Optimization of Photoelectrochemical Water Oxidation for Hydrogen Peroxide Synthesis in α-Fe ₂ O ₃ via Codoping and Oxygen Vacancies

Photoelectrocatalysis, which utilizes light energy and catalysts to convert water into H₂O₂, is a promising method for H₂O₂ production. Hematite (α-Fe₂O₃) is considered a highly promising photoanode owing to its favorable band structure and excellent stability in alkaline solutions. However, severe carrier recombination in the bulk and at the α-Fe₂O₃ surface limits the catalytic activity and stability of the photoelectrode. In this study, we prepared a Pt/Ti:α-Fe₂O₃-HAc photoanode through the codoping of Pt and Ti, followed by acetic acid (HAc) treatment to enhance photoelectrochemical H₂O₂ production. The synthesis involved a hydrothermal process to achieve uniform doping, followed by calcination. The resulting photoanodes were characterized by using techniques for phase identification and morphological analysis. The optimized Pt/Ti:α-Fe₂O₃-HAc exhibits a H₂O₂ Faradaic efficiency of 75.6% and a yield of 0.42 μmol min^-1 cm^-2 at 1.7 V_RHE. Experimental analysis and theoretical calculations indicate that Pt and Ti codoping, along with oxygen vacancy modification, increases the charge density at the Fe sites and shifts the Fe d-band center downward, thereby enhancing effective photoelectrochemical (PEC) hydrogen peroxide production. This work presents a novel strategy for interfacial modification via synergistic Pt and Ti codoping and surface defect engineering, which enhances charge separation efficiency in semiconductors. This photoanode design approach could be applicable to related photoanodes for photoelectrosynthesis of hydrogen peroxide.