Electrochemical Investigation of V ₂ O ₅ as a High-Performance Material for Supercapacitors and Electrocatalysis

Phase-pure orthorhombic vanadium pentoxide (V 2 O 5 ) nanostructures synthesized via a solvothermal method are systematically evaluated for their dual functionality in electrochemical energy storage and electrocatalytic water-splitting applications. Electrochemical investigations in three aqueous electrolytes reveal superior supercapacitor performance in alkaline 6 M KOH, achieving the highest areal capacitance of 31 mF cm –2 at 5 mV s –1, energy density of 0.86 μWh cm –2, and power density of 0.8 mW cm –2 . The supercapacitor further demonstrates outstanding long-term stability, preserving 95% of its initial capacitance after 10,000 charge–discharge cycles. In addition, the electrochemical performance of the supercapacitor is investigated in acidic H 2 SO 4 electrolyte and neutral Na 2 SO 4 electrolyte. For water-splitting applications in 1 M KOH, V 2 O 5 exhibits promising bifunctional electrocatalytic activity with low overpotentials of 177 mV for the hydrogen evolution reaction and 478 mV for the oxygen evolution reaction at 10 mA cm –2, with a high electrochemically active surface area of 51 cm 2 facilitating abundant active sites for catalytic reactions. These findings demonstrate that V 2 O 5 nanostructures represent versatile materials for sustainable energy applications, offering dual functionality as high-performance supercapacitor electrodes and efficient water-splitting electrocatalysts.