Facet-tunable coral-like Mo2C catalyst for electrocatalytic hydrogen evolution reaction

Developing efficient and stable transition metal-based electrocatalysts for the hydrogen evolution reaction (HER) in alkaline media remains a great challenge due to slow water dissociation kinetics. Here, a novel coral-like porous nitrogen-doped Mo2C electrocatalyst (3D Mo2C) derived from ZIF-8 doped with phosphomolybdic acid hydrate (POM) was proposed for the electrocatalytic hydrogen evolution reaction via facet regulation. Density functional theory (DFT) calculations clarified that the Mo2C (0 0 2) facet accelerated water dissociation, while the Mo2C (1 0 1) facet more easily adsorbed H* to generate H2. Thus, Mo2C facets (1 0 1) and (0 0 2) with a suitable ratio showed synergistic effects to exhibit excellent alkaline HER performance. The coral-like porous Mo2C exposed sufficient active sites and facilitated electron and mass transfer to accelerate alkaline HER. The 3D Mo2C (1:1) catalyst exhibited excellent HER activity with a low overpotential of 110 mV and a small Tafel slope of 73.9 mV dec−1 in 1 M KOH.