ZhengHua Wang - Cochemist

Nickel foam supported hierarchical Co9S8 nanostructures for asymmetric supercapacitors

Co-reporter:Xiaoqing Mao;Wei Kong;Weizhi Wang

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 3) pp:1142-1148

Publication Date(Web):2017/01/30

DOI:10.1039/C6NJ02800D

In this work, nickel foam supported Co9S8 nanostructures are fabricated by a facile two-step hydrothermal process. The Co9S8 nanostructures have a hierarchical structure in which the Co9S8 nanotubes are wrapped by Co9S8 nanosheets. The Co9S8 nanostructures are in situ grown on nickel foam by the hydrothermal process and can be directly used as electrodes for supercapacitors without any further treatment. The Co9S8 electrode exhibits a high specific capacitance up to 2166 F g−1 at a discharge current density of 1 A g−1 and a capacitance retention of 74% at 20 A g−1. Furthermore, the Co9S8 electrode shows a good cycling stability with 75.8% capacitance retention after 4000 charge–discharge cycles. An asymmetric supercapacitor device was assembled by using Co9S8 and porous carbon as the positive and negative electrode materials, respectively. The device displays an excellent electrochemical capability. This work demonstrates that the hierarchical Co9S8 nanostructures are desirable for application as advanced supercapacitor electrode materials.

Nickel foam supported hierarchical Co9S8 nanostructures for asymmetric supercapacitors

Co-reporter:Xiaoqing Mao;Wei Kong;Weizhi Wang

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 3) pp:1142-1148

Publication Date(Web):2017/01/30

DOI:10.1039/C6NJ02800D

In this work, nickel foam supported Co9S8 nanostructures are fabricated by a facile two-step hydrothermal process. The Co9S8 nanostructures have a hierarchical structure in which the Co9S8 nanotubes are wrapped by Co9S8 nanosheets. The Co9S8 nanostructures are in situ grown on nickel foam by the hydrothermal process and can be directly used as electrodes for supercapacitors without any further treatment. The Co9S8 electrode exhibits a high specific capacitance up to 2166 F g−1 at a discharge current density of 1 A g−1 and a capacitance retention of 74% at 20 A g−1. Furthermore, the Co9S8 electrode shows a good cycling stability with 75.8% capacitance retention after 4000 charge–discharge cycles. An asymmetric supercapacitor device was assembled by using Co9S8 and porous carbon as the positive and negative electrode materials, respectively. The device displays an excellent electrochemical capability. This work demonstrates that the hierarchical Co9S8 nanostructures are desirable for application as advanced supercapacitor electrode materials.

Synthesis of a hierarchical cobalt sulfide/cobalt basic salt nanocomposite via a vapor-phase hydrothermal method as an electrode material for supercapacitor

Co-reporter:Long Liu;Heng Rong;Jiajing Li;Xiaowei Tong

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 20) pp:12147-12152

Publication Date(Web):2017/10/09

DOI:10.1039/C7NJ02350B

In this work, a hierarchical structured cobalt sulfide/cobalt basic salt nanocomposite is successfully synthesized by using cobalt basic salt nanowires as a precursor through a vapor-phase hydrothermal process. The as-obtained hierarchical structured cobalt sulfide/cobalt basic salt nanocomposite can be applied as an electrode material for supercapacitors, it exhibits a high specific capacitance of 1984 F g−1 at a current density of 1 A g−1, a good rate capability of 78.6% capacitance retention at a high current density of 20 A g−1 and an excellent cycle stability of 90.2% capacitance retention after 5000 charge–discharge cycles. The specific capacitance of the cobalt sulfide/cobalt basic salt nanocomposite is much higher than that of the cobalt basic salt. The excellent electrochemical performances of the cobalt sulfide/cobalt basic salt nanocomposite can be attributed to its unique hierarchical nanostructure.

Platinum nanoparticles supported on core–shell nickel–carbon as catalyst for methanol oxidation reaction

Co-reporter:Zhenghua Wang, Chenchen Lu, Wei Kong, Yehui Zhang, Jiajing Li

Journal of Alloys and Compounds 2017 Volume 690(Volume 690) pp:

Publication Date(Web):5 January 2017

DOI:10.1016/j.jallcom.2016.08.088

•Pt Nanoparticles were directly supported on Ni–C without using any stabilizer, template or surfactant.•Ni–C–Pt catalysts exhibit excellent catalytic activities for methanol oxidation reaction.•The catalytic activities of Ni–C–Pt nanocomposite with different Pt loading were studied.In this study, we report the fabrication of a trilaminar core–shell structured Ni–C–Pt nanocomposite and its application as catalyst for methanol oxidation reaction. The Ni nanosphere core with a mean diameter of about 130 nm has a good magnetic response, which facilitates the separation and collection of the nanocomposite. The Pt shell is made up of many tiny Pt nanoparticles with diameter of only several nanometers. The high specific surface area of Pt nanoparticles results in high catalytic activity and high Pt utilization. The carbon interlayer acts as a linker for the Ni core and Pt shell. The influence of Pt loading content in the Ni–C–Pt nanocomposite is studied, and the results indicate that the Ni–C–Pt nanocomposite with a 28% Pt loading exhibits the highest catalytic activity for methanol oxidation reaction.

Facile synthesis of gold–platinum dendritic nanostructures with enhanced electrocatalytic performance for the methanol oxidation reaction

Co-reporter:Yehui Zhang, Chenchen Lu, Guili Zhao and Zhenghua Wang

RSC Advances 2016 vol. 6(Issue 57) pp:51569-51574

Publication Date(Web):10 May 2016

DOI:10.1039/C6RA06370E

In this work, bimetallic gold–platinum (Au–Pt) dendritic nanoparticles with different Au/Pt ratios are synthesized via a surfactant-free wet-chemical route. The as-prepared products can be applied as a catalyst for the methanol oxidation reaction, and the results indicate that the Au–Pt dendritic nanoparticles with an Au/Pt ratio of 1:2.86 demonstrate the best catalytic performance. The surfactant-free method avoids the use of surfactants which can provide products with clean surfaces. Control experiments show that the catalytic performance of the Au–Pt samples is much higher than that of a poly(vinylpyrrolidone) (PVP) capped sample. Furthermore, the catalytic performance of the AuPt-2 sample with an Au/Pt ratio of 1:2.86 is much better than that of the commercial Pt/C catalyst and pure Pt nanoparticles. Thus, this work indicates that the Au–Pt dendritic nanoparticles may be used as efficient catalysts for direct methanol fuel cells.

Homogeneous core–shell NiCo2S4 nanostructures supported on nickel foam for supercapacitors

Co-reporter:Wei Kong, Chenchen Lu, Wu Zhang, Jun Pu and Zhenghua Wang

Journal of Materials Chemistry A 2015 vol. 3(Issue 23) pp:12452-12460

Publication Date(Web):07 May 2015

DOI:10.1039/C5TA02432C

In this study, we report the fabrication of NiCo2S4 with a homogeneous core–shell nanostructure in which NiCo2S4 nanotubes are wrapped by NiCo2S4 nanosheets. The core–shell structured NiCo2S4 was in situ grown on nickel foam and can be directly applied as a supercapacitor electrode. Electrochemical tests demonstrate that the NiCo2S4 electrode achieved a high specific capacitance of 1948 mF cm−2 at a current density of 1 mA cm−2, a good rate capability, and an excellent cycling stability. The outstanding performance of the NiCo2S4 electrode can be attributed to its core–shell architecture with good mechanical and electrical contact and rich redox reactions, as well as high transport rate for both electrolyte ions and electrons. By applying NiCo2S4 as the positive electrode and porous carbon as the negative electrode, an asymmetric supercapacitor device was fabricated and it exhibited an excellent electrochemical performance. These results demonstrate that the homogeneous core–shell NiCo2S4 nanostructure is promising for supercapacitor applications.

Gold–platinum bimetallic nanotubes templated from tellurium nanowires as efficient electrocatalysts for methanol oxidation reaction

Co-reporter:Chenchen Lu, Wei Kong, Huying Zhang, Bo Song, Zhenghua Wang

Journal of Power Sources 2015 Volume 296() pp:102-108

Publication Date(Web):20 November 2015

DOI:10.1016/j.jpowsour.2015.07.049

•Au–Pt bimetallic nanotubes were synthesized via a sacrificial template method.•Au–Pt bimetallic catalysts exhibit excellent electrocatalytic activities.•The catalytic activities of samples with different Au/Pt ratio were studied.In this paper, gold–platinum (Au–Pt) bimetallic nanotubes with different Au/Pt ratio are successfully synthesized through a simple wet-chemical reduction route in which tellurium (Te) nanowires serve as both sacrificial template and reducing agent. The hollow nanostructure of Au–Pt nanotubes is formed due to Kirkendall effect. The as-prepared Au–Pt nanotubes can be applied as catalyst for methanol oxidation reaction, and the results indicate that the Au–Pt nanotubes with an Au/Pt ratio of 1:1 show the best electrochemical catalytic performances. Furthermore, the catalytic activity of the Au–Pt nanotubes is also better than Pt nanotubes and commercial Pt/C catalyst.

ZnCo2O4 nanowire arrays grown on nickel foam for high-performance pseudocapacitors

Co-reporter:Shubo Wang, Jun Pu, Yao Tong, Yuanyuan Cheng, Yan Gao and Zhenghua Wang

Journal of Materials Chemistry A 2014 vol. 2(Issue 15) pp:5434-5440

Publication Date(Web):10 Jan 2014

DOI:10.1039/C3TA14941B

Uniform ZnCo2O4 nanowire arrays were directly grown on nickel foam through a facile hydrothermal method and subsequent thermal treatment process. The ZnCo2O4 nanowires have diameters of about 100 nm and lengths of up to 5 μm. The as-obtained ZnCo2O4 nanowire array loaded nickel foam can be directly applied as an electrode for high-performance supercapacitors. Electrochemical measurements show that the ZnCo2O4/nickel foam electrode has high specific capacitance (1625 F g−1 at 5 A g−1), excellent rate capability (59% capacitance retention at 80 A g−1) and good cycling stability (94% capacitance retention over 5000 charge–discharge cycles). This work demonstrates that ZnCo2O4 nanowires are highly desirable for application as advanced electrochemical electrode materials.

Preparation and Electrochemical Characterization of Hollow Hexagonal NiCo2S4 Nanoplates as Pseudocapacitor Materials

Co-reporter:Jun Pu, Fangling Cui, Sibin Chu, Tingting Wang, Enhong Sheng, and Zhenghua Wang

ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 4) pp:809

Publication Date(Web):December 23, 2013

DOI:10.1021/sc400472z

In this study, the binary transition metal sulfide NiCo2S4 with a novel hollow hexagonal nanoplate (HHNs) structure has been synthesized through a sacrificial template method based on the Kirkendall effect. The hollow nanoplates have an average diameter of about 200 nm, thickness of about 50 nm, and shell thickness of about 10 nm. The resulting samples were characterized by means of XRD, XPS, EDX, SEM, TEM, and HRTEM. The electrochemical characterization results demonstrate that NiCo2S4 hollow hexagonal nanoplates exhibit a high specific capacitance of 437 F g–1 in a 3 M KOH aqueous electrolyte at a current rate of 1 A g–1, along with a superior rate capability and Coulombic efficiency stability, indicating their potential application as electrode materials for supercapacitors.Keywords: Hollow hexagonal nanoplates; Kirkendall effect; NiCo2S4; Supercapacitors;

Co9S8 nanotube arrays supported on nickel foam for high-performance supercapacitors

Co-reporter:Jun Pu, Zhenghua Wang, Konglin Wu, Nan Yu and Enhong Sheng

Physical Chemistry Chemical Physics 2014 vol. 16(Issue 2) pp:785-791

Publication Date(Web):28 Oct 2013

DOI:10.1039/C3CP54192D

Uniform Co9S8 nanotube arrays on conductive nickel foam were successfully synthesized through a facile two-step hydrothermal method and were directly applied as the electrode for high-performance electrochemical capacitors. The formation of the tubular structure of Co9S8 can be attributed to the nanoscale Kirkendall effect. SEM and TEM images show that most of the Co9S8 nanotubes have hexagonal sections. The diameter of the Co9S8 nanotubes is about 120–200 nm and the wall thickness is of 40–60 nm. Cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance measurements are applied to investigate the electrochemical performance of the Co9S8 nanotubes. The specific capacitance of the Co9S8 nanotubes is 1775 F g−1 at 4 A g−1, and 1483 F g−1 at 24 A g−1, indicating the high rate capability. Also, the Co9S8 nanotubes exhibit stable cycling performance.

Ag–Pt core–shell nanocomposites for enhanced methanol oxidation

Co-reporter:Yao Tong, Jun Pu, Haiyan Wang, Shubo Wang, Chang Liu, Zhenghua Wang

Journal of Electroanalytical Chemistry 2014 Volume 728() pp:66-71

Publication Date(Web):15 August 2014

DOI:10.1016/j.jelechem.2014.06.030

Ag–Pt core–shell nanocomposites composed of Ag nanoparticle core and ultra-thin Pt nanorods shell have been successfully synthesized via a simple wet-chemical route at room temperature. The influence of reacting temperature on the final product was studied, and the results showed that Pt dendrites instead of Pt nanorods were formed at elevated temperature. The as-synthesized Ag–Pt core–shell nanocomposites were applied as catalyst for the methanol electro-oxidation reaction, and the results indicate that the Ag–Pt core–rods nanocomposites have the best steady-state catalytic activity and high catalytic activity.Graphical abstractAg–Pt core–shell nanocomposites composed of Ag nanoparticle core and ultra-thin Pt nanorods shell were synthesized via a simple wet-chemical route at room temperature, and they showed good catalytic activities when acted as catalyst for the methanol electro-oxidation reaction.

Direct Growth of NiCo2S4 Nanotube Arrays on Nickel Foam as High-Performance Binder-Free Electrodes for Supercapacitors

Co-reporter:Jun Pu;Tingting Wang;Haiyang Wang;Yao Tong;Chenchen Lu;Wei Kong;Dr. Zhenghua Wang

ChemPlusChem 2014 Volume 79( Issue 4) pp:577-583

Publication Date(Web):

DOI:10.1002/cplu.201300431

Abstract

Arrays of NiCo₂S₄ nanotubes on nickel foam were prepared by means of a two-step method, and were directly applied as a binder-free supercapacitor electrode. Such a binder-free method enables intimate contact between the current collector and the active materials, and can effectively improve ion and charge transportation. As a result, the electrochemical performances of supercapacitors can be improved. The as-prepared NiCo₂S₄ nanotubes/Ni foam electrode shows a high specific capacitance (738 F g⁻¹ at 4 A g⁻¹), excellent rate capability (78 % capacitance retention at 32 A g⁻¹), and good cycling stability (retention capacity of 93.4 % after 4000 cycles), which suggests its promising application for electrochemical capacitors.

InSitu Growth of Noble-Metal Nanoparticles on Cu2O Nanocubes for Surface-Enhanced Raman Scattering Detection

Co-reporter:Jie Wang;Fangling Cui;Sibin Chu;Xiaoquan Jin;Jun Pu ;Dr. Zhenghua Wang

ChemPlusChem 2014 Volume 79( Issue 5) pp:684-689

Publication Date(Web):

DOI:10.1002/cplu.201400028

Abstract

Gold and silver nanoparticles with a narrow size distribution were grown in situ on the surfaces of Cu₂O nanocubes through a wet-chemical reduction route. The Cu₂O nanocubes serve as both the substrate and reducing agent. The as-prepared Cu₂OAu and Cu₂OAg nanocomposites still retain the cubic morphology of the original Cu₂O nanocubes. The Cu₂OAu and Cu₂OAg nanocomposites can serve as effective surface-enhanced Raman scattering (SERS) substrates. Rhodamine 6G as a Raman probe was applied to determine the effects of the SERS substrates; the results show that Cu₂OAg nanocomposites have higher sensitivity and good reproducibility. Furthermore, the Cu₂OAg substrate was also applied to detect plasticizers, such as dimethyl phthalate and dibutyl phthalate, and shows potential applications in the area of food safety screening.

InSitu Growth of Noble-Metal Nanoparticles on Cu2O Nanocubes for Surface-Enhanced Raman Scattering Detection

Co-reporter:Jie Wang;Fangling Cui;Sibin Chu;Xiaoquan Jin;Jun Pu ;Dr. Zhenghua Wang

ChemPlusChem 2014 Volume 79( Issue 5) pp:

Publication Date(Web):

DOI:10.1002/cplu.201400037

Abstract

Invited for this month’s cover is the group of Prof. Zhenghua Wang from Anhui Normal University, China. The cover picture shows the synthesis of Cu₂O/noble metal nanocomposites. The as-obtained nanocomposites are applied as SERS substrates with high sensitivity and good reproducibility, which can be used for the detection of food contaminants. Read the full text of the article at 10.1002/cplu.201400028

Cover Picture: InSitu Growth of Noble-Metal Nanoparticles on Cu2O Nanocubes for Surface-Enhanced Raman Scattering Detection (ChemPlusChem 5/2014)

Co-reporter:Jie Wang;Fangling Cui;Sibin Chu;Xiaoquan Jin;Jun Pu ;Dr. Zhenghua Wang

ChemPlusChem 2014 Volume 79( Issue 5) pp:

Publication Date(Web):

DOI:10.1002/cplu.201400039

Nano CuO-catalyzed C–H functionalization of 1,3-azoles with bromoarenes and bromoalkenes

Co-reporter:Wu Zhang, Yujie Tian, Na Zhao, Yuanyuan Wang, Jia Li, Zhenghua Wang

Tetrahedron 2014 70(36) pp: 6120-6126

Publication Date(Web):

DOI:10.1016/j.tet.2014.04.065

Porous hexagonal NiCo2O4 nanoplates as electrode materials for supercapacitors

Co-reporter:Jun Pu, Jie Wang, Xiaoquan Jin, Fangling Cui, Enhong Sheng, Zhenghua Wang

Electrochimica Acta 2013 Volume 106() pp:226-234

Publication Date(Web):1 September 2013

DOI:10.1016/j.electacta.2013.05.092

Porous hexagonal NiCo2O4 nanoplates with an average diameter of about 100 nm and average thickness of about 25 nm have been successfully synthesized through a facile hydrothermal process and subsequent calcination in air. The calcination temperature involved has obvious affection upon the porous structures as well as the resultant capacitive performances. The NiCo2O4 sample obtained at a calcination temperature of 300 °C has a specific surface area of 67.1 m2 g−1, and a specific capacitance of 294 F g−1 at a current density of 1 A g−1. The long-term cycling stability test showed good rate retention of 89.8% of the highest capacitance after 3000 cycles. Therefore, the porous hexagonal NiCo2O4 nanoplates are excellent electrode material for supercapacitors.

Synthesis of polycrystalline cobalt selenide nanotubes and their catalytic and capacitive behaviors

Co-reporter:Zhenghua Wang, Qiang Sha, Fengwei Zhang, Jun Pu and Wu Zhang

CrystEngComm 2013 vol. 15(Issue 29) pp:5928-5934

Publication Date(Web):22 May 2013

DOI:10.1039/C3CE40152A

Polycrystalline Co0.85Se nanotubes are successfully prepared by using Co(CO3)0.35Cl0.20(OH)1.10 nanorods as precursor through a solvothermal process. The as-prepared Co0.85Se nanotubes show efficient catalytic performance for decomposition of hydrazine hydrate at room temperature. The catalysts can be repeatedly used and their repeatability is also excellent. The Co0.85Se nanotubes can also be applied as supercapacitor electrode materials. Galvanostatic charge–discharge measurements show that the Co0.85Se nanotube electrode has a specific capacitance of 238 F g−1 at a current density of 1 A g−1 after 100 cycles of activation, and retaining 90.3% of the capacitance after the next 1900 cycles.

Shape-controlled synthesis of ternary nickel cobaltite and their application in supercapacitors

Co-reporter:Jun Pu, Xiaoquan Jin, Jie Wang, Fangling Cui, Sibin Chu, Enhong Sheng, Zhenghua Wang

Journal of Electroanalytical Chemistry 2013 Volume 707() pp:66-73

Publication Date(Web):15 October 2013

DOI:10.1016/j.jelechem.2013.08.021

A facile hydrothermal method and subsequent annealing approach have been successfully developed to synthesize ternary nickel cobaltite hexapods, hexagonal prisms and nanowires. The products were investigated in detail by means of XRD, FESEM, TEM, HRTEM, BET, TGA and XPS. The hexapods have six clusters, and every cluster has many typical nanorods with diameter of about 10 nm and length of 1.2 μm. The nanowires are uniform in size, with diameters of about 10 nm. The hexagonal prisms with average size of about 120 nm have the highest BET specific surface area of 74.66 m2 g−1 and a pore volume of 0.1874 cm3 g−1, which exhibited superior specific capacitance of 663 F g−1 at a current density of 1 A g−1. It has impressive cycling stability with 88.4% initial capacitance retained after 5000 cycles at 4 A g−1, revealing the excellent stability of the electrode.

Template synthesis of Cu2−xSe nanoboxes and their gas sensing properties

Co-reporter:Zhenghua Wang, Fei Peng, Yichun Wu, Li Yang, Fengwei Zhang and Jiarui Huang

CrystEngComm 2012 vol. 14(Issue 10) pp:3528-3533

Publication Date(Web):12 Mar 2012

DOI:10.1039/C2CE06752H

Cu2−xSe nanoboxes with a well-defined hollow structure are successfully synthesized by using Cu2O nanocubes as sacrificial hard templates through a convenient wet-chemical method. Field-emission scanning electron microscopy (FESEM) observation shows that the Cu2−xSe nanocrystals have cubic morphology that are alike to the Cu2O templates. Transmission electron microscopy (TEM) observation shows that the Cu2−xSe nanocrystals have a hollow interior, and they are made of many tiny nanoparticles. The as-prepared Cu2−xSe nanoboxes exhibit a good response and reversibility to some organic gases, such as ethanol and acetone. The responses of the Cu2−xSe nanoboxes to 100 ppm ethanol and acetone are 35.1 and 32.1, respectively, at a working temperature of 300 °C. These results show that the Cu2−x Se nanoboxes are highly promising for gas sensor applications.

Synthesis, characterization and photocatalytic activity of Zn(OH)F hierarchical nanofibers prepared by a simple solution-based method

Co-reporter:Yin Peng, Hai-Yan Zhou and Zheng-Hua Wang

CrystEngComm 2012 vol. 14(Issue 8) pp:2812-2816

Publication Date(Web):07 Feb 2012

DOI:10.1039/C2CE06389A

Zn(OH)F nanofibers with novel 3D-hierarchical structures have been synthesized from the reactions of Zn(NO3)2, hexamethylenetetramine (HMT) and NaF on a large scale by a facile solution-based method. Their structures and morphologies were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The Zn(OH)F hierarchical architectures were assembled by many nanowires with a diameter of 20 nm. Their structures are dependent on the concentration of the reactants and the temperature of the reaction. The photocatalytic properties of these Zn(OH)F nanofibers were investigated by the decomposition of organic compounds and organic dyes under UV light irradiation and the results show that they have good photocatalytic activities.

Photocatalytic synthesis of M/Cu2O (M = Ag, Au) heterogeneous nanocrystals and their photocatalytic properties

Co-reporter:Zhenghua Wang, Suping Zhao, Shiyu Zhu, Yanling Sun and Mei Fang

CrystEngComm 2011 vol. 13(Issue 7) pp:2262-2267

Publication Date(Web):24 Jan 2011

DOI:10.1039/C0CE00681E

M/Cu2O (M = Ag, Au) heterogeneous nanocrystals are successfully prepared by depositing noble metal nanoparticles onto the surfaces of Cu2O octahedral nanocrystals through a simple photocatalytic process. The samples are characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The influence of the light source and solution temperature on the deposition of noble metal (taking Ag as an example) nanoparticles has been studied. The experimental results show that visible light is more favorable for the deposition of Ag nanoparticles onto Cu2O nanocrystals, and a solution temperature of more than 30 °C can prevent the erosion of Cu2O. The photocatalytic properties of the prepared M/Cu2O heterogeneous nanocrystals are studied, showing enhanced photocatalytic activities.

Urchin-like CdS microspheres self-assembled from CdS nanorods and their photocatalytic properties

Co-reporter:Zhenghua Wang, Ling Pan, Lingling Wang, Hui Wang

Solid State Sciences 2011 Volume 13(Issue 5) pp:970-975

Publication Date(Web):May 2011

DOI:10.1016/j.solidstatesciences.2011.02.006

Urchin-like CdS microspheres were successfully prepared via a facile hydrothermal route. The CdS microspheres were self-assembled from CdS nanorods with average diameters of about 30 nm and lengths of about 200 nm. The volume ratio of water/ethylenediamine (water/en) played a key role in morphology of products including assembled nanorods and dispersed nanorods. In addition, we characterized the photocatalytic property of the urchin-like CdS microspheres under visible light, which showed good photocatalytic activities.

Ligand-Free CuO Nanospindle Catalyzed Arylation of Heterocycle C–H Bonds

Co-reporter:Wu Zhang, Qinglong Zeng, Xinming Zhang, Yujie Tian, Yun Yue, Yujun Guo, and Zhenghua Wang

The Journal of Organic Chemistry 2011 Volume 76(Issue 11) pp:4741-4745

Publication Date(Web):April 20, 2011

DOI:10.1021/jo200452x

CuO nanospindles have been developed to efficiently catalyze the direct arylation of heterocycle C–H bonds with moderate to excellent yields. This reaction can be applied to heterocycles such as benzoxazole, benzothiazole, and 1-methylbenzimidazole in the presence of a more environmentally friendly inorganic base like K2CO3 under ligand-free catalytic conditions. In addition, the catalyst can be recycled and reused without any significant decrease in catalytic activity.

Rapid growth of t-Se nanowires in acetone at room temperature and their photoelectrical properties

Co-reporter:Zhenghua Wang;Shiyu Zhu

Frontiers of Optoelectronics 2011 Volume 4( Issue 2) pp:188-194

Publication Date(Web):2011 June

DOI:10.1007/s12200-011-0163-8

Trigonal selenium (t-Se) nanowires with uniform sizes were obtained through the conversion from freshly prepared amorphous selenium (a-Se) nanoparticles in acetone at room temperature. The experimental results show that some organic solvents, such as acetone and pyridine can dramatically promote the conversion from a-Se to t-Se, and t-Se with different morphologies like nanowires and microrods can be obtained. Acetone is an appropriate medium for obtaining t-Se nanowires in a short time. The as-prepared t-Se nanowires were characterized and confirmed by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The photoelectrical properties of t-Se nanowires were investigated, which shows their potential uses in the fabrication of microdevices or photo-switches.

Formation of single-crystal tellurium nanowires and nanotubes via hydrothermal recrystallization and their gas sensing properties at room temperature

Co-reporter:Zhenghua Wang, Lingling Wang, Jiarui Huang, Hui Wang, Ling Pan and Xianwen Wei

Journal of Materials Chemistry A 2010 vol. 20(Issue 12) pp:2457-2463

Publication Date(Web):08 Feb 2010

DOI:10.1039/B924462J

Single-crystal tellurium nanowires and nanotubes were selectively synthesized from tellurium powder through a hydrothermal recrystallization route. The nanowires have an average diameter of 40 nm and lengths of several micrometers, while the nanotubes have diameters of 100–200 nm and lengths of 1–2 µm. The morphologies of the as-obtained tellurium nanocrystals could be controlled by tuning the amount of hydrochloric acid added in the hydrazine hydrate solution. The experimental results demonstrated that tellurium powder could be dissolved and recrystallized in hydrazine hydrate solution under hydrothermal conditions. A dissolution–recrystallization mechanism was proposed for the conversion from tellurium powder to tellurium nanowires or nanotubes. The gas sensing properties of as-synthesized tellurium nanowires and nanotubes were investigated in detail, which revealed that the as-prepared tellurium nanowires and nanotubes, especially the tellurium nanowires, exhibited excellent sensitivity to NH3 at room temperature. The response times of the tellurium nanowires and nanotubes were 5 s and 18 s, and the recovery times were 720 s and 170 s, respectively, which are shorter than those reported for tellurium films. The as-prepared tellurium nanostructures could have potential applications in nanosensors.

Co9S8 nanotubes synthesized on the basis of nanoscale Kirkendall effect and their magnetic and electrochemical properties

Co-reporter:Zhenghua Wang, Ling Pan, Haibo Hu and Suping Zhao

CrystEngComm 2010 vol. 12(Issue 6) pp:1899-1904

Publication Date(Web):04 Feb 2010

DOI:10.1039/B923206K

Polycrystalline Co9S8 nanotubes were successfully fabricated by using Co(CO3)0.35Cl0.20(OH)1.10 nanorod bunches as sacrificial hard templates through a hydrothermal route. The samples were characterized by means of XRD, XPS, SEM and TEM. The Co9S8 nanotubes were formed due to the nanoscale Kirkendall effect, which can be explained by the difference in diffusion rates between the cobalt source and the sulfur ion. Magnetic measurements indicate that the Co9S8 nanotubes show a paramagnetic property instead of a ferromagnetic property, which can be attributed to the tiny sizes of the component nanoparticles. The electrochemical properties of the Co9S8 nanotubes demonstrate that they deliver a large discharge capacity, which might find possible applications as an electrode material in lithium batteries.

Ag-Coated Fe3O4@SiO2 Three-Ply Composite Microspheres: Synthesis, Characterization, and Application in Detecting Melamine with Their Surface-Enhanced Raman Scattering

Co-reporter:Haibo Hu, Zhenghua Wang, Ling Pan, Suping Zhao and Shiyu Zhu

The Journal of Physical Chemistry C 2010 Volume 114(Issue 17) pp:7738-7742

Publication Date(Web):April 14, 2010

DOI:10.1021/jp100141c

Ag nanoparticles with average sizes of 20 nm were well-dispersed on the surfaces of Fe3O4@SiO2 composite microspheres through a simple wet-chemical method employing the Ag-mirror reaction. The as-synthesized Ag-coated Fe3O4@SiO2 three-ply composite microspheres are monodisperse and bifunctional, with ferromagnetic and surface-enhanced Raman scattering (SERS) properties. The products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX). SERS signals of typical analytes such as rhodamine 6G (Rh 6G) were observed on Ag nanoparticles from the Ag-coated Fe3O4@SiO2 microspheres, even though the concentration of the analyte was as low as 1 × 10−15 M (Rh 6G). The Ag-coated Fe3O4@SiO2 microspheres were applied to detecting melamine, and strong SERS signals were obtained with melamine concentration of 1 × 10−6 M. This work may provide a potential and unique technique to detect melamine.

One-pot synthesis of single-crystalline Cu2O hollow nanocubes

Co-reporter:Zhenghua Wang, Hui Wang, Lingling Wang, Ling Pan

Journal of Physics and Chemistry of Solids 2009 Volume 70(3–4) pp:719-722

Publication Date(Web):March–April 2009

DOI:10.1016/j.jpcs.2009.02.011

Single-crystalline Cu2O hollow nanocubes have been successfully synthesized via a simple wet chemical route in the absence of any surfactants or templates. By studying the growth process of the Cu2O hollow nanocubes, we found that the Cu2O hollow nanocubes were formed through a reducing and simultaneously etching process. The speed of reducing Cu(OH)2 into Cu2O was much faster than the speed of etching Cu2O. As a result, Cu2O solid nanocubes were firstly formed, and then the solid nanocubes were gradually etched into hollow nanocubes.

Controlled synthesis of Cu2O cubic and octahedral nano- and microcrystals

Co-reporter:Zhenghua Wang;Hui Wang;Lingling Wang ;Ling Pan

Crystal Research and Technology 2009 Volume 44( Issue 6) pp:624-628

Publication Date(Web):

DOI:10.1002/crat.200900136

Abstract

Cubic and octahedral Cu₂O nano- and microcrystals were selectively synthesized via a simple wet chemical reduction route at room temperature, with CuCl₂ and NaOH as starting reactants, and ascorbic acid or hydrazine hydrate as the reducer. Hydrazine hydrate could be preferentially adsorbed on different crystal faces of Cu₂O, affecting the growth rate along the 〈100〉 to that along the 〈111〉 direction, which resulted in the formation of octahedral Cu₂O crystals. When ascorbic acid was used as the reducer, the growth rate along the 〈100〉 to that along the 〈111〉 direction was different, which resulted in the formation of cubic Cu₂O crystals. The size of cubic and octahedral Cu₂O crystals could be varied by adjusting the molar ratio of OH^– to Cu²⁺. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

PEG-Mediated Hydrothermal Growth of Single-Crystal Tellurium Nanotubes

Co-reporter:Zhenghua Wang, Lingling Wang and Hui Wang

Crystal Growth & Design 2008 Volume 8(Issue 12) pp:4415-4419

Publication Date(Web):September 30, 2008

DOI:10.1021/cg800064a

Single-crystal tellurium nanotubes can be directly grown from commercially available tellurium powder with the mediation of poly(ethylene glycol) through a hydrothermal process. Scanning electon microscopy images show that most of the tellurium nanotubes have hexagonal cross sections, with diameters in the range of 200−400 nm and lengths in the range of 5−20 μm. The growth of tellurium nanotubes occurred through a dissolution−recrystallization process. First, tellurium powder dissolved into water as atoms or atoms clusters. Then tellurium atoms or atoms clusters grew into tellurium nanotubes. Poly(ethylene glycol) played important roles in the formation of tellurium nanotubes. It promoted the dissolution of tellurium powder into water under hydrothermal conditions. And also, it controlled the growth of tellurium nanotubes. This approach may be helpful for the growth of other inorganic nanomaterials with one-dimensional structure.

Nickel–cobalt hydroxide nanosheets arrays on Ni foam for pseudocapacitor applications

Co-reporter:Jun Pu, Yao Tong, Shubo Wang, Enhong Sheng, Zhenghua Wang

Journal of Power Sources (15 March 2014) Volume 250() pp:250-256

Publication Date(Web):15 March 2014

DOI:10.1016/j.jpowsour.2013.10.108

Co9S8 nanotube arrays supported on nickel foam for high-performance supercapacitors

Co-reporter:Jun Pu, Zhenghua Wang, Konglin Wu, Nan Yu and Enhong Sheng

Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 2) pp:NaN791-791

Publication Date(Web):2013/10/28

DOI:10.1039/C3CP54192D

Uniform Co9S8 nanotube arrays on conductive nickel foam were successfully synthesized through a facile two-step hydrothermal method and were directly applied as the electrode for high-performance electrochemical capacitors. The formation of the tubular structure of Co9S8 can be attributed to the nanoscale Kirkendall effect. SEM and TEM images show that most of the Co9S8 nanotubes have hexagonal sections. The diameter of the Co9S8 nanotubes is about 120–200 nm and the wall thickness is of 40–60 nm. Cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance measurements are applied to investigate the electrochemical performance of the Co9S8 nanotubes. The specific capacitance of the Co9S8 nanotubes is 1775 F g−1 at 4 A g−1, and 1483 F g−1 at 24 A g−1, indicating the high rate capability. Also, the Co9S8 nanotubes exhibit stable cycling performance.

ZnCo2O4 nanowire arrays grown on nickel foam for high-performance pseudocapacitors

Co-reporter:Shubo Wang, Jun Pu, Yao Tong, Yuanyuan Cheng, Yan Gao and Zhenghua Wang

Journal of Materials Chemistry A 2014 - vol. 2(Issue 15) pp:NaN5440-5440

Publication Date(Web):2014/01/10

DOI:10.1039/C3TA14941B

Uniform ZnCo2O4 nanowire arrays were directly grown on nickel foam through a facile hydrothermal method and subsequent thermal treatment process. The ZnCo2O4 nanowires have diameters of about 100 nm and lengths of up to 5 μm. The as-obtained ZnCo2O4 nanowire array loaded nickel foam can be directly applied as an electrode for high-performance supercapacitors. Electrochemical measurements show that the ZnCo2O4/nickel foam electrode has high specific capacitance (1625 F g−1 at 5 A g−1), excellent rate capability (59% capacitance retention at 80 A g−1) and good cycling stability (94% capacitance retention over 5000 charge–discharge cycles). This work demonstrates that ZnCo2O4 nanowires are highly desirable for application as advanced electrochemical electrode materials.

Formation of single-crystal tellurium nanowires and nanotubes via hydrothermal recrystallization and their gas sensing properties at room temperature

Co-reporter:Zhenghua Wang, Lingling Wang, Jiarui Huang, Hui Wang, Ling Pan and Xianwen Wei

Journal of Materials Chemistry A 2010 - vol. 20(Issue 12) pp:NaN2463-2463

Publication Date(Web):2010/02/08

DOI:10.1039/B924462J

Single-crystal tellurium nanowires and nanotubes were selectively synthesized from tellurium powder through a hydrothermal recrystallization route. The nanowires have an average diameter of 40 nm and lengths of several micrometers, while the nanotubes have diameters of 100–200 nm and lengths of 1–2 µm. The morphologies of the as-obtained tellurium nanocrystals could be controlled by tuning the amount of hydrochloric acid added in the hydrazine hydrate solution. The experimental results demonstrated that tellurium powder could be dissolved and recrystallized in hydrazine hydrate solution under hydrothermal conditions. A dissolution–recrystallization mechanism was proposed for the conversion from tellurium powder to tellurium nanowires or nanotubes. The gas sensing properties of as-synthesized tellurium nanowires and nanotubes were investigated in detail, which revealed that the as-prepared tellurium nanowires and nanotubes, especially the tellurium nanowires, exhibited excellent sensitivity to NH3 at room temperature. The response times of the tellurium nanowires and nanotubes were 5 s and 18 s, and the recovery times were 720 s and 170 s, respectively, which are shorter than those reported for tellurium films. The as-prepared tellurium nanostructures could have potential applications in nanosensors.

Homogeneous core–shell NiCo2S4 nanostructures supported on nickel foam for supercapacitors

Co-reporter:Wei Kong, Chenchen Lu, Wu Zhang, Jun Pu and Zhenghua Wang

Journal of Materials Chemistry A 2015 - vol. 3(Issue 23) pp:NaN12460-12460

Publication Date(Web):2015/05/07

DOI:10.1039/C5TA02432C

In this study, we report the fabrication of NiCo2S4 with a homogeneous core–shell nanostructure in which NiCo2S4 nanotubes are wrapped by NiCo2S4 nanosheets. The core–shell structured NiCo2S4 was in situ grown on nickel foam and can be directly applied as a supercapacitor electrode. Electrochemical tests demonstrate that the NiCo2S4 electrode achieved a high specific capacitance of 1948 mF cm−2 at a current density of 1 mA cm−2, a good rate capability, and an excellent cycling stability. The outstanding performance of the NiCo2S4 electrode can be attributed to its core–shell architecture with good mechanical and electrical contact and rich redox reactions, as well as high transport rate for both electrolyte ions and electrons. By applying NiCo2S4 as the positive electrode and porous carbon as the negative electrode, an asymmetric supercapacitor device was fabricated and it exhibited an excellent electrochemical performance. These results demonstrate that the homogeneous core–shell NiCo2S4 nanostructure is promising for supercapacitor applications.