Electrodeposition Coupled with In Situ Selenization for Sb2Se3 Thin Films toward Enhanced Photoelectrochemical Performance

Abstract Photoelectrochemical (PEC) water splitting is a crucial approach for achieving sustainable solar hydrogen production. Antimony selenide (Sb2Se3) is recognized as a highly promising photocathode for PEC water splitting. However, the omnipresent selenium vacancies (VSe) in Sb2Se3 severely limit its photoelectric performance. In this study, a dense and uniform precursor film is fabricated by precisely controlling the electrodeposition potential. Subsequently, in situ vapor-phase selenization is conducted to create a selenium-rich atmosphere, which achieves synergistic optimization of defect passivation, grain growth, and active sites. The optimized sample achieves a photocurrent density of −0.25 mA cm–2 (vs RHE), which is 15.6 times that of the nonselenized sample, accompanied by an 11 mV positive shift in the onset potential. Characterization and performance tests reveal that the selenium-rich atmosphere also optimizes the band structure and lowers the energy barrier for the HER. This work provides new insights and a feasible strategy for developing efficient and scalable noble-metal-free catalysts for solar hydrogen production.