High-Entropy Transition Metal Dichalcogenides As Exceptional Electrocatalysts of Hydrogen Evolution Reaction (HER)

Abstract

Hydrogen is a unique energy carrier in that it can be produced via diverse pathways utilizing a variety of available feedstocks, including natural gas, biomass, and water. Electrolysis of water is among the most versatile methods of hydrogen generation that currently play a significant role in hydrogen gas production [1]. Among different water splitting technologies, low temperature electrolysis emerges as superior contender, demonstrating high current density (2 Am-2), low working temperature (82 oC) and operation under high pressures of H2 (~200 bar) [2]. However, one of its main weaknesses is the high cost and scarcity of platinum (Pt), which is an essential element of conventional electrolytic systems. Hence, the development of novel, efficient Pt-free electrocatalysts for hydrogen evolution reaction (HER) belongs to the major objectives of the water splitting materials research. This talk highlights a new family of high-entropy materials – multi-principal element transition metal dichalcogenides (HE-TMDCs) – that show exceptional electrocatalytic activity approaching the water-splitting activity of platinum in HER. Novel HE-TMDCs, developed with support from Ames Laboratory’s LDRD funding, are single-phase, layered materials, which are built from several different 3d – 5d metals (M = Mo, W, Nb, Ta etc.) and chalcogens (X=S, Se), e.g. (M,M’,M’)(X,X’) [3]. Their electrochemical performance will be presented, and compared with those of conventional binary TMDCs, and Pt. Electrode preparation techniques, the electrochemical measurements and possible reasons for the exceptional performance of the HE-TMDCs electrodes will be discussed.