Electrodeposition of Amorphous Molybdenum Chalcogenides from Ionic Liquids and Their Activity for the Hydrogen Evolution Reaction

This work reports on the general electrodeposition mechanism of tetrachalcogenmetallates from 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide. Both tetrathio- and tetraselenomolybdate underwent anodic electrodeposition and cathodic corrosion reactions as determined by UV–vis spectroelectrochemistry. Electrodeposition was carried out by cycling the potential between the anodic and cathodic regimes. This resulted in a film of densely packed nanoparticles of amorphous MoS x or MoSe x as determined by SEM, Raman, and XPS. The films were shown to have high activity for the hydrogen evolution reaction. The onset potential (J = 1 mA/cm2) of the MoS x film was E = −0.208 V vs RHE, and that of MoSe x was E = −0.230 V vs RHE. The Tafel slope of MoS x was 42 mV/decade, and that of MoSe x was 59 mV/decade.