Shape Regulation of CeO₂ Nanozymes Boosts Reaction Specificity and Activity

Abstract

Among reported nanozymes, CeO 2 seems to be the only transition metal oxide that can mimic phosphatase and peroxidase by catalyzing substrate dephosphorylation and oxidation (with H 2 O 2 ). However, no consensus on the key Ce species was reached in the literature using spherical CeO 2 enclosed by ( 111) and (100) surfaces, not to mention the further control of its reaction specificity. In this study, octahedral and cubic CeO 2 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 H 2 O 2 . This correlation was further evidenced by the electron-rich Ce species on (100) surface, hindering the first reaction while promoting the latter.

Regulating the H2O2 Activation Pathway on a Well-Defined CeO2 Nanozyme Allows the Entire Steering of Its Specificity between Associated Enzymatic Reactions

“…On the other hand, although facet-dependent enzyme-like activities have been reported for CeO 2 (and other nanozymes), only a few research groups have focused on the control of specificity/selectivity among enzymatic reactions, which is a very challenging issue in the field. − Single-atom nanozymes were recently demonstrated to tune the selective activation between two different substrates, H 2 O 2 and O 2 , for the control of their POD-like and oxidase-like activities. , Our group also found that CeO 2 nanozymes in different shapes can interact very differently with H 2 O 2 and phosphate-containing molecules and hence the control of their reaction specificity between the POD-like and phosphatase-like reactions. , In comparison, regulating a single substrate and hence the control of reaction specificity over a given material is an even greater challenge. To the best of our knowledge, the Tremel group is the only group so far regulating H 2 O 2 on mesoporous CeO 2 nanozymes for tunable POD-like and HPO-like activities, although the reaction specificity is unsatisfactory .…”

“…45,46 Our group also found that CeO 2 nanozymes in different shapes can interact very differently with H 2 O 2 and phosphatecontaining molecules and hence the control of their reaction specificity between the POD-like and phosphatase-like reactions. 47,48 In comparison, regulating a single substrate and hence the control of reaction specificity over a given material is an even greater challenge. To the best of our knowledge, the Tremel group is the only group so far regulating H 2 O 2 on mesoporous CeO 2 nanozymes for tunable POD-like and HPO-like activities, although the reaction specificity is unsatisfactory.…”

A comprehensive exploration of the latest innovations for advancements in enhancing selectivity of nanozymes for theranostic nanoplatforms

“…9a). 122 Surface Ce species on the cube have a higher electron density, promoting PODlike activity with ∼10 and ∼49 times higher reactivity than those on the sphere and octahedron surfaces, respectively. Zhang's group has achieved the selectivity of nanozymes through ingenious HOMO/LUMO-mediated strategies, eliminating the need for additional modifications (Fig.…”