Magnetron-sputtered Cu gas diffusion electrodes for efficient CO₂ electroreduction

Electrochemical CO₂ reduction (CO₂RR) is considered a promising strategy for the sustainable conversion of carbon dioxide into valuable chemicals and fuels using renewable electrical energy. Among various catalyst materials investigated for CO₂RR, copper remains one of the most attractive due to its unique capability to produce multicarbon products, including ethylene, ethanol, and other hydrocarbons. The development of efficient and stable Cu-based catalysts operating under industrially relevant conditions is therefore of significant scientific and technological interest. In this work, Cu thin films deposited by magnetron sputtering onto gas diffusion electrodes (GDEs) were investigated as catalysts for electrochemical CO₂ reduction under high-current-density conditions. Copper catalyst layers with thicknesses of 100 nm, 150 nm, and 200 nm were prepared and tested in a CO₂-fed flow cell at current densities ranging from −140 mA/cm² to −200 mA/cm². Product distribution and Faradaic efficiencies were determined using GC-MS/TCD analysis. Structural and surface characterization of the sputtered Cu layers was performed using XRD, FTIR, SEM, and contact profilometry to establish correlations between catalyst morphology, surface structure, and electrochemical activity. The obtained results demonstrate that the properties of magnetron-sputtered Cu films strongly influence CO₂RR selectivity, catalytic efficiency, and operational stability. The presented approach highlights magnetron sputtering as a controllable and scalable method for fabrication of Cu-based gas diffusion electrodes for efficient electrochemical CO₂ conversion.