Precision Molecular Sieving Enabled by Tunable Slit-like Nanochannels in Anodic Aluminum Oxide-Supported MXene/GO Composite Membranes

Overcoming the permeance-selectivity trade-off in membrane-based separations requires materials with precisely defined nanochannels and robust molecular sieving capabilities. Two-dimensional nanomaterials offer such control; however, random stacking of nanosheets often produces disordered transport pathways that limit separation performance. Here, we report anodic aluminum oxide-supported Ti₃C₂Tx MXene/graphene oxide (GO) composite membranes with tunable interlayer spacing and enhanced sheet alignment for ultrahigh molecular sieving. Large-area GO flakes seal structural defects within the MXene scaffold while inducing well-aligned, slit-like nanochannels. At an optimized MXene/GO weight ratio of 1:1, the composite membranes achieve a H₂ permeance of 2681.6 GPU (2011.2 GPU under mixed-gas conditions) with a H₂/CO₂ selectivity of 536.3 (457.1 under mixed-gas conditions), substantially surpassing the performance of state-of-the-art membranes. Molecular simulations reveal that ordered interlayer galleries and tailored slit pores underpin this exceptional molecular sieving behavior. This scalable composite platform enables high-precision separations for applications such as gas purification, advanced water treatment, and organic solvent nanofiltration.