Highly b-oriented MFI mixed matrix membranes composed of few-nm-thick nanosheets offer promising opportunities for energy-efficient and cost-effective gas separation. Avoiding thermal treatment for activating MFI nanosheets (i.e., to open the micropores of MFI) is highly desired to improve the dispersion yields and scalability. Here, we report an aqueous ultraviolet ozone treatment for the activation of MFI nanosheets along the b-axis, which enables the fabrication of micrometer-thick b-oriented MFI mixed matrix membranes on polymer substrates by solution casting. The CO2/N2 separation performance is significantly enhanced by the integration of nanosheets with enriched hydroxyl groups (a selectivity of 40±6 was observed at ambient conditions), with high CO2 permeance (194±50 GPU) due to the enhanced adsorption and reduced diffusion path. This liquid-based activation of MFI nanosheets prevents the commonly observed aggregation issues for air-calcinated nanosheets, resulting in very high nanosheet utilization yield that can enable scalable production of large area zeolite mixed matrix membranes.
