Recently, various efforts have been carried out against global warming across the world. CCS (Carbon dioxide Capture and Storage) technology, CCUS (Carbon dioxide Capture, Utilization and Storage) technology, and DAC (Direct Air Capture) technology are valuable techniques for CO2 reduction. In order to realize this technology, gas separation using high gas permeable membrane has been recognized as an attractive environmentally friendly process due to its high efficiency, low energy cost and simple operation. Our group has been studying composite membrane consisted of polymer and surface-modified nanoparticles and developed unique concept “nano-space”, polymer/nanoparticle interface with high permeability. We believe developing novel membrane materials with nano-space contribute to solving environmental issues and realize sustainable society.