Unravelling the true active site for CeO2-catalyzed dephosphorylation

Dephosphorylation that removes a phosphate group from substrate is an important reaction for both environmental protection and living organisms. Recent studies have demonstrated that CeO2 can efficiently catalyze this reaction via the activation of ester hydrolysis by surface Ce cations. However, different interpretations can be found among literatures on the physiochemical properties of Ce presumably due to the lack of a proper tool that can provide surface information in both qualitative and quantitative manner. Herein, the chemical state (or acidity) and corresponding concentration of surface Ce on various host CeO2 facets is differentiated and quantified for the first time by probe-assisted nuclear magnetic resonance (NMR) and X-ray absorption spectroscopy (XAS). The chemical state (or acidity) of surface Ce is found the key factor in this reaction (cf. their concentration) that > 4000 % increase in k constant can be easily achieved if host CeO2 facet is wisely selected.