In situ photochemical synthesis noble-metal-free NiS on CdS-diethylenetriamine nanosheets for boosting photocatalytic H2 production activity

Cadmium sulfide (CdS), as a promising semiconductor photocatalyst, has been widely investigated in the hydrogen (H-2) evaluation field from splitting water, in order to settle environmental problems and energy shortages. But serious photocorrosion and low visible light absorption limited its H-2 production performance. In our work, we first synthesized inorganic-organic CdS-diethylenetriamine (CdS-DETA) nanosheets via microwave hydrothermal method. The small organic amine molecules will link normal CdS nanoparticles together to form nanosheets with large surface area, which can reduce overpotential of H-2 evolution reaction and promoted the separation of photo-induced carriers. Then, the nickel sulfide (NiS) was deposited on the surface of CdS-DETA by a fast and simple photochemical method, demonstrating that the H-2 production performance was further improved. Specifically, the best H-2 production rate of NiS/CdS-DETA composite is up to 230.6 mu mol.h(-1) under visible light, which is 8.42 and 1.72 times as high as that of pure CdS nanoparticles and CdS-DETA hybrid, and even stronger than that of Pt/CdS-DETA (173.8 mu mol.h(-1)). Moreover, the photocatalytic H-2 evolution rate is still stable after 16 h of cycle testing. Besides, the photocatalytic mechanism using NiS as a cocatalyst has also been proposed, where NiS can effectively accelerate the separation of photoinduced holes and electrons for CdS-DETA. This work embodied a feasible method to design photocatalysts to convert sun light into clean H-2 energy more efficiently and stably.