Enhancing the electrocatalytic water splitting efficiency for amorphous MoSx

•Catalysts is synthesized by a fast, low-temperature and scalable thermolysis.•NbCl5-added MoSx systems improve more HER performance than MoSx.•Only 1 wt% NbCl5 in the MoSx catalysts results in enhancement in HER.•The S22− is the active species for electrocatalytic HER in MoSx systems.

Amorphous molybdenum sulfide (MoSx) materials have been considered as cheap and promising catalysts for hydrogen evolution reaction (HER). In this contribution, we report that the amorphous MoSx catalysts prepared by the low temperature thermolysis of the (NH4)2MoS4 precursors on carbon clothes (catalyst loading: 3.2 mg/cm2) exhibit a Tefal slope of 50.5 mV/dec and a high exchange current density of 1.5 × 10−3 mA/cm2 in 0.5 M H2SO4 solutions. Spectroscopic studies of the amorphous MoSx catalysts show that the increase of HER efficiency is positively correlated to the concentration of S22− species, providing strong evidence to support the argument that S22− is an active species for electrocatalytic HER. Additionally, the method for preparing catalysts is simple, scalable and applicable for large-scale production.