Improved Hydrogen Evolution Reaction Performance using MoS2-WS2 Heterostructures by Physicochemical Process

Abstract

This report describes the synthesis of a layered molybdenum disulfide (MoS2)-tungsten disulfide (WS2) heterostructure onto fluorine doped tin oxide covered glass substrates using a combination of chemical bath deposition and RF sputtering techniques. FESEM images revealed that the MoS2-WS2 heterostructure surface consisted of a cauliflower structured array of grains with spherical structures. The vertically aligned atomic layers were explored by transmission electron microscopy images for MoS2-WS2 heterostructure. Hydrogen evolution reaction (HER) kinetics show over potentials of 151 and 175 mV @ 10 mA/cm(2) with Tafel slope values of 90 and 117 mV/decade for pristine MoS2 and WS2 electrocatalysts, respectively. Improved electrocatalytic activity for HER was established with overpotential 129 mV 10 mA/cm(2) and Tafel slope 72 mV/decade for the MoS2-WS2 heterostructure. The MoS2-WS2 heterostructure electrocatalyst showed robust continuous HER performance over 20 h in an acidic solution. This improved electrochemical performance emerges from the elevation of electron-hole separation at the layer interfaces and sharing of active edge sites through the interface. This study provides the basis to develop new applications for transition-metal dichalcogenides heterostructures in future energy conversion systems.