Silver-doped molybdenum carbide catalyst with high activity for electrochemical water splitting

A hybrid catalyst composed of silver (Ag) doped wire-like molybdenum carbide (Mo_xC_y) with pure β-phase and carbon nanotubes (CNTs) was coated well on a carbon rod electrode for the hydrogen evolution reaction (HER). The effects of Ag loading amount and carbonization temperature on the crystal form of Mo_xC_y were investigated in detail. It is found that the Mo_xC_y crystal form can be tuned by adjusting the preparation conditions, and nanostructured wire-like Mo₂C with pure β-phase was obtained at a temperature over 750 °C. Ag/Mo_xC_y composite nanomaterials were investigated by X-ray diffraction, UV/vis spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy and Brunauer-Emmett-Teller surface area analysis. The hybrid catalyst was further deposited on the carbon nanotube (CNT) modified carbon rod substrate. Due to the high surface area and 3D porous network-like microstructure, the Ag/Mo₂C/CNTs hybrid electrode showed enhanced catalytic performance when comparing with the corresponding pure one. Particularly, for the Ag-doped Mo₂C/CNTs hybrid electrode with an optimum 1 Ag : 5 Mo molar ratio of the precursors, a current density of 10 mA cm^-2 was obtained by applying an overpotential of 142 mV in 0.5 mol L^-1 H₂SO₄ solution. It is expected that such a hybrid electrode can be widely applied for effective electrolysis of water to produce hydrogen.