Notable improvement of capacitive performance of highly nanoporous carbon materials simply by a redox additive electrolyte of p-nitroaniline

Highly nanoporous carbon materials have been produced by a synchronous carbonization/graphitization process, using magnesium citrate serves as the carbon source and nickel nitrate as graphitization catalyst. The carbonization temperature plays a crucial role in determining the porosity and graphitization. The lower temperature favors for the formation of larger porosity, whilst higher temperature for better crystallinity. Resultantly, a high BET surface area of 2587.13 m(2) g(-1) and large total pore volume of 4.64 cm(3) g(-1) appear, the case of C-800 sample, thereby resulting in a large specific capacitance of 305.3 F g(-1) at 1 A g(-1) from the contribution of electric double layer capacitances. More importantly, we demonstrate a novel redox active additive of p-nitroaniline (PNA) into the 6 mol L-1 KOH electrolyte to largely improve the capacitance by the quick self-discharge redox reaction of H+/e(-). The C-800-2 sample with the PNA concentration of 2 mmol delivers largely improved capacitance of 502.1 F g(-1) at 1 A g(-1), which is almost 1.65 fold increase. Apparently, the present PNA is commercially available, and highly effective for elevating the specific capacitance and might be implemented for the wide supercapacitor application. (C) 2015 Elsevier B.V. All rights reserved.