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

Interface engineering in heterogeneous catalysis is fascinating because of the modulation of charge-transfer processes and catalytic activity. Herein, by constructing Fe(III)–TiO 2 systems with different interfacial contact facets, {101} and {001} facets, we demonstrate the facet-dependent interfacial charge transfer properties of TiO 2 /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} TiO 2 /Fe(III) exhibits significantly higher photocatalytic activity than {001} TiO 2 /Fe(III). Photoelectrochemical measurements and computational calculations suggest that the {101} TiO 2 /Fe(III) interface significantly promotes interfacial electron transfer compared with the {001} TiO 2 /Fe(III) interface owing to the facet-specific electron–hole transport properties of the {101} and {001} facets in the TiO 2 crystals. The reduced Fe(III) nanoclusters on the {101} TiO 2 surface facilitate the reduction of adsorbed O 2 molecules to H 2 O 2 via multielectron transfer processes and simultaneously promote hole generation in VB(TiO 2 ) 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.