Co3O4|CoP Core–Shell Nanoparticles with Enhanced Electrocatalytic Water Oxidation Performance

Developing high performance, cost-effective, and durable electrocatalysts that must be derived from non-noble metals is crucial for alkaline oxygen evolution reaction (OER). OER, which takes place at the anode, is accepted as a major obstacle for commercialization due to its sluggish kinetics. In this study, a two-step synthesis method, such as a hydrothermal process followed by the annealing of the reactants in an Ar-filled Swagelok cell, is briefly described to obtain a cubic type of Co3O4 core and CoP shell. As a result of synergy, Co3O4|CoP demonstrates an onset overpotential of 280 mV and reaches a current density of 10 mA cm–2 at an overpotential of 320 mV in an alkaline medium (pH = 13.5). The electronic property of the heterojunction is verified by the Tauc plot and valence band XPS. The band structure indicates that Co3O4|CoP exhibits a more metallic character than pristine Co3O4 due to the fact that the charge transfer process is faster. Further, the introduction of CoP significantly modifies the redox processes of Co3O4, which we examined with the help of large amplitude alternating current voltammetry (LA-ACV). The mechanistic study suggests that "catalytic performance is directly related to the peak-to-peak current density" of the redox process of the combined catalyst and reactant.