For the used Ag200P36 catalyst, after only 15 min of CO2RR (Fig. ), the electrolyte has penetrated into the grain structure of the Ag, demonstrated by a peak of the K signal directly on the surface and a fast decrease away from the surface, with the inverse behavior for the Ag intensity. After 24 hours of CO2RR testing (Fig. ) we see that the penetration of K in the Ag is far more pronounced, while the Ag signal grows much slower with the distance from the surface. This is an effect of the modified grain structure of Ag (see AFM image of Fig. The results suggest a synergistic effect of the PTFE as a substrate and the plasma treatment on the selectivity and stability of the Ag-based electrode for the CO2RR. The enhanced stability compared to the carbon-based substrate is attributed to the high hydrophobicity of the PTFE substrate, which helps prevent flooding. PTFE as a substrate for Cu-based catalysts has already shown promising results towards the production of C2 compounds. The hydrophobicity plays a significant role in enhancing the CO2 local concentration in the vicinity of the catalyst by avoiding electrolyte entering the porous GDE structure, and hence disturbing the supply of CO2 to the catalytically active sites, which is a key requirement for successful CO2RR. A further improvement in stability and selectivity was achieved by oxygen plasma treatment of the Ag. The formed Ag oxide species are reduced under the CO2RR reaction conditions leading to further catalyst re-structuring and enhancing its porosity. The enhanced stability and selectivity of these plasma treated catalysts can be attributed to the higher number of stable defects on the surface and higher electrochemical surface area.