Synergistic Effects of Co–Fe Boosts the Transformation of CO2 into C6+ Dicarboxylic Acids up to Gram-Scale under Mild Conditions

Electrochemical carboxylation of 1,3-dienes with carbon dioxide (CO2) is a feasible method to obtain dicarboxylic derivatives, which are important synthetic intermediates of polymers and pharmaceuticals. However, due to unavoidable byproducts and unfriendly conditions, the formation of pure dicarboxylic acids has been limited. In this work, we report that a bimetallic phosphating CoFeP catalyst on nickel foam (CoFeP/NF) served as a remarkable electrode, which transforms CO2 into multicarbon (C6+) dicarboxylic acids. The synergistic effects of CoFeP catalyst between Co and Fe allow activation of 1,3-dienes mainly, in which electron transfer easier to the 1,3-dienes proceeded to afford radical anion of the diene, pursuant carboxylation with CO2 and further electron transfer formed the ultimate carboxylated products. The reaction can occur in a commercial flow cell with gram-scale amplification. The dicarboxylic acid obtained was up to 1.08 g at a 5 mmol scale of 1,3-dienes, illustrating high electrocatalytic activity and practical application of CoFeP/NF.