Post‐Oxidation Integrating Assembly‐Confined Pyrolysis to Boost POD‐Like Activity of Non‐Metal Nanozyme and Engineer Colorimetric Hydrogel for On‐Site Detection of PFAS

Abstract Nanozymes have become attractive candidates for advanced sensors, yet enhancing peroxidase (POD)‐like activity of non‐metal nanozymes with minimized oxidase activity interference and broad‐spectrum recognition capability for per‐ and polyfluoroalkyl substances (PFASs) remains challenging. Herein, we developed a “post‐oxidation integrating assembly‐confined pyrolysis” methodology for constructing high‐activity and exclusive POD‐like B, N co‐doped carbon nanozymes. Glucose and boronic acid‐involved assembly‐confined pyrolysis drove the formation of flake‐like intermediate template containing B─C bond, endowing the resultant nanozymes with well‐defined two‐dimensional (2D) morphology and abundant active sites. Interestingly, ammonium persulphate oxidation enabled POD‐like activity with at least 155.48% times and at most 310.15% times higher than controls via improving ─C═O content, sp 2 ‐C crystal domain and N doping level. Thus, a colorimetric hydrogel sensor was constructed by embedding 2D‐BN@C‐0.90 (highest activity) into polyvinyl alcohol and agarose to deliver on‐site PFAS information through an image processing algorithm, featuring low cost, ease of operation, and portability. The results demonstrated that PFASs‐bearing ─SO 3 H showed the highest inhibition efficiency, followed by ─COOH‐containing PFASs, whereas PFASs with ─OH produced the lowest one. The developed methodology promotes the scalable creation of high‐activity non‐metal nanozymes, and the as‐constructed hydrogel can tender accurate PFAS information, advancing environmental monitoring and food safety.