Facet-Dependent Interfacial Charge Transfer in Fe(III)-Grafted TiO₂ Nanostructures Activated by Visible Light

Abstract

Interface engineering in heterogeneous catalysis is fascinating because of the modulation of charge-transfer processes and catalytic activity. Herein, by constructing Fe(III)–TiO2 systems with different interfacial contact facets, {101} and {001} facets, we demonstrate the facet-dependent interfacial charge transfer properties of TiO2/Fe(III) system activated by visible light. Although the photoreactivity of the {001} facet is documented to be higher than that of the {101} facet under UV light, phenol photodegradation experiments reveal that under visible light {101} TiO2/Fe(III) exhibits significantly higher photocatalytic activity than {001} TiO2/Fe(III). Photoelectrochemical measurements and computational calculations suggest that the {101} TiO2/Fe(III) interface significantly promotes interfacial electron transfer compared with the {001} TiO2/Fe(III) interface owing to the facet-specific electron–hole transport properties of the {101} and {001} facets in the TiO2 crystals. The reduced Fe(III) nanoclusters on the {101} TiO2 surface facilitate the reduction of adsorbed O2 molecules to H2O2 via multielectron transfer processes and simultaneously promote hole generation in VB(TiO2) to oxidize organic contaminants. These findings demonstrate the crucial roles of the facet in determining interfacial charge transfer processes and will be applicable for designing high-performance catalysts.