AgO-decorated multi-dimensional chrysanthemum-like NiCo2O4 mounted on nickel foam as a highly efficient and stable electrocatalyst for the oxygen evolution reaction

Abstract

AgO nanoparticles were successfully integrated into NiCo₂O₄ nanosheets for enhanced electrochemical catalysis ability and stability in the oxygen evolution reaction (OER). The chrysanthemum-like NiCo₂O₄/AgO composites mounted on nickel foam (NF) were synthesized by a hydrothermal–calcination method. AgO upgraded the ratio of Co³⁺/Co²⁺ and thus regulated the intrinsic activity of the species. The highly hierarchical structure of NiCo₂O₄/AgO composed of 0D AgO nanoparticles, 1D NiCo₂O₄ needles, 2D NiCo₂O₄ nanosheets, and 3D chrysanthemum-like bundles grown on NF bestowed the high surface area and mesoporous structure for the easy evolution of O₂. The Ni atoms in NiCo₂O₄ originating in situ from NF in the process of AgO formation produced an integrated electrode of the active component of NiCo₂O₄ bound on NF with a superb highway for charge transfer. AgO significantly tuned the structure and physicochemical properties of NiCo₂O₄. As a result, NiCo₂O₄/AgO/NF exhibited excellent OER performance with an overpotential of 232 mV to obtain a current density of 10 mAcm⁻² in an alkaline electrolyte, and the catalyst showed a small loss of the initial catalyst activity for 50 h and over 5000 cycles. This study provides a pathway for developing high-performance OER electrocatalysts.