Impact Electrochemistry of MoS₂: Electrocatalysis and Hydrogen Generation at Low Overpotentials

Abstract

MoS2 materials have been extensively studied as hydrogen evolution reaction (HER) catalysts. In this study nanoparticulate MoS2 is explored as a HER catalyst through impact voltammetry. The onset potential was found to be −0.10 V (vs RHE) at pH 2, which was confirmed to be due to HER by scale-up of the impact experiment to generate and collect a sufficient volume of the gas to enable its identification as hydrogen via gas chromatography. This is in contrast to electrodeposited MoS2, which was found to be stable in pH 2 sulfuric acid solution with an onset potential of −0.29 V (vs RHE), in good agreement with literature. XPS was used to categorize the materials and confirm the chemical composition of both nanoparticles and electrodeposits, with XRD used to analyze the crystal structure of the nanoparticles. The early onset of HER was postulated from kinetic analysis to be due to the presence of nanoplatelets of about 1–3 trilayers participating in the impact reactions, and AFM imaging confirmed the presence of these platelets.

Comparative Studies of Atomically Thin Proton Conductive Films to Reduce Crossover in Hydrogen Fuel Cells

“…MoS 2 is one of the most studied transition metal dichalogenides (TMD) due to its potential in both semiconductor devices and electrochemical devices . MoS 2 in the context of fuel cell applications has been used to facilitate the oxygen reduction reaction (ORR) and as a hydrogen evolution catalyst (HER) for electrolyzers. − However, it has not been explored for crossover mitigation, as it has been suggested that proton conduction through exfoliated MoS 2 flakes is not substantial .…”