Electrodeposition of amorphous molybdenum sulfide thin film for electrochemical hydrogen evolution reaction

Amorphous molybdenum sulfide (MoS x ) is a highly active noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER). The MoS x was prepared by electrochemical deposition at room temperature. Low-cost precursors of Mo and S were adopted to synthesize thiomolybdates solution as the electrolyte. It replaces the expensive (NH) 2 MoS 4 and avoid the poison gas (H 2 S) to generate or employ. The (MoO 2 S 2 ) 2− , (MoOS 3 ) 2− and (MoS 4 ) 2− ions were determined by UV–VIS spectroscopy. The electrodeposition of MoS x was confirmed with XRD, XPS and SEM. The electrocatalyst activity was measured by polarization curve. The electrolyte contained (MoO 2 S 2 ) 2− ion and (MoOS 3 ) 2− ion electrodeposit the MoS x thin film displays a relatively high activity for HER with low overpotential of 211 mV at a current density of 10 mA cm −2 , a relatively high current density of 21.03 mA cm −2 at η = 250 mV, a small Tafel slope of 55 mV dec −1 . The added sodium dodecyl sulfate (SDS) can efficient improve the stability of the MoS x film catalyst.