CO2-RR-MODCAT · Towards the discovery of efficient CO2 electroreduction catalysts: well-defined RuOx and MoSx nano catalysts

Towards the discovery of efficient CO2 electroreduction catalysts: well-defined RuOx and MoSx nano catalysts

Electrochemical devices – such as fuel cells in electric vehicles and electrolysers – are progressively entering our daily lives. They also have the potential to revolutionize the production of bulk chemicals and fuels, by converting CO2 into valuable compounds through the direct use of renewable electricity. Indeed, one could imagine operating an electrochemical cell that converts CO2 to syngas (a mixture of CO and H2) or ethanol through the electro-oxidation of water and the simultaneous electro-reduction of CO2. This ideal cell would be directly powered by renewable electricity. As a matter of fact, the integration of renewable energy sources (e.g., wind and solar) into our current energy, transportation and chemical sectors represents a formidable societal, scientific and technological challenge. In order to enable this technology, major breakthroughs are necessary to discover efficient electrode materials, i.e., electrocatalysts, capable to accelerate target reactions. In the frame of the MSCA fellowship I investigated two promising classes of materials that can be utilized for this technology. In the first project I explored the application of RuO2-based electrodes to produce methanol from CO2. In the second project I investigated the application of gold electrodes for the formation of CO from CO2. The overall goal was to develop new, active and selective functional materials on the basis of fundamental insight obtained studying and investigating model systems (electrodes with well-defined surface features). A thorough analysis of RuO2 based electrodes showed that these electrodes bind CO2 too strongly. The further reduction of CO2 to methanol was found to be impossible, in contrast with what reported in past literature studies and what suggested by theoretical predictions. At any rate, these “negative” results offer important guidelines to improve our understanding of these complex surfaces. Important new findings were instead achieved through the study of gold surfaces. The nature of the catalytically active sites was clearly identified. It was confirmed that the reaction rate on steps-rich surfaces is ca. one order of magnitude faster than on atomically flat surfaces. Noteworthy, it was observed how the parallel competing reaction does not follow the same trend. This knowledge will be crucial to design application-relevant catalysts with optimal density of active sites and therefore with improved activity towards the target product.

Data: CORDIS, © European Union