Multiple Phases of Molybdenum Carbide as Electrocatalysts for the Hydrogen Evolution Reaction

Abstract Molybdenum carbide has been proposed as a possible alternative to platinum for catalyzing the hydrogen evolution reaction (HER). Previous studies were limited to only one phase, β‐Mo 2 C with an Fe 2 N structure. Here, four phases of Mo‐C were synthesized and investigated for their electrocatalytic activity and stability for HER in acidic solution. All four phases were synthesized from a unique amine–metal oxide composite material including γ‐MoC with a WC type structure which was stabilized for the first time as a phase pure nanomaterial. X‐ray photoelectron spectroscopy (XPS) and valence band studies were also used for the first time on γ‐MoC. γ‐MoC exhibits the second highest HER activity among all four phases of molybdenum carbide, and is exceedingly stable in acidic solution.