Metallic copper incorporated ionic liquids toward maximizing CO2 separation properties

• Dissociation mechanism of copper flakes into surface activated nanoparticles.
• Facilitated CO2 transport by the carrier-mediated mechanism.
• CuNPs as both CO2 carriers and barriers regarding N2 transport.

We report the facilitated CO2 transport membrane by in situ preparation of copper nanoparticles by ionic liquid, such as HmimNO3. The dissociation mechanism of micro-sized copper flakes into surface activated copper nanoparticles in terms of the interface dipole at the organic/metal was suggested. Firstly, HmimNO3 adsorbed onto pristine micro-sized copper flakes consisted of clusters, and then the concentration of electrons in the NO3- lead to the positive charging of the vacuum side. The built-in potential at the interface of HmimNO3/Cu clusters was able to bring out the repulsive force among the positive charged Cu clusters, resulting in the formation of CuNPs. Furthermore, the fabricated Cu nanoparticles (CuNPs) could be utilized as not only CO2 carriers, but also barriers regarding N2 and CH4 transport. The ideal CO2/CH4 and CO2/N2 separation factor of HmimNO3 membranes with a polysulfone asymmetric support was 2.3 and 2.6, respectively. The HmimNO3/CuNPs nanocomposite showed selectivity for CO2/CH4 and CO2/N2 was found to be 6.2 and 7.4, respectively. This implied the surface positive polarized CuNPs addition could be one of the effective strategies toward maximizing CO2 separation.