Interfacial Engineering of 2D/2D BiVO4/V2CTx Heterostructures for Enhanced Symmetric Supercapacitor Performance Across Various Electrolytes

Abstract

Engineering well-defined heterostructured composites is an effective strategy for improving the electrochemical performance of energy storage systems. In this study, a 2D/2D BiVO4/V2CTx heterostructure was synthesized via a simple hydrothermal method and, for the first time, systematically tested as a symmetric supercapacitor electrode in neutral (1 M Na2SO4), alkaline (1 M KOH), and acidic (1 M H2SO4) electrolytes. The composite showed better electrochemical performance compared to pristine V2CTx, with specific capacitances of 191.5 F g-1, 107 F g-1, and 239 F g-1 in Na2SO4, KOH, and H2SO4, respectively, at 0.016 A g-1. A high energy density of 83.3 Wh kg-1 at 147.5 W kg-1 was achieved in the neutral electrolyte, along with excellent rate capability and Coulombic efficiency. These improvements arise from the synergistic interaction between BiVO4 and V2CTx, which increases active site accessibility and promotes efficient ion and electron transport. Overall, the results show that the BiVO4/V2CTx heterostructure is a promising and versatile electrode material for high-performance supercapacitors.