Hydrogen-bonding-engineered 2D MXene nanochannels with reduced mass transfer resistance for high-permeability water purification

Two-dimensional (2D) nanochannels in lamellar membranes hold great promise for water purification owing to their distinctive mass transfer properties. However, the fabrication of precisely engineered 2D nanochannels featuring well-aligned structures and tailored surface properties for high-performance membrane separation remains a significant challenge. Herein, we report a carboxylation-induced hydrogen bonding engineering strategy to construct 2D Ti₃C₂T_x MXene nanochannels with minimized mass transfer resistance. Experimental and simulation results indicate that chemically grafted carboxyl groups strengthen hydrogen bonding interactions adjacent nanosheets and promote their self-assembling into well-aligned 2D nanochannels. Additionally, enhanced hydrogen bonding interactions between water molecules and nanochannel walls also suppress random water molecule motion for improved water permeation. These synergistic effects reduce both the external mass transfer resistance from water-wall collisions and internal resistance from water-water collisions. Consequently, the optimized membrane demonstrates permeance of 1860 L m⁻² h⁻¹ bar⁻¹, representing a 13-fold improvement over pristine MXene membranes, while achieving >96 % removal efficiency for organic dyes and oil contaminants. This work sheds new light on the rational design of advanced lamellar membranes.