Influence of the PTFE Membrane Thickness on the CO₂ Electroreduction Performance of Sputtered Cu‐PTFE Gas Diffusion Electrodes

Abstract

Gas diffusion electrodes (GDE) obtained by sputtering metal films on polytetrafluoroethylene (PTFE) membranes are among the most performant electrodes used to electrochemically reduce CO2. The present work reveals several essential aspects for fabricating performant PTFE‐based gas diffusion electrodes (GDEs) for CO2 electroreduction (CO2R). We show that adding an additive layer (a mixture of carbon and Nafion™ or Nafion™ only) is required for stabilizing the metal catalyst film (Cu), deposited via sputtering on the PTFE membrane, during the CO2R experiments. We found that the PTFE membrane thickness used in the GDE fabrication plays an essential role in electrode performance. The quantification of the products formed during the CO2R conducted in a flow‐cell electrolyzer revealed that on thinner membranes, CO2R is the dominant process while on thicker ones, the H2 formation is promoted. Thus, the PTFE membrane influences the CO2 transport to the catalyst layer and can be used to promote the CO2R while maintaining a minimum H2 production.

Recent Progress on Electrode Design for Efficient Electrochemical Valorisation of CO2, O2, and N2

“…As a stark contrast, the carbon‐fibre‐based electrode only lasts for less than one hour under identical reaction conditions [11a] . However, the PTFE substrate itself is not conductive, and the catalyst loaded on top has been found to detach easily (even at low current densities) [34] . For these reasons, the PTFE‐based electrode usually needs to be coated with an additive layer (e.g., graphite, carbon or metal) to enable the transport of electrons and stabilise the catalyst in the application [11a, 34] .…”

“…However, the PTFE substrate itself is not conductive, and the catalyst loaded on top has been found to detach easily (even at low current densities) [34] . For these reasons, the PTFE‐based electrode usually needs to be coated with an additive layer (e.g., graphite, carbon or metal) to enable the transport of electrons and stabilise the catalyst in the application [11a, 34] . This foreign layer, however, might increase the interfacial resistance and impact the reaction environment, potentially lowering the gas reduction performance.…”

Forschungstransfer: Elektrochemische CO2‐Reduktion

“…Dadurch ergeben sich über die Entwicklung von Katalysatoren und GDEs hinaus neue Forschungs-und Kooperationsmöglichkeiten. [20][21][22] Bei der Entscheidung, welche Reaktionen zu beobachten sind, ist es wichtig, dass Wissenschaftler:innen sich der Wechselwirkungen zwischen Anode und Kathode bewusst sind. Die Chemie an Anode, Membran und Elektrolyt beeinflusst die Kathode und umgekehrt.…”

Highly selective Ag foam gas diffusion electrodes for CO2 electroreduction by pulsed hydrogen bubble templation

“…27 Non-conductive GDLs based on polytetrafluoroethylene (PTFE) have become popular only recently and provide higher flooding resistance and achieve more stable conditions with improved CO 2 RR activity. 23,[28][29][30][31][32] On top of the GDLs, a coating of the active catalytic layer needs to be airbrushed, 33 doctor-bladed, 34,35 sputtered 32,36,37 or electrochemically deposited [38][39][40] to achieve a porous 3D composite structure. Luo et al 41 reported a manufacturing strategy to enhance the CO 2 RR activity by electrochemical deposition of a porous Zn catalyst on a Cu substrate and turning the metal structure into a GDE by fine-tuning with hydrophobic parts.…”