Revealing mechanism of transition metals doping in chlorapatite as single-atom nanozymes for high electrocatalytic activity of Fenton/Fenton-like reaction

Abstract

Chemodynamic therapy (CDT) induced by endogenous overexpression of hydrogen peroxide based on nanozyme is an emerging tumor therapy strategy that has been abstracted widespread attention. However, the present efficacy of nanozyme catalytic therapy is severely limited by the low atomic availability and the few active sites of nanozyme. Herein, by means of density functional theory calculations, the catalytic performance of substituted or interstitial single transition metals doped in chlorapatite matrix (TM-CAP) for Fenton/Fenton-like reaction was systematically studied, aiming to screen out efficient and highly cyclic single-atom nanozymes (SAzymes). The Coint-CAP SAzymes showed unprecedented superiority among all candidates with the limit potential of −1.92 V under the characteristic acidic conditions of the tumor microenvironment, and exhibited excellent catalyst regeneration ability compared with neutral conditions. Ultimately, it is proved that compared with substitution doping, the interstitial doping of single Co atom significantly improves the inherent activity of Fenton/Fenton-like reaction. This was ascribed to the charge rearrangement of SAzymes surface caused by interstitial doping of Co, which enabled Ca site near the Co site to stably synergistically bind *OH species. Moreover, the screened Co interstitial doped chlorapatite (Coint-CAP) SAzymes with excellent thermodynamic stability and anti-agglomeration ability not only had a smaller cell volume change and band gap, but also was easy to be synthesized experimentally. This work aimed at guiding experimental design of artificial SAzymes with desired active center and electronic properties based on reported theoretical results of the structure–property relationship of active sites.