TiO2 Nanoflowers Decorated with FeOx Nanocluster and Single Atoms by Atomic Layer Deposition for Peroxidase-Mimicking Nanozymes

Nanozymes have great potential to replace natural enzymes due to their multiple enzyme-mimicking properties in practical applications, and the development of high-efficiency nanozymes is of great necessity. Herein, FeOx/TiO2 nanozymes with confined structures were synthesized by atomic layer deposition (ALD), among which the 70FeOx/TiO2 nanozymes with highly dispersed Fe single atoms and FeOx nanoclusters confined in the pores of TiO2 nanoflower supports exhibit optimized peroxidase activity. Furthermore, the ultrathin modification strategy of ALD (1-cycle TiO2) followed by reduction treatment was conducted to achieve the 1TiO2-70FeOx/TiO2-H nanozymes, whose enzyme-like activity is almost 2 times higher than that of 70FeOx/TiO2 counterparts. Investigation of the catalytic mechanism shows that atomic-level modification of TiO2 modifies the FeOx electron states, contributing to the stronger capability to generate hydroxyl radical, which results in remarkably enhanced peroxidase activity. The present work may provide new insights into the rational design of high-efficiency nanozymes at an atomic level.