Electronic-State Manipulation of Surface Titanium Activates Dephosphorylation over TiO₂ Near Room Temperature

Dephosphorylation that removes a phosphate group from substrates is an important reaction for not only living organisms but also environmental protection. Although CeO₂ has been shown to catalyze this reaction, as one of the rare earth elements, cerium is low in natural abundance and has a narrow global distribution (> 90% of these reserves are located within six countries). It is thus imperative to find another element/material with high worldwide abundance that can also efficiently extract the phosphate out of agricultural wastes for phosphorus recycle. Using para-nitrophenyl phosphate (p-NPP) as the model compound, we demonstrate herein that TiO₂ with F-modified (001) surface can activate p-NPP dephosphorylation at temperature as low as 40 °C. By probe-assisted nuclear magnetic resonance (NMR), it was revealed that the strong electron withdrawing effect of fluorine makes Ti atoms (i.e., the active sites) on (001) surface very acidic. The bidentate adsorption of p-NPP on this surface further promotes its subsequent activation with barrier ~20 kJ/mol lower than that of pristine (001) and (101) surfaces, allowing the activation of this reaction at nearly room temperature (from > 80 °C).