Defect engineering to accelerate charge transport in LaFeO3 photocathodes via thermal oxidation: A combined experimental and theoretical study

In order to improve poor charge carrier transport properties of p-type oxide semiconductors, the post thermal treatment under oxygen atmosphere is systematically studied as a defect engineering strategy for LaFeO3 photocathodes. The post-thermal oxidation process significantly decreases the photo-generated charge recombination and promotes the charge transport properties of LaFeO3 photocathodes. The density functional theory calculations and experimental analyses indicate that the thermal oxygen treatment can promote the formation of La vacancy and the reduction of the oxygen vacancy in LaFeO3, which facilitates its bulk charge transport by increasing hole carrier density. The optimized LaFeO3 photocathode yields an O2 reduction photocurrent density of −313 µA/cm2 at 0.6 V vs RHE in O2-saturated KOH solution under 1 sun irradiation. Additionally, we also investigated the feasibility of photoreduction of water by using a Pt-deposited LaFeO3 photocathodes. [Display omitted] •Thermal oxygen treatment promotes the formation of La vacancy in p-LaFeO3 photocathodes.•It facilitates bulk charge transport and enhances water reduction performance.•It can be an effective strategy for defect engineering for other p-type oxide-based photocathodes.