The roles of oxygen vacancies in LaFeO3 photocathodes in photoelectrochemical water splitting

Abstract

In this study, we prepared oxygen vacancies (VO) modified LaFeO3 particles using a simple molten salt method by tuning the cation (La3+) deficiency. The existence of VO was confirmed by studying its crystal structure and surface chemical state. By testing the photoelectrochemical (PEC) activity of the Vo modified La1-xFeO3-σ photocathodes in a 0.1 M NaOH electrolyte under visible light, the results demonstrate that the as-prepared La0.9FeO3-σ shows good stability and superior IPCE, which is 3.27 times that of the pristine LaFeO3. Even through VO modification is an effective strategy for regulating the PEC performance of a semiconductor, the charge carrier density in semiconductor is not directly proportional to the amount of VO, as excessive VO may lead to deterioration of the electrochemical reaction due to interfacial charge recombination. Introducing suitable amount of VO into LaFeO3 can improve the light absorption, boost charge carrier transfer and separation efficiency, narrow the bandgap, and enhance the electrocatalytic reaction dynamics at the semiconductor surface.