Synergistic interface engineering and P-doping in Co9S8/Ni3S2 heterostructures for boosting oxygen evolution electrocatalysis

Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is critical for sustainable energy conversion. Herein, a P-doped Co 9 S 8 /Ni 3 S 2 heterostructure with a hierarchical nanoarray architecture is fabricated on nickel foam via an in situ growth strategy. Structural characterizations reveal a dense, three-dimensional hierarchical coral-like architecture, composed of ultrathin nanosheets intricately decorated with fine nanorods. High-resolution TEM analysis confirms the construction of Co 9 S 8 /Ni 3 S 2 hetero-interfaces characterized by abundant lattice distortions and grain boundary defects. X-ray photoelectron spectroscopy analysis reveal that phosphorus incorporation induces a redistribution of local electron density at the active sites, suggesting a favorable modulation of the electronic structure that promotes intrinsic catalytic activity. Benefiting from the synergistic effects of abundant interfacial defects, rapid charge and mass transport channels, and the modulated electronic environment, the as-prepared catalyst exhibits enhanced OER performance. In 1.0 M KOH electrolyte, the heterostructure requires a low overpotential of 234.84 mV to deliver a current density of 10 mA cm −2 along with a small Tafel slope of 19 mV dec −1 and sustains continuous operation for over 500 h. This study offers valuable insights into the coupling of interface engineering and heteroatom doping for constructing high-performance transition metal sulfide electrocatalysts.