An Electrochemical Reactor for the CO2 Reduction in Gas Phase by Using Conductive Polymer Based Electrocatalysts

Abstract

We discussed here on a novel approach to reduce CO₂ back to liquid fuels by using an electrochemical device working in gas phase. Operating under solvent-less conditions is very attractive and has many advantages with respect to a slurry reactor working in liquid phase: easier recovery of the products, no problems of CO₂ solubility, different reaction mechanism favouring C-C bond formation and producing longer chains of products. The materials used as electrocatalysts consist of conjugated microporous polymers (TPE-CMP) doped with Pt nanoparticles (acting as active phase) and mixed with carbon nanotubes (CNT) to guarantee a high electronic conductivity. The presence of the polymer may strongly enhance CO₂ absorption due to its pore structure which is completely p-conjugated. The electrocatalytic composite materials were fully characterized and tested in the electrocatatalytic process of CO₂ conversion in gas phase. The catalytic experiments were performed by using a homemade electrochemical cell with three-electrode configuration. The two compartments are separated by a membrane electrode assembly (MEA) consisting of a proton conductive membrane in contact with a gas diffusion layer. The active composite material was located between these two layers. Results showed good performances in terms of liquid product formation (methanol, ethanol, acetone, isopropanol, etc.) due to the high local concentration of CO₂ on the polymer surface where the active metal nanoparticles are deposited. The results are very promising and open new possibilities in the electrocatalytic conversion of CO₂ to liquid fuels by exploiting solar energy and closing the CO₂ cycle of its production/consumption.