Low Temperature Synthesis of WS2 Using PECVD for Hydrogen Evolution Catalysis

Hydrogen holds tremendous promise as one of many alternatives for clean energy generation with high energy density and zeroes environmental impact. Hydrogen can be easily produced by using Platinum-based catalyst to efficiently lowers the large potential of electrolysis, but confined due to scarce and expensiveness. Transition metal dichalcogenides (TMDCs) such as MX2 (M stands for Mo or W, Nb, Ta etc. and X= S, Se etc.) is essential materials which show promising catalytic activity. The bond between the metal and the chalcogen is a covalent bond, and the three layers themselves are held together by a weak van der Waals force. Tungsten Disulfide (WS2) is a representative transition metal dichalcogenide (TMDC), has been freshly pursued as one of the promising alternatives for hydrogen evolution reaction (HER). Tungsten Disulfide is one of the promising TMDC materials due to its various application in electronics, catalysis, optical and other fields. The WS2 elements were previously synthesized by different processes such as mechanical exfoliation, chemical exfoliation, chemical vapor deposition etc. In this work, we report a strategy for synthesis few layers of WS2 at relatively low temperature (300 °C) using plasma enhanced chemical vapor deposition (PECVD) technique. The PECVD technology utilized to grow WS2 thin film directly on the 4-inch Si-SiO2 wafer. The quality of a synthesized WS2 was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), High-resolution transmission electron microscopy (HR-TEM), and energy dispersive spectrometry (EDS) mapping. The thickness of the synthesized WS2 film was found to be around a few nanometers and showed multilayered structure (~5-6 layers). The PECVD shows the advantage for the large area synthesis of WS2 thin film with high uniformity, purity, and reproducibility for the mass production. The PECVD technology utilized to directly grown on glassy carbon electrode (GCE) for analysis of HER performance without any transfer process. The catalysis shows overpotential (η) of 0.50 V and Tafel slope 122.0 mV/decade. The HER performance of synthesized films was similar or higher when compared with drop casting technique. Figure 1