CO2 conversion to synthetic fuels using non-CRM catalysts

To date CO₂ increasing emissions into the atmosphere represent a significant environmental threat that needs to be halted. Electrochemical reduction of CO₂ (CO₂RR) is deemed to be one of the most promising techniques to convert CO₂ and water into green fuels, thus reducing CO₂ emissions and storing renewable energy. Past studies have shown that the range of products that can be obtained from CO₂RR are highly dependent on the electrocatalyst employed. Among the most commonly used electrocatalysts for electrochemical CO₂ reduction in alkaline conditions there is copper, which electrochemically converts CO₂ into more than 30 products, including hydrocarbons and alcohols [1], however, Cu-based electrodes present poor selectivity towards the formation of specific products. Nevertheless, a higher efficiency of the catalyst toward CO₂RR can be obtained by proper engineering the catalytic surface in order to have a sufficient number of active sites. Experimental data demonstrated that a mixture of Cu-based structures with oxidizing states going from 0 to 2 can be obtained for the cathode through the oxalated method whilst a NiFeOx based catalyst was prepared for the anode according to the co-precipitation procedure. A membrane electrode assembly (MEA) was developed by cold pressing anode, cathode and a commercial anion exchange membrane as a polymeric solid electrolyte. Electrodes were prepared by spray coating deposition of a catalytic inks, prepared by sonicating a certain amount of the synthetized powder in ethanol, on a suitable support respectively a Sigracet GDL for the cathode and Bekaert Ni felt for the anode. Electrochemical experiments were carried out with a complete zero-gap cell operating under alkaline conditions at a 300 mA cm² current density. Data from gas-chromatographic (GC) analyses of liquid and gaseous effluents from the cathode outlet stream were found to be in line with results featured in the literature regarding the promotion of intermediates that may lead to secondary reactions with production of gases such as H₂, CO, C₂H₄ alongside to carbonaceous fuels like Et-OH and Pr-OH.