Interlayer current collectors optimize the surface micro-cracks of gas diffusion electrode for stable CO2 electrolysis

Abstract

Gas diffusion electrode (GDE)-based flow cells are promising platforms for CO2 electrolysis, yet their practical application is hindered by critical challenges related to GDE stability at high current densities. While hydrophobic expanded polytetrafluoroethylene (PTFE)-based GDEs demonstrate inherent flooding resistance, their poor electrical conductivity necessitates the addition of conductive layers. However, the structure reconstruction of these conductive layers induces surface micro-crack formation and propagation, ultimately compromising electrode stability through serious flooding and hydrogen evolution reaction. In this work, a hydrophobic carbon layer is intercalated between the conductive layer and the catalyst layer as interlayer current collector to optimize the surface micro-cracks and enhance GDE stability for CO2 electrolysis. Scanning electron microscopy images showed fewer surface micro-cracks in the intercalated GDE, leading to lower Ohmic loss and more integrated conductive layer. Real-time electrode surface monitoring showed that the intercalated GDE effectively suppressed surface flooding. COMSOL simulations explained that surface micro-cracks cause uneven local current distribution of catalysts, contributing to device instability. As a result, the Cu deposited PTFE-based GDE with the intercalated carbon current collector operated stably for more than 40 h with a FE(C2+) of ∼72% at current density of 600 mA cm−2. This stability is 8 times longer than that of the GDE without intercalation. This work provides an effective approach for designing GDE structures to improve the stability of flow-cell devices in CO2 electrolysis applications.