Sb₂Se₃/CdSe thin film photocathode for efficient hydrogen production

A highly efficient narrow-band-gap photoelectrode plays a vital role in achieving solar-to-hydrogen conversion. In this work, we report a novel Sb₂Se₃/CdSe/Pt photocathode, and the activity of this photocathode was studied. The photocathode was fabricated via electrodeposition followed by annealing and surface modification with a CdSe monolayer and Pt cocatalyst. The photocurrent density of the Sb₂Se₃/CdSe/Pt photocathode is ca. -6.9 mA cm^-2 at -0.2 V_RHE in near-neutral pH buffered solution, which is 2.3 times that of the Sb₂Se₃/Pt photoelectrode. The enhanced photoelectrochemical (PEC) performance is owing to the successful construction of the Sb₂Se₃/CdSe p-n heterojunction, which contributes to effective charge separation and transfer. Additionally, the effect of the Sb₂Se₃ layer thickness on the photocurrent was investigated, which suggests that an appropriate thickness of Sb₂Se₃ layer is necessary for sufficient light absorption and efficient hole transport. This work develops a novel Sb₂Se₃-based p-n heterojunction photocathode using a facile fabrication approach, which provides a practical pathway for developing cost-effective PEC devices with wide solar spectrum utilization.