Bionic design of cytochrome c oxidase-like single-atom nanozymes for oxygen reduction reaction in enzymatic biofuel cells

Designing an artificial enzyme, from the perspective of bionics, to mimic the catalytic activity of natural enzymes is highly desirable but remains challenges. In response to the simulation of biological structure, we developed cytochrome c oxidase (CcO)-like single-atom nanozymes with FeN5 active centers (FeN5 SAs) in this work. Similar to the spatial structure of heme a3 in natural CcO, the active center of FeN5 SAs is axial N-coordinated heme-like structure and can be served as oxygen-binding site to complete oxygen reduction reaction (ORR) in respiratory electron transport chain by catalyzing the oxidation of cytochrome c (Cyt c). Depending on this bionic structure, furthermore, FeN5 SAs exhibited competitive electrocatalytic performance towards ORR with a half-wave potential of 0.67 V (vs. RHE) at neutral condition. Coupling a glucose dehydrogenase (GDH) bioanode, the FeN5 SAs-based glucose/O2 enzymatic biofuel cell (EBFC) obtained a maximum power density of 149.2 ± 4.0 μW cm−2 with an open circuit potential of 0.40 ± 0.01 V. In this study, inspired by the native structure of enzymes, we develop CcO-like FeN5 SAs and expand its application in EBFCs, which may provide an rational research approach to advance the development of nanozymes.