Activation of CO₂ by ionic liquid EMIM-BF₄ in the electrochemical system: a theoretical study

The electrochemical reduction of CO₂ to CO by an ionic liquid EMIM-BF₄ is one of the most promising CO₂ reduction processes proposed so far with its high Faradaic efficiency and low overpotential. However, the details of the reaction mechanism are still unknown due to the absence of fundamental understandings. In this study, the most probable and stable geometries of EMIM-BF₄ and CO₂ were calculated by quantum chemistry in combination with exhaustive search. A possible reaction pathway from CO₂ to CO catalyzed by EMIM-BF₄, including the most plausible intermediates and the corresponding transition states, was proposed. The role of EMIM-BF₄ is explained as forming a complex of [EMIM-COOH]^- with CO₂ followed by decomposing to CO.