Abstract：
The graphene oxide (GO) membrane displays promising potential in efficiently filtering ions from water. However, the precise mechanism behind its effectiveness remains elusive, particularly due to the lack of direct experimental evidence at the atomic scale. To shed light on this matter, state-of-the-art techniques are employed such as integrated differential phase contrast-scanning transmission electron microscopy and electron energy loss spectroscopy, combined with reverse osmosis (RO) filtration experiments using GO membranes. The atomic-scale observations after the RO experiments directly reveal the binding of various ions including Na+, K+, Ca2+, and Fe3+ to the defects, edges, and functional groups of GO. The remarkable ion-sieving capabilities of GO membranes are confirmed, which can be attributed to a synergistic interplay of size exclusion, electrostatic interactions, cation-π, and other non-covalent interactions. Moreover, GO membranes modified by external pressure and cation also demonstrated further enhanced filtration performance for filtration. This study significantly contributes by uncovering the atomic-scale mechanism responsible for ion sieving in GO membranes. These findings not only enhance the fundamental understanding but also hold substantial potential for the advancement of GO membranes in reverse osmosis (RO) filtration.
摘要：
氧化石墨烯（GO）膜在有效过滤水中的离子方面显示出很有希望的潜力。然而,其有效性背后的精确机制仍然难以捉摸，特别是由于缺乏原子尺度的直接实验证据。为了阐明这件事，采用了最先进的技术，如集成微分相衬扫描透射电子显微镜和电子能量损失谱，结合使用GO膜的反渗透（RO）过滤实验。RO实验后的原子级观察直接揭示了包括Na在内的各种离子的结合，K+,Ca2+,和Fe3+的缺陷，边缘,和GO的官能团。GO膜的显着离子筛分能力得到证实，这可以归因于尺寸排斥的协同作用，静电相互作用，阳离子π,和其他非共价相互作用。此外，通过外部压力和阳离子改性的GO膜还表现出进一步增强的过滤性能用于过滤。这项研究通过揭示负责GO膜中离子筛分的原子尺度机制做出了重大贡献。这些发现不仅增强了基本的理解，而且对于GO膜在反渗透（RO）过滤中的进步具有很大的潜力。
