(Invited) Power-to-Value: Metal Foam Catalysts for the Electrochemical Conversion of CO 2

The electrochemical conversion of CO 2 (denoted as CO 2 RR) has attained significant interest in the catalysis research worldwide over the recent years as it provides means of transforming an environmentally harmful molecule back into products of higher value (e.g. high energy density fuels, chemical feedstock and useful commodity chemicals such as carbon monoxide). This process becomes particularly sustainable when using the surplus of electric power produced from renewable hydro, wind or solar sources (power-to-value concept). Substantial progresses have already been made during the last decade in the tailored design of novel catalyst materials needed to increase the energy efficiency of the CO 2 /water co-electrolysis and to guide the product distribution reaction into the desired direction. These progresses remained, however, restricted to the fundamental research whereas no technologically and economically feasible process could be established on an industrial scale so far. One key challenge left is related to the particular stability of the catalyst materials, a crucial pre-requisite for any industrial application of catalytic processes. In this contribution, concepts for the design of monometallic and bimetallic CO 2 RR catalysts will be discussed that are based on the additive-assisted electroplating of high-surface area metal foams. Main target products of the CO 2 RR addressed herein are formate (Bi foams), syngas (Ag foams; see Figure below) as valuable chemical feedstock for a subsequent non-electrochemical conversion process (Fischer-Tropsch, Rheticus process/Siemens-Evonik), and high energy density fuels (e.g. ethanol, n-propanol; bimetallic AgCu foams and co-alloed PdCu foams). Advanced operando Raman spectroscopy will be demonstrated to be highly useful for the identification of active catalyst species under CO 2 electrolysis conditions. Figure 1