Morphology Control of WS2 Nanoflakes Using Chemical Vapor Deposition for Improving the Photocatalytic Activity of the WS2/TiO2 Heterostructure

Chemical vapor deposition (CVD) is one of the successfultechniquesfor the synthesis of two-dimensional transition metal dichalcogenides(TMDCs) with different morphologies, sizes, and crystal qualities,which are beneficial for different research fields and applications.However, a controllable growth of 2D tungsten disulfide (WS2) with different orientations and sizes is still a challenging issue.In this study, we demonstrate a controllable synthesis of WS2 flakes by optimizing the CVD growth conditions. The results revealedthat tuning the growth pressure successfully provides control overthe orientation of the grown flakes. This monitoring allows for achievingvertically standing WS2 nanoflakes, with maximum exposureto the edge active sites. Aiming for enhanced photocatalytic activity,the construction of vertical WS2 nanoflake/TiO2 nanorod heterostructure was obtained by optimizing the height betweenthe precursor and the substrate, which provides control over the sizeof the flakes. In addition, the achieved WS2/TiO2 heterostructures were evaluated as a photocatalyst for RhodamineB degradation and photoelectrochemical activity (PEC).