Shape Regulation of CeO₂ Nanozymes Boosts Reaction Specificity and Activity

Among reported nanozymes, CeO₂ seems to be the only transition metal oxide that can mimic phosphatase and peroxidase by catalyzing substrate dephosphorylation and oxidation (with H₂O₂). However, no consensus on the key Ce species was reached in the literature using spherical CeO₂ enclosed by (111) and (100) surfaces, not to mention the further control of its reaction specificity. In this study, octahedral and cubic CeO₂ preferentially terminated by (111) and (100) surfaces were found to exhibit high reaction specificity (and activity) towards each of the above reactions. Spectroscopic evidence suggests that this is closely associated with the Lewis acidity (or electron density) of surface Ce species. The acidic Ce species on (111) surface can catalyze substrate dephosphorylation at room temperature but do not for substrate oxidation with H₂O₂. This correlation was further evidenced by the electron-rich Ce species on (100) surface, hindering the first reaction while promoting the latter.