller than that on the MGA template. The penetrated etch pits played an important role in the reduction of threading dislocations. These results indicate that the quality of the GaN films is improved by using an EMGA template.
Co-reporter:Jie Du, Yongzhong Wu, Xiaopeng Hao, Xian Zhao
Journal of Molecular Structure 2011 Volume 1006(1–3) pp:650-654
Publication Date(Web):14 December 2011
DOI:10.1016/j.molstruc.2011.10.025
Water-soluble CdTe QDs modified by thioglycolic acid were synthesized with a facile one-pot method. Two-photon excited fluorescence spectroscopic technique was used to study the interaction between TGA-capped CdTe quantum dots and folic acid. Experiments results showed that the two-photon fluorescence of TGA-capped CdTe QDs in PBS buffer solution was quenched in the presence of folic acid. A good linear relationship was observed between the two-photon fluorescence intensity of TGA-capped CdTe QDs and the concentration of folic acid. The two-photon excited fluorescence quenching mechanism was also presented.Highlights► Two-photon excited fluorescence has minimum autofluorescence interference. ► The technique has wider linear range of detecting FA. ► The technique has better precision. ► Application of two-photon excited fluorescence broadens.
Co-reporter:Haibo Gong, Xiaopeng Hao, Yongzhong Wu, Bingqiang Cao, Hongyan Xu, Xiangang Xu
Journal of Solid State Chemistry 2011 Volume 184(Issue 12) pp:3269-3272
Publication Date(Web):December 2011
DOI:10.1016/j.jssc.2011.10.018
Transformation from Te nanorods to CdTe nanoparticles was achieved with the assistance of EDTA as a ligand under hydrothermal conditions. Experimental results showed that at the beginning of reaction Te nucleated and grew into nanorods. With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. Finally, nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were obtained. The effects of EDTA on the morphology and formation of CdTe nanoparticles were discussed in consideration of the strong ligand-effect of EDTA, which greatly decreased the concentration of Cd2+. Furthermore, the possible formation process of CdTe nanoparticles from Te nanorods was further proposed. The crystal structure and morphology of the products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Graphical AbstractFirstly, Te nucleated and grew into nanorods in the presence of EDTA2−. Then CdTe nucleus began to emerge on Te nanorods and finally monodispersed CdTe nanoparticles were obtained. Highlights► EDTA serves as a strong ligand with Cd2+. ► The existence of EDTA constrains the nucleation of CdTe and promotes the formation of Te nanorods. ► With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. ► Nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were finally obtained.
Co-reporter:Zhiliang Xiu, Yongzhong Wu, Xiaopeng Hao, Lei Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 386(1–3) pp:135-140
Publication Date(Web):5 August 2011
DOI:10.1016/j.colsurfa.2011.07.018
Uniform, dense, and thickness controllable silver shells coated on mono-dispersed SiO2 microspheres were prepared by one-pot silver mirror reaction on the surface of Sn2+-sensitized colloidal SiO2 spheres. Different thickness of SiO2-encapsulating layer was fabricated by the hydrolysis of tetraethyl orthosilicate (TEOS) in isopropanol solution. The change of the Ag shell with the heating process could be reflected from the UV–vis absorption spectrum. The outer SiO2 layer provided greatly improved thermal stability of the Ag shell (20 nm) up to 300 °C.Graphical abstractSchematic illustration of the formation process of SiO2@Ag@SiO2 core–shell microspheres.Highlights► A simple and green method was explored to synthesize SiO2@Ag microspheres. ► Glucose was utilized as a mild and green reductant, and only a few hours needed. ► The optical properties could be tailored by altering the Ag shell's thickness. ► The outer SiO2 layer provided improved thermal stability up to 300 °C.
Co-reporter:Haibo Gong, Xiaopeng Hao, Yongzhong Wu, Bingqiang Cao, Wei Xia, Xiangang Xu
Materials Science and Engineering: B 2011 Volume 176(Issue 13) pp:1028-1031
Publication Date(Web):15 August 2011
DOI:10.1016/j.mseb.2011.05.026
Co-reporter:Fukun Ma, Mengxia Wang, Yongliang Shao, Lijuan Wang, Yongzhong Wu, Zhengping Wang and Xiaopeng Hao
Journal of Materials Chemistry A 2017 - vol. 5(Issue 10) pp:NaN2565-2565
Publication Date(Web):2017/02/08
DOI:10.1039/C7TC00131B
Boron carbon nitride (BCN) nanosheets have gained increased attention as a novel semiconductor because of their controllable band-gap and environmentally-friendly properties. This study presents a facile ‘thermal substitution’ method for preparing BCN nanosheets through substitutional C doping into hexagonal boron nitride nanosheets (BNNSs) at 850 °C. ‘Thermal substitution’ is an effective method used to tune the band-gap of BCN nanosheets by adjusting the amount of carbon atoms incorporated. After irradiation by laser pulses at 1064 and 532 nm, the as-obtained BCN nanosheets exhibit excellent nonlinear optical (NLO) performance. The NLO absorption properties of the nanosheets shift from saturable absorption to reverse saturable absorption. The corresponding NLO performance can be adjusted by controlling the carbon content in the BCN nanosheets. The developed BCN nanosheets can be utilised as a new and advanced NLO material for sensitive optical components and laser protection.
Co-reporter:Zheng Xie, Qingqing Du, Yongzhong Wu, Xiaopeng Hao and Chunyan Liu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 41) pp:NaN9886-9886
Publication Date(Web):2016/09/23
DOI:10.1039/C6TC02035F
A facile and efficient approach for the preparation of silane-functionalized graphene quantum dot (SiGQD) nanofluids is described. The functionalized SiGQDs are self- and co-polymerized with silane to easily obtain the arbitrary concentration (0–100%) of SiGQD doped organically modified silicate gel glasses with good processability. The glasses feature arbitrary concentration doping, transparency, homogeneity, various solid structures, luminescence and full-UV shielding capability and are thus suitable for the preparation of bulk hybrid nanocomposites. The SiGQDs with functional groups attached to the surface are strongly photoluminescent both in solution (quantum yield = 82%) and in the solid state (96%). The trace amounts of UV light in daylight could excite these materials and could be observed by the naked eye. The resultant SiGQDs and their gel glasses can absorb and convert UV light into blue light, which can be effectively modulated by the arbitrary concentration of the SiGQDs. These non-toxic, low cost, heavy metal-free, and eco-friendly SiGQDs and their corresponding gel glass systems are promising candidates for high performance UV filters as well as optical materials and devices.
Co-reporter:Xue Zhao, Jie Du, Yongzhong Wu, Hongzhi Liu and Xiaopeng Hao
Journal of Materials Chemistry A 2013 - vol. 1(Issue 38) pp:NaN11753-11753
Publication Date(Web):2013/07/24
DOI:10.1039/C3TA12335A
CdTe quantum dots coated by octamercaptopropyl polyhedral oligomeric silsesquioxane (OM-POSS) were applied to detect trace Cu2+. This detection method is based on selectively quenching the fluorescence originating from the CdTe QDs in the presence of Cu2+. The research showed a low interference response of the POSS-coated CdTe QDs towards other metal ions. The POSS-coated CdTe QDs obtained a higher sensitivity than NAC-coated CdTe QDs. The quenching mechanism is discussed on the basis of the competitive binding of the thiol groups of the OM-POSS between the CdTe QDs and the metal ions. The Stern–Volmer plots at different temperatures show that the fluorescence of the POSS-coated CdTe QDs was quenched by Cu2+ through a static quenching mechanism. The response of the QDs fluorescence intensity is linearly proportional to the Cu2+ concentration ranging from 1 × 10−8 to 1 × 10−6 mol L−1 with a detection limit of 2.3 × 10−9 mol L−1. Furthermore, the method has been successfully applied to the detection of Cu2+ in water samples.
Co-reporter:Xiaoyan Liu, Weijia Zhou, Zhengmao Yin, Xiaopeng Hao, Yongzhong Wu and Xiangang Xu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 9) pp:NaN3921-3921
Publication Date(Web):2012/01/24
DOI:10.1039/C2JM14369K
TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells and photocatalysis. In this paper, single-crystalline rutileTiO2 nanorod arrays were fabricated on the GaN based light emitting diodes (LEDs) with a TiO2 seed layer by an acid hydrothermal process. The morphologies and the crystallinity of the rutileTiO2 nanorod arrays on GaN wafer were characterized by scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction. The optical properties of surface-textured TiO2/GaN were measured and analyzed by photoluminescence. The influence and dependence of the TiO2 nanorod array with the different densities and diameters on the light output of the fabricated GaN wafers were investigated. The light extraction efficiency of GaN LEDs was enhanced by the single-crystalline rutileTiO2 nanorod array, which showed an eight-fold increase in photoluminescence intensity compared to the normal planar surface. The mechanisms for the enhanced light output of GaN LEDs by the single-crystalline rutileTiO2 nanorod arrays were discussed.
Co-reporter:Jie Du, Xianlei Li, Shengjiang Wang, Yongzhong Wu, Xiaopeng Hao, Chengwei Xu and Xian Zhao
Journal of Materials Chemistry A 2012 - vol. 22(Issue 22) pp:NaN11395-11395
Publication Date(Web):2012/04/13
DOI:10.1039/C2JM30882G
In this paper, a microwave-assisted synthesis method has been used to prepare highly luminescent GSH-capped Zn1−xCdxTe alloyed quantum dots, with pollutant-free sodium tellurite (Na2TeO3) as the Te source. The size and composition-dependent absorption and photoluminescence spectra of the as-prepared alloyed QDs can be tuned from 500 nm to 610 nm, and the photoluminescent quantum yield of our synthesized alloyed QDs can reach up to 90%. The in vitro cytotoxicity studies (MTT-assay) demonstrate that the cytotoxicity of the GSH-capped Zn1−xCdxTe alloyed QDs can be reduced to a small extent due to the incorporation of the Zn ions. Green emitting GSH-capped Zn1−xCdxTe alloyed QDs are successfully used for A549 cellular imaging on a laser scanning confocal microscopy. Our systematic investigation clearly shows that these high-performance Zn1−xCdxTe alloyed QDs are highly promising biological fluorescent labels in biological applications.
