An electrochemical reactor for the CO2 reduction in gas phase by using conductive polymer based electrocatalysts

Interests in carbon dioxide have recently been grown for the new idea of CO2 as a future source of carbon to face the depletion of fossil fuels and reduce the greenhouse gas emissions. Closing the CO2 cycle will be possible whereas i) new catalytic composite materials (able to absorb and convert CO2 to fuels, also favouring the formation of C-C bonds) and ii) novel electrochemical devices (designed on purpose to maximize the catalytic activity) are both developed [1]. In this context, we report here on a new approach to reduce CO2 back to liquid fuels by using an electrochemical device working in gas phase. The materials used as electrocatalysts consist of conjugated microporous polymers [2], doped with Pt nanoparticles and mixed with carbon nanotubes to increase conductivity. The presence of the polymer may strongly enhance CO2 absorption due to the pore structure which is completely π-conjugated. The electrocatalytic materials were fully characterized by FTIR, also using CO probe molecules, SS-NMR, TGA and N2 physisorption at 77 K. Tests of CO2 reduction were performed by using a homemade electrochemical cell with three-electrode configuration. The two compartments are separated from a membrane electrode assembly (MEA) consisted of a proton conductive membrane in contact with a carbon cloth. 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 polymer surface where the active metal nanoparticles are deposited on. [1] C. Genovese, C. Ampelli, S. Perathoner, G. Centi, J. Catal., 308 (2013), 237-249. [2] Y. Xu, L. Chen, Z. Guo, A. Nagai, D. Jiang, J. Am. Chem. Soc., 133 (2011), 17622-17625.