InFeO3 photoelectrode with two-dimensional superlattice for visible- and ultraviolet-light-driven water splitting

Abstract

Thin film of indium iron oxide, InFeO3, with a two-dimensional natural superlattice structure was proposed as one of the candidate photoelectrodes for visible- and ultraviolet-light-driven water splitting. A first principle calculation shows that InFeO3 is a charge transfer-type insulator with a bandgap energy (Eg) of 2.5 eV. Flat band potentials are calculated from Mulliken electronegativities, and they show an appropriately placed conduction band to enable H2 evolution. Despite its wide Eg, the photocurrent of InFeO3 in the visible region is comparable to that of α-Fe2O3 (Eg = 2.1 eV), a conventional oxide photoelectrode, possibly owing to its intrinsic structural anisotropy, reducing recombination losses of photogenerated electron–hole pairs. Furthermore, InFeO3 shows enhanced light absorption and photocurrent in the ultraviolet region compared with α-Fe2O3. The onset potential of photocurrent of InFeO3 is significantly lower than that of α-Fe2O3. These properties suggest that InFeO3 is a promising candidate for water splitting by visible and ultraviolet light.