Boosted Charge Separation and Enhanced PEC Performance in Au–In ₂ S ₃ /TiO ₂ Nanorod Photoanodes

Photoelectrocatalytic (PEC) technology integrates the advantages of both photocatalysis and electrocatalysis. It utilizes semiconductors to absorb sunlight as an energy source and applies a potential to facilitate the timely and directional transfer of photogenerated electrons, effectively achieving the physical separation of the photoanode and cathode. This is widely considered a primary factor in improving catalytic efficiency. In this study, In 2 S 3 thin films and Au particles were prepared by hydrothermal and electrochemical deposition for robust attachment to TiO 2 nanorods based on a fluorine-doped tin oxide (FTO) substrate, which greatly improves carrier transfer during the PEC process. The results showed that the cutoff wavelength of Au–In 2 S 3 /TiO 2 was red-shifted to 535.6 nm. Under illumination without bias, the photoelectric current density of Au–In 2 S 3 /TiO 2 reached 2.582 mA/cm 2, 18-fold that of TiO 2 . Linear sweep voltammetry results indicated that under illumination at 0.8 V, the photoelectric current density of Au–In 2 S 3 /TiO 2 was 7.956 mA/cm 2, 24.7-fold that of TiO 2, and 3.1-fold that of Au–In 2 S 3 /TiO 2 under illumination without bias (0 V). The methanol-assisted test to amplify the hydrogen production signal revealed that, under illumination at 0.8 V bias (vs Ag/AgCl), the methanol-assisted hydrogen production rate of Au–In 2 S 3 /TiO 2 was 2.51 mL/cm 2, 3-fold higher than that under illumination alone (0.71 mL/cm 2 ). This study provides new insights for methanol-assisted PEC hydrogen evolution reactions and serves as a reference for the design of high-performance photocatalysts.