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

[Display omitted] •Tri-arm CdS/ZnS nanorods were synthesized by a facile deposition for the first time.•The optimized CZS0.5 presented H2 evolution rate of 805.5 μmol/h with the AQE of 50.61%.•Tri-arm CdS and ZnS formed an analogous type-II charge transfer mechanism.•The dodecylamine molecules adsorbed on CdS can efficiently enhance the proton adsorption.•The type-II heterostructure and proton adsorption jointly contributed to enhancing activity. A new photocatalyst, the tri-arm CdS/ZnS core–shell nanorod, is carefully designed for the first time, where tri-arm 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 μmol/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.