Construction of a Two-Dimensional GO/Ti₃C₂T_X Composite Membrane and Investigation of Mg²⁺/Li⁺ Separation Performance

Graphene oxide (GO) two-dimensional (2D) membranes with unique layer structures and tunable layer spacing have special advantages and great potential in the field of water treatment. However, GO membranes face the issues of weak anti-swelling ability as well as poor permeability. We prepared GO/Ti₃C₂T_X 2D composite membranes with 2D/2D structures by intercalating Ti₃C₂T_X nanosheets with slightly smaller sizes into GO membranes. Ti₃C₂T_X intercalation can effectively expand the layer spacing of GO, thereby substantially enhancing the flux of the composite membrane (2.82 to 6.35 L·m^-2·h^-1). Moreover, the GO/Ti₃C₂T_X composite membrane exhibited a good Mg²⁺/Li⁺ separation capability. For the simulated brine, the separation factor of M2 was 3.81, and the salt solution flux was as high as 5.26 L·m^-2·h^-1. Meanwhile, the incorporation of Ti₃C₂T_X nanosheets significantly improved the stability of GO/Ti₃C₂T_X membranes in different pH environments. This study provides a unique insight into the preparation of highly permeable and ion-selective GO membranes.