Perspectives on water-facilitated CO2 capture materials

Abstract

Efficient separation of CO₂ from other gases has become an issue of world-wide concern. Intrigued by the fascinating carbonic anhydrase-catalysed CO₂ hydration and deprotonation in biological organisms, researchers have found that water can play a significant role in fast and selective CO₂ transport (e.g. facilitating transport, salting-out effect, swelling, synergic sorption, etc.) and have managed to fabricate super CO₂ capture materials by judiciously introducing water into solids. Considering that water usually exists in industrial CO₂ resources and often acts as a negative impurity due to competitive sorption and pore blockage, exploring CO₂ capture materials with the aid of water has become an important emerging strategy to provide general and excellent paradigms for practical CO₂ capture technologies. In this sense, we propose a new concept, “water-facilitated CO₂ capture (WFCC) materials”, which refers to solid materials (either adsorbents or membranes) with a remarkable improvement in CO₂ capture performance due to entrapped water. In this way, we endeavor to answer an important question: when and how water contributes to this drastic enhancement. Strategies to avoid the negative effects of water and to enable WFCC are also tentatively proposed.