Grazing incidence X-ray dif fraction (GI-XRD) was next used to examine the crystalline structures of the asprepared foams, data are displayed in Figure . Pure Cu foam exhibited mainly the typical reflection peaks for cubic metallic copper with a small contribution from Cu2O, while the various as-prepared Cu-Sn bimetallic foams showed a mixture of metallic copper and Cu2O phases. Additionally, the pure electrodeposited Sn exhibited several ref lection peaks attributed to metallic Sn. No significant shifts are observed in the Cu ref lection peaks of the all as-synthesized Cu-Sn f oams compared to pure Cu. The f oams with low Sn contents did not exhibit any noticeable signal f or Sn (metallic or oxide), suggesting the electrodeposited Sn exists in an amorphous state or is below the detection threshold for XRD. Taken together, there is no clear evidence of the formation of crystalline Cu-Sn alloys. Cu-In bimetallic foams with low In content (≤48 at. %) exhibited mainly reflection peaks f or the metallic copper with small contribution of metallic In, while Cu-In f oams with higher In contents beyond 48 at. % displayed a mixture of metallic In and Cu. Again, the as-prepared Cu-In bimetallic f oams did not show evidence of crystalline Cu-In alloy f ormation. It is worth noting that, while the Cu-rich Cu-Sn f oams exhibited very strong peaks for Cu2O with very low contribution of metallic Cu, the Cu-rich Cu-In f oams showed only metallic Cu ref lections. However, as described later in section 3.3, XAS measurements under CO2 electrolysis conditions suggest the f ormation of Cu-In and Cu-Sn alloys, in addition to the existence of In and Sn oxides (see section 3.3 f or more details). Furthermore, XPS (more surf ace-sensitive) analyses of these samples (air-exposed), showed the existence of a thin surface oxide shell f or all the as-prepared Cu-In and Cu-Sn bimetallic catalysts (see Figure ). We only measured XAS and XPS f or the Cu-In and Cu-Sn bimetallic foams with the best CO2ER performance towards either CO or HCOO - .