Composition-Tunable Antiperovskite Cux In1-x NNi3 as Superior Electrocatalysts for the Hydrogen Evolution Reaction.

A group of newly reported antiperovskite nitrides Cux In1-x NNi3 (0≤x≤1) with tunable composition are employed as electrocatalysts for the hydrogen evolution reaction (HER). Cu0.4 In0.6 NNi3 shows the highest intrinsic performance among all developed catalysts with an overpotential of merely 42 mV at 10 mA cmgeo -2 . Stability tests at a high current density of 100 mA cmgeo -2 show its super-stable performance with only 7 mV increase in overpotential after more than 60 hours of measurement, surpassing commercial Pt/C (increase of 170 mV). By partial substitution, the derived antiperovskite nitride achieves a smaller kinetic barrier of water dissociation compared to the unsubstituted InNNi3 and CuNNi3 , revealed by first-principle calculations. It is found that the partially substituted Cux In1-x NNi3 possesses a thermal neutral and desirable Gibbs free energy of hydrogen for HER, ascribed to the tailoring of the energy of d-band center arose by the A-site (A=Cu or In) substitution and a resulting optimization of adsorbate interactions.