Modulation of Cobalt-Based Bifunctional Electrochemical Water Splitting Catalysts via Oxygen Vacancies and Phosphorus Doping

Electrochemical water splitting for hydrogen production is a crucial technological pathway for obtaining green hydrogen and has emerged as an effective method to address environmental pollution and the energy crisis. However, the scarcity of raw materials for noble metal hydrogen evolution catalysts, such as platinum-carbon (Pt/C) and ruthenium/iridium (Ru/Ir), makes the development of non-precious metal electrocatalytic materials an urgent priority.This study developed a high-performance cobalt-based bifunctional water electrolysis catalyst (P-Ov-Co₃O₄/NF-Z) using nickel foam (NF) as a substrate, through a strategy combining vacuum heat treatment and phosphorus doping. The results indicate that phosphorus doping significantly increases the total oxygen vacancy content. The P-Ov-Co₃O₄/NF-Z catalyst exhibits remarkable bifunctional activity: for the hydrogen evolution reaction (HER), it requires an overpotential of only 61 mV at a current density of −10 mA·cm⁻², which is close to the 55 mV required by the Pt/C@NF benchmark. For the oxygen evolution reaction (OER), the overpotential is 228 mV at 10 mA·cm⁻², significantly outperforming IrO₂@NF and the undoped sample. The Tafel slopes for HER and OER are 78.67 mV·dec⁻¹ and 110.4 mV·dec⁻¹, respectively. Furthermore, the catalyst demonstrates excellent stability at current densities of 50, 100, and 300 mA·cm⁻², maintaining performance for 148 hours (HER) and 192 hours (OER).This work provides new insights and strategies for the preparation of non-precious metal electrocatalytic materials.