The role of facet engineered surface and interface in CdS nanostructures toward solar driven hydrogen evolution

Crystal facet of materials is an important parameter that affects the catalytic properties of photocatalysts. In this study, taking CdS as a prototype, we demonstrate the different role of facet as surface active site and interfacial charge migration channel. CdS nanorods exposed with {1 0 0} facet and CdS nanosheets exposed with {0 0 1} facet can be synthesized via simple wet chemical methods. In photocatalytic reaction, experimental results demonstrate that pristine CdS nanorods show higher hydrogen evolution rate (16.99 μmol/h) than that of pristine CdS nanosheets (4.97 μmol/h). As a contrast, when integrating with Pt cocatalyst forming Pt-CdS hybrids, the loading of Pt can improve the hydrogen evolution rate of CdS nanorods by 9.99-folds, significantly lower than CdS nanosheets (26.41-folds). In the case of using pristine CdS as catalysts, {1 0 0} facet is more beneficial for proton adsorption compared to {0 0 1} facet, leading to higher performance of CdS nanorods exposed with {1 0 0} facet as surface reaction sites. As for Pt/CdS catalysts, photogenerated electrons can more effectively transfer across the CdS {0 0 1}-Pt interface than that of CdS {1 0 0}-Pt interface, resulting in higher enhancement factors of CdS nanosheets after loading of Pt cocatalysts. These results may provide ideas for designing photocatalysts based on facet engineering.