Electrodepositing MOFs into laminated graphene oxide membrane for CO2 capture

Abstract

Due to increased CO2 emissions from the combustion of fossil fuels, considerable efforts have been made in CO2 capture. The preparation of a membrane with higher mechanical qualities and large CO2 adsorption capacity, however, remains the main obstacle. Here, using an in-situ anodic electrodeposition approach, we grow HKUST-1 MOFs into the graphene oxide (GO) two-dimensional (2D) nanochannels. A three-stage mechanism for the confined growth of MOFs during electrodeposition has been proposed. Through the inventive layer-by-layer confinement structural growth, MOFs@GO composite membranes with hierarchical pore structure were prepared. An extremely high CO2 adsorption capacity of 194.1 cm3/g and CO2/N2 adsorption ideal selectivity of 276.5 were achieved at 273 K and atmospheric pressure because of the synergistic effect of nanoconfined HKUST-1 and GO. The composite membrane prepared by electrodeposition method can expose more metal active sites in the presence of hierarchical porous structures, thus enhancing the CO2 adsorption capacity. In addition, incorporating the HKUST-1 into GO nanochannels demonstrates 50.6% and 138.13% improvement in hardness and elastic modulus over pristine GO membrane, respectively. This provides a promising method for developing high-performance CO2 capture membrane system under normal temperature and pressure conditions. It is also generally applicable for growing other MOFs@GO composite membranes, such as Cu-BDC@GO and Cu-BDC-NH2@GO membranes, respectively, and more suitable for large-scale industrial production.