Strain Heterogeneity Engineering Enhances the Activity and Stability of Co ₃ O ₄ for Oxygen Evolution Reaction

Strain engineering is regarded as a promising strategy for regulating oxygen evolution reaction (OER) performance. However, single strain modulation often struggles to balance the catalytic activity and stability. Thus, strain heterogeneity engineering was successfully applied in Co3O4 through tungsten (W) doping (W-Co3O4) in this work. The W not only induces lattice tensile strain in the Co3O4 lattice but also generates compressive strain through local bond length contraction, thereby synergistically enhancing the catalytic activity and stability. This strain heterogeneity endows W2%-Co3O4 with outstanding OER activity and stability in 1.0 M KOH (235 mV@10 mA cm–2). In a two-electrode system, the W2%-Co3O4||W2%-Co3O4 electrolyzer required only 1.45 V to reach 10 mA cm–2. Under industrial anion exchange membrane water electrolysis (AEMWE) conditions (60 °C, 1.0 M KOH), it achieved 1 A cm–2 at 1.85 V and maintained stable operation for over 100 h. Furthermore, the W doping promotes the transformation of the OER pathway from the adsorption evolution mechanism (AEM) to the oxide pathway mechanism (OPM) while reducing the free energy barrier of the rate-determining step (RDS) and the d–p band center energy level difference. These effects collectively contribute to the enhanced catalytic performance and stability. This work provides an effective design strategy for the simultaneous improvement of catalyst activity and stability through strain heterogeneity engineering.