Enhanced Photocatalytic Activity in 2D-1D WS2/TiO2 and 2D-2D MoS2/WS2 Heterosystems

Two-dimensional (2D) tungsten disulphide (WS2) based heterostructures with modified interfaces have huge potential for photocatalytic applications. Integrating WS2 with one-dimensional (1D) titanium dioxide (TiO2) and 2D molybdenum disulphide (MoS2) structures to form heterostructures, enhances its photocatalytic activity. The enrichment in photocatalytic activity of heterostructures may get affected by the electronic interaction at the interface as well as morphology and dimensionality also affect the catalytic activity. In this context, the present work focuses on the enrichment of photocatalytic activity by different tungsten disulphide (WS2) based heterostructures, which may get influenced by the interfacial interaction. In the present work, two different heterostructures 2D-1D WS2/TiO2 and 2D-2D MoS2/WS2 are formed using the hydrothermal method. Scanning electron microscopy (SEM) confirmed the morphology of prepared heterostructures. X-ray photoelectron spectroscopy (XPS) analysis further revealed that the integration of 1D and 2D nanostructures with WS2 has been found effective to alter the interface by the development of the Ohmic and Schottky barrier. Moreover, Fourier transformation infra-red (FTIR) spectroscopy confirms the presence of W-S, S-S, Mo-S, and Ti-O bonds in the prepared heterostructures. Furthermore, current-voltage (I-V) data graphically illustrated the conductivity of catalysts. I-V curves confirm the presence of Schottky and ohmic barriers and the higher electrical conductivity of 2D-2D MoS2/WS2 heterostructures, which facilitates the charge carrier's transportation. 2D-1D WS2/TiO2 and 2D-2D MoS2/WS2 heterostructures are further explored for photocatalytic activity by the methylene blue dye degradation. The overall catalytic activity of 2D-2D MoS2/WS2 is better than 2D-1D WS2/TiO2 and WS2, respectively. This result was accounted as 2D-2D MoS2/WS2 had the highest conductivity and better charge separation at the interface in comparison to the other two synthesised catalysts.