Sustainable membrane-coated electrodes for CO2 electroreduction to methanol in alkaline media

Abstract

CO2 electroreduction has high potential to combine carbon capture utilization and energy storage from renewable sources. The key challenge is the construction of highly efficient electrodes giving optimal CO2 conversion to high-value products. In this regard, research on electrode structures remains as an important task to face. Despite the advancements in gas diffusion electrodes (GDEs) to facilitate CO2 transfer and electrode efficiency, the catalyst is still vulnerable to be swept by the gas and liquid electrolyte, reducing the stability. We report the fabrication of novel membrane-coated electrodes (MCEs), by coating an anion exchange membrane over a copper (Cu):chitosan (CS) catalyst layer onto the carbon paper. CS and poly(vinyl) alcohol (PVA) were chosen for membrane preparation and catalyst binder, where Cu was embedded in the polymer matrix as nanoparticles or ion-exchanged in a layered stannosilicate or zeolite Y, to improve their hydrophilic, conductive, mechanical, and environmentally-friendly properties considered relevant to the sustainability of the electrode fabrication and performance. The intimate connection between the CS:PVA polymer membrane over-layer and the CS/Cu catalytic layer protects the MCEs from material losses, enhancing the CO2 conversion to methanol, even in high alkaline medium. A maximum Faraday Efficiency to methanol of 68.05% was achieved for the 10CuY/CS:PVA membrane over-layer.