(726c) 2D Layered Double Hydroxide Membranes with Inherent CO2-Selective Transport Channels for Efficient Carbon Capture

2D membranes have shown great potential for precise molecular separation owing to the atomic-scale thickness and well-defined interlayer nanochannels. Rational design of channel’s size and surface chemistry is critical for the selective transfer of target molecules. The currently reported 2D material membranes for efficient CO₂ separation are primarily built by introducing cross-linking agents or intercalating agents. In this study, we demonstrate a novel 2D material membrane with inherent CO₂-selective transport channels based on layered double hydroxide (LDH) without any additional crosslinking or intercalating steps. The intrinsic breathing effect toward CO₂ of LDH enables CO₂ molecules transfer through the interlayer nanochannels by CO₃^2- ions form. Moreover, the membrane nanochannel size is tuned by the CO₃^2- ions from the initial 0.7nm to 0.3nm, which exhibit a distinct sieving property for CH₄ molecules (0.38nm) while not for CO₃^2- (ionic radius of 0.136 nm). The unique breathing effect and size-sieving effect jointly contribute to the inherent CO₂-favorable nanochannels within LDH membranes. The resulted ultrathin 2D LDH membrane with thickness of 30nm exhibit excellent CO₂/CH₄ separation performance with CO₂ permeance of 150 GPU and CO₂/CH₄ selectivity of 33. This study is anticipated to extend the materials and strategies for design of the CO₂ preferential transport channels in membranes.