Among all novel 2D materials used for membrane separation, graphitic carbon nitride (g-C3N4) has gained more attention in recent years because of its catalytic activity. Density functional theory has revealed that there are three or two types of nitrogen and carbon atoms based on their partial charges in the g-C3N4 structure, which are assumed to interact with water differently. This work used classical molecular dynamics (MD) to elucidate how these different edge atoms interact with water molecules and ions. Results indicated that nitrogen-terminated membranes were superior in all cases, but increasing slit size resulted in independency of water flux from the terminal atoms type. The significant permeability of nitrogen-terminated membranes was ascribed to hydrogen bonding between water and nitrogen atoms, which was proved through various analyses. It also revealed that the more partial charges on some nitrogen atoms attract more water molecules and facile water transport by reducing the energy barrier. These partial charges also affect ions passing based on their charges. Besides this, adding just one layer of g-C3N4 in multilayered membranes could improve salt rejection significantly but lead to a significant decrease in permeability. Briefly, this work proved that g-C3N4 nano-slits have great potential to be utilized as membrane material. In addition, it revealed the water and ions transport mechanism through the nano-slits, which could give more details to proper g-C3N4 membrane design.

在用于膜分离的所有新型二维材料中，石墨氮化碳（g-C3N4）因其催化活性而近年来受到越来越多的关注。密度泛函理论表明，根据 g-C3N4 结构中的部分电荷，存在三种或两种类型的氮和碳原子，并假定它们与水的相互作用不同。这项工作使用经典分子动力学（MD）来阐明这些不同边缘原子如何与水分子和离子相互作用。结果表明，氮封端膜在所有情况下都更优越，但增加狭缝尺寸导致水通量与末端原子类型无关。氮封端膜的显着渗透性归因于水和氮原子之间的氢键，这一点通过各种分析得到证明。它还表明，一些氮原子上更多的部分电荷会吸引更多的水分子，并通过降低能垒来促进水的传输。这些部分电荷也会根据其电荷影响离子的通过。除此之外，在多层膜中仅添加一层 g-C3N4 可以显着提高脱盐率，但会导致渗透性显着下降。简而言之，这项工作证明了 g-C3N4 纳米狭缝作为膜材料具有巨大的潜力。此外，它揭示了水和离子通过纳米缝隙的传输机制，这可以为正确的 g-C3N4 膜设计提供更多细节。