CO2 Electroreduction in Organic Aprotic Solvents: A Mini Review

Abstract

An annual increase of CO2 concentrations in the atmosphere causes global environmental problems, addressed by systematic research to develop effective technologies for capturing and utilizing carbon dioxide. Electrochemical catalytic reduction is one of the effective directions of CO2 conversion into valuable chemicals and fuels. The electrochemical conversion of CO2 at catalytically active electrodes in aqueous solutions is the most studied. However, the problems of low selectivity for target products and hydrogen evolution are unresolved. Literature sources on CO2 reduction at catalytically active cathodes in nonaqueous mediums, particularly in organic aprotic solvents, are analyzed in this article. Two directions of cathodic reduction of CO2 are considered—nonaqueous organic aprotic solvents and organic aprotic solvents containing water. The current interpretation of the cathodic conversion mechanism of carbon (IV) oxide into CO and organic products and the main factors influencing the rate of CO2 reduction, Faradaic efficiency of conversion products, and the ratio of direct cathodic reduction of CO2 are given. The influence of the nature of organic aprotic solvent is analyzed, including the topography of the catalytically active cathode, values of cathode potential, and temperature. Emphasis is placed on the role of water impurities in reducing CO2 electroreduction overpotentials and the formation of new CO2 conversion products, including formate and H2.

Deciphering Electrolyte Selection for Electrochemical Reduction of Carbon Dioxide and Nitrogen to High‐Value‐Added Chemicals

“…[ 126 ] Additionally, a higher cathodic potential window can be observed during CO 2 RR and NRR process in organic solvents because of the suppression of HER owing to the absence of protons compared with H 2 O, which means that the electrocatalytic reactions can be performed under a large potential range. [ 50,127,128 ]…”

“…[126] Additionally, a higher cathodic potential window can be observed during CO 2 RR and NRR process in organic solvents because of the suppression of HER owing to the absence of protons compared with H 2 O, which means that the electrocatalytic reactions can be performed under a large potential range. [50,127,128] The research of non-aqueous electrolytes on CO 2 RR was initially started by Kaiser and Heitz in 1973. [129] They found that the main CO 2 reduction products are either CO and CO 3 2− (strong metal-CO 2 interaction) or oxalate (weak metal-CO 2 interaction), which is in accordance with their proposed mechanism (Figure 11).…”

Electrochemical CO2reduction with ionic liquids: review and evaluation

“…Much research work has already been conducted and even summarized in review articles. 46,[54][55][56][57] However, we feel that the recent studies now leading to a rapidly improving performance call for a fresh update. Also, such constant improvement in technological development attracts great attention and interest toward novel implementations.…”

Investigation of Molecular Mechanism of Cobalt Porphyrin Catalyzed CO2 Electrochemical Reduction in Ionic Liquid by In-Situ SERS

“…Additionally, the limited solubility of CO 2 in aqueous solution results in low faradaic efficiency for the products. To overcome these challenges, organic solvents and room-temperature ionic liquids (RTILs) have been implemented as solvents for the reaction [ 8 , 9 , 10 ].…”