Bridging Oxidase- and Oxygen Reduction Electro-Catalysis by Model Single-Atom Catalysts

Nanocatalysts with enzyme-like catalytic activities, such as oxidase-mimics, are extensively used in biomedicine and environmental treatment. Searching enzyme-like nanomaterials, clarifying the origins of catalytic activity and developing activity assessment methodologies are therefore of great significance. Here we report that the oxidase- and oxygen reduction reaction (ORR) electro-catalysis can be well-bridged based on their identical activity origins, which makes the facile electrocatalytic ORR activity measurements intrinsically applicable to the oxidase-like activity evaluations. Inspired by natural heme-copper oxidases, Cu/Fe doped single-atom catalysts (SACs) were first synthesized and used as model catalysts. Chromogenic reactions, electrochemical voltammetric measurements and density functional theory calculations further verify the linear relationship between their oxidase-like and ORR catalytic activities of the catalysts, thus an effective descriptor () are proposed for the rapid enzymic catalyst evaluation. The enhanced tumour therapeutic efficacy of SACs has been evidenced to result from their oxidase-like/ORR activities, which prove that numerous ORR electrocatalysts are promising candidates for oxidase mimics and tumour therapy. The synergistic catalytic effect of the biomimetic hetero-binuclear Cu-Fe centres has also been probed thoroughly.