Anion-Dependent CO2 Uptake in Ionic-Liquid-Modified Multilayer Graphene

Ionic-liquid-assisted modification of graphene offers a promising strategy for tailoring adsorption environments for CO2 capture. Here, we experimentally investigate the influence of ionic liquid anions on CO2 uptake behavior in multilayer graphene processed under identical conditions. FTIR measurements reveal distinct CO2 absorption signatures for graphene treated with different ionic liquids, with PF6–-treated graphene exhibiting the strongest response, while pristine graphite and the ionic liquids themselves do not exhibit detectable CO2 absorption. Time-dependent FTIR measurements show a progressive evolution of the CO2 absorption signal toward saturation upon continuous exposure. Raman spectroscopy indicates that ionic-liquid treatment induces structural and electronic modifications of multilayer graphene that depend on the anion employed. The observed experimental trends are qualitatively consistent with previous theoretical predictions regarding anion-dependent modifications in graphene/ionic liquid systems and highlight the potential of ionic-liquid-assisted graphene modification for engineering graphene-based materials for CO2 capture applications.