One-pot synthesis of transition-metal-sulfides decorated CdS by low-temperature KSCN flux: An effective route to strengthen the interface for enhanced photocatalytic H evolution.

The performance of decorated photocatalysts is highly dependent on the interfacial contact between the cocatalyst and the substrate photocatalyst, which is essentially determined by their fabrication routes. Herein, a simple one-pot preparation method based on low-temperature KSCN flux was developed for the synthesis of sulfide photocatalysts with MS/CdS (MS = CoS, NiS, CuS, SnS, MoS, and WS) as prototypes. The results indicate that a sulfidation of Cd and the cocatalyst precursors can be achieved successively in the reaction system, which facilitates the formation of a welded interface as the cocatalysts can grow epitaxially on the formed CdS surface. The KSCN flux serves not only as a reaction medium but also as S precursor. Most of the MS (except for WS) could be successfully fabricated and deposited in situ on CdS. However, only the transition-metal-sulfides (TMSs, MoS, CoS, and NiS) decorated samples showed enhanced photocatalytic H evolution reaction (HER) performance and the activities decreased in the order of MoS > CoS > NiS. The sample loaded with 1 %MoS demonstrated the highest activity, which was 25 times higher than that of the pristine CdS. The superior HER performance could be ascribed to the loading of the active MoS sites for HER and the intimate tandem type I (between CdS and 2H-MoS) and Schottky (between 2H- and 1T-MoS) junctions for separation of photoinduced charge carriers. Compared to the conventional preparation methods, the developed one-pot flux route demonstrates remarkable advantages in fabricating highly efficient MoS/CdS photocatalyst besides its convenience, versatility, and scalability. We believe that, in addition to CdS, the developed route can also be applied to synthesize other sulfide-based photocatalysts.