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 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.