Investigation on Electrochemical Capture of CO, by Quinone Derivatives Based on in situ FTIR Spectroelectrochemistry

The electrochemical capture process of CO2 by quinone derivatives, 2, 6-dichloro-1, 4-benzoquinone ( DCBQ) and 2,6-dimethoxy-1,4- benzoquinone( DMOBQ), in acetonitrile solutions were investigated by in situ FTIR spectroelectrochemistry. There are two well-defined couples of redox peaks of both derivatives in acetonitrile solvent in cyclic voltammetry curve ( CV), which indicates that the electrochemical reactions undergo two-step one -electron transfer. Due to the different electrophilicity of substituent, the quinone derivatives react with CO2 through different process after the addition of CO2. The CV of DCBQ still presents two couples of redox peaks with the second couple of redox peaks shifts positively; while only one couple of redox peaks appears in the CV of DMOBQ. The results of in situ FTIR experiments further indicated the different mechanisms of capture CO2 by DMOBQ and DCBQ. DCBQ undergoes the EEC mechanism, in which CO2 is captured by the two-step one -electron reduction products dianion DCBQ2-. However, DMOBQ undergoes ECE mechanism to capture CO2 by the one electron transfer product anion radical DMOBQ -. Furthermore, the quantitative analysis of the reduction products of capture CO2 was carried out. The stoichiometric is 1 1 to the two derivatives.