Modulating Ce³⁺ Sites in Ce-Zr Oxide Nanocatalysts through Protamine Biomineralization for Organophosphate Dephosphorylation

Catalytic is a crucial reaction for environmental detoxication of pesticides and neutralization of various molecules classified as chemical warfare agents. Herein, we report on a series of tunable Ce−Zr-based metal oxides, (Zr_aCe_1–aO_x) prepared using a facile biomineralization technique, as catalysts for organophosphates dephosphorylation. Synchrotron scattering and spectroscopy methods showcase that Zr_aCe_1–aO_x catalysts are highly defective and exhibit an abundance of Ce³⁺ sites that promote oxygen vacancies needed for enhanced dephosphorylation reactions. The catalytic performance was assessed using a model para-nitrophenyl phosphate reaction and showcases a strong dependence on Zr dopant concentration and subsequent tuning of the Ce³⁺/Ce⁴⁺ ratio. Analysis of synchrotron datasets allowed structure-performance correlations between the Ce³⁺ concentration and associated oxygen vacancies, the dephosphorylation rate constant, and Zr concentration to be established, confirming that Ce³⁺ as active sites is positively correlated with the rate constant. We envision that similar biomineralization approaches can be used to fabricate Ce³⁺-rich Ce−Zr oxide for environmental application in dephosphorylation and other hydrolysis reactions.