Motivated by the design of high-performance membranes for helium (He) separation, the He separation properties of the C₉N₄ membrane was systemically investigated via the combination of first-principles methods and molecular dynamics simulations. The gases (He, Ne, Ar, N₂, O₂, CO, CO₂, and CH₄) are all weakly physisorbed on the C₉N₄ membrane. The diffusion energy barrier for He is just 0.07 eV, but that of Ne, Ar, N₂, O₂, CO, CO₂, and CH₄ molecules is 0.14, 0.87, 0.55, 0.27, 0.44, 0.65, and 1.45 eV, respectively. The C₉N₄ monolayer exhibits ultra-high He selectivity relative to other gases in a wide temperature range. The He permeance of the C₉N₄ membrane is 1.5 × 10⁻³ mol·s⁻¹·m⁻²·Pa⁻¹ at room temperature, which is much higher than the acceptance value of industrial production standard. In addition, MD simulations reveal that the He separation process should be operated below 500 K so that can obtain the ultra-highly purified He gas via the C₉N₄ membrane. It thus shows that the C₉N₄ membrane has excellently high selectivity and permeance for He separation, and it is hopefully inspired experimentalists to realize the promising He separation membrane based on the C₉N₄ monolayer.

受用于氦 (He) 分离的高性能膜设计的启发，C 的 He 分离特性₉N₄ 和 CH₂、CO、CO₂ 、O₂ 膜上。 He 的扩散能垒仅为 0.07 eV，而 Ne、Ar、N₄N₉）都是弱物理吸附在 C₄ 和 CH₂ 、CO、CO₂、O₂膜进行了系统研究。气体（He、Ne、Ar、N₄₉N₄ 单层相对于较宽温度范围内的其他气体。 C₉N₄膜的He渗透率为1.5 × 10 ⁻³mol·s⁻¹·m<室温下 a i=37>−2·Pa⁻¹ 远高于可接受值工业生产标准。此外，MD模拟表明He分离过程应在500 K以下进行，这样才能通过C₉获得超高纯度的He气N₄膜。由此可见，C₉N₄膜具有极高的选择性以及 He 分离的渗透率，希望能够启发实验者实现基于 C₉N单层。