Abstract:

Low-temperature KSCN molten salt method has been used for one-pot fabrication of decorated sulfide-based photocatalysts. However, the reaction system is actually short of S precursor, as it is determined by the decomposition of relatively stable KSCN, which may not be conducive to the production of high-performance catalysts. To this end, a modified KSCN flux route with a dosage of external S source was developed and used for the one-pot preparation of sulfide photocatalyst with 1% MoS₂/CdS as the prototype. The results indicated that, compared with the sample (MC) prepared in conventional KSCN flux, a highly efficient sample enriched with seldom reported Cd vacancy (Ⅴ_Cd, MC-S) could be readily fabricated under the S^2--rich environment. Furthermore, both the size of CdS and MoS₂ could be substantially reduced from micrometer to nanometer scale as more nuclei could be introduced in the flux, which leads to a few-layer MoS₂ that can be uniformly and tightly anchored on CdS with the average size of only ~33 nm. Consequently, the resulting MC-S demonstrated an exceptional H₂ evolution activity of 15.01 mmol h^-1 g^-1, a significant 6.5-fold improvement over its counterpart (MC) prepared through traditional KSCN molten salt method. The high activity can be mainly ascribed to the introduction of Ⅴ_Cd and the close interface between small CdS and few-layer MoS₂, which both benefit electron-hole separation. The preparation mechanism of the samples was tentatively compared and discussed from the difference in the nucleation and the development of crystals. We believe that this improved preparation method will also benefit the synthesis of other high-performance sulfide-based photocatalysts.

Key words: Cd vacancy, MoS₂/CdS, KSCN molten salt method, Hydrogen evolution, Photocatalysis