[EMIM]OTf (1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, >98%) Ionic Liquid as Electrolyte Additive for CO2 Electroreduction (CO2RR), CCO2RREAILEMIMOTf

In electrochemical CO2 reduction (CO2RR), [EMIM]OTf (1-Ethyl-3-methylimidazolium trifluoromethanesulfonate) is a prominent ionic liquid used as an electrolyte additive to lower the overpotential and steer selectivity toward Carbon Monoxide (CO).The "EMIM" cation is the active component that interacts with the CO2 molecule, while the "OTf" (triflate) anion provides high chemical and thermal stability, making it a reliable choice for long-term electrolysis experiments.

The most significant impact of [EMIM]OTf is its ability to stabilize the initial, energy-intensive step of CO2 reduction. (1) Lowering the Overpotential: The [EMIM]+ cation forms a complex with the CO2 molecule at the electrode surface. This interaction stabilizes the CO2'- radical anion, which is the most difficult intermediate to form. (2) Hydrogen Bond Stabilization: The acidic proton at the C2 position of the imidazolium ring can form a hydrogen bond with the oxygen atoms of the CO2 intermediate, further lowering the activation energy barrier. (3) Shifting Selectivity: By making the formation of the CO2'- intermediate easier, [EMIM]OTf allows CO2 reduction to occur at much lower negative potentials—voltages where the competing Hydrogen Evolution Reaction (HER) is not yet dominant.

While the [EMIM] cation does the "heavy lifting" at the interface, the Triflate (OTf) anion offers specific benefits compared to other ionic liquids like [EMIM][BF4]: (1) Hydrolytic Stability: Unlike BF4-, which can slowly decompose into HF in the presence of water, [OTf]- is extremely stable in aqueous mixtures. (2) Low Viscosity: [EMIM]OTf has a relatively low viscosity for an ionic liquid, which helps maintain fast mass transport of CO2 to the electrode surface. (3) Conductivity: It provides excellent ionic conductivity, helping to reduce the overall cell voltage and heat generation in the electrolyte.

Part Number	CCO2RREAILEMIMOTf (C-CO2RR-EA-ILEMIMOTf)
CAS	145022-44-2
Chemical Formula/Structure	C7H11F3N2O3S
Appearance	Transparent Liquid
Molecular Weight	260.23
[EMIM]OTf on Cu Catalyst	Suppresses HER; promotes C1 products.
[EMIM]OTf on Ag Catalyst	Dramatically lowers CO onset potential.
[EMIM]OTf on Bi Catalyst	Promotes Formate (HCOO-) production.
Package Grade	25 g/bottle (other package sizes, such as 100 g, 500 g can be supplied upon request)

References

(1）Y. Wang, et al., Descriptors for Electrochemical CO2 Reduction in Imidazolium-Based Electrolytes, ACS Catal. 2024, 14, 21, 16166–16174. 

(2) Y. Wang, et al., Ionic Liquids Promoted Transformation of Carbon Dioxide, Chem. Rev. 2025, 125, 13, 6057–6129.