Fabrication of Flower-Shaped Sb₂S₃/Fe₂O₃ Heterostructures for Enhanced Photoelectrochemical Performance

Antimony sulfide (Sb₂S₃) has been recognized as a catalytic material for splitting water by solar energy because of its suitable narrow band gap, high absorption coefficient, and abundance of elements. However, many deep-level defects in Sb₂S₃ result in a significant recombination of photoexcited electron-hole pairs, weakening its photoelectrochemical performance. Here, by using a simple hydrothermal and spin-coating method, we fabricated a step-scheme heterojunction of Sb₂S₃/α-Fe₂O₃ to improve the photoelectrochemical performance of pure Sb₂S₃. Our Sb₂S₃/α-Fe₂O₃ photoanode has a photocurrent density of 1.18 mA/cm² at 1.23 V vs reversible hydrogen electrode, 1.39 times higher than that of Sb₂S₃ (0.84 mA/cm²). In addition, our heterojunction has a lower onset potential, a higher absorbance intensity, a higher incident photon-to-current conversion efficiency, a higher applied bias photon-to-current efficiency, and a lower charge transfer resistance compared to pure Sb₂S₃. Based on ultraviolet photoelectron spectroscopy, we constructed a step-scheme band structure of Sb₂S₃/α-Fe₂O₃ to explain its photoelectrochemical enhancement. This work offers a promising strategy to optimize the performance of Sb₂S₃ photoelectrodes for solar-driven photoelectrochemical water splitting.