Multifunctional Sb2O3–Bi2O3 nano-leaves for record-high supercapacitor energy density and efficient HER and OER catalysis

Abstract

A hierarchically porous Sb₂O₃–Bi₂O₃ (AO–BiO) nano-leaf architecture was synthesized directly onto a nickel-foam via a simple in situ chemical route and explored as a multifunctional electrode for energy storage and water splitting applications. The synergistic coupling between Sb₂O₃ and Bi₂O₃, together with abundant oxygen vacancies and an open three-dimensional framework, enables rapid ion/electron transport and enhanced redox activity. As a symmetric supercapacitor electrode, AO–BiO delivers a high specific capacitance of 1738 F g⁻¹ at 5 A g⁻¹, an energy density of 149 Wh kg⁻¹ at a power density of 9540 W kg⁻¹, and 78% specific capacitance retention after 10 000 cycles. In addition, the AO–BiO electrode exhibits excellent bifunctional electrocatalytic activity for overall water splitting, requiring low overpotentials of 248 mV (OER) and 112 mV (HER) at 10 mA cm⁻², with stable operation over 40 h. These results demonstrate a clear structure–property–performance relationship and highlight Sb₂O₃–Bi₂O₃ nanostructures as promising and durable electrodes for integrated energy storage and hydrogen production benefits.