Ni-Directed biphase N-doped Mo 2 C as an efficient hydrogen evolution catalyst in both acidic and alkaline conditions.

The development of efficient and low-cost catalysts is of great significance for the future application of the electrocatalytic hydrogen evolution reaction (HER). Herein, a series of Ni,N co-doped Mo 2 C nanostructures (Ni x -Mo 2 C/N) with different Ni content levels are fabricated. The phase-directing effect of Ni on Mo 2 C/N is observed, which is in charge of the phase transformation of Mo 2 C/N from an α - to a β -phase. At the optimized Ni-doping level, biphase Ni 15 -Mo 2 C/N exhibits outstanding HER activity under both acidic and alkaline conditions. In particular, under alkaline conditions, Ni 15 -Mo 2 C/N delivers an overpotential of only 105.0 mV, accompanied by a low Tafel slope of 44.96 mV dec -1 . The performance is comparable to commercial 20% Pt/C and higher than most state-of-the-art Mo 2 C-based catalysts as well.