Development of novel technologies for the efficient and reversible capture of CO₂ is highly desired. In the last decade, CO₂ capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO₂ by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO₂ using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid–amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO₂ absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO₂ capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined.

Cobalt coordinated covalent organic frameworks have attracted increasing interest in the field of CO₂ photoreduction to CO, owing to their high electron affinity and predesigned structures. However, achieving high conversion efficiency is challenging since most Co related coordination environments facilitate fast recombination of photogenerated electron-hole pairs. Here, we design two kinds of Co-COF catalysts with oxygen coordinated Co atoms and find that after tuning of coordination environment, the reported Co framework catalyst with Co-O₄ sites exhibits a high CO production rate of 18000 µmol g⁻¹ h⁻¹ with selectivity as high as 95.7% under visible light irradiation. From in/ex-situ spectral characterizations and theoretical calculations, it is revealed that the predesigned Co-O₄ sites significantly facilitate the carrier migration in framework matrixes and inhibit the recombination of photogenerated electron-hole pairs in the photocatalytic process. This work opens a way for the design of high-performance catalysts for CO₂ photoreduction.

Experiments and calculations have provided strong evidence for the H-bonds and the roles in the properties and reactions of ILs. H-bonds influence ionic pairing, stacking and self-assembling, and further influence properties ILs. Using ILs as catalysts and solvents, many reactions can be activated by the presence of H-bonds, which reduce reaction barriers and stabilize transition states.

Amaranthus waste is reported to be a single precursor to synthesize highly porous nitrogen-doped carbon as a superior oxygen reduction electrocatalyst.