Highly Stable Nanocrystal Engineered Palladium Decorated Cuprous Oxide Photocathode for Hydrogen Generation

Abstract Photocorrosion stability and the discrepancy between optical absorption and carrier diffusion length of cuprous oxide (Cu₂O) thin films are the main limiting factors for hydrogen evolution and practical applications of Cu₂O photocathodes. In this paper, by nanocrystal engineering the Cu₂O optical absorbing thin film, the photocorrosion stability can be significantly improved. Furthermore, palladium (Pd) nanostructures are used to both act as a cocatalysis and address the discrepancy between optical absorption and carrier diffusion length of cuprous oxide and improve the photocatalytic activity of Cu₂O photocathodes. By tuning the crystal quality of thin Cu₂O film and Pd nanostructures through controlling the sputtering power of Cu₂O and in situ plasma of substrate, the impact of the degree of crystallinity of thin Cu₂O film and Pd nanostructures on photocorrosion stability and photocatalytic activity of prepared photocathodes are investigated in detail. Systematic characterization of prepared samples by using X‐ray diffraction, high‐resolution transmission electron microscopy, and scanning electron microscope analysis indicates that improving the crystallinity of deposited Cu₂O thin film and Pd nanostructures can significantly improve the photocorrosion stability and performance of Cu₂O based photocathodes.