▎ 摘　　要

Aiming to achieve enhanced photocatalytic activity and stability toward the generation of H-2 from water, we have synthesized noble metal-free core-shell nanoparticles of graphene (G)-wrapped CdS and TiO2 (CdS@G@TiO2) by a facile hydrothermal method. The interlayer thickness of G between the CdS core and TiO2 shell is optimized by varying the amount of graphene quantum dots (GQD) during the synthesis procedure. The most optimized sample, i.e., CdS@50G@TiO2 generated 1510 mu mole g(-1) h(-1) of H-2 (apparent quantum efficiency (AQE) = 5.78%) from water under simulated solar light with air mass 1.5 global (AM 1.5G) condition which is similar to 2.7 times and similar to 2.2 time superior to pure TiO2 and pure CdS respectively, along with a stable generation of H-2 during 40 h of continuous operation. The increased photocatalytic activity and stability of the CdS@50G@TiO2 sample are attributed to the enhanced visible light absorption and efficient charge separation and transfer between the CdS and TiO2 due to incorporation of graphene between the CdS core and TiO2 shell, which was also confirmed by UV-vis, photoelectrochemical and valence band XPS measurements.