Co-reporter:Weixin Zhang;Xiaoning Yang;Qian Zhu;Kun Wang;Jianbo Lu;Min Chen;Zeheng Yang
Industrial & Engineering Chemistry Research October 22, 2014 Volume 53(Issue 42) pp:16316-16323
Publication Date(Web):2017-2-22
DOI:10.1021/ie502737t
Cu2O/Ag composite nanospheres (CNSs) with tunable Ag coverage and optical properties have been prepared based on a one-pot room temperature method by adding AgNO3 solution to fresh Cu2O nanosphere-produced mother solution in various ratios. Ag+ ions can be reduced by the primary Cu2O nanospheres in the acidic solution, and the obtained Ag nanoparticles can be deposited on the surfaces of the Cu2O nanospheres. The photocatalytic activity of Cu2O/Ag CNSs has been evaluated for photodegradation of methyl orange (MO) dye under visible-light irradiation, which demonstrates that Cu2O nanospheres with Ag loading exhibit significantly enhanced photocatalytic activity compared with pure Cu2O counterparts, and their photocatalytic properties depend on the coverage density of Ag nanoparticles. The enhanced photocatalytic activity can be attributed to the deposition of Ag acting as electron sinks to prevent the recombination of the photogenerated electrons and holes, and the plasmon resonances of the Ag nanoparticles generating more electron–hole pairs in the semiconductor.
Co-reporter:Zeheng Yang, Kun Wang, Zongming Shao, Yuan Tian, Gongde Chen, Kai Wang, Zhangxian Chen, Yan Dou, Weixin Zhang
Journal of Solid State Chemistry 2017 Volume 246() pp:278-283
Publication Date(Web):February 2017
DOI:10.1016/j.jssc.2016.11.023
•Fe2O3 hierarchical arrays was prepared by in-situ hydrothermal chemical oxidation.•F− ions play an important role in the formation of the Fe2O3 hierarchical arrays.•Fe2O3 hierarchical arrays show high catalytic activity to methylene blue degradation.Hierarchical array catalysts with micro/nano structures on substrates not only possess high reactivity from large surface area and suitable interface, but intensify mass transfer through shortening the diffusion paths of both reactants and products for high catalytic efficiency. Herein, we first demonstrate fabrication of Fe2O3 hierarchical arrays grown on stainless-steel substrates via in-situ hydrothermal chemical oxidation followed by heat treatment in N2 atmosphere. As a Fenton-like catalyst, Fe2O3 hierarchical arrays exhibit excellent catalytic activity and life cycle performance for methylene blue (MB) dye degradation in aqueous solution in the presence of H2O2. The Fe2O3 catalyst with unique hierarchical structures and efficient transport channels, effectively activates H2O2 to generate large quantity of •OH radicals and highly promotes reaction kinetics between MB and •OH radicals. Immobilization of hierarchical array catalysts on stainless-steel can prevent particles agglomeration, facilitate the recovery and reuse of the catalysts, which is expected promising applications in wastewater remediation.The in-situ synthesis of Fe2O3 hierarchical arrays on stainless-steel substrates was reported for the first time, which exhibit excellent catalytic activity performance for methylene blue (MB) dye degradation in aqueous solution in the presence of H2O2.
Co-reporter:Bing Guo, Junhao Zhao, Xiaoming Fan, Wei Zhang, Sheng Li, Zeheng Yang, Zhangxian Chen, Weixin Zhang
Electrochimica Acta 2017 Volume 236(Volume 236) pp:
Publication Date(Web):10 May 2017
DOI:10.1016/j.electacta.2017.03.133
•Li1.2Ni0.13Co0.13-xMn0.54AlxO2(1-y)F2y material was modified via Al&F co-doping.•Al&F co-doping mitigates intrinsic layered-to-spinel transition of the material.•Al&F co-doping effectively inhibits its capacity fade and voltage decay.•Al&F co-doping endows it with higher rate capacity and enhanced thermal stability.Lithium-rich layered compound cathode materials recently attract ever-growing attention in lithium ion batteries for electric vehicles and energy storage devices due to their high discharge capacities of over 250 mAh g−1 and low cost. However, they still suffer from capacity fade, voltage decay and poor rate capability and thermal stability. In this paper, the Al&F co-doped Li1.2Ni0.13Co0.13-xMn0.54AlxO2(1-y)F2y cathode material has been successfully prepared via a co-precipitation reaction and a subsequent solid phase calcination. The resulting material combines the advantages of both Al-doping and F-doping, which can effectively mitigate the intrinsic layered-to-spinel phase transformation, and as a consequence, inhibits the capacity fade and voltage decay: delivering a discharge capacity of 217 mAh g−1 with retention of 88.21% and an average discharge voltage decay of 0.4019 V upon 150 cycling at 0.5 C. On the other side, with an increased electronic and ionic conductivity, this co-doping practice enhances the rate capability by a considerable extent that it delivers a discharge capacity of 157 mAh g−1 at 10 C, thus facilitating its application for quick charging devices. In addition, the thermal stability related with battery safety is significantly meliorated. Specifically, the co-doped cathode material exhibits an initial exothermal peak at a higher temperature of 273 °C and a much less overall heat generation of 221 J g−1 compared to the 210 °C and 755 J g−1 for the pristine one. In conclusion, the anion/cation co-substitution strategy has been demonstrated to be of great promise for the improvement of lithium-rich layered cathode materials.Download high-res image (184KB)Download full-size image
Co-reporter:Maoqin Qiu, Yuan Tian, Zhangxian Chen, Zeheng Yang, Wenming Li, Kai Wang, Lei Wang, Kun Wang and Weixin Zhang
RSC Advances 2016 vol. 6(Issue 78) pp:74376-74383
Publication Date(Web):28 Jul 2016
DOI:10.1039/C6RA12674J
Self-doping by Ti3+ and introducing oxygen vacancies in TiO2 is an important and effective strategy to extend its optical absorption from the UV into the visible region. In this paper, we report the synthesis of a series of Ti3+ self-doped TiO2 nanocrystals via a hydrothermal method using TiCl3 and (NH4)2TiF6 as the source of Ti3+ and Ti4+, respectively. The oxidation of Ti3+ can be inhibited by (NH4)2TiF6 based on Le Chatelier's principle. The samples are characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, field-emission scanning electron microscopy and transmission electron microcopy, respectively. The results indicate that Ti3+ is localized in the bulk of the as-prepared TiO2 nanocrystals, rather than on the surface. In comparison with pristine TiO2, the Ti3+ self-doped TiO2 nanocrystals exhibit an enhanced photocatalytic activity of 86.3% towards the photodegradation of methylene blue solution under simulated solar light irradiation and 99% under natural solar irradiation. It is found that the molar ratio of Ti4+/Ti3+ used during the synthesis has significant effects on the photocatalytic activity of Ti3+ self-doped TiO2 photocatalysts, since the electronic structures of the resulting Ti3+ self-doped TiO2 nanocrystals can be finely tuned by changing the ratios. The significantly enhanced photocatalytic activity should be due to the self-doping of Ti3+ in TiO2 nanocrystals, which not only increases the optical absorption in the visible light region, but also helps to spatially separate the photogenerated charge carriers.
Co-reporter:Sheng Li, Guo Ma, Bing Guo, Zeheng Yang, Xiaoming Fan, Zhangxian Chen, and Weixin Zhang
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 35) pp:9352
Publication Date(Web):August 17, 2016
DOI:10.1021/acs.iecr.6b02463
Spinel LiNi0.5Mn1.5O4 hollow spheres with micro- and nanostructures have been successfully synthesized based on the coprecipitation method followed by postheat treatment. A uniform and spherical precursor was obtained by controlling the reaction kinetics in the nucleation–crystallization process of forming nickel and manganese carbonates simply by employing NaHCO3 instead of Na2CO3 as precipitating agent. Single-shelled and double-shelled LiNi0.5Mn1.5O4 hollow spheres were derived of the spherical carbonate precursors via tuning the calcination kinetics. The as-prepared LiNi0.5Mn1.5O4 hollow spheres deliver a discharge capacity of 128.9 mAh g–1 at 0.1 C rate and maintain a capacity retention of 95% at 0.5 C after 100 cycles. Importantly, even at high rate of 30 C, it can still exhibit a discharge capacity of 100 mAh g–1. The excellent rate capability and cycling stability are mainly attributed to its hollow micro- and nanostructure, which could shorten Li+ ions’ diffusion path and buffer the volume change during repeated Li+ insertion–extraction processes.
Co-reporter:Guo Ma;Sheng Li;Dr. Weixin Zhang;Dr. Zeheng Yang;Shulin Liu;Dr. Xiaoming Fan;Fei Chen;Yuan Tian;Weibo Zhang;Dr. Shihe Yang;Dr. Mei Li
Angewandte Chemie International Edition 2016 Volume 55( Issue 11) pp:3667-3671
Publication Date(Web):
DOI:10.1002/anie.201511196
Abstract
One-dimensional (1D) micro- and nanostructured electrode materials with controllable phase and composition are appealing materials for use in lithium-ion batteries with high energy and power densities, but they are challenging to prepare. Herein, a novel ethanol–water mediated co-precipitation method by a chimie douce route (synthesis conducted under mild conditions) has been exploited to selectively prepare an extensive series of manganese-based electrode materials, manifesting the considerable generalizability and efficacy of the method. Moreover, by simply tuning the mixed solvent and reagents, transition metal oxide bars with differing aspect ratios and compositions were prepared with an unprecedented uniformity. Application prospects are demonstrated by Li-rich 0.5 Li2MnO3⋅0.5 LiNi1/3Co1/3Mn1/3O2 bars, which demonstrate excellent reversible capacity and rate capability thanks to the steerable nature of the synthesis and material quality. This work opens a new route to 1D micro- and nanostructured materials by customizing the precipitating solvent to orchestrate the crystallization process.
Co-reporter:Guo Ma;Sheng Li;Dr. Weixin Zhang;Dr. Zeheng Yang;Shulin Liu;Dr. Xiaoming Fan;Fei Chen;Yuan Tian;Weibo Zhang;Dr. Shihe Yang;Dr. Mei Li
Angewandte Chemie 2016 Volume 128( Issue 11) pp:3731-3735
Publication Date(Web):
DOI:10.1002/ange.201511196
Abstract
One-dimensional (1D) micro- and nanostructured electrode materials with controllable phase and composition are appealing materials for use in lithium-ion batteries with high energy and power densities, but they are challenging to prepare. Herein, a novel ethanol–water mediated co-precipitation method by a chimie douce route (synthesis conducted under mild conditions) has been exploited to selectively prepare an extensive series of manganese-based electrode materials, manifesting the considerable generalizability and efficacy of the method. Moreover, by simply tuning the mixed solvent and reagents, transition metal oxide bars with differing aspect ratios and compositions were prepared with an unprecedented uniformity. Application prospects are demonstrated by Li-rich 0.5 Li2MnO3⋅0.5 LiNi1/3Co1/3Mn1/3O2 bars, which demonstrate excellent reversible capacity and rate capability thanks to the steerable nature of the synthesis and material quality. This work opens a new route to 1D micro- and nanostructured materials by customizing the precipitating solvent to orchestrate the crystallization process.
Co-reporter:Lei Wang;Zhangxian Chen;Mengqiu Huang;Zeheng Yang;Pan Sun
Catalysis Letters 2016 Volume 146( Issue 7) pp:1283-1290
Publication Date(Web):2016/07/01
DOI:10.1007/s10562-016-1751-4
Cyclohexanone is an important intermediate for the fabrication of synthetic polymers such as Nylon in chemical industry. A green synthesis of cyclohexanone under mild conditions using environmental friendly oxidants and non-precious catalysts is highly desired. Herein, one-dimensional crystalline h-WO3 nanorods have been synthesized via a facile hydrothermal method. The h-WO3 nanorods are assembled by the closely packed and highly aligned thin nanowires with the lengths up to 10 μm and diameters of about 10 nm, growing along the [001] direction. The h-WO3 nanorods are used as the catalyst for the first time in the selective oxidation of cyclohexanol to cyclohexanone by aqueous hydrogen peroxide. The effective catalysis by h-WO3 nanorods remarkably increases the yield of cyclohexanone from 3.1 to 78.6 %, under the mild conditions (80 °C, ambient pressure). With a high recyclability, the h-WO3 nanorods have shown great potentials in green chemistry for the synthesis of cyclohexanone by the catalytic oxidation of cylohexanol.
Co-reporter:Junjun Zhang, Heyun Gu, Xiaoning Yang, Min Chen, Zeheng Yang and Weixin Zhang
RSC Advances 2015 vol. 5(Issue 12) pp:8537-8543
Publication Date(Web):23 Dec 2014
DOI:10.1039/C4RA10916C
A high-efficiency cannonite Bi2O(OH)2SO4 nanobelt photocatalyst has been successfully synthesized with sodium dodecyl sulfate (SDS) as both the coordinating agent and sulfur source through hydrolytic reaction based on a facile one-step hydrothermal process. Surface morphology analysis indicates that the products consist of ultralong nanobelts with widths around 30–50 nm, thicknesses of approximately 10 nm and lengths up to hundreds of micrometers. It is worth noting that these single crystalline nanobelts are self-assembled in the form of macroscopic architecture suspended in the solution which could be transferred onto substrates as thin films on a large scale. The as-prepared cannonite nanobelt films exhibit high photocatalytic activity for the degradation of organic dye wastewater such as rhodamine B (RhB), methylene blue, methyl orange and Congo red aqueous solutions under visible-light irradiation and have advantages of easy catalyst separation and recovery over commonly used powder-form catalysts. This new promising photocatalyst shows potential application in the treatment of dye-containing wastewaters.
Co-reporter:He Cheng, Gongde Chen, Weixin Zhang, Maoqin Qiu, Zeheng Yang, Xiao Zhu, Guo Ma and Yu Fu
RSC Advances 2015 vol. 5(Issue 54) pp:43630-43638
Publication Date(Web):06 May 2015
DOI:10.1039/C5RA04524J
Different TiO2 micro/nanostructures have been hydrothermally prepared through controlling the hydrolysis and nucleation rate of Ti4+ ions by urea and H2O2 in a (NH4)2TiF6 aqueous solution. Anatase TiO2 nanorods with diameters of 10–30 nm and lengths up to 300–500 nm were evolved from the intermediate monoclinic H2Ti5O11·3H2O in the presence of H2O2 and urea, whereas TiO2 core–shell nanospheres with diameters of 300–500 nm were obtained with the sole assistance of urea via the Ostwald ripening effect and TiO2 microspheres with diameters of about 1–2 μm were formed in the presence of only H2O2. Photocatalytic degradation of Rhodamine B (RhB) has been used to evaluate their activities. The results indicate that the anatase TiO2 nanorods have superior photocatalytic efficiency to the core–shell nanospheres and microspheres counterparts owing to their larger specific surface area and higher yield of ˙OH radicals. This work not only offers a simple and promising route to the controllable synthesis of various TiO2 architectures, but also provides new insight for improving the photocatalytic performance of TiO2 through morphological engineering, which will have potential applications in environmental remediation.
Co-reporter:Yingmeng Zhang;Dr. Weixin Zhang;Dr. Zeheng Yang;Heyun Gu;Qing Zhu;Dr. Shihe Yang;Dr. Mei Li
Angewandte Chemie International Edition 2015 Volume 54( Issue 13) pp:3932-3936
Publication Date(Web):
DOI:10.1002/anie.201410807
Abstract
Assembling micro-/nanostructured arrays on conducting substrates allows the integration of multiple functionalities into modern electronic devices. Herein, a novel self-sustained cycle of hydrolysis and etching (SCHE) is exploited to selectively synthesize an extensive series of metal oxide micro-/nanostructured arrays on a wide range of metal substrates, establishing the generality and efficacy of the strategy. To demonstrate the potential application of this method, the as-prepared NiO porous nanobelt array was directly used as the anode for lithium-ion batteries, exhibiting excellent capacity and rate capability. Conclusively, the SCHE strategy offers a systematic approach to design metal oxide micro-/nanostructured arrays on metal substrates, which are valuable not only for lithium-ion batteries but also for other energy conversion and storage systems and electronic devices at large.
Co-reporter:Yingmeng Zhang;Dr. Weixin Zhang;Dr. Zeheng Yang;Heyun Gu;Qing Zhu;Dr. Shihe Yang;Dr. Mei Li
Angewandte Chemie 2015 Volume 127( Issue 13) pp:4004-4008
Publication Date(Web):
DOI:10.1002/ange.201410807
Abstract
Assembling micro-/nanostructured arrays on conducting substrates allows the integration of multiple functionalities into modern electronic devices. Herein, a novel self-sustained cycle of hydrolysis and etching (SCHE) is exploited to selectively synthesize an extensive series of metal oxide micro-/nanostructured arrays on a wide range of metal substrates, establishing the generality and efficacy of the strategy. To demonstrate the potential application of this method, the as-prepared NiO porous nanobelt array was directly used as the anode for lithium-ion batteries, exhibiting excellent capacity and rate capability. Conclusively, the SCHE strategy offers a systematic approach to design metal oxide micro-/nanostructured arrays on metal substrates, which are valuable not only for lithium-ion batteries but also for other energy conversion and storage systems and electronic devices at large.
Co-reporter:Weixin Zhang, Zaoyuan Zhou, Wenran Zhao, Zeheng Yang and Xiaoning Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 16) pp:5800-5808
Publication Date(Web):31 Jan 2014
DOI:10.1039/C3TA14722C
The utilization of well-aligned hybrid one-dimensional hollow nanostructured arrays is a promising strategy for the development of transition metal oxides as high-cycle-life stability and high-rate performance electrode materials for lithium ion batteries. Here we report a chemical replacement route to prepare well-aligned Cu2−xSe-coated CuO nanotube arrays with diameters of 400 nm and length of several micrometers, based on Cu(OH)2 nanotube arrays grown on a copper substrate as precursors. As an integrated anode for lithium ion batteries, the Cu2−xSe-coated CuO nanotube array on a copper substrate is capable of delivering a high cycling capacity of 764 mA h g−1 after 100 cycles at a current density of 0.08 mA cm−2 (0.1 C), and retains a discharge capacity of 382.5 mA h g−1 and 94.5 mA h g−1 at current densities of 10 mA cm−2 (12.5 C) and 20 mA cm−2 (25 C), respectively, exhibiting superior performance to the bare CuO nanotube array film. The synergistic effect of the successful integration of the CuO nanotubes with the Cu2−xSe semiconducting coating layer significantly contributes to the enhanced electrochemical properties of the Cu2−xSe-coated CuO nanotube array anode.
Co-reporter:Zeheng Yang, Feifei Xu, Weixin Zhang, Zhousheng Mei, Bo Pei, Xiao Zhu
Journal of Power Sources 2014 Volume 246() pp:24-31
Publication Date(Web):15 January 2014
DOI:10.1016/j.jpowsour.2013.07.057
•Multishelled NiO hollow nanospheres were prepared via layer-by-layer self-assembly.•Double-shelled NiO hollow nanospheres exhibit superior supercapacitive performance.•Large surface area and porosity account for the excellent electrochemical properties.In this work, we demonstrate a facile layer-by-layer (LBL) self-assembly method for controllable preparation of single-, double-, and triple-shelled NiO hollow nanospheres by calcining Ni(OH)2/C precursors formed at different stage. It is observed that the external nanoflakes of the NiO hollow nanospheres are inherited from the Ni(OH)2 precursors organized on the surface of carbon spheres via a self-assembly growth process and the inner shells result from the formation of different Ni(OH)2 layers within the carbon spheres during different preparation cycles. Supercapacitive performance of the three types of NiO hollow nanospheres as active electrode materials has been evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge. The results indicate that double-shelled NiO hollow nanosphere sample with largest surface area (92.99 m2 g−1) exhibits the best electrochemical properties among the three NiO hollow nanosphere samples. It delivers a high capacitance of 612.5 F g−1 at 0.5 A g−1 and demonstrates a superior long-term cyclic stability, with over 90% specific capacitance retention after 1000 charge–discharge cycles. This excellent performance is ascribed to the short diffusion path and large surface area of the unique hollow structure with nanoflake building blocks for bulk accessibility of faradaic reaction.
Co-reporter:Jun Zhang, Jianbo Lu, Doucheng Bian, Zeheng Yang, Qing Wu, and Weixin Zhang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 31) pp:12209-12215
Publication Date(Web):July 17, 2014
DOI:10.1021/ie501743b
Hierarchical LiFePO4 microplates have been synthesized by a solvothermal approach in ethanol solvent with self-prepared amorphous FePO4 particles as precursors. The microplates expose a large scale of the (010) faces with a mean length of 2.5 μm, width of 1.5 μm and thickness of 200–500 nm. Furthermore, the hierarchical LiFePO4 microplates are composed of nanosheets with a size of 50 nm and thickness of 10 nm. When the solvent ethanol was replaced by a mixture of water–ethanol (1/1, by volume) in the reaction, a distinctive morphology, the LiFePO4 microflower, was obtained. After coating carbon, the LiFePO4/C microplates deliver a high discharge capacity of 157 mAh g–1 at 0.1 C, and exhibit excellent rate capability and cycling performance, which are much better than those for the LiFePO4/C microflowers.
Co-reporter:Zeheng Yang, Yumei Yang, Xiao Zhu, Gongde Chen, and Weixin Zhang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 23) pp:9608-9615
Publication Date(Web):2017-2-22
DOI:10.1021/ie500358p
An outward coating method has been successfully employed to prepare CuO/MnO2 nanorod array films based on the impregnation of Cu(OH)2 nanorod array films with manganese nitrate aqueous solution and heat post-treatment. The as-prepared CuO/MnO2 nanorod array films as heterogeneous catalysts successfully address such issues as easy agglomeration, difficult separation, and possible secondary pollution related to powder catalysts. Furthermore, they exhibit catalytic oxidation activity for the degradation of acid fuchsin (AF) dye in aqueous solution superior to that of bare CuO nanorod array films in the presence of H2O2, because of the synergistic effects of both CuO and MnO2. The effects of the initial concentration of aqueous AF solution and H2O2 dosage on the catalytic oxidation performance were evaluated, indicating that the degradation ratio of AF can reach up to 94.05%. Life-cycle performance and scaleup of the catalytic oxidative degradation process demonstrate the durability and potential engineering application of CuO/MnO2 nanorod array films in dye wastewater treatment.
Co-reporter:Zaoyuan Zhou;Wenran Zhao;Zeheng Yang
Journal of Electronic Materials 2014 Volume 43( Issue 2) pp:359-368
Publication Date(Web):2014 February
DOI:10.1007/s11664-013-2905-4
CuSe with a hierarchical hollow structure formed from nanoplates has been successfully prepared by a replacement etching method with Cu(OH)2 nanowire bundles as precursors. The large difference between the solubility products of Cu(OH)2 and CuSe results in the formation of Cu(OH)2 CuSe core shell structures as intermediates. The CuSe with a hierarchical hollow structure is obtained when the Cu(OH)2 core is dissolved in ammonia solution. Use of the CuSe with a hierarchical hollow structure as electrode material for lithium ion batteries results in enhanced electrochemical properties, including initial coulombic efficiency and cycling performance, compared with use of CuSe nanoparticles. The relatively stable structure of CuSe with a hierarchical hollow structure is believed to be the main reason for the enhanced electrochemical performance.
Co-reporter:Weixin Zhang;Wenran Zhao;Zaoyuan Zhou
Frontiers of Chemical Science and Engineering 2014 Volume 8( Issue 1) pp:64-72
Publication Date(Web):2014 March
DOI:10.1007/s11705-014-1402-5
In this paper, α-MnO2 micronests composed of nanowires were fabricated via a hydrothermal reaction of MnSO4·H2O and K2S2O8 solutions. The α-MnO2 micronests were demonstrated to have a higher adsorption capacity than Γ-MnO2 microspheres due to their large specific surface area. The amount of Congo red adsorbed per unit weight of α-MnO2 micronests increased significantly from 114 to 282 mg·g−1 with concentration of Congo red solution increasing from 50 to 200 mg·L−1, but it had a little change with temperature. Kinetics, isotherms and thermodynamics for the adsorption of Congo red on α-MnO2 micronests were examined. The adsorption process followed the pseudo-second-order kinetics with good correlation. The experimental data were analyzed by Langmuir and Freundlich models, and equilibrium data fitted the Langmuir isotherm very well with maximum monolayer adsorption capacity of 625 mg·g−1 at 22 °C. The adsorption was spontaneous and endothermic according to thermodynamic studies. The experimental results indicate that α-MnO2 micronests possess a high adsorption capacity and could be employed as a replacement of traditional sorbents.
Co-reporter:Yingmeng Zhang, Weixin Zhang, Mei Li, Zeheng Yang, Gongde Chen and Qiang Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 45) pp:14368-14374
Publication Date(Web):16 Sep 2013
DOI:10.1039/C3TA13018E
A cosurfactant-mediated microemulsion synthesis of free-standing CuO arrays with hierarchical micro-cog architectures on copper substrates has been successfully established. The CuO cog-array films directly employed as anode electrodes derive from thermal dehydration of Cu(OH)2 arrays grown from copper substrates in the presence of AOT–n-butanol–isooctane–water microemulsions. Introducing n-butanol as a cosurfactant into the ternary AOT–isooctane–water system increases the rigidity of the reverse micelles and it can be selectively adsorbed on particular crystal faces, leading to well-aligned arrays as well as enlarged aspect ratios with average heights of over 6 μm and diameters of 1–2 μm. This result sharply contrasts with the multilayer film of micro-cog particles with a shortened aspect ratio prepared in the absence of n-butanol. The CuO film electrodes of free-standing micro-cog-arrays exhibit excellent electrochemical performance, including a long cycling life (with capacity retention of 91.6% at 1 C over 300 cycles) and outstanding rate capability even at high current rates (about 466 and 418 mA h g−1 at high rates of 12 and 15 C) in lithium ion batteries.
Co-reporter:Weixin Zhang, Hui Wang, Yingmeng Zhang, Zeheng Yang, Qiang Wang, Jianfeng Xia, Xiaoning Yang
Electrochimica Acta 2013 Volume 113() pp:63-68
Publication Date(Web):15 December 2013
DOI:10.1016/j.electacta.2013.09.043
•Cu2(OH)2CO3 nanosphere films on Cu foil have been prepared by a facile microemulsion synthesis.•Porous CuO nanosphere films can be prepared from Cu2(OH)2CO3 nanosphere film precursor.•Porous CuO nanosphere films have better electrochemical properties than CuO nanorod films.Porous CuO nanosphere films have been successfully prepared through post-heat treatment of Cu2(OH)2CO3 nanosphere films, which were formed on copper foil immersed in a water-in-oil (W/O) microemulsion. The electrochemical performance of the porous CuO nanosphere film as anode materials for lithium ion batteries indicates that at the current density of 0.1 C, it exhibits higher initial coulombic efficiency (70.4%) and reversible discharge capacity (799.7 mA h g−1 after 100 cycles) than the CuO nanorod film on copper foil, which was obtained via aqueous solution oxidation reaction followed by post-heating in N2 flow. The excellent performance can be attributed to the novel porous nanosphere structure grown on the current collecting substrate, which could not only shorten the diffusion path of lithium ion and provide appropriate contact area between electrode and electrolyte, but also increase the electrical conductivity of the electrode. More generally, the strategy based on synthesis within confined reaction media, rather than direct synthesis in bulk solution, offers a new approach to the design of micro/nanostructured transition metal oxides grown on the current collecting substrate used as anodes in lithium ion batteries with enhanced electrochemical performance.
Co-reporter:Chunyan Zeng, Weixin Zhang, Shaixia Ding, Zeheng Yang, Hui Zeng and Zhangcheng Li
CrystEngComm 2013 vol. 15(Issue 25) pp:5127-5133
Publication Date(Web):19 Apr 2013
DOI:10.1039/C3CE40232K
Ultra-long Ag2Se crystalline nanowires with lengths up to several hundred micrometers and diameters of 100–300 nm have been successfully fabricated by water evaporation-induced growth method at 120 °C for 6 h. Experiments have revealed that the growth of Ag2Se crystalline nanowires is dominated by oriented attachment mechanism. The continuous water evaporation plays an important role for the formation of long nanowires, since it can cause high overall supersaturation and crystallite–solution interfacial supersaturation in the system, which can induce secondary nucleation, and thus promote the oriented attachment growth of long crystalline nanowires. Therefore, it is promising that the water evaporation-induced growth method could be developed for the synthesis of other 1D inorganic nanomaterials.
Co-reporter:Chunyan Zeng;Bin Bin Li;Xiaofeng Xu
Journal of Materials Science 2013 Volume 48( Issue 11) pp:3936-3942
Publication Date(Web):2013 June
DOI:10.1007/s10853-013-7197-9
Wide band gap BexZn1−xO nanorod arrays on Zn foil substrates have been successfully prepared for the first time by a facile hydrothermal method at 80 °C for 24 h. The structure, morphology, and optical properties of the nanorod arrays were studied by X-ray diffraction (XRD), field emission scanning electron microscopy, and photoluminescence (PL). The composition x and band gap energy of the BexZn1−xO nanorod arrays were calculated from XRD and PL results, respectively. The results show that the PL emission peak energy increased with increasing x, as expected, and these materials should be suitable for developing UV-based optoelectronics.
Co-reporter:Weixin Zhang;Jie Xing;Zeheng Yang
Frontiers of Chemical Science and Engineering 2013 Volume 7( Issue 2) pp:192-201
Publication Date(Web):2013 June
DOI:10.1007/s11705-013-1319-4
The TiO2 hollow nanospheres with diameters of about 230 nm were prepared by a simple and controllable route based on hydrolysis of Ti(OBu)4 on the surfaces of the Cu2O solid nanospheres followed by inward etching of the Cu2O nanospheres. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The further post-heat treatment led to the high crystallization of the TiO2 hollow nanospheres. The photocatalytic performances of these samples were evaluated for the photodegradation of rhodamine B (RhB) under UV-light irradiation. The as-prepared TiO2 hollow nanospheres showed higher photocatalytic activity than the CuO and the CuO/TiO2 hollow nanospheres. Effects of temperature and time for post-heat treatment of TiO2 as well as initial RhB concentrations on the RhB photodegradation have also been studied. The results show that the TiO2 hollow nanospheres have the good reusability as photocatalysts and are promising in waste water treatment.
Co-reporter:Lingling Chen, Weixin Zhang, Cheng Feng, Zeheng Yang, and Yumei Yang
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 11) pp:4208-4214
Publication Date(Web):February 23, 2012
DOI:10.1021/ie202044v
Well-aligned ZnSe nanotube arrays with diameters of 300–400 nm and wall thicknesses of 60–70 nm have been controllably prepared based on a replacement/etching method, with ZnO nanorod arrays on zinc substrate as sacrificial templates. An obvious difference of the solubility product (Ksp) between the ZnSe wall and ZnO core materials is crucial for the direct replacement of one type of anions by the other. Ammonia as the chemical etching agent is also important for dissolving ZnO nanorod core. The photocatalytic activities of the as-prepared ZnSe nanotube arrays have been studied for the degradation of methyl orange aqueous solution and compared with those of ZnO nanorod arrays and the intermediates including ZnO/ZnSe core/sheath nanorod arrays and partially dissolved ZnO core/ZnSe sheath nanorod arrays, respectively. The results indicate that ZnSe nanotube arrays exhibit superior photocatalytic performance to the other three nanostructured arrays, which can be mainly attributed to their full hollow interior nanotubes providing more accessibility to the dye molecules and more reactive adsorption/desorption sites for photocatalytic reactions. Furthermore, the ZnSe nanotube arrays have successfully overcome the shortcomings related to photocatalyst recovery and stability, which the powder-form photocatalysts usually face. ZnSe nanotube arrays as photocatalysts are expected to be promising in sewage water treatment.
Co-reporter:Weixin Zhang, Hui Zeng, Zeheng Yang, Qiang Wang
Journal of Solid State Chemistry 2012 Volume 186() pp:58-63
Publication Date(Web):February 2012
DOI:10.1016/j.jssc.2011.11.042
A new strategy has been presented to the controllable synthesis of CuInS2 hollow nanospheres based on the Cu2O solid nanospheres as the precursor in the absence of any surfactant. Specifically, the CuInS2 hollow nanospheres result from hydrothermal transformation of the intermediate Cu7S4 hollow nanospheres derived from Cu2O solid nanosphere precursor by the Kirkendall effect in the conversion process. The CuInS2 hollow nanospheres with diameters of about 250 nm are assembly of nanoparticles with an average size of 20–30 nm. The composition, structure, and morphology of the Cu2O precursor, the Cu7S4 intermediate, and final CuInS2 product have been, respectively, characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Different from investigation of photovoltaic properties, in this work, the as-prepared CuInS2 hollow nanospheres have been explored as anode materials for rechargeable lithium ion batteries. They deliver a large initial discharge capacity of 1144 mAh g−1 and exhibit good cycle performance with a discharge capacity of 265 mAh g−1 after 20 cycles, which are superior to those of CuInS2 nanoparticles. The suitable surface area and relatively stable structure of the CuInS2 hollow nanospheres play an important role in their enhanced electrochemical performance as anode materials.Graphical abstractCuInS2 hollow nanospheres was successfully prepared from Cu2O solid nanospheres in the absence of any surfactant, which can deliver a large initial discharge capacity of 1144 mAh g−1 and exhibit good cycle performance.Highlights► CuInS2 hollow nanospheres were synthesized hydrothermally from Cu2O nanospheres. ► The CuInS2 hollow nanospheres present high discharge capacities as anode materials. ► Better cycling performance can be attributed to its hollow structure.
Co-reporter:Xiaojing Zhang;Zeheng Yang
Frontiers of Chemical Science and Engineering 2012 Volume 6( Issue 3) pp:246-252
Publication Date(Web):2012 September
DOI:10.1007/s11705-012-1299-9
A solvothermal method has been successfully used to prepare nanostructured hydroxyapatite (HA) hollow spheres with average diameters of about 500 nm and shell thicknesses of about 100 nm in a glycerin/water mixed solvent. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM) images show that the shells of the HA hollow spheres are actually composed of nanosheets with thicknesses of about 10 nm. By tuning the glycerin/water volume ratio, two other kinds of HA solid spheres with average diameters of about 6 or 20 μm were assembled from nanoflakes. The properties of the different kinds of spheres as drug delivery carriers were evaluated. Ibuprofen (IBU) was chosen as the model drug to load into the HA samples. The nanostructured HA samples showed a slow and sustained release of IBU. The HA hollow spheres exhibited a higher drug loading capacity and more favorable release properties than the HA solid spheres and thus are very promising for controlled drug release applications.
Co-reporter:Weixin Zhang, Cheng Feng, Zeheng Yang
Sensors and Actuators B: Chemical 2012 Volume 165(Issue 1) pp:62-67
Publication Date(Web):April 2012
DOI:10.1016/j.snb.2012.02.013
Well-aligned arrays of polycrystalline ZnS nanotubes with close-tips have been successfully prepared by using ZnO nanorod arrays grown on zinc substrate as sacrificial precursors. The method is based on chemical conversion and inward etching of the ZnO sacrificial precursors. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images show that the highly ordered ZnS nanotube arrays are 300 nm in average diameter, 6–8 μm in length and about 60 nm in wall thickness. A room temperature photoluminescence-type gas sensing device based on the nanostructured arrays has been established to investigate their humidity sensing properties. ZnS nanotube array-based sensor presents higher response and quicker response/recovery than the intermediate ZnO/ZnS nanorod arrays and the precursor ZnO nanorod arrays, respectively. Moreover, the ZnS nanotube array-based sensor exhibits good linearity in response to relative humidity (RH) and reliable reproducibility in a wide range of RH at room temperature. Compared with powder-form nanomaterials, the as-prepared nanotube arrays as the humidity sensing materials can provide much more open surfaces between neighboring nanotubes and inner surfaces inside the nanotubes and allow for easy diffusion and efficient transportation of sensed gas. As a prototype sensor, the nanotube arrays can avoid tedious process of fabricating a sensor from powder and may hold great potential applications in humidity sensing.
Co-reporter:Weixin Zhang, Chunyan Zeng, Mei Kong, Yanmei Pan, Zeheng Yang
Sensors and Actuators B: Chemical 2012 Volume 162(Issue 1) pp:292-299
Publication Date(Web):20 February 2012
DOI:10.1016/j.snb.2011.12.080
In this work, α-MnO2 hierarchical hollow nanospheres with diameters of 1–2.5 μm, which are composed of densely aligned nanowires with diameters of 10–15 nm and length of about 1 μm on the shell, have been prepared via a simple water-evaporation-induced self-assembly (WEISA) route. MnSO4·H2O and (NH4)2S2O8 have been used as raw materials with the presence of Ag+ ions in the reaction system. Experiments reveal that α-MnO2 hierarchical hollow nanospheres derive from solid nanospheres composed of nanowire clusters shortly after evaporation (0.5 h) and finally split into randomly dispersed nanowires with longer evaporation time (8 h). The process can be explained with Ostwald ripening mechanism. In addition to the evaporation time, the existence of Ag+ ions plays an important role in controlling the phase and morphology of the evaporation product. Furthermore, the ammonia gas sensing properties of the as-prepared samples have been investigated at room temperature with a simply adapted resistance-type gas sensor. The sensors exhibit good sensing performances with quick response and recovery, good repeatability and no need for heat regeneration. The results indicate that the sensor based on α-MnO2 hierarchical hollow nanospheres exhibits higher response to ammonia gas than the one based on α-MnO2 nanowires.
Co-reporter:Qiang Wang, Weixin Zhang, Zeheng Yang, Shaoying Weng, Zhuojie Jin
Journal of Power Sources 2011 Volume 196(Issue 23) pp:10176-10182
Publication Date(Web):1 December 2011
DOI:10.1016/j.jpowsour.2011.08.046
Hierarchical LiFePO4 microflowers have been successfully synthesized via a solvothermal reaction in ethanol solvent with the self-prepared ammonium iron phosphate rectangular nanoplates as a precursor, which is obtained by a simple water evaporation method beforehand. The hierarchical LiFePO4 microflowers are self-assemblies of a number of stacked rectangular nanoplates with length of 6–8 μm, width of 1–2 μm and thickness of around 50 nm. When ethanol is replaced with the water–ethanol mixed solvent in the solvothermal reaction, LiFePO4 micro-octahedrons instead of hierarchical microflowers can be prepared. Then both of them are respectively modified with carbon coating through a post-heat treatment and their morphologies are retained. As a cathode material for rechargeable lithium ion batteries, the carbon-coated hierarchical LiFePO4 microflowers deliver high initial discharge capacity (162 mAh g−1 at 0.1 C), excellent high-rate discharge capability (101 mAh g−1 at 10 C), and cycling stability, which exhibits better electrochemical performances than carbon-coated LiFePO4 micro-octahedrons. These enhanced electrochemical properties can be attributed to the hierarchical micro/nanostructures, which can take advantage of structure stability of micromaterials for long-term cycling. Furthermore the rectangular nanoplates as the building blocks can improve the electrochemical reaction kinetics and finally promote the rate performance.Graphical abstractHighlights► Hierarchical LiFePO4 microflowers assembled by thin rectangular nanoplates have been synthesized. ► Hierarchical LiFePO4 microflowers deliver excellent electrochemical performance. ► Hierarchical micro/nanostructures take the advantages of both nanometer-sized building blocks and micro-sized assemblies, which facilitate fast electrochemical reaction kinetics and good structural stability.
Co-reporter:Bo Pei, Qiang Wang, Weixin Zhang, Zeheng Yang, Min Chen
Electrochimica Acta 2011 Volume 56(Issue 16) pp:5667-5672
Publication Date(Web):30 June 2011
DOI:10.1016/j.electacta.2011.04.024
A hydrothermal reaction has been adopted to synthesize pure LiFePO4 first, which was then modified with carbon coating and cupric ion (Cu2+) doping simultaneously through a post-heat treatment. X-ray diffraction patterns, transmission electron microscopy and scanning electron microscopy images along with energy dispersive spectroscopy mappings have verified the homogeneous existence of coated carbon and doped Cu2+ in LiFePO4 particles with phospho-olivine structure and an average size of 400 nm. The electrochemical performances of the material have been studied by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge measurements. The carbon-coated and Cu2+-doped LiFePO4 sample (LFCu5/C) exhibited an enhanced electronic conductivity of 2.05 × 10−3 S cm−1, a specific discharge capacity of 158 mAh g−1 at 50 mA g−1, a capacity retention of 96.4% after 50 cycles, a decreased charge transfer resistance of 79.4 Ω and superior electrode reaction reversibility. The present synthesis route is promising in making the hydrothermal method more practical for preparation of the LiFePO4 material and enhancement of electrochemical properties.Highlights► Hydrothermal reaction has been adopted to synthesize LiFePO4 with a narrow size distribution. ► LiFePO4 was modified with carbon coating and cupric cation (Cu2+) doping simultaneously. ► Electrochemical properties of LiFePO4 were improved by carbon coating and cupric cation doping.
Co-reporter:Mei Kong, Weixin Zhang, Zeheng Yang, Shaoying Weng, Zhangxian Chen
Applied Surface Science 2011 Volume 258(Issue 4) pp:1317-1321
Publication Date(Web):1 December 2011
DOI:10.1016/j.apsusc.2011.08.127
Abstract
CuO hollow nanospheres with an average diameter of 400 nm and shell thickness of 40 nm have been successfully synthesized via a simple thermal oxidation strategy with Cu2O solid nanospheres as the precursor. The products have been characterized by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. The formation of CuO hollow nanospheres mainly results from the Kirkendall effect on the basis of temperature-dependent experiments. Furthermore, the electrochemical performance of CuO hollow nanospheres as anode materials for lithium ion batteries has been evaluated by cyclic voltammetry and galvanostatic discharge-charge experiments. The as-prepared CuO hollow nanospheres assembled by nanoparticles exhibit higher initial discharge capacity and better cycle performance than the reported CuO nanoparticles. The hierarchical hollow nanospheres have been demonstrated to take the advantages of nanoparticles and hollow architectures, which could not only shorten the lithium ion transport distance and increase the kinetics of conversion reactions, but also provide suitable electrode/electrolyte contact area and accommodate the volume change associated with lithium ion insertion and extraction.
Co-reporter:Weixin Zhang, Lingling Chen, Zeheng Yang, Jing Peng
Sensors and Actuators B: Chemical 2011 Volume 155(Issue 1) pp:226-231
Publication Date(Web):5 July 2011
DOI:10.1016/j.snb.2010.11.052
Orthorhombic Li3PO4 hollow nanospheres and solid particles have been successfully prepared respectively via a simple neutralization reaction between H3PO4 and LiOH aqueous solutions, by just changing the adding sequence of H3PO4 and LiOH aqueous solutions (with PVP) in dropwise. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM) images display Li3PO4 hollow nanospheres with average diameters of about 400 nm and wall thickness of about 50 nm which is actually composed of nanoparticles with sizes of 20–50 nm, and Li3PO4 solid particles with lengths of 100–500 nm and widths of 100–250 nm. The photoluminescence (PL) properties of the samples reveal that the Li3PO4 hollow nanospheres show stronger PL intensity than the Li3PO4 solid particles. Furthermore, an adapted photoluminescence-type gas sensor based on Li3PO4 hollow nanospheres has been devised and its sensing property to humidity has also been investigated. This novel sensor exhibits good sensitivity, ideal linearity, quick response/recovery, and reliable repeatability in a very wide humidity range at room temperature.
Co-reporter:Jun Xu, Chun-Sing Lee, Yong-Bing Tang, Xue Chen, Zhen-Hua Chen, Wen-Jun Zhang, Shuit-Tong Lee, Weixin Zhang and Zeheng Yang
ACS Nano 2010 Volume 4(Issue 4) pp:1845
Publication Date(Web):March 8, 2010
DOI:10.1021/nn9013627
Facile chemical approaches for the controllable synthesis of CuSe, CuInSe2 nanowire, and CuInSe2/CuInS2 core/shell nanocable bundles were developed. Hexagonal CuSe nanowire bundles with lengths up to hundreds of micrometers, consisting of many aligned nanowires with a diameter of about 10−15 nm, were prepared by reacting cubic Cu2−xSe nanowire bundles with a sodium citrate solution at room temperature. The CuSe nanowire bundles were then used as self-sacrificial templates for making bundles of tetragonal chalcopyrite CuInSe2 nanowires by reacting with InCl3 via a solvothermal process. Furthermore, bundles of CuInSe2/CuInS2 core/shell nanocables were obtained by adding sulfur to the reaction system, and the shell thickness of the polycrystalline CuInS2 in the nanocables increased with increasing S/Se molar ratios. It was found that the small radius of copper ions allows their fast outward diffusion from the interior to the surface of nanowires to react with sulfur atoms/anions and indium ions to form a CuInS2 shell. Enhanced optical absorption in the vis−NIR region of CuInSe2/CuInS2 core/shell nanocable bundles is demonstrated, which is considered beneficial for applications in optoelectronic devices and solar energy conversion.Keywords: bundles; core/shell nanocables; CuInS2; CuInSe2; CuSe; phase transformation
Co-reporter:Weixin Zhang and Shihe Yang
Accounts of Chemical Research 2009 Volume 42(Issue 10) pp:1617
Publication Date(Web):July 31, 2009
DOI:10.1021/ar900105c
The full potential of nanotechnology can be unleashed only when one is able not only to synthesize a rich variety of nanoscale building blocks but also assemble them into various patterns at the supramolecular and supracluster levels. In particular, the application of nanoparticle and nanowire materials often requires their assembly in the form of thin films, preferably on conductive surfaces for electrical addressing, control, and detection. Although a dazzling array of nanostructures has been fabricated by bottom-up approaches, one of the contemporary challenges is to assemble these nanostructures so that they introduce and realize functionalities. An alluring avenue is to simultaneously accomplish both the nanostructure synthesis and assembly on a useful substrate in a parallel fashion, affording the advantages of simplicity, low cost, and high throughput. In this Account, we review our recent work on growing inorganic nanowires (for example, metal sulfides, metal oxides, and so forth) directly from and on metal substrates in arrays without using templates and catalysts. This method of engineering nanowire arrays on metal substrates integrates the nanowire synthesis and assembly into a parallel process, both in time and in space, by exploiting in situ chemistry on the metal substrates. Both gas-phase and solution-phase approaches have been developed to synthesize the aligned nanowires; here, full advantage is taken of interfacial kinetics of restricted diffusion and surface-specific reactions, often accompanied by new interfacial growth mechanisms. The setting of nanowire arrays on metal substrates has allowed exploration of their application potentials in areas such as field electron emission and chemical sensing. The approaches described here are general, and we predict that they will be extended to more inorganic materials, such as metal halides. Moreover, as more control is achieved with synthetic methods, inorganic nanowire arrays should provide unusual magnetic, optical, and electronic properties for nanostructural engineers willing to confront the attendant challenges. Accordingly, applications for which there is a current impetus for progress, such as solar cells or lithium ion secondary batteries, might well be addressed with this methodology.
Co-reporter:Jun Xu;Zeheng Yang;Shaixia Ding;Chunyan Zeng;Lingling Chen;Qiang Wang;Shihe Yang
Advanced Functional Materials 2009 Volume 19( Issue 11) pp:1759-1766
Publication Date(Web):
DOI:10.1002/adfm.200801430
Abstract
By a facile water evaporation process without adding any directing agent, Cu2-xSe nanowire bundles with diameters of 100–300 nm and lengths up to hundreds of micrometers, which comprise crystalline nanowires with diameters of 5–8 nm, are obtained. Experiments reveal the initial formation/stacking of CuSe nanoplates and the subsequent transformation to the Cu2-xSe nanowire bundles. A water-evaporation-induced self-assembly (WEISA) mechanism is proposed, which highlights the driving force of evaporation in promoting the nanoplate stacking, CuSe-to-Cu2-xSe transformation and the growth/bundling of the Cu2-xSe nanowires. The simplicity, benignancy, scalability, and high-yield of the synthesis of this important nanowire material herald its numerous applications. As one example, the use of the Cu2-xSe nanowire bundles as a photoluminescence-type sensor of humidity is demonstrated, which shows good sensitivity, ideal linearity, quick response/recovery and long lifetime in a very wide humidity range at room temperature.
Co-reporter:Weixin Zhang, Zhangxian Chen and Zeheng Yang
Physical Chemistry Chemical Physics 2009 vol. 11(Issue 29) pp:6263-6268
Publication Date(Web):13 May 2009
DOI:10.1039/B821452B
Well-defined and uniform double-walled Cu7S4 nanoboxes with an average edge length of about 400 nm have been successfully synthesized by using Cu2O nanocubes as sacrificial template based on an inward replacement/etching method. The key step of the process involves repeated formation of Cu7S4 layer in Na2S solution and dissolution of the Cu2O core in ammonia solution for two consecutive cycles. Experiments show that the time of dissolving Cu2O core with ammonia solution plays a key role in the preparation of double-walled Cu7S4. The as-prepared samples have been characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and photoluminescence analysis. NH3 sensing properties of Cu7S4 nanoboxes with single and double walls have been investigated at room temperature with a simply adapted photoluminescence-type gas sensor. The results revealed that the double-walled Cu7S4 nanobox sensor exhibited enhanced performances such as higher sensitivity and shorter response time in ammonia gas sensing compared with the single-walled one.
Co-reporter:Jun Xu, Yong-Bing Tang, Weixin Zhang, Chun-Sing Lee, Zeheng Yang, and Shuit-Tong Lee
Crystal Growth & Design 2009 Volume 9(Issue 10) pp:4524
Publication Date(Web):August 18, 2009
DOI:10.1021/cg9005339
Highly ordered array of hierarchical nanotubes constructed from Cu2O hollow nanospheres with a diameter of 165−185 nm and shell thickness of 20−40 nm has been synthesized by using an array of Cu(OH)2 nanorods as a sacrificial template. The formation of Cu2O nanotubes is considered to be the result of the “Kirkendall effect”, while evolution of the Cu2O hollow nanospheres from solid nanospheres in the walls results from the “Ostwald ripening” process. Furthermore, the Kirkendall effect in nanoscaled synthesis has been directly proven by the successful design and synthesis of arrays of Cu2O/Cu2−xSe heterogeneous nanotubes constructed from Cu2O hollow seminanospheres covered on both the inner and the outer surfaces of Cu2−xSe sheaths with a thickness about 5−10 nm, in which the diffusion rate of copper ions through the Cu2−xSe sheaths is shown to be double that of ascorbic acid molecules during the reaction process. This work offers a new strategy to study the diffusion rate relationship between diffusion couple in nanoscaled synthesis and provides a novel approach for controllable synthesis of hierarchical architectures with dual hollow nanostructures.
Co-reporter:Ze-heng Yang, Da-peng Zhang, Wei-xin Zhang, Min Chen
Journal of Physics and Chemistry of Solids 2009 Volume 70(Issue 5) pp:840-846
Publication Date(Web):May 2009
DOI:10.1016/j.jpcs.2009.04.004
Uniform Cu2O nanospheres have been successfully synthesized by reducing CuSO4 with ascorbic acid in sucrose solution at room temperature. The diameter of the Cu2O nanospheres can be tuned from 90 to 280 nm by adding different amounts of sucrose in the solution. Furthermore, CuS hollow nanospheres with different diameters have been obtained based on the Kirkendall effect using the as-prepared Cu2O nanospheres as sacrificial templates. Cu2O/Cu7.2S4 core/shell nanospheres and Cu7.2S4 hollow nanospheres are obtained as the intermediate products at different stages of the conversion process. Through the post-treatment of sodium citrate solution, Cu7.2S4 hollow nanospheres can be changed into CuS hollow nanospheres. The products are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM). Optical properties of the products have also been studied.
Co-reporter:Zeheng Yang, Chunyan Luan, Weixin Zhang, Anping Liu, Shupei Tang
Thin Solid Films 2008 Volume 516(Issue 18) pp:5974-5980
Publication Date(Web):31 July 2008
DOI:10.1016/j.tsf.2007.10.085
ZnO thin films assembled with large-scale ZnO nanostructured arrays, including nanorod, nanoflower and corn-like nanorod, have been respectively fabricated on zinc substrates by a chemical solution approach. ZnO thin films of different nanorod arrays were obtained through the hydrothermal treatment of Zn foils at 60 °C, respectively in NH3·H2O solution and in the mixed solution of NH3·H2O and NaOH. Whereas ZnO thin films consisting of nanoflowers and corn-like nanorod arrays were obtained respectively in the two kinds of solutions when mechanical oscillation is used instead of hydrothermal treatment. Compared with hydrothermal synthesis, mechanical oscillation provides a convenient approach for nanostructure synthesis.
Co-reporter:Weixin Zhang, Chunyan Luan, Zeheng Yang, Xueting Liu, Dapeng Zhang, Shihe Yang
Applied Surface Science 2007 Volume 253(Issue 14) pp:6063-6067
Publication Date(Web):15 May 2007
DOI:10.1016/j.apsusc.2007.01.005
Abstract
In this work, we report a simple liquid reduction approach to prepare Cu2O hollow microsphere film and hollow nanosphere powder with Cu(OH)2 nanorods as precursor and ascorbic acid as the reductant at 60 °C. When Cu(OH)2 nanorod array film grown on a copper foil is used as the precursor, Cu2O thin film made up of hollow microspheres with average diameter of 1.2 μm is successfully prepared. When the Cu(OH)2 nanorods are scraped from the copper foil and then used as the precursor, Cu2O hollow nanosphere powder with the average diameter of 270 nm is obtained. The samples are characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and ultraviolet–vis light (UV–vis) absorption spectra. A possible formation mechanism of Cu2O hollow spheres is discussed.
Co-reporter:Zeheng Yang, Jun Xu, Weixin Zhang, Anping Liu, Shupei Tang
Journal of Solid State Chemistry 2007 Volume 180(Issue 4) pp:1390-1396
Publication Date(Web):April 2007
DOI:10.1016/j.jssc.2007.02.008
A simple solution route has been developed to prepare nanostructured CuO with Cu(NO3)2·3H2O and NaOH as starting materials. CuO nanoribbons or nanorods and their assemblies into hierarchical structures have been synthesized, respectively, by controlling the molar ratio of NaOH to Cu(NO3)2, reaction temperature and the concentration of the starting NaOH solution. Experiments demonstrate that the molar ratio of NaOH to Cu(NO3)2 is an important parameter which may decide whether CuO exists in nanoribbons (nanorods) or assemblies into hierarchical structures. Whether Cu(NO3)2 is dissolved in ethanol or water also influences the formation of monodispersed CuO nanoribbons (nanorods). The growth mechanism of these nanostructures is discussed. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy (HRTEM) and their optical absorption spectra were also studied.CuO nanorods/nanoribbons and their assemblies into hierarchical structures have been synthesized, respectively, by manipulating reaction conditions in a simple solution route.
Co-reporter:Weixin Zhang;Xiangbin Ren;Zeheng Yang
Frontiers of Chemical Science and Engineering 2007 Volume 1( Issue 4) pp:365-371
Publication Date(Web):2007 October
DOI:10.1007/s11705-007-0066-9
The crystalline α-MnO2 and β-MnO2 nanorods have been successfully prepared via a facile hydrothermal method from γ-MnOOH nanorods precursor, respectively. The samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscope (FESEM) and Fourier transformed infrared spectra (FTIR). The morphology and structure of γ-MnOOH nanorods precursors have a great influence on the crystal structure of the obtained products. The α-MnO2 nanorods are prepared from the 100°C γ-MnOOH precursor, while the β-MnO2 nanorods are obtained from the 150°C γ-MnOOH precursor, respectively. Besides, the catalytic activity of the prepared α-MnO2 and β-MnO2 nanorods for the H2O2 decomposition has been investigated comparatively, and the latter shows better catalytic activity.
Co-reporter:Zeheng Yang, Yuancheng Zhang, Weixin Zhang, Xue Wang, Yitai Qian, Xiaogang Wen, Shihe Yang
Journal of Solid State Chemistry 2006 Volume 179(Issue 3) pp:679-684
Publication Date(Web):March 2006
DOI:10.1016/j.jssc.2005.11.028
Single-crystalline nanorods of β-MnO2, α-Mn2O3 and Mn3O4 were successfully synthesized via the heat-treatment of γ-MnOOH nanorods, which were prepared through a hydrothermal method in advance. The calcination process of γ-MnOOH nanorods was studied with the help of Thermogravimetric analysis and X-ray powder diffraction. When the calcinations were conducted in air from 250 to 1050 °C, the precursor γ-MnOOH was first changed to β-MnO2, then to α-Mn2O3 and finally to Mn3O4. When calcined in N2 atmosphere, γ-MnOOH was directly converted into Mn3O4 at as low as 500 °C. Transmission electron microscopy (TEM) and high-resolution TEM were also used to characterize the products. The obtained manganese oxides maintain the one-dimensional morphology similar to the precursor γ-MnOOH nanorods. Further experiments show that the as-prepared manganese oxide nanorods have catalytic effect on the oxidation and decomposition of the methylene blue (MB) dye with H2O2.Single-crystalline nanorods of β-MnO2, α-Mn2O3 and Mn3O4 were successfully synthesized in large-scale via the heat-treatment of γ-MnOOH nanorod precursors, which were prepared through a hydrothermal method in advance. Further experiments show that the as-prepared manganese oxide nanorods have catalytic effect on the oxidation and decomposition of the methylene blue (MB) dye with H2O2.
Co-reporter:Zeheng Yang, Weixin Zhang, Qiang Wang, Xinmin Song, Yitai Qian
Chemical Physics Letters 2006 Volume 418(1–3) pp:46-49
Publication Date(Web):25 January 2006
DOI:10.1016/j.cplett.2005.10.076
Abstract
In this Letter, we report the facile synthesis of novel porous and hollow microspheres of cubic Mn2O3 nanocrystals of 50–100 nm via the heat-treatment of MnCO3 microspheres, which were prepared simply by reacting the MnCl2 · 2H2O with Na2CO3 in aqueous solution at ambient temperature and pressure. The products were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and field-emission scanning electron microscopy. Through TEM observation, the growth mechanism of the MnCO3 microspheres was revealed and the possible formation mechanism of the porous and hollow structure of the nanocrystalline Mn2O3 microspheres was also proposed.
Co-reporter:Weixin Zhang, Yi Liu, Zeheng Yang, Shupei Tang, Min Chen
Solid State Communications 2004 Volume 131(Issue 7) pp:441-445
Publication Date(Web):1 August 2004
DOI:10.1016/j.ssc.2004.06.007
Li2MnO3 with different nanostructures was synthesized through a solid-state reaction. MnOOH nanorods and nanowires prepared via the hydrothermal method were used as precursors, respectively, to react with Li(OH)·H2O to prepare nanostructured Li2MnO3 in the temperature range from 500 to 800 °C. The samples were characterized by XRD, TEM, ESR and FTIR results. Based on the experimental results, the dehydration–oxidation-combination (DOC) formation mechanism of Li2MnO3 was proposed.
Co-reporter:Weixin Zhang, Yingmeng Zhang, Zeheng Yang, Gongde Chen, Guo Ma, Qiang Wang
Chinese Journal of Chemical Engineering (January 2016) Volume 24(Issue 1) pp:48-52
Publication Date(Web):1 January 2016
DOI:10.1016/j.cjche.2015.07.015
For the ever-growing demand of advanced lithium-ion batteries, it is highly desirable to grow self-supported micro-/nanostructured arrays on metal substrates as electrodes directly. The in-situ growth of electrode materials on the conducting substrates greatly simplifies the electrode fabrication process without using any binders or conductive additives. Moreover, the well-ordered arrays closely connected to the current collectors can provide direct electron transport pathways and enhanced accommodation of strains arisen from lithium ion lithiation/delithiation. This article summarizes our recent work on design and construction of lithium-ion battery electrodes on metal substrates. An aqueous solution-based process and a microemulsion-mediated process have been respectively presented to control the kinetic and thermodynamic processes for the micro-/nanostructured array growth on metal substrates, with particular attention to CuO nanorod arrays and micro-cog arrays successfully prepared on Cu foil substrates. They can be directly used as binder-free electrodes to build advanced lithium-ion batteries with high energy, high safety and high stability.
Co-reporter:Zhangxian Chen, Weixin Zhang, Zeheng Yang
Journal of Crystal Growth (1 June 2009) Volume 311(Issue 12) pp:3347-3351
Publication Date(Web):1 June 2009
DOI:10.1016/j.jcrysgro.2009.03.038
Ag3CuS2 nanocages were successfully fabricated for the first time via a convenient ion-exchange route by Ag+ reacting with Cu7S4 18-facet hollow nanopolyhedra. The average size and shell thickness of Ag3CuS2 nanocages were around 400 and 30 nm, respectively. Room-temperature response of Ag3CuS2 nanocages to ammonia was investigated by photoluminescence-type sensor. Sensing results suggested that these hollow-structured Ag3CuS2 exhibited better performances including higher sensitivity, shorter response and recovery time than their rod-shape counterparts. A possible hole trapping mechanism was proposed.
Co-reporter:Weixin Zhang, Zhangxian Chen and Zeheng Yang
Physical Chemistry Chemical Physics 2009 - vol. 11(Issue 29) pp:NaN6268-6268
Publication Date(Web):2009/05/13
DOI:10.1039/B821452B
Well-defined and uniform double-walled Cu7S4 nanoboxes with an average edge length of about 400 nm have been successfully synthesized by using Cu2O nanocubes as sacrificial template based on an inward replacement/etching method. The key step of the process involves repeated formation of Cu7S4 layer in Na2S solution and dissolution of the Cu2O core in ammonia solution for two consecutive cycles. Experiments show that the time of dissolving Cu2O core with ammonia solution plays a key role in the preparation of double-walled Cu7S4. The as-prepared samples have been characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and photoluminescence analysis. NH3 sensing properties of Cu7S4 nanoboxes with single and double walls have been investigated at room temperature with a simply adapted photoluminescence-type gas sensor. The results revealed that the double-walled Cu7S4 nanobox sensor exhibited enhanced performances such as higher sensitivity and shorter response time in ammonia gas sensing compared with the single-walled one.
Co-reporter:Yingmeng Zhang, Weixin Zhang, Mei Li, Zeheng Yang, Gongde Chen and Qiang Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 45) pp:NaN14374-14374
Publication Date(Web):2013/09/16
DOI:10.1039/C3TA13018E
A cosurfactant-mediated microemulsion synthesis of free-standing CuO arrays with hierarchical micro-cog architectures on copper substrates has been successfully established. The CuO cog-array films directly employed as anode electrodes derive from thermal dehydration of Cu(OH)2 arrays grown from copper substrates in the presence of AOT–n-butanol–isooctane–water microemulsions. Introducing n-butanol as a cosurfactant into the ternary AOT–isooctane–water system increases the rigidity of the reverse micelles and it can be selectively adsorbed on particular crystal faces, leading to well-aligned arrays as well as enlarged aspect ratios with average heights of over 6 μm and diameters of 1–2 μm. This result sharply contrasts with the multilayer film of micro-cog particles with a shortened aspect ratio prepared in the absence of n-butanol. The CuO film electrodes of free-standing micro-cog-arrays exhibit excellent electrochemical performance, including a long cycling life (with capacity retention of 91.6% at 1 C over 300 cycles) and outstanding rate capability even at high current rates (about 466 and 418 mA h g−1 at high rates of 12 and 15 C) in lithium ion batteries.
Co-reporter:Weixin Zhang, Zaoyuan Zhou, Wenran Zhao, Zeheng Yang and Xiaoning Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 16) pp:NaN5808-5808
Publication Date(Web):2014/01/31
DOI:10.1039/C3TA14722C
The utilization of well-aligned hybrid one-dimensional hollow nanostructured arrays is a promising strategy for the development of transition metal oxides as high-cycle-life stability and high-rate performance electrode materials for lithium ion batteries. Here we report a chemical replacement route to prepare well-aligned Cu2−xSe-coated CuO nanotube arrays with diameters of 400 nm and length of several micrometers, based on Cu(OH)2 nanotube arrays grown on a copper substrate as precursors. As an integrated anode for lithium ion batteries, the Cu2−xSe-coated CuO nanotube array on a copper substrate is capable of delivering a high cycling capacity of 764 mA h g−1 after 100 cycles at a current density of 0.08 mA cm−2 (0.1 C), and retains a discharge capacity of 382.5 mA h g−1 and 94.5 mA h g−1 at current densities of 10 mA cm−2 (12.5 C) and 20 mA cm−2 (25 C), respectively, exhibiting superior performance to the bare CuO nanotube array film. The synergistic effect of the successful integration of the CuO nanotubes with the Cu2−xSe semiconducting coating layer significantly contributes to the enhanced electrochemical properties of the Cu2−xSe-coated CuO nanotube array anode.
