An ultrathin TiO2 interfacial layer enhancing the performance of an FeVO4 photoanode for water splitting

Abstract

Iron vanadate (FeVO₄) is a promising photoanode for photoelectrochemical (PEC) water splitting because of its unique electronic band structure, in particular the bandgap of 2.1 eV. However, its PEC performance is limited by the charge recombination at transparent conducting substrate/photoanode interface. Herein, we demonstrate that the introduction of an ultrathin (1.1 nm) TiO₂ layer between FTO and an FeVO₄ photoanode by atomic layer deposition (ALD) technology can well address the issue of interfacial charge recombination, this is because the large valence band offset between TiO₂ and FeVO₄ can effectively suppress back hole transfer and subsequently improve charge separation. As expected, the modified photoanode exhibited an enhanced PEC water splitting performance. We believe that the strategy of fabricating an ultrathin TiO₂ interfacial layer as a hole blocking barrier can also benefit other photoanodes.