Regulating the hierarchical distribution of oxygen vacancies through Ce doping and NaBH4reduction to enhance Co2NiO4supercapacitor performance.

Abstract

In this study, Co₂NiO₄with a tunable and hierarchical distribution of oxygen vacancies was synthesized via Ce doping and NaBH₄reduction to enhance its electrochemical performance. Ce doping through a hydrothermal method gave rise to lattice distortions and uniform oxygen vacancies at asymmetric sites, thereby improving the mobility and concentration of carriers within Co₂NiO₄. Moreover, the NaBH₄reduction process brought about a considerable number of oxygen vacancies and surface-active sites, both of which contributed to the increased conductivity and specific capacitance. Characterization results indicated that the Ce/Co₂NiO₄-Vo nanosheets with surface burrs exhibited an abundant distribution of oxygen vacancies, resulting in a boost of the material's specific capacitance while ensuring stability. At a 1 A g^-1current density, these nanosheets achieved a maximum specific capacitance of 1493.6 F g^-1. When tested at 10 A g^-1, Ce/Co₂NiO₄-Vo retained 88.47% of its initial capacitance after undergoing 5000 cycles. The synthesized Ce/Co₂NiO₄-Vo was further combined with activated carbon (AC) to form an asymmetric supercapacitor configuration known as Ce/Co₂NiO₄-Vo//AC, attaining an 80.51 Wh kg^-1energy density at 800 W kg^-1power density. This study provides innovative strategies and highlights advancements in the high-performance supercapacitors and energy storage solutions.