Pulse method for long-term stable and selective CO2 electrolysis to ethene on copper-based gas diffusion electrodes

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The electrochemical reduction of anthropogenic carbon dioxide (CO2) to valuable substances represents a promising technology for limiting the threatening global warming. In this so-called CO2RR, surplus electricity from renewable energy sources is used and thus it also positively contributes to stabilizing the electrical power grid. Copper, in particular, is used as an electrocatalyst for the reaction, as it plays a special role and is capable of forming C-C bonds. A reaction to ethylene would be particularly economical, since it has a reactive double bond and can be used in a variety of ways as an industrial base chemical. A disadvantage, however, is the low selectivity of copper, which leads to the formation of a large number of products that have to be separated. On the other hand, there is the low long-term stability of the catalyst and the process, which results in a significant decrease in the yield of hydrocarbons in favor of parasitic hydrogen evolution. The pulsed potential method, as already verified in own preliminary work, leads to a significant improvement in the stability and selectivity of the ethylene generation. As a working hypothesis, it is assumed that the pulsed method can reduce either the concentration gradients in the reactor, reduce the poisoning of the catalyst and/or periodically form new catalyst surfaces. However, which of these working hypotheses is correct can only be determined by coupling CO2RR with operando analytics. We aim to address this challenge in this bilateral project by combining the complementary expertise of both PIs in electrochemical engineering, new materials, as well as in innovative fabrication and operando characterization methods to evaluate the mechanism of the pulse method on gas diffusion electrodes (GDEs) in flow cells under operating conditions that are close to reality. The application-oriented findings will allow us to make knowledge-based suggestions regarding the optimal design of GDEs and operation modes of electrolytic CO2RR cells in future applications.