Lewis acid‒base interaction for CO2 adsorption

“Lewis acid‒base interaction means that the Lewis acid provides the lone electron pairs to the electron pair acceptor (Lewis base), and subsequently the Lewis acid and base bind in the form of covalent coordinate bond. For example, a nitrogen-abundant carbon surface derived from the alkaline activation of N-containing polymer exhibited a strong affinity to CO2 owing to the improved basicity and increased electron density, which anchored the electron-deficient CO2 molecules via Lewis acid‒base interaction (Sivadas et al., 2016). Similar with N doping, acid-pretreated biomass carbon adsorbent possessed abundant oxygenated groups on the surface, which obtained electrons from the nearby atoms to form a electron-donor, thus adsorbing more CO2 molecules via Lewis acid‒base interaction (Álvarez-Gutiérrez et al., 2016). In addition to the surface decoration of electronegative atoms generated by in-situ decomposition or pretreatment, the basicity and electron density can be adjusted by modifying the carbon with metal oxides (Nowrouzi et al., 2018). With a low ratio of metallic charge to the radius, O2‒ ions in the metal oxides were formed with a low coordination number, which interacted with CO2 to produce surface carbonates due to the strong basicity (Yong et al., 2001).”

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