MoS2 laminate membranes with structural-phase-dependent permeation for molecular separation
Mengwei Sun, Zhiwei Li, Qiuyan Wang, Ning Zhang, Rui Xie, Xiao‐Jie Ju, Wei Wang, Zhuang Liu, Liang‐Yin Chu
Abstract
Membranes enable the molecular separation by steric exclusion and Donnan repulsion. However, the membrane separation of cesium ion (Cs+) from the alkali-metal ions remains a challenge due to their similar physicochemical properties. Here, we explore the implementation of a MoS2 laminate membrane with structural-phase-dependent permeation for Cs+ separation. The Cs+ permeation rate grows 14.5 times as the 1T′-phase MoS2 in the membrane increases from 19.6% to 84.3%, which is ca. an order of magnitude faster than that of the Li+ ions. The ionic dehydration energy and affinity of sulfur-polarization-induced electronegative sites on 1T′-MoS2 to the Cs+ are essential factors resulting in the “knock-on” hopping that describes the preferential delivery of Cs+ in the 1T′-MoS2 channels. Further insight shows that the MoS2 phase structure plays a crucial role in the permeability of Cs+ and as such would bring inspiring thoughts and opportunities in design and fabrication of cutting-edge membranes for alkali-metal ionic separation.