Facile synthesis of N-doped V₂O₅@g-C₃N₄ electrodes for enhanced symmetric supercapacitor application

Rapid exhaustion of fossil fuel is the foremost genesis of numerous natural calamities and diminution of finite non-renewable energy resources impacts notable changes in the energy storage norms. Thus, supercapacitors are emerging as one of the best energy storage devices to facilitate good capacity retention, fast-charging and longer life cycle, preventing energy scarcity for later. Here, we demonstrate an environmentally friendly synthesis approach to produce N-doped VO₂ (at room temperature) and g-C₃N₄, N-doped V₂O₅, and various stoichiometries of N-doped V₂O₅@g-C₃N₄ nanocomposites, using thermal treatment of N-doped VO₂ and melamine at 450 °C for 2 h in air medium. V₂O₅@g-C₃N₄ electrodes depict excellent electrochemical performance for symmetric supercapacitor device (SSD) applications as the stacked morphology of thin integrated long flakes contribute to greater surface area and large number of active sites. The application of neutral electrolyte (Na₂SO₄) exhibits significant enhancement in charge storage and transport electro-kinetics for VCN electrodes. Among all, the optimized N-doped V₂O₅@g-C₃N₄ nanocomposite (1:4; VCN-4) electrodes proclaim the maximum specific capacitance of 294 F/g at 1 A/g with cyclic stability of 86 % over 5000 cycles. Lastly, fabricated two-electrode SSD device shows excellent energy and power density, such as 20.5 Wh/kg at 0.6 W/kg (at 1 A/g current density). N-doped V₂O₅@g-C₃N₄ electrode is one of the best transition metal oxide/carbon nanocomposites for enhanced SSD performance, provided by multiple oxidation states for effortless doping of nitrogen, easy availability, cheap retail price with good tensile strength and electrical conductivity, etc.