Controlling Pt co-catalyst loading in a WO3 quantum dot and MoS2 nanosheet composite Z-scheme system for enhanced photocatalytic H2 evolution.

A solid-state Z-scheme system, synergistic integration the advantages of various narrow band semiconductors, is considered to be a potential strategy to develop efficient photocatalyst for operation under visible light illumination. However, the charge separation efficiency of these systems has always been reduced by disordered electron transfer between coupling semiconductors. In this work, we constructed a direct Z-scheme system MoS2-Pt-WO3 through the loading of WO3 quantum dots onto MoS2 nanosheets and the selective depositing of Pt co-catalyst onto MoS2. XRD, TEM, AFM and XPS, etc. were used to confirm the successful preparation of the targeted photocatalyst. This photocatalytic system showed high visible-light-driven H2 evolution activity (802.2 μmol·h-1·g-1) and good photostability. Control experiment and mechanism analysis suggested that the remarkable performance can be attributed to the heterojunction formed WO3 and MoS2 and the vectorial electron transfer (WO3→MoS2→Pt) achieved by selectively loading Pt co-catalyst.