Cu/CdS/MnO_x Nanostructure-Based Photocatalyst for Photocatalytic Hydrogen Evolution

Using cocatalysts to improve photocatalytic performance has become a common strategy. Dual cocatalysts deposited on semiconductors can effectively restrain charge recombination and counterreaction whereas cocatalysts would not be deposited on a position as anticipated in most situations, so that their roles would not be fully exploited to the fullest. Herein a Cu/CdS/MnOx (CSM) heterostructured photocatalyst was designed that not only exhibits excellent photocatalytic performance and stability but also achieves spatial separation of the photocarrier by the cocatalysts. As a reduction cocatalyst, Cu NPs tend to capture electrons, while as an oxidation cocatalyst, MnOx NPs prefer to collect holes. A hexagonal CdS crystal, with characteristics of different electron-rich and hole-rich facets, can direct the Cu NPs and MnOx NPs to deposit selectively on the corresponding facets without mixing. The unique structural features of the photocatalyst greatly suppress the recombination of photoinduced electrons and holes, facilitating the separation and transport of charges. The prolonged lifetime of photogenerated carriers and accelerated surface-reactive kinetics can be confirmed by time-resolved fluorescence spectra (TRPL) and photoelectrochemical characterization. The optimized 1% CSM photocatalyst shows a maximum H2 evolution rate of 5965.03 μmol h–1 g–1, which is about 5.3-fold that of neat CdS. This work provides dual cocatalysts with great potential to modify the photocatalytic activity of semiconductors for better applications.