In this work, the authors report a simple methodology to tune and quantify the surface structure on copper catalysts. They first record the voltammetric lead underpotential deposition (UPD) on different single facets, providing a tool to correlate active sites with copper geometries. Their work also opens new opportunities to selectively tailor the facet distribution on copper via electroplating techniques in halide-rich aqueous solutions, which is essential to design a well-defined nanostructured catalyst. Therefore, I think that this interesting manuscript is suitable for being published in Chemical Science after addressing the following concerns.

1. XRD is a is an effective method for determining crystal planes. It is suggested that the XRD of different facets copper catalysts should also be presented.

2. The structure information of different facets copper catalysts should be included in the details of the DFT calculation.

3. The degree of surface reconstruction induced by chloride on copper may play a key role in the conversion of the CO2 to C2+ multicarbon products. If the performance for electrochemical CO2RR of different facets copper catalysts is provided, the application prospect of the method will be better demonstrated.