Interfacial engineering and rapid thermal crystallization of Sb₂S₃ photoanodes for enhanced photoelectrochemical performances

Antimony sulfide (Sb₂S₃) is a promising material for photoelectrochemical (PEC) devices that generate green hydrogen from sunlight and water. In this study, we present a synthesis of high-performance Sb₂S₃ photoanodes via an interface-engineered hydrothermal growth followed by rapid thermal annealing (RTA). A TiO₂ interfacial layer plays a crucial role in ensuring homogeneous precursor deposition, enhancing light absorption, and forming efficient heterojunctions with Sb₂S₃, thereby significantly improving charge separation and transport. RTA further improves crystallinity and interfacial contact, resulting in dense and uniform Sb₂S₃ films with enlarged grains and fewer defects. The optimized Sb₂S₃ photoanode achieves a photocurrent density of 2.51 mA/cm² at 1.23 V vs. the reversible hydrogen electrode (RHE), one of the highest reported for Sb₂S₃ without additional catalysts or passivation layers. To overcome the limitations of oxygen evolution reaction (OER), we employ the iodide oxidation reaction (IOR) as an alternative, significantly lowering the overpotential and improving charge transfer kinetics. Consequently, it produces a record photocurrent density of 8.9 mA/cm² at 0.54 V vs. RHE. This work highlights the synergy between TiO₂ interfacial engineering, RTA-induced crystallization, and IOR-driven oxidation, offering a promising pathway for efficient and scalable PEC hydrogen production.