Strategic Design for High-Efficiency Oxygen Evolution Reaction (OER) Catalysts by Triggering Lattice Oxygen Oxidation in Cobalt Spinel Oxides.

Abstract

High-efficiency catalysts with refined electronic structures are highly desirable for promoting the kinetics of the oxygen evolution reaction (OER) and enhancing catalyst durability. This study comprehensively explores strategies involving metal doping and oxygen vacancies for enhancing the acidic OER catalytic activity of Co₃O₄. Through extensive screening of 3d and 4d transition metals using density functional theory (DFT) simulations, we demonstrate that the incorporation of metal dopants and oxygen vacancies into Co₃O₄ potentially triggers a transition from the adsorbate evolution mechanism (AEM) to the lattice oxygen oxidation mechanism (LOM) in the oxygen evolution reaction (OER). While the formation of the O-O bond in the intermediate *OOH poses challenges, a significantly reduced overpotential facilitates efficient conversion of O to O₂ through the LOM in *OH and lattice oxygen. Additionally, we find that Mn doping can significantly improve the stability of the catalyst. Building upon the rationale above, we employed a dual doping strategy in subsequent experiments to enhance both the activity and stability. Our final design involved the codoping of Mn and Ru in Co₃O₄, along with an appropriate amount of oxygen vacancies. This catalyst demonstrates a low overpotential (η₁₀ = 230 mV) compared to pure Co₃O₄ and maintains stable operation for over 120 h, representing a 12-fold increase. By exploring and harnessing the LOM, more efficient, stable, and cost-effective OER catalysts can be designed, providing crucial support for technologies such as water electrolysis in clean energy.