Selection of Low‐Cost Ionic Liquid Electrocatalyst for CO₂ Reduction in Propylene Carbonate/Tetrabutylammonium Perchlorate

Abstract

Abstract Electrochemical reduction of carbon dioxide (CO 2 ) to carbon monoxide (CO) has attracted increasing attention, because this method provides a new route for CO 2 recycling utilization. As CO 2 is chemically inert, this reaction requires a high over‐potential. Therefore, it is highly desirable to develop an electrocatalyst to accelerate this reaction. In the present work, we have investigated numerous imidazolium ionic liquids (ILs) with the aim of looking for a low‐cost homogeneous catalyst with high efficiency. By comparison, 1‐butyl‐3‐methylimidazolium chloride ([Bmim][Cl]) has been selected as the most cost‐effective. To further reduce the cost of [Bmim][Cl], we added [Bmim][Cl] into propylene carbonate(PC)/tetrabutylammonium perchlorate (Bu 4 NClO 4 ), and used it as the electrocatalyst. Our experimental results show that [Bmim][Cl] has a high catalytic effect for CO 2 reduction. The catalytic mechanism of [Bmim][Cl] has been discussed based on electrochemical impedance spectroscopy. It is explained as follows: CO 2 was first reduced to the high‐energy CO 2 .− radical through a one‐electron transfer. The generated CO 2 .− radical further reacts with [Bmim] + , resulting in the formation of a complex [CO 2 −Bmim]. Thus, the activation energy of CO 2 reduction has been reduced.