Dodecylamine coordinated tri-arm CdS nanorod wrapped in intermittent ZnS shell for greatly improved photocatalytic H2 evolution

A new photocatalyst, the tri-arm CdS/ZnS core-shell nanorod, is carefully designed for the first time, where triarm CdS nanorods are decorated by dodecylamine (DDA) molecules and then wrapped in an intermittent ZnS shell. The resultant photocatalyst with a CdS/ZnS mole ratio of 0.5 (CZS0.5) presents a significantly improved H2 evolution rate of 726.0 mu mol/h (3 mg of catalysts, equal to 242.0 mmol/g/h) in the absence of co-catalysts, which is currently the highest value in CdS-based catalysts. The apparent quantum efficiency of CZS0.5 reaches 50.61% at 380 nm. The significantly enhanced photocatalytic performance can be attributed to a win-win situation between the analogous type-II mechanism formed in the CdS/ZnS heterojunction and the H+ adsorption resulting from the DDA molecules. Due to the analogous type-II mechanism, photogenerated electrons are transferred from the ZnS shell to the CdS nanorod. Owing to the decoration of DDA, many H+ ions are adsorbed on CdS. Thus, the photogenerated electrons gathered in CdS can be captured quickly and in a timely manner by the adsorbed proton H+ to produce hydrogen, which effectively suppresses the recombination of photogenerated electrons and holes. This study may bring new insights for developing other photocatalysts with high performance by using small organic molecules.