7,7,8,8-Tetracyanoquinodimethane-assisted one-step electrochemical exfoliation of graphite and its performance as an electrode material

Nanoscale ◽  
2014 ◽  
Vol 6 (9) ◽  
pp. 4864-4873 ◽  
Author(s):  
Partha Khanra ◽  
Chang-No Lee ◽  
Tapas Kuila ◽  
Nam Hoon Kim ◽  
Min Jun Park ◽  
...  

Water-dispersible functionalized graphene via one-step electrochemical exfoliation of graphite was prepared using 7,7,8,8-tetracyanoquinodimethane (TCNQ) anions as surface modifiers and electrolytes. The specific capacitance value of TCNQ-modified graphene measured with electrolytes (1 M KOH) was 324 F g−1 at a current density of 1 A g−1.

NANO ◽  
2019 ◽  
Vol 14 (07) ◽  
pp. 1950085 ◽  
Author(s):  
Puhong Wen ◽  
Jingjing Guo ◽  
Lijun Ren ◽  
Chuanchuan Wang ◽  
Yuzhu Lan ◽  
...  

1D [Formula: see text]-MoO3 nanobelts were prepared using ammonium heptamolybdate tetrahydrate [(NH[Formula: see text]Mo7O[Formula: see text]H2O] as raw material by one-step hydrothermal method without template or guide agent at 180∘C. The layered [Formula: see text]-MoO3 nanobelt electrode has favorable electrochemical performance, and displays a fairly high specific capacitance, which can be up to 445[Formula: see text]F/g at a current density of 0.5[Formula: see text]A/g.


Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3509 ◽  
Author(s):  
Xinyu Lei ◽  
Mu Li ◽  
Min Lu ◽  
Xiaohui Guan

A new carbon-coated nickel sulfides electrode material (NST/CNTs@C) has been synthesized through an easy-to-operate process: NiS2/CNTs which was prepared by a hydrothermal method reacted with BTC (1,3,5-benzenetricarboxylic acid) under the condition of water bath heating to obtain the precursor, and then the precursor was calcined in 450 °C under a nitrogen atmosphere to obtain NST/CNTs@C. The electrochemical performance of NST/CNTs@C has been greatly improved because the formation of a carbon-coated layer effectively increased the specific surface area, reduced the charge transport resistance and inhibited the morphological change of nickel sulfides in the charge–discharge process. Compared with pure NiS2 and NiS2/CNTs, NST/CNTs@C presented great specific capacitance (620 F·g−1 at a current density of 1 A·g−1), better cycle stability (49.19% capacitance retention after 1000 cycles) and more superior rate capability (when the current density was raised to 10 A·g−1 the specific capacitance remained 275 F·g−1).


Author(s):  
Tianrui Wang ◽  
Yupeng Su ◽  
Mi Xiao ◽  
Meilian Zhao ◽  
Tingwu Zhao ◽  
...  

AbstractCoTe@reduced graphene oxide (CoTe@rGO) electrode materials for supercapacitors were prepared by a one-step hydrothermal method in this paper. Compared with that of pure CoTe, the electrochemical performance of CoTe@rGO was significantly improved. The results showed that the optimal CoTe@rGO electrode material has a remarkably high specific capacitance of 810.6 F/g at a current density of 1 A/g. At 5 A/g, the synthesized material retained 77.2% of its initial capacitance even after 5000 charge/discharge cycles, thereby demonstrating good cycling stability. Moreover, even at a high current density of 20 A/g, the composite electrode retained 79.0% of its specific capacitance at 1 A/g, thus confirming its excellent rate performance. An asymmetric supercapacitor (ASC) with a wider potential window and higher energy density was assembled by using 3 M KOH as the electrolyte, the CoTe@rGO electrode as the positive electrode, and active carbon as the negative electrode. The operating voltage of the supercapacitor could be increased to 1.6 V, and its specific capacitance could reach 112.6 F/g at 1 A/g. The specific capacitance retention rate of the fabricated supercapacitor after 5000 charge/discharge cycles at 5 A/g was 87.1%, which confirms its excellent cycling stability. In addition, the ASC revealed a high energy density of 40.04 W·h/kg at a power density of 799.91 W/kg and a high power density of 4004.93 W/kg at an energy density of 33.43 W·h/kg. These results collectively show that CoTe@rGO materials have broad application prospects.


2019 ◽  
Vol 10 ◽  
pp. 781-793 ◽  
Author(s):  
Mamta Sham Lal ◽  
Thirugnanam Lavanya ◽  
Sundara Ramaprabhu

A Cu/CuO/porous carbon nanofiber/TiO2 (Cu/CuO/PCNF/TiO2) composite uniformly covered with TiO2 nanoparticles was synthesized by electrospinning and a simple hydrothermal technique. The synthesized composite exhibits a unique morphology and excellent supercapacitive performance, including both electric double layer and pseudo-capacitance behavior. Electrochemical measurements were performed by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The highest specific capacitance value of 530 F g−1 at a current density of 1.5 A g−1 was obtained for the Cu/CuO/PCNF/TiO2 composite electrode in a three-electrode configuration. The solid-state hybrid supercapacitor (SSHSC) fabricated based on this composite exhibits a high specific capacitance value of 330 F g−1 at a current density of 1 A g−1 with 78.8% capacitance retention for up to 10,000 cycles. At the same time, a high energy density of 45.83 Wh kg−1 at a power density of 1.27 kW kg−1 was also realized. The developed electrode material provides new insight into ways to enhance the electrochemical properties of solid-state supercapacitors, based on the synergistic effect of porous carbon nanofibers, metal and metal oxide nanoparticles, which together open up new opportunities for energy storage and conversion applications.


2015 ◽  
Vol 39 (11) ◽  
pp. 8430-8438 ◽  
Author(s):  
Mingming Yao ◽  
Zhonghua Hu ◽  
Yafei Liu ◽  
Peipei Liu

A novel electrode material of three-dimensional hierarchical NiCo2S4@NiMoO4core/shell nanospheres was synthesized by a facile two-step hydrothermal method. These hierarchical NiCo2S4@NiMoO4core/shell nanospheres exhibit a high specific capacitance of 1714 F g−1at a current density of 1 A g−1, which indicated the excellent electrochemistry performance.


2021 ◽  
Vol 5 (5) ◽  
pp. 129
Author(s):  
Yapeng Wang ◽  
Yanxiang Wang ◽  
Chengjuan Wang ◽  
Yongbo Wang

As one of the most outstanding high-efficiency and environmentally friendly energy storage devices, the supercapacitor has received extensive attention across the world. As a member of transition metal oxides widely used in electrode materials, manganese dioxide (MnO2) has a huge development potential due to its excellent theoretical capacitance value and large electrochemical window. In this paper, MnO2 was prepared at different temperatures by a liquid phase precipitation method, and polyaniline/manganese dioxide (PANI/MnO2) composite materials were further prepared in a MnO2 suspension. MnO2 and PANI/MnO2 synthesized at a temperature of 40 °C exhibit the best electrochemical performance. The specific capacitance of the sample MnO2-40 is 254.9 F/g at a scanning speed of 5 mV/s and the specific capacitance is 241.6 F/g at a current density of 1 A/g. The specific capacitance value of the sample PANI/MnO2-40 is 323.7 F/g at a scanning speed of 5 mV/s, and the specific capacitance is 291.7 F/g at a current density of 1 A/g, and both of them are higher than the specific capacitance value of MnO2. This is because the δ-MnO2 synthesized at 40 °C has a layered structure, which has a large specific surface area and can accommodate enough electrolyte ions to participate the electrochemical reaction, thus providing sufficient specific capacitance.


2016 ◽  
Vol 40 (8) ◽  
pp. 6881-6889 ◽  
Author(s):  
Cuiping Yu ◽  
Yan Wang ◽  
Jianfang Zhang ◽  
Xia Shu ◽  
Jiewu Cui ◽  
...  

Novel nanocomposite NiCo2O4/C-TNAs were synthesized for high-performance supercapacitors with a specific capacitance of 934.9 F g−1 at a current density of 2 A g−1.


2019 ◽  
Vol 48 (28) ◽  
pp. 10652-10660 ◽  
Author(s):  
Tarugu Anitha ◽  
Araveeti Eswar Reddy ◽  
Yedluri Anil Kumar ◽  
Young-Rae Cho ◽  
Hee-Je Kim

A bunch of PbMoO4/CdMoO4 nanocube-like structures exhibit superior specific capacitance and cycling stability to PbMoO4 and CdMoO4 electrodes.


2017 ◽  
Vol 20 (4) ◽  
pp. 197-204
Author(s):  
Weiliang Chen ◽  
Shuhua Pang ◽  
Zheng Liu ◽  
Zhewei Yang ◽  
Xin Fan ◽  
...  

Polypyrrole with hierarchical dendritic structures assembled with cauliflower-like structure of nanospheres, was synthesized by chemical oxidation polymerization. The structure of polyryrrole was characterized by Fourier transform infrared spectrometer and scanning electron microscopy. The electrochemical performance was performed on CHI660 electrochemical workstation. The results show that oxalic acid has a significant effect on morphology of PPy products. The hierarchical dendritic PPyOA(3) electrodes possess a large specific capacitance as high as 744 F/g at a current density of 0.2 A/g and could achieve a higher specific capacitance of 362 F/g even at a current density of 5.0 A/g. Moreover, the dendritic PPy products produce a large surface area on the electrode through the formation of the channel structure with their assembled cauliflower-like morphology, which facilitates the charge/electron transfer relative to the spherical PPy electrode. The spherical dendritic PPyOA(3) electrode has 58% retention of initial specific capacitance after 260 cycles. The as-prepared dendritic polypyrrole with high performance is a promsing electrode material for supercapacitor.


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