Efficient hydrogen production in an innovative S-doped CoMoO4-based electrolytic cell: 12.97% less energy consumption

Abstract

It is desirable to produce hydrogen on a large scale at a low energy consumption through water electrolysis. Herein, CoMoO4 and S-doped CoMoO4 (S-CoMoO4) nanosheets are synthesized. Compared with CoMoO4, S-CoMoO4 shows an efficient electrocatalytic activity of water splitting, because the doping of S increases molecule/ion adsorption, oxygen vacancies (VO), electron transfer ability and electrochemically active surface. Furthermore, density functional theory (DFT) calculation confirms that the enhanced activity mainly results from the moderate rise in d-state energy level (Ed) caused by the doping of S, which obviously improves the adsorptions of H2O and OH−. Moreover, glycerol oxidation reaction (GOR) is employed to substitute for sluggish oxygen evolution reaction (OER), with the aim to improve hydrogen evolution reaction (HER). Compared to conventional electrolytic cell (2.135 V), the cell voltage (1.858 V) of GOR-based one at 50 mA cm−2 has decreased by 12.97%, indicating that to produce the same amount of hydrogen, about 12.97% of electric energy can be economized. Besides, this innovative system (97.3%) also has a higher Faradaic efficiency than the conventional electrolyzer, confirming a higher energy conversion. The innovative system can be used for hydrogen production at less energy consumption.