Electrophoretic Deposition of Nitrogen-Boron Co-Doped Graphene for High Performance Supercapacitors
Authors: Kumar Amit , Kumar Nagesh , Singh Pragya , Leu Jihperng , Tseng Tseung-Yuen 
Published: February 2020

In present condition, the ever-growing demand for sustainable and renewable energy resources, limited fossil fuels and environment issues like solar, wind, global warming and hydro energy have become a focal point of the leading world power and research [1-2]. Recently, supercapacitors due to their high power density (>10 kWkg-1), long cycle life (>105 cycles) and fast charge discharge response have captivated much interest. However, the poor energy density of supercapacitors (SCs) is the main issue, which hinders their potential industrial utilization [3-4]. However poor energy density of supercapacitor (SCs) is the main issue, which hinders their high potential industrial utilization. Basically, carbon based materials (CNT, graphene, activated carbon and mesoporous carbon) are used as the active electrode materials for the development of practical electric double layer supercapacitors (EDLCs). Besides this, the chemical doping of foreign atoms (such as N, B, P, I and S) in the carbon based materials is an effective tool to achieve the electron-donor characteristics, which effectively enhance the electrochemical performance of the material [5]. Such doping of heteroatoms in graphene would provide acid/base characteristics for upgraded electrochemical properties. Among the pure graphene, N and B co-doped graphene has attracted a lot of interest because of its superior electrochemical properties, cost-effective and eco-friendly behavior.
In this work we developed a simple one step hydrothermal method to prepare N, B co-doped graphene at low temperature 180°C. Melamine diborate precursor has been utilized as source of N and B. Electrodes fabrication process done by the electrophoretic deposition (EPD) technique at 50 V. Best fabricated sample, labeled as NBG-0.7, exhibits highest specific capacitance of 217 Fg-1 at the scan rate of 5 mVs-1 which is about 1.2 times higher than the specific capacitance (180 Fg-1 at 5 mVs-1) of pristine reduced graphene oxide. The structural analysis, morphological studies, thermal stability and specific surface area of pure rGO and N, B co-doped graphene have been investigated via XRD, FE-SEM, TGA, TEM and BET surface area analyzer. The electrochemical measurements have been carried out using three electrodes measurement system in 6M KOH electrolyte using cyclic voltammetry (CV), galvanostatic charge-discharge cycling (GCD) and electrochemical impedance spectroscopy (EIS).
Keywords: N, B co-doping; reduced graphene oxide; energy storage; supercapacitors
References：
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[2] Renewable Energy Policy Network for the 21 st Century (REN21), Renewables Global Status Report, 2016, ISBN 978–3-9818107–0-7.
[3] H. Jiang, P. S. Lee and C. Li, Energy Environ. Sci., 2013, 6, 41.
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[5] Yong Qin, Jie Yuan , Juan Li, Dongchang Chen, Yong Kong, Fuqiang Chu ,Yongxin Tao, and Meilin Liu Adv. Mater. 2015, 27, 5171–5175.

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