Hydrothermal synthesis of pyramid-like In₂S₃ film for efficient photoelectrochemical hydrogen generation

Herein, the pyramid-like In₂S₃ film was synthesized for photoelectrochemical (PEC) hydrogen generation using a facile hydrothermal route for the first time. The hydrothermal time was crucial to determine the morphology and composition of the as-prepared films. When the hydrothermal time lasted for 24 h, the pyramid-like In₂S₃ film could be achieved. With the increased hydrothermal time, the photocurrent first increased and then decreased, and the pyramid-like In₂S₃ film prepared for 24 h showed the highest photocurrent. After an annealing treatment, the photocurrent could be improved to 2.7 mA cm⁻² at 0.78 V vs. RHE, and a substantial hydrogen generation was observed. Compared to previously reported In₂S₃ films with different morphologies, the pyramid-like In₂S₃ film exhibited better PEC property. It was revealed that the remaining In₂O₃ after the synthesis of In₂S₃ had a great influence on the PEC performance. The pyramid-like In₂S₃ film with a moderate amount of In₂O₃ induced an efficient charge separation and transfer, as well as good light-absorption ability, which led to the superior PEC performance. This work has demonstrated great potentials of the pyramid-like In₂S₃ film for PEC hydrogen generation and opened a promising avenue towards the design and fabrication of novel pyramid-like nanostructures.