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Kai Junge Puring, Daniel Siegmund, Jana Timm, Florian Möllenbruck, Steffen Schemme, Roland Marschall, Ulf-Peter Apfel

• The electrochemical conversion of \(CO_{2}\) into commodity chemicals or fuels is an attractive reaction for sustainable \(CO_{2}\) utilization. In this context, the application of gas diffusion electrodes is promising due to efficient \(CO_{2}\) mass transport. Herein, a scalable and reproducible method is presented for polytetrafluoroethylene (PTFE)-bound copper gas diffusion electrodes (GDEs) via the dry-pressing method and compositional parameters are emphasized to alter such electrodes. The assembly of the catalytic layer plays a critical role in the electrode performance, as elevated bulk hydrophobicity coupled with good surface wettability is observed to offer highest performance in 0.5 m KHCO\(_3\). With optimized electrodes, formate, CO, and H\(_2\) are obtained at a current density of 25 mA cm\(^{−2}\) as main products in 1 m KOH in faradaic efficiencies (FEs) of 27%, 30%, and 36%. At 200 mA cm\(^{−2}\), an altered product composition with ethylene (33% FE) and ethanol (9% FE) along with H\(_2\) (33% FE) is observed. In addition, \(\it n\)-propanol is observed with 7% faradaic efficiency. The results indicate that the composition of the GDE has a severe influence on the electrode performance and setting proper hydrophobicity gradients within the electrode is key toward developing a successful electrochemical \(CO_{2}\) reduction.