Heterojunction-Mediated Co-Adjustment of Band Structure and Valence State for Achieving Selective Regulation of Semiconductor Nanozymes.

Improving reaction selectivity is the next target for nanozymes to mimic natural enzymes. Currently, the majority of strategies in this field are exclusively applicable to metal-organic-based or organic-based nanozymes, while limited in regulating metal oxide-based semiconductor nanozymes. Herein, taking semiconductor Co 3 O 4 as an example, a heterojunction strategy to precisely regulate nanozyme selectivity by simultaneously regulating three vital factors including band structure, metal valence state, and oxygen vacancy content is proposed. After introducing MnO 2 to form Z-scheme heterojunctions with Co 3 O 4 nanoparticles, the catalase (CAT)-like and peroxidase (POD)-like activities of Co 3 O 4 can be precisely regulated since the introduction of MnO 2 affects the position of the conduction bands, preserves Co in a higher oxidation state (Co 3+ ), and increases oxygen vacancy content, enabling Co 3 O 4 -MnO 2 exhibit improved CAT-like activity and reduced POD-like activity. This study proposes a strategy for improving reaction selectivity of Co 3 O 4 , which contributes to the development of metal oxide-based semiconductor nanozymes.