Electronic structure engineering of N-doped carbon nanozyme via incorporating Cl and sp3-hybridized defected carbon for organophosphorus pesticides assay.

After high-temperature etching of metal-free porous N -doped carbon with NaCl, the doped Cl atoms significantly enhance the peroxidase-like activity of the nanozyme. [Display omitted] Metal-free carbon-based nanozymes often exhibit superior chemical stability and detection reliability compared to their metal-doped counterparts. However, their catalytic activity remains an area ripe for further enhancement. Herein, we successfully prepared a chlorine (Cl)-modified, metal-free, and porous N -doped carbon nanozyme (Cl x -pNC) via NaCl molten etching. The incorporation of Cl induced an increase in the intrinsic defects of sp3-hybridized carbon within Cl x -pNC and optimized the electronic structure of the N -connected carbon atoms. Remarkably, the peroxidase (POD)-like activity of Cl x -pNC was enhanced twelvefold compared to porous N -doped carbon (pNC). Theoretical simulations highlighted that the introduction of Cl not only promoted H 2 O 2 adsorption but also lowered the energy barrier for its decomposition, facilitating the generation of active intermediates and thus boosting POD-like activity. Based on the POD mimic activity of Cl x -pNC, we developed a colorimetric platform for OPs detection utilizing a cascade amplification strategy. This work provides insights into the rational design of carbon-based nanozymes and the development of nanozyme-based colorimetric biosensors. [ABSTRACT FROM AUTHOR]