Mesoporous graphitic carbon nitride synthesized using biotemplate as a high-performance electrode material for supercapacitor and electrocatalyst for hydrogen evolution reaction in acidic medium

Mesoporous graphitic carbon nitride (MGCN) is extensively studied as a catalyst for various processes, such as photocatalysis, CO2 reduction, etc. Recently, it has been used as an electroactive material for supercapacitor. This article reports the improved capacitance properties and enhanced electrocatalytic activity of MGCN towards hydrogen evolution reaction (HER). MGCN is synthesized by using environmentally benign, biotemplate, namely, carboxymethyl cellulose. X-ray diffraction and electron microscopic studies confirm the formation of the stacked layer structure. X-ray photoelectron spectroscopic, elemental analysis, thermogravimetric analysis, and nitrogen sorption studies reveal that C/N ratio and surface area of MGCN depend on the precursor to the template ratio. A highest specific capacitance of 286 F g(-1) is obtained at a current density of 0.75 A g(-1) for MGCN synthesized using 0.3 g of carboxymethyl cellulose (MGCN-0.3), which is higher than that of MGCN synthesized using 0.1 (MGCN-0.1), and 0.5 g (MGCN-0.5) of carboxymethyl cellulose. Supercapacitor devices fabricated in symmetrical configuration using MGCN-0.3 outperforms various nitrogen doped carbonaceous materials. On the other hand, overpotential of 272 mV s(-1) at a current density of 10 mA cm(-2) and a Tafel slope of 101 mV dec(-1) obtained for MGCN-0.5 towards HER is better than that of several composites of graphitic carbon nitride reported in the literature.