Probing the Performance Limitations in Thin-Film FeVO4 Photoanodes for Solar Water Splitting

Abstract

FeVO4 is a potentially promising n-type multimetal oxide semiconductor for photoelectrochemical water splitting based on its favorable optical band gap of ca. 2.06 eV that allows for the absorption of visible light up to around 600 nm. However, the presently demonstrated photocurrent values on FeVO4 photoanodes are yet considerably low when comparing with α-Fe2O3, although FeVO4 can absorb comparable wavelengths of sunlight as α-Fe2O3. Donor-type doping and constructing nanoporous film morphology have afforded desirable (but far from satisfactory) improvements in FeVO4 photoanodes, whereas the fundamental properties, such as absorption coefficients and the nature of optical transition, and a quantitative analysis of the efficiency losses for FeVO4 photoanodes remain elusive. In the present study, we conduct a thorough experimental analysis of structural, optical, charge transport, and surface catalysis properties of FeVO4 thin films to investigate and clarify how and where the efficiency losses occur. Bas...