Effect of Areal Parameter\nof Sputtered Cu Layers on\nC<sub>2</sub> Products for CO<sub>2</sub> Electroreduction

The CO<sub>2</sub> electrochemical reduction (CO<sub>2</sub>ER)\nto produce valuable multicarbon products represents a promising approach\nfor enhancing CO<sub>2</sub> conversion. While previous research has\ninvestigated the impact of Cu electrode surface topography on C<sub>2</sub> production, it is important to note that other parameters\nwere also altered concurrently with changes in roughness. To isolate\nthe specific effect of surface texture on CO<sub>2</sub> electroreduction,\nthis study prepared Cu layers with varying textures using the sputtering\nmethod with a varied sputtering time. To characterize the surface\nfeatures of the sputtered Cu layers, the developed interfacial area\nratio (<i>S</i><sub>dr</sub>), known as areal parameter,\nwas introduced, with the aim of correlating it with C<sub>2</sub> product\nselectivity. The results of this study indicate that the improved\nselectivity of C<sub>2</sub> products can be attributed to higher <i>S</i><sub>dr</sub> values, primarily due to a rougher and finer\nsurface texture that increases the local concentration of CO and OH<sup>–</sup>. This research underscores the significance of surface\ntopography and offers perspectives for designing efficient Cu electrodes\nfor the CO<sub>2</sub>ER.