Oxygen vacancy–engineered Bi–Mn–Al oxide / reduced graphene oxide heterojunctions for high–performance supercapacitors

This work presents a novel approach to enhance the specific energy of supercapacitors by developing Bi2O3/Mn3O4/Mn2AlO4(OV)/rGO multiphase oxygen vacancy heterostructures via dealloying and hydrothermal self-growth strategy. The synergy between reduced graphene oxide (rGO) heterostructures and oxygen vacancy defects generates an internal polarized electric field that accelerates ion transport and enhances electrochemical response through an interconnected conductive network. This innovation extends the operating voltage from 0.6 to 0.8 V, significantly improving material energy storage. An asymmetric supercapacitor assembled with Bi2O3/Mn3O4/Mn2AlO4(OV)/rGO//rGO delivers a specific energy of 333 Wh kg−1 and a specific power of 6.3 kW kg−1 at a cell voltage of 4.9 V. At the highest specific power (31 kW kg−1), the specific energy remains at 204 Wh kg−1. Density functional theory (DFT) simulations further validate that the synergy of oxygen vacancies and heterostructures enhances conductivity, narrows the bandgap, and improves surface properties, unveiling novel theoretical perspectives on ion transport dynamics within oxygen vacancy heterostructures.