A poly(vinyl pyrrolidone) (PVP)/Ag nanoparticles (AgNPs)/7,7,8,8-Tetracyanoquinodimethane (TCNQ)/ dioctyl phthalate (DOP) composite membrane using positively charged silver nanoparticles was prepared for CO2 separation. Positively polarized silver nanoparticles were generated by TCNQ, known as an electron acceptor for CO2 carrier. In the separation of CO2 and N2, the composite membrane consisting of PVP/AgNPs/TCNQ/DOP showed that only polar CO2 could be selectively separated by a reversible reaction with the positively polarized silver nanoparticles. Furthermore, the addition of DOP as a plasticizer enhanced gas permeance through the glassy PVP, and the CO2/N2 selectivity performance reached 103.8. The PVP/AgNPs/TCNQ/DOP composite membranes were characterized by FTIR spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and scanning electron microscopy.