Regulating the Hierarchical Distribution of Oxygen Vacancies Through Ce Doping and NaBH4 Reduction to Enhance Co2NiO4 Supercapacitor Performance

Abstract In this study, Co2NiO4 with tunable and hierarchical distribution of oxygen vacancies was synthesized via Ce Doping and NaBH4 Reduction to enhance its electrochemical performance. The 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 carrier within Co2NiO4. Moreover, the NaBH4 reduction process brought in 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 the material's specific capacitance while ensuring stability. At a 1 A g-1 current density, these nanosheets achieved a 1493.6 F g-1 as maximum specific capacitance. 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 (ASC) configuration known as Ce/Co2NiO4-Vo//AC, attaining a 80.51 Wh kg-1 energy density at 800 W kg-1 power density. This study provides innovative strategies and highlight in the high-performance supercapacitors developed and energy storage solutions.