Thermo- and Photocatalytic Activation of CO₂ in Ionic Liquids Nanodomains

Ionic liquids (ILs) are considered to be potential material devices for CO₂ capturing and conversion to energy-adducts. They form a cage (confined-space) around the catalyst providing an ionic nano-container environment which serves as physical-chemical barrier that selectively controls the diffusion of reactants, intermediates, and products to the catalytic active sites via their hydrophobicity and contact ion pairs. Hence, the electronic properties of the catalysts in ILs can be tuned by the proper choice of the IL-cations and anions that strongly influence the residence time/diffusion of the reactants, intermediates, and products in the nano-environment. On the other hand, ILs provide driving force towards photocatalytic redox process to increase the CO₂ photoreduction. By combining ILs with the semiconductor, unique solid semiconductor-liquid commodities are generated that can lower the CO₂ activation energy barrier by modulating the electronic properties of the semiconductor surface. This mini-review provides a brief overview of the recent advances in IL assisted thermal conversion of CO₂ to hydrocarbons, formic acid, methanol, dimethyl carbonate, and cyclic carbonates as well as its photo-conversion to solar fuels.