Enhancing Oxygen Evolution Reaction Activity in NiCo ₂ O ₄ Catalysts Through Morphology and Oxygen Vacancy Engineering

ABSTRACT Developing oxygen evolution reaction (OER) catalysts that combine high performance with cost‐effectiveness is a critical challenge for advancing the commercialization of anion exchange membrane water electrolysis (AEMWE). Practical application is often hindered by issues such as poor batch reproducibility and low‐cost efficiency. To address these limitations, this study proposes a morphology–engineering strategy centered on oxygen vacancy modulation. Using nickel cobaltite as a model system, this strategy employs a low‐cost, low‐alkalinity solution medium and a gradient annealing process to achieve an optimal combination of tailored morphology and controlled oxygen vacancy concentration. Experimental characterization and density functional theory (DFT) calculations reveal that an appropriate annealing temperature (400°C) effectively constructs active coordination sites, facilitates the proton‐coupled electron transfer process, and thereby significantly enhances the OER performance. The performance loss after continuous operation for 112 h in the AEMWE single‐cell device is negligible, highlighting its excellent uniformity and stability. This work not only confirms the crucial role of the oxygen‐vacancy‐modulated morphology–engineering strategy in improving the OER performance of spinel oxides but also provides important insights and a technical pathway for designing highly active catalysts suitable for practical water electrolysis systems.