Vertical 1T/2H-WS2 nanoflakes grown on 2D-C3N4: Multiple charge transfer channels designed for enhanced photocatalytic activity.

Two-dimensional (2D) sulfides have attracted much attention as a promising photocatalyst for the hydrogen evolution reaction. In this work, a highly active and stable vertical 1T/2H-WS2 nanoflakes grown on 2D-C3N4 with multiple charge transfer channels through a simple and efficient colloidal strategy is reported. This three-dimensional (3D) composite presents the usual semiconducting 2H phase WS2 as well as the unusual distorted octahedral 1T phase WS2, which vertically connect 2D-C3N4 constructing an interesting 3D structure with more active sites. The H2 production rate of the optimal product has reached 350.75 μmol·g-1·h-1, which is 66.8 and 8.2 times higher than the rate of 2D-C3N4 and 1T/2H-WS2 respectively. The predominant charge transfer occurs between 2D-C3N4 and 2H-WS2 nanoflakes due to their vertical connection and the matched energy structure while the existence of the metallic 1T-WS2 acts as a cocatalyst with an enhanced conductivity to provide multiple charge transfer channels over its basal and edge sites for H+ reduction.