Preparation and electrochemical properties of C/g-C₃N₄/CuO composite electrode materials for supercapacitor applications

To enhance supercapacitor performance, a C/g-C₃N₄/CuO composite was synthesized via hydrothermal synthesis using g-C₃N₄/CuO as the substrate and glucose as the carbon source. SEM, XRD, and XPS confirmed successful material synthesis. The optimized C/g–C₃N₄–3.5/CuO composite achieved a specific capacitance of 48.92 F/cm2 at 2 mA/cm2 and retained 88.55% of its capacity after 10000 cycles. The aqueous device exhibited a retention rate of 91.66% after 5000 cycles, with an energy density of 292.36 μWh/cm2 and a power density of 400 μW/cm2. The solid-state device achieved an energy density of 319.01 μWh/cm2 and a power density of 896.49 μW/cm2. This material combines the nitrogen active sites of g-C₃N₄, the high theoretical capacitance of CuO, and the excellent conductivity of carbon, achieving comprehensive performance enhancement. It can drive LEDs for over 400 s, demonstrating broad prospects in the field of energy storage.