Pressure‐Responsive Two‐Dimensional Metal–Organic Framework Composite Membranes for CO₂ Separation

Abstract

Abstract The regulation of permeance and selectivity in membrane systems may allow effective relief of conventional energy‐intensive separations. Here, pressure‐responsive ultrathin membranes (≈100 nm) fabricated by compositing flexible two‐dimensional metal–organic framework nanosheets (MONs) with graphene oxide nanosheets for CO 2 separation are reported. By controlling the gas permeation direction to leverage the pressure‐responsive phase transition of the MONs, CO 2 ‐induced gate opening and closing behaviors are observed in the resultant membranes, which are accompanied with the sharp increase of CO 2 permeance (from 173.8 to 1144 gas permeation units) as well as CO 2 /N 2 and CO 2 /CH 4 selectivities (from 4.1 to 22.8 and from 4 to 19.6, respectively). The flexible behaviors and separation mechanism are further elucidated by molecular dynamics simulations. This work establishes the relevance of structural transformation‐based framework dynamics chemistry in smart membrane systems.