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 ΔG_H∗ 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 ΔG_H∗ 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.

二维电子化物Ca ₂ N具有较强的电子转移能力和较低的功函数，是析氢反应（HER）催化剂的潜在候选者。在这项工作中，基于密度泛函理论计算，我们采用两种策略来提高Ca ₂ N单分子层的HER催化活性：引入Ca或N空位和掺杂过渡金属原子（TM，指Ti，V，Cr，Mn， Fe、Zr、Nb、Mo、Ru、Hf、Ta 和 W）。有趣的是，引入N空位后Ca _{2 N单分子层的}吉布斯自由能ΔG H _∗降至-0.146 eV，表现出良好的HER催化活性。值得注意的是，Ca _{2的 HER 催化活性}TM 掺杂可以进一步增强 N 单层，单 Mo 和双 Mn 掺杂的 Ca ₂ N 的吉布斯自由能 Δ G _H∗预计分别为 0.119 和 0.139 eV。本研究结果将为二维电子化物Ca ₂ N单分子层的HER催化应用提供良好的理论指导。