Electrochemical-repaired porous graphene membranes for precise ion-ion separation

• Published in: Nature communications Vol. 15; no. 1; pp. 4006 - 11
• Main Authors: Zhou, Zongyao, Zhao, Kangning, Chi, Heng-Yu, Shen, Yueqing, Song, Shuqing, Hsu, Kuang-Jung, Chevalier, Mojtaba, Shi, Wenxiong, Agrawal, Kumar Varoon
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13.05.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 147/143; 147/3; 639/301/357/918/1055; 639/638/898; 639/925/918/1053; Electrochemistry; Fabrication; Graphene; Humanities and Social Sciences; Ion flux; Lithium ions; Magnesium; Masks; Membranes; multidisciplinary; Polymers; Pore size; Pore size distribution; Pores; Science; Science (multidisciplinary); Selectivity; Separation; Size distribution
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-48419-6

The preparation of atom-thick porous lattice hosting Å-scale pores is attractive to achieve a large ion-ion selectivity in combination with a large ion flux. Graphene film is an ideal selective layer for this if high-precision pores can be incorporated, however, it is challenging to avoid larger non-selective pores at the tail-end of the pore size distribution which reduces ion-ion selectivity. Herein, we develop a strategy to overcome this challenge using an electrochemical repair strategy that successfully masks larger pores in large-area graphene. 10-nm-thick electropolymerized conjugated microporous polymer (CMP) layer is successfully deposited on graphene, thanks to a strong π-π interaction in these two materials. While the CMP layer itself is not selective, it effectively masks graphene pores, leading to a large Li + /Mg 2+ selectivity from zero-dimensional pores reaching 300 with a high Li + ion permeation rate surpassing the performance of reported materials for ion-ion separation. Overall, this scalable repair strategy enables the fabrication of monolayer graphene membranes with customizable pore sizes, limiting the contribution of nonselective pores, and offering graphene membranes a versatile platform for a broad spectrum of challenging separations. The preparation of atom-thick lattices with Å-scale pores is desirable for achieving ion selectivity and high ion flux. Here authors present a cm-scale membrane made of atom-thick graphene film hosting zero-dimensional pores spanning only a few Å, repaired using an in situ electrochemical strategy, yielding high Li + /Mg 2+ separation performance.