Effect of electron redistribution on H adsorption and hydrogen production efficiency

Abstract

Water electrolysis is a promising, carbonless technology for hydrogen production, however, its widely industrial application is severely limited by the extensive energy consumption caused by sluggish oxygen evolution reaction (OER) kinetics. Herein, the simple Mn doping is employed to finely tune sulfur vacancies (V). The thoeretic calculations prove that the electron structure has been well controlled. Compared with perfect MoS (without V), the electron re-distribution of Mn-doped MoS with V (Vs-Mn-MoS) exhibits the both modes: electron depletion near the V and electron accumulation between two Mo atoms. Furthermore, the well-controlled electron structure obviously promotes H adsorption. The experimental results shows that the 5 wt% Mn–MoS exhibits an excellent hydrogen evolution reaction (HER) activity (79 mV/10 mA cm, 55.46 mV dec), which is better than the other MoS-based electrolysts in the previous reports. Moreover, an innovative substitution anode reaction is designed, namely, glycerol oxidation reaction (GOR)-based symmetric electrolyser with Mn–MoS as the both electrodes. At 60 mA cm, the cell voltage of GOR-based electrolyser has decreased by 14.8 %, and its Faradaic efficiency for HER increases by 10.04 % compared to conventional water-based one. This result proves that about 14.8 % of electric energy can be economized. Thus, this innovative electrocatalysis system could be promising for industrial hydrogen production.