Enhanced hydrogen evolution for MoS2/CNTs induced by ethylene-glycol via charge transfer and proton concentration in acid solution

MoS2, as a promising alternative to Pt-based electrocatalysts for hydrogen evolution reaction (HER) aroused more and more interests owing to its low-cost and Pt-like activity. However, its practical application is severely restricted due to the insufficient active sites and poor conductivity of MoS2. Herein, ethylene glycol (EG) modified MoS2 grown on carbon nanotubes (EG-MoS2@CNTs) were synthesized via a solvent thermal method. At a Mo loading of 4.64 wt%, EG-MoS2@CNTs exhibited dramatic electrochemical HER performance compared with MoS2 and MoS2@CNTs in acid solution. The overpotential value and Tafel slope of EG-MoS2@CNTs were 188 mV and 87 mV/dec, respectively. As X-ray photoelectron spectroscopy (XPS), Raman spectra and Zeta potential show that EG could not only increase the basal-edge-rich defects and the defects between Mo and S atoms, but also induce the charge transferred from MoS2@CNTs to EG which are more favorable of adsorbing H*. In addition, EG could enrich the proton concentration around MoS2. As a result, the HER kinetics are dramatically improved for EG-MoS2@CNTs compared with MoS2@CNTs under the same condition. This study suggested that the introduction of EG could significantly increased the HER kinetics of MoS2@CNTs and transform inert CNTs into highly active HER electrocatalysts with low Mo loading. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.