Anomalous enhancement of humid CO₂ capture by local surface bound water in polar carbon nanopores.

Abstract

Removal of confined space carbon dioxide (CO₂) that is in low concentration and with coexisting water is necessary but challenging by physical adsorption method. To make the removal process effective, rendering the nanopore surface hydrophobic to resist water is the popular way. Instead of preventing water from occupying the nanopores, in this work, we propose to utilize the guest water for the spatially selective formation of local surface bound water and further induce the preferential CO₂ capture. We observe an anomalous enhancement of CO₂ capture performance under humid conditions over carbon nanopores with spatially selective polar sites. It is evidenced that the surface bound water is formed at non-CO₂-selective areas of polar carbon nanopores, thus creating additional CO₂ trapping sites. This work may inspire the design of environment tolerable materials for molecular separation and purification under harsh conditions.