Plasma-engineered graphene quantum dot-based nanocomposites as smart CO2-philic membranes with extremely high separation performance

Abstract

Carbon dioxide (CO2) capture, separation and utilization with membrane-based technologies are important for the development of carbon neutral society. However, conventional membranes are facing the difficulties of energy-consuming fabrication, expensive and toxic chemicals, and low efficient performance. Here, we report the CO2-Philic, optical-active nitrogen-doped graphene quantum dot (NGQD)-embedded polyether-block-amide (Pebax)-based membranes for highly efficient CO2 separation and sensitive on-line CO2 detection. The NGQDs with abundant surface functionalities are synthesized from bioresource chitosan using a customized microplasma process. The plasma-engineered NGQDs with defined zero-dimensional (0D) geometry, surface functional groups and nitrogen dopants can enhance the CO2-philicity for CO2 capture and separation. Moreover, the NGQDs can not only generate the angstrom (Å)-level channels, but also tune the morphologies, pore structures, crystallinities of the nanophases, and functional groups of the Pebax-based membranes, leading to extremely high CO2 separation performance with a 415 Barrer CO2 permeability and a 125 CO2/N2 selectivity. Furthermore, the stable solid-state PL emission of the fabricated GQD@Pebax membranes enables the sensitive on-line monitoring of CO2 concentrations during the CO2 separation. Our work provides an understanding of the CO2 capture and transport with nanomaterials-based composites and a plasma engineering of advanced functional materials for clean energy, environmental and biomedical applications.