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

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 overpotentials of 151 and 175 mV @ 10 mA/cm² 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/cm² 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.