Tuning the catalytic microenvironment by incorporating P atoms into Co₉S₈ with enhanced water splitting catalytic activity

Construction of efficient and durable electrocatalysts for overall water splitting remains a challenge. In this report, we successfully construct an efficient water-splitting electrocatalyst by incorporating P atoms into Co₉S₈ (P-Co₉S₈), which significantly modulates the catalytic microenvironment. The resulting P-Co₉S₈ composites feature a unique porous nanoflake structure, providing a large surface area and abundant electron transport pathways at the electrode–electrolyte interface. The optimized P-Co₉S₈ composites demonstrate exceptional catalytic performance, requiring only 271 mV for oxygen evolution reaction and 80 mV for hydrogen evolution reaction in 1 M KOH under 10 mA cm⁻², respectively. Theoretical calculations and experimental data confirm that the incorporation of P atoms into Co₉S₈ significantly alters the electronic structure, promotes charge-localized redistribution, and optimizes the energy barrier during the electrochemical reaction process. These results highlight the efficacy of tuning the catalytic microenvironment via the introduction of heteroatoms into metal sulfides as a potent method for engineering high performance water-splitting electrocatalysts.