Lattice Defects Coupled with Support Modification Enable a BiNi-Co ₃ O ₄ /CP Catalyst for High-Efficiency Acidic Oxygen Evolution Reaction

Lattice defect engineering and support modification are effective strategies for modulating catalyst electronic structures and enhancing the intrinsic activity. This study reports the in situ synthesis of a Bi and Ni codoped Co 3 O 4 catalyst on carbon paper (BiNi-Co 3 O 4 /CP) via a one-step molten salt method, integrating dual strategies. Bi doping, with its larger atomic radius, induces abundant lattice defects in the Co 3 O 4 surface, optimizing the electronic structure of Co active sites and markedly boosting the inherent catalytic activity. Concurrently, the synergistic interaction between Ni and Bi facilitates the formation of a tailored porous carbon support, which increases the active site exposure and promotes bubble desorption. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirms that the formation of the *OOH intermediate is significantly lowered by BiNi-Co 3 O 4 /CP, as is interfacial water adsorption. In 0.5 M H 2 SO 4 solution, the BiNi-Co 3 O 4 /CP catalyst demonstrates outstanding performance for the acidic oxygen evolution reaction (OER), achieving an ultralow overpotential of 275 mV at 10 mA cm –2 with 110 h stability. This work establishes the synergistic “lattice defect-support modification” approach as a paradigm for designing acidic OER electrocatalysts with high efficiency and stability.