Car-CeO 2 Nanozymes with Oxygen Vacancies and Nucleophilic Sites for Enhanced Organophosphorus Toxin Hydrolysis

The development of highly active and green heterogeneous catalysts for the hydrolysis of organophosphorus pesticides (OPs) is of great significance but still faces enormous challenges. In this paper, inspired by microenvironment regulation, a carnosine-modified cerium dioxide (Car-CeO2) nanozyme was synthesized for efficient hydrolysis of the OPs. Among them, the electron-donating effect of imidazole groups and the coordination effect of amino and carboxyl groups endowed Car-CeO2 with more abundant oxygen vacancies, which, in turn, made it easier to attract phosphate groups. Meanwhile, the imidazole group in the carnosine not only contributed to the generation of Ce-OH nucleophilic sites but also served as a "proton shuttle", releasing and recovering protons in a timely manner to stabilize the transition state and promote hydrolysis in an orderly way. It was determined by potentiometric acid-base titration that there was a linear correlation between the total surface acidity of the CeO2-based nanomaterials and their hydrolysis activity. Based on this, an imidazole group-driven oxygen vacancy and Ce-OH dual-site cocatalytic mechanism (OV and Ce-OH DSCM) was proposed. Furthermore, the development of wastewater purification devices indicated that Car-CeO2 had promising practical application potential.