Mott-Schottky Au/Co3O4 decorated on carbon cloth substrate as an efficiently bifunctional electrocatalyst for hydrogen and oxygen evolution reactions

Catalytic materials for water splitting must possess pivotal characteristics such as cost-effectiveness, robust stability, and high performance towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this study, we utilize a designed Mott-Schottky material, Au/Co₃O₄, developed in conjunction with a low cost and robust material: carbon cloth. The findings reveal that 30 minutes of UV exposure is optimal for depositing Au NPs, achieving the best balance between maximizing Au loading content and minimizing potential photochemical corrosion of Co₃O₄. The CC-30 material exhibits low overpotentials of 121 mV for the HER and 160 mV for the OER in 1.0 M KOH. Consequently, the overall water-splitting process necessitates a low cell voltage of 1.51 V. Remarkably, the electrode maintains excellent durability, with a negligible increase of 0.06 V after 100 hours of continuous electrolysis in a 3 M KOH solution. FT-IR and EIS analysis during the reaction demonstrated that Au promotes faster charge transfer and stabilizes a higher Co^2⁺ ratio during HER, facilitating redox transformations. Notably, in the OER, the Au/Co₃O₄ interface accelerates the transition from Co^3⁺ to Co^4⁺, promoting the formation of a -C=O intermediate and enabling -O-O- detachment, which enhances gas evolution kinetic. Furthermore, density functional theory calculation reveals that various Au (111) and Co₃O₄ (111) interface structures result in opposite charge redistributions at the interface.