Characterization of Vertically Aligned MoS2 Thin Film on Mo Electrode for Hydrogen Evolution Catalyst

Vertically aligned MoS 2 (V-MoS 2 ) thin film was investigated to achieve a cost-effective hydrogen evolution reaction (HER) catalyst. As a simple method, the V-MoS 2 film was deposited by partial sulphurisation of RF sputtered Mo film. The residual Mo layer was used as a bottom electrode instead of an expensive conductive substrate such as a glassy carbon. Different thicknesses of V-MoS 2 were deposited to investigate an HER catalyst characteristic for the V-MoS 2 /Mo structure. The crystallinity of V-MoS 2 was maintained even though the thickness of V-MoS 2 was controlled, and was confirmed by comparing the X-ray diffraction, Raman measurement, and estimated exchange current density. As the thickness of V-MoS 2 was decreased to 50 nm, the overpotential and Tafel slope were reduced to 0.38 V at 10 mA/cm 2 and 87 mV/dec, respectively. Based on the theoretical tendency of Tafel slope decline, the estimated optimal V-MoS 2 thickness was 40 nm for the V-MoS 2 /Mo structure. The fabrication process for V-MoS 2 and the estimated result from the variation of the thickness of V-MoS 2 could help to realise a cost-effective HER catalyst using MoS 2 .