Small changes, big differences: Modified KSCN flux route for one-pot synthesis of Cd vacancy-enriched MoS2/CdS and the enhanced photocatalytic H2 evolution performance

Low-temperature KSCN flux 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% MoS 2 /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 MoS 2 could be substantially reduced from μm to nm scale as more nuclei could be introduced in the flux, which leads to a few-layer MoS 2 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 H 2 evolution activity of 15.01 mmol h −1 g −1 — a significant 6.5-fold improvement over its counterpart (MC) prepared through traditional KSCN flux. The high activity can be mainly ascribed to the introduction of V Cd and the close interface between small CdS and few-layer MoS 2 , 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.