Au-Assisted CHO Formation Promotes O₂ Activation for HCHO Oxidation over Au/Co₃O₄

In this study, we systematically investigate HCHO oxidation on Au/Co₃O₄ single-atom catalysts (SACs) using density functional theory (DFT) combined with ab initio thermodynamics. The most stable configuration under realistic conditions is identified as Au substituting a tetrahedral Co atom on the pristine surface. The reaction pathway involves HCHO adsorption, C-H cleavage to form CHO*, followed by O₂ activation, and the decomposition of COOH* to CO₂. Importantly, Au plays a dual promotional role: it not only significantly lowers the energy barrier of C-H dissociation, but also, through the generated CHO*, indirectly facilitates the subsequent O₂ adsorption and activation on the Co site. Electronic structure analysis reveals that Au enhances charge transfer and facilitates hydrogen migration, while CHO* groups change the electronic state of Co, promoting O₂ activation. This work provides a new perspective on O₂ activation by uncovering the crucial yet previously overlooked role of the intermediate, and offers a strategic guide for the design of high-performance single-atoms catalysts.