CeVO4 Nanozymes Catalyze the Reduction of Dioxygen to Water without Releasing Partially Reduced Oxygen Species

: In this study, we report a remarkably active CeVO4 nanozyme that functionally mimics cytochrome c oxidase (CcO), the terminal enzyme in the respiratory electron transport chain, by catalyzing a four-electron reduction of dioxygen to water. The nanozyme catalyzes the reaction by using cytochrome c (Cyt c), the biological electron donor for CcO, at physiologically relevant pH. The CcO activity of the CeVO4 nanozymes depends on the relative ratio of surface Ce3+ /Ce4+ ions, the presence of V5+ and the surface-Cyt c interactions. The complete reduction of oxygen to water takes place without release of any partially reduced oxygen species (PROS) such as superoxide, peroxide and hydroxyl radicals.