Achieving photocatalytic water reduction and oxidation over narrow bandgap FeVO4

Abstract

The exploration of novel oxide photocatalysts with narrow bandgaps is highly desirable for efficient photocatalytic water splitting. However, this is rather challenging as reducing the bandgap generally leads to severe charge recombination in photocatalysts. To address these issues, the present work demonstrates, for the first time, the synthesis and application of triclinic FeVO4 with an absorption edge of 575 nm for visible-light-driven photocatalytic water reduction and oxidation. Based on it, the Cr doping strategy is implemented on the FeVO4 photocatalyst to further promote the charge separation and the photocatalytic water splitting performance, achieving an apparent quantum efficiency (AQE) of 0.26% at 420 nm (± 15 nm) for an O2 evolution reaction. Detailed analysis shows that an impurity level below the conduction band minimum originating from the Cr 3d orbital is formed after Cr doping, facilitating the prolonged absorption edge and the enhanced charge separation. This work inaugurates the application field of the narrow bandgap particulate FeVO4 photocatalyst in photocatalytic water splitting, and validates that charge separation can be promoted by Cr doping, both of which are promising to be further developed for efficient solar energy conversion.