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

It is introduced that MnO₂ through a one-step formation of Z-scheme heterojunctions with Co₃O₄ while synergistically regulating three vital factors including band structure, metal valence state and oxygen vacancy content, resulting in improving the reaction selectivity with H₂O₂ as substrate. Based on efficient O₂ production capacity, Co₃O₄-MnO₂/MB nanoplatform within integrating diagnosis and therapy which combines photodynamic and photothermal therapy is developed.

Abstract

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 Co₃O₄ 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 MnO₂ to form Z-scheme heterojunctions with Co₃O₄ nanoparticles, the catalase (CAT)-like and peroxidase (POD)-like activities of Co₃O₄ can be precisely regulated since the introduction of MnO₂ affects the position of the conduction bands, preserves Co in a higher oxidation state (Co³⁺), and increases oxygen vacancy content, enabling Co₃O₄-MnO₂ exhibit improved CAT-like activity and reduced POD-like activity. This study proposes a strategy for improving reaction selectivity of Co₃O₄, which contributes to the development of metal oxide-based semiconductor nanozymes.