Under OCP (open circuit potential) and dry conditions, all the investigated catalyst materials including the bimetallic foams showed two strong peaks located at ~522-527 and ~619-623 cm -1 . We measured Raman spectra of different Cu oxide/hydroxide standards (e.g., Cu2O, CuO, Cu(OH)2) f or comparison, see Figure . Since these two af orementioned peaks do not perfectly match with any of the single oxide/hydroxide standards, we attribute them to a mixture of Cu2O and CuO with Cu2O as dominant surface species, which is in a good alignment with the obtained XPS results. For in-situ measurements (see the experimental section f or more details), the as -prepared catalyst materials are f irst pre-activated (reduced) by applying constant cathodic current of -2 mA cm -2 in CO2-saturated solution of 0.1 M KHCO3 until reaching -0.4 V. Then, a constant potential of interest is applied f or 2 hours to replicate relevant CO2ER conditions. Interestingly, Cu-In bimetallic foams exhibited different activation-reduction behavior compared to the Cu-Sn bimetallic f oams. The initial Cu2O/CuO surf ace oxides of the as-prepared Cu-In bimetallic foams seem to be dynamically reduced with near-instantaneous f ormation of basic copper carbonate phase (metastable malachite/azurite like materials, Cu2CO3(OH)2/Cu3(CO3)2(OH)2), indicated by observation of vanishing Cu2O/CuO peaks at 525 and 620 cm -1 and the immediate appearance of several new peaks assigned f or malachite/azurite phases, as shown in Figure and Figure . On the other hand, the Cu2O/CuO peaks (at 514-527 and 620 cm -1 ) of the as-synthesized Cu-Sn bimetallic foams are not f ading away during the preactivation step, but rather they evolve into a one very strong peak at 585 cm -1 , which completely disappears within 10 minutes of the pre-activation step, as shown in Figure and.