Al₂O₃‐Functionalized Carbon Nanomembranes with Enhanced Water Permeance and Selectivity for Efficient Air Dehumidification

Abstract Precise control of pore size and surface properties is crucial for effective and efficient membrane separation, yet it remains challenging with conventional polymer‐based membranes. In this study, this gap is addressed by integrating atomic layer deposition (ALD) of Al 2 O 3 with nanometer‐thin carbon nanomembranes (CNMs) to achieve ultra‐selective separation properties. Structural characterizations confirm uniform Al 2 O 3 deposition and the preservation of the CNM structure. The ALD process allows for precise modulation of the nanopore structure. Despite the pore shrinkage upon ALD, the increased hydrophilicity offered by Al 2 O 3 enhances water permeance, achieving an exceptionally high water vapor permeation rate of 1.9 × 10 −5 mol · s −1 · m −2 · Pa −1 and a water vapor/nitrogen selectivity higher than 1 × 10 4 , surpassing that of conventional polymer and graphene oxide‐based membranes. These results demonstrate the potential of Al 2 O 3 ‐functionalized CNMs for advanced applications in gas separation and air dehumidification.