The efficient conversion of carbon dioxide (CO₂) to the valuable chemicals is of great significance but the development of robust catalyst is still an interesting and challenging issue. Four novel ionic liquids are facilely synthesized with the ability to adsorb carbon dioxide (CO₂). [BZTMA⁺][⁻O₂EEPZ⁺][Br⁻] and [DBUH⁺][⁻O₂EEPZ⁺][Br⁻] could catalyze the cycloaddition of CO₂ into cyclic carbonates under atmospheric pressure at 50 °C with 99.3 % and 97.5 % yields in the absence of co-catalyst and solvent. Moreover, the [DBUH⁺][⁻O₂EEPZ⁺][Br⁻] could be reutilized by 11 times with a slightly decreased product yield. A new mechanism is proposed by the density functional theory (DFT). The excellent catalytic performance is mainly attributed to the ability of ionic liquids to adsorb CO₂. After the CO₂ is adsorbed, the formed intermediate would push the electrons towards the Br^- anion leading to the stronger nucleophilic activation. This work introduces a new pathway to explore the ionic liquids for the chemical fixation of CO₂.

将二氧化碳 (CO ₂ )有效转化为有价值的化学品具有重要意义，但开发稳健的催化剂仍然是一个有趣且具有挑战性的问题。四种具有吸附二氧化碳 (CO ₂ )能力的新型离子液体很容易合成。[BZTMA ⁺ ][ ⁻ O ₂ EEPZ ⁺ ][Br ⁻ ] 和[DBUH ⁺ ][ ⁻ O ₂ EEPZ ⁺ ][Br ⁻ ] 可以催化CO ₂的环加成反应在没有助催化剂和溶剂的情况下，在 50 °C 和大气压下分别以 99.3% 和 97.5% 的产率合成环状碳酸酯。此外，[DBUH ⁺ ][ ^- O ₂ EEPZ ⁺ ][Br ^- ] 可重复利用 11 次，但产率略有下降。密度泛函理论（DFT）提出了一种新机制。优异的催化性能主要归功于离子液体对CO _{2 的}吸附能力。CO ₂被吸附后，形成的中间体会将电子推向 Br ^-阴离子导致更强的亲核活化。这项工作为探索用于化学固定 CO ₂的离子液体开辟了一条新途径。