▎ 摘　　要

Ion sieving is significantly important in many fields such as life science, resource utilization, and environmental protection. However, unlike biological ion channels, realizing efficient ion sieving using two-dimensional (2D) membranes with artificial ion channels is severely restrained because of swelling. In this work, we demonstrated that graphene oxide membranes (GOMs) with the interlayer spacings controlled by K+ (K-GOMs) provide a remarkably enhanced ion sieving performance in mono-/multi-valent mixed ion systems, in which ion selectivity is more than 1 order of magnitude than that of untreated GOMs. The highest selectivity of Na+/Fe3+ for K-GOMs reached up to 159.1, which is superior to most of the state-of the art NF or 2D membranes, and the competitive permeation rate of Na+ ions still remained at 0.48 mol m(-2) h(-1). Additionally, the K-GOMs also showed an outstanding stability in the long-term test. Further, the K-GOMs also presented high selectivity for multi-valent/multi-valent mixed ion systems. Overall, this study gives a full picture of the excellent performance of K-GOMs based on the size effect for ion sieving and exhibits great value in real-world applications such as desalination, water treatment, battery, and even in life science.