In Situ Defect Engineering of Fe‐MIL for Self‐Enhanced Peroxidase‐Like Activity

Abstract Defect engineering is an effective strategy to enhance the enzyme‐like activity of nanozymes. However, previous efforts have primarily focused on introducing defects via de novo synthesis and post‐synthetic treatment, overlooking the dynamic evolution of defects during the catalytic process involving highly reactive oxygen species. Herein, a defect‐engineered metal–organic framework (MOF) nanozyme with mixed linkers is reported. Over twofold peroxidase (POD)‐like activity enhancement compared with unmodified nanozyme highlights the critical role of in situ defect formation in enhancing the catalytic performance of nanozyme. Experimental results reveal that highly active hydroxyl radical (•OH) generated in the catalytic process etches the 2,5‐dihydroxyterephthalic acid ligands, contributing to electronic structure modulation of metal sites and enlarged pore sizes in the framework. The self‐enhanced POD‐like activity induced by in situ defect engineering promotes the generation of •OH, holding promise in colorimetric sensing for detecting dichlorvos. Utilizing smartphone photography for RGB value extraction, the resultant sensing platform achieves the detection for dichlorvos ranging from 5 to 300 ng mL −1 with a low detection limit of 2.06 ng mL −1 . This pioneering work in creating in situ defects in MOFs to improve catalytic activity offers a novel perspective on traditional defect engineering.