Enhancing hydrogen evolution reaction performance of transition metal doped two-dimensional electride Ca2N

Two-dimensional electride Ca2N has strong electron transfer ability and low work function, which is a potential candidate for hydrogen evolution reaction (HER) catalyst. In this work, based on density functional theory calculations, we adopt two strategies to improve the HER catalytic activity of Ca2N monolayer: introducing Ca or N vacancy and doping transition metal atoms (TM, refers to Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Ru, Hf, Ta and W). Interestingly, the Gibbs free energy ΔGH∗ of Ca2N monolayer after introducing N vacancy is reduced to -0.146 eV, showing good HER catalytic activity. It is highlighted that, the HER catalytic activity of Ca2N monolayer can be further enhanced with TM doping, the Gibbs free energy ΔGH∗ of single Mo and double Mn doped Ca2N are predicted to be 0.119 and 0.139 eV, respectively. The present results will provide good theoretical guidance for the HER catalysis applications of two-dimensional electride Ca2N monolayer.