Electroreduction of carbon dioxide (CO₂) is one of the most promising ways to valorise CO₂ as a source of carbon. The development of novel, efficient and scalable catalysts for CO₂ electroreduction within electrolysers is still a big challenge. CO₂ reduction reaction (CO₂RR) can lead to different products. Among them, CO is the most versatile and used in large scale industrial processes. While various metals have been shown to efficiently reduce CO₂ to CO, gold (Au) is still the benchmark for this process due to the high selectivity and efficiency. However, silver (Ag) is considered the best candidate as active metal for scaling up the CO₂ reduction reaction toward CO and the main alternative to Au. Previous studies have shown how to improve CO selectivity with different Ag morphologies, particle size, surface modifications etc. However, studies for an efficient, fast, scalable, and economically sustainable method to prepare Ag electrode are still scarce.

Here, we report the preparation of sustainable, efficient and stable gas diffusion electrodes utilizing Ag as catalyst for the CO₂ electroreduction to CO. These cathodic materials are prepared by sputter deposition and subjected to post-deposition modification using dry, reactive processes.  The catalyst is uniformly deposited as a thin layer on the porous structure of PTFE minimizing the amount of Ag required. Our approach allows for fine tuning of the morphology, chemical composition and loading of Ag and their impact on the CO₂RR. These electrodes have been evaluated for the CO₂ electroreduction and for electrocatalytic studies in a flow reactor with gas-fed CO₂. Optimized electrodes show high activity, with current densities > 20 mA*cm^-2 at -1,15 V vs. RHE, and faradaic efficiency for CO > 90 %.  The stability is tested over periods up to 24 hours showing a significant impact of the post-deposition modification. Indeed, higher porosity, roughness and electrochemical surface area have been achieved after the modification. Noteworthy, our approach allows for outstanding performances using a minimal amount of metal, significantly lower than commercial Ag-loaded GDEs, while using the processing advantages of sputtering as an industrial state-of-the-art, high-throughput, and roll-to-roll compatible technique. Moreover, this route enables the deposition of different metals and alloys of tailored composition for the electrocatalytic CO₂ reduction beyond CO.