FeNiSn-based perovskite hydroxide modified Ti-Fe2O3 with interfacial regulation for photoelectrochemical water oxidation

•FNS/Ti-Fe2O3-150 exhibits a significant photocurrent density of 3.15 mA/cm2 at 1.23 V vs. RHE, which is much higher than that of Ti-Fe2O3 (0.52 mA/cm2).•The efficient transfer of photogenerated holes from the bulk to the surface of FNS/Ti-Fe2O3-150 is guaranteed by the reduced transfer resistance, which is arose from the close contact between Ti-Fe2O3 and FeNiSn(OH)6 and increased charge carrier density after the heat treatment.•After the deposition of FeNiSn(OH)6 and the post-treatment, the photogenerated holes captured by the surface states are easily to react with water rather than recombination with electrons.