Light-Mediated Modulation of Enzyme-Mimetic Activity of CuMnO 2 Nanosheets.

As typical copper-based-manganese delafossites, CuMnO 2 nanoflakes (CuMnO 2 NFs) display excellent light absorption capacity, showing great promise for facile regulation of catalysis reactions by light stimulation. Here, we report that the as-prepared CuMnO 2 NFs possess intrinsic peroxidase- and oxidase-like activities, which are capable of catalyzing the oxidation of the enzymatic substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H 2 O 2 or O 2 , respectively. Additionally, CuMnO 2 NFs exhibit significant light-enhanced dual enzyme-like performance (peroxidase and oxidase) for accelerating the oxidation of TMB, owing to a much greater light-induced reactive oxygen species (ROS) yield. The light-induced hydroxyl radicals (·OH) and superoxide radicals (O 2 •- ) hold the key to rapidly catalyzing the oxidation of TMB into the two-electron charge transfer complex diamine, subsequently improving the oxidation capacity and enzyme-like activity of CuMnO 2 NFs as peroxidase and oxidase mimics. These findings confirm an efficient way to improve the enzyme-like performance of nanozymes and regulate the reactive oxygen species (ROS) level by simply employing irradiated light. This work also provides a general method for constructing external field-modulated smart nanozymes and an insightful approach to the corresponding enzyme-mimetic reaction mechanism.