Oriented construction between crystal facet homojunction and S vacancies on CdS for boosting photocatalytic H2 evolution

Though the different exposed crystal facets of cadmium sulfide (CdS) catalysts have been demonstrated to enhance their photocatalytic activity , the mechanism behind H 2 evolution on these diverse facets remains elusive. Here, we synthesized CdS photocatalysts with co-exposed (101) and (002) crystal facets, incorporating S vacancies via a hydrothermal method within the temperature range from 80 to 240 °C. The resulting CdS nanorods exhibited exposed (002) and (101) crystal facets, demonstrating abundant S vacancies, and showcased a notable photocatalytic hydrogen (H 2 ) evolution activity of 467.67 μmol g −1 ·h −1 —approximately 144 times higher than that of CdS nanoparticles . Both experimental results and density functional theory (DFT) calculations showed the significance of co-exposed (101) and (002) crystal facets as self-constructed crystal homojunctions on CdS, facilitating efficient spatial separation of photogenerated charges. Additionally, co-exposed (101) and (002) crystal facets with S vacancies, stemming from the mismatched lattice, were observed to enhance the adsorption of water (H 2 O) molecules. This, in turn, reduced the energy required for H 2 dissociative adsorption , providing thermodynamic advantages. The understanding of the synergistic effect between self-constructed (101) and (002) facet junctions and S vacancies on CdS for boosting photocatalytic H 2 evolution holds promise for expanding the applications of CdS-based materials in various photocatalytic processes.