In-situ interlaminar growth of an azine-linked covalent organic framework in the Ti3C2TX membrane for molecule sieving with stable and high-efficiency performance

Abstract

Two-dimensional (2D) MXene membranes have attracted significant attention for their high efficiency in molecule separation. In this study, an interlaminar in-situ growth strategy was employed to incorporate TpHz into the adjacent layer space between the Ti₃C₂T_x nanosheets of the 2D Ti₃C₂T_x membrane. In the typical synthesis process, due to the hydrophilic nature of Ti₃C₂T_x, the aqueous phase monomer diffuses through the Ti₃C₂T_x layers, reacts with the organic phase monomer in the top-surface and generate TpHz in-situ. Gradually, TpHz grows into the interlaminar space of the Ti₃C₂T_x nanosheets and the interior of the membrane. Owing to the charge transfer interaction existing between the TpHz and Ti₃C₂T_x nanosheets, the adjacent layer space between the Ti₃C₂T_x nanosheets is broadened without compromising the structural stability of the composite membranes. Accordingly, the TpHz/Ti₃C₂T_x composite membrane (TTCM) exhibit highly efficient molecule sieving properties and excellent structural stability, with a high pure water permeance of 986.5 L m⁻² h⁻¹·bar⁻¹ and a rejection rate of over 95.0 % for anionic organic dyes. Additionally, the TpHz/Ti₃C₂T_x layer, with the thickness of only 160 nm, in the TTCM could withstand 80 h of water and solution flushing at a flow rate of 40 L min⁻¹ in cross-flow filtration tests, maintaining stable solution permeance of 448 L m⁻² h⁻¹·bar⁻¹ and rejection rates of 95.3 % demonstrating its high structural stability and potential for expanding industrial application in molecule sieving processes.