In-situ growth of 2D SnS₂ nanosheets on planar Sb₂S₃ photocathodes and exploration to enhance stability

As a narrow-bandgap semiconductor, antimony sulfide (Sb₂S₃) exhibits a strong light response while being non-toxic and environmentally benign. These combined properties position it as a leading candidate for the development of low-cost and efficient photoelectrodes. However, severe recombination of photogenerated carriers on Sb₂S₃ photocathode surfaces poses a significant challenge, which not only affects the photoelectrochemical (PEC) performance but also leads to unsatisfactory long-term stability of the photoelectrodes. Therefore, enhancing the transportation and separation of photogenerated carriers on an Sb₂S₃ surface is crucial for improving its PEC water-splitting performance. To this end, constructing heterojunctions through energy band engineering represents a highly significant strategy. In this work, we used a microwave solvothermal method to construct an Sb₂S₃/SnS₂ type Ⅱ heterojunction by regulating the reaction parameters. On this basis, FeOOH particles were further modified by a solution immersion method to form an Sb₂S₃/SnS₂/FeOOH composite photocathode. Compared to the Sb₂S₃ monomer, the Sb₂S₃/SnS₂ photoelectrode exhibited a 6.14-fold enhancement in photocurrent density, reaching up to 3.07 mA cm⁻² (0 V_RHE). Compared to the Sb₂S₃ monomer (5.44%), the incident photon-to-current conversion efficiency value of Sb₂S₃/SnS₂ was 14.12% (735 nm). Also, the charge injection efficiency of Sb₂S₃/SnS₂ increased from 6.34% to 45.55%. In a one-hour stability test, the photocurrent density of the Sb₂S₃/SnS₂/FeOOH composite photocathode showed no significant attenuation and could produce 2.59 μmol cm⁻² hydrogen per hour. This work opens a pathway for developing stable and efficient Sb₂S₃ photoelectrodes.