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

Abstract

Cadmium sulfide (CdS), as a promising semiconductor photocatalyst, has been widely investigated in the hydrogen (H2) evaluation field from splitting water, in order to settle environmental problems and energy shortages. But serious photocorrosion and low visible light absorption limited its H2 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 H2 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 H2 production performance was further improved. Specifically, the best H2 production rate of NiS/CdS-DETA composite is up to 230.6 μmol·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 μmol·h−1). Moreover, the photocatalytic H2 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 H2 energy more efficiently and stably.