Mechanochemical Synthesis of Highly Disordered Transition Metal Dichalcogenide Nano Catalysts for Hydrogen Evolution Reaction

Abstract

Although transition metal dichalcogenide (TMD) catalysts have been widely studied, their large-scale production remains a challenge. In this study, a readily scalable and ubiquitous mechanochemical synthesis method, for the production of TMD nano catalysts, is developed. For the first time, the direct mechanochemical synthesis of MoS₂ and MoSe₂ nano catalysts from easily accessible elemental precursors (Mo, S and Se) is demonstrated. About 2 g of MoS₂ and MoSe₂ nano powder could be produced in a single batch with a yield of 94.3% and 90.9%, respectively. The synthesized catalysts are in the form of nanosheets whose thickness range from 5 to 10 layers and have a highly disordered structure that is coveted for catalysis applications. The MoS₂ and MoSe₂ nanosheets exhibit an excellent catalytic activity in hydrogen evolution reaction with an overpotential of 275 and 211 mV to deliver 100 mA cm⁻² current density and a Tafel slope of 75 and 48 mV dec⁻¹, respectively. Nearly amorphous structure of the nanosheets incorporating point defects and sulfur/selenium vacancies is the main contributing factor to the high catalytic activity. The proposed method can be implemented to the synthesis of other nano TMDs, fueling future research activity.