The prospect of valorizing anthropogenic CO2 emissions by converting this greenhouse gas into added-value products (e.g., CO, formate) through electrochemical conversion in near-neutral aqueous media holds great research interest. While palladium-based catalysts have been repeatedly shown to display a switchable selectivity between CO and formate at high vs. low overpotentials, respectively, a large fraction of the total current is used to convert water into hydrogen as a parasitic byproduct. This is especially true for carbon-supported materials at high overpotentials (i.e., ≤ − 0.7 V vs. the reversible hydrogen electrode), in which the conversion of water to H2 on carbon and of CO2 to CO on Pd occur at comparable rates. Therefore, the removal of this carbon concomitant to the use of unsupported structures that can maintain a high surface area (e.g., as in aerogels) holds the promise of leading to higher selectivities towards CO2 reduction products. Additionally, alloying of metals is a well-researched approach to modify the adsorption kinetics of intermediate species enabling improvement in activity and the tuning of the selectivity towards a certain product. Specifically, alloys of palladium and platinum have been shown to possess high activities for formate generation from CO2 over a wide potential range [1].With this motivation, in this work, unsupported PdPt-aerogels were synthesized in five alloy compositions (from Pd50Pd50 to Pd90Pt10) and as pure metals (Pd100 and Pt100) at a constant web thickness of 6 ± 1 nm using a novel ethanolic synthesis approach [2]. The aerogels’ structure was studied using high-resolution transmission and scanning electron microscopies (HR-TEM, SEM) confirming the homogeneity of the materials. The alloying-degree of the PdPt aerogels was thereafter investigated using ex-situ X-ray absorption spectroscopy (XAS) measurements from which we derived the Cowley short-range order parameter [3], finding all compositions to be random alloys of Pd and Pt with a stoichiometry in good agreement with the Pt:Pd ratios aimed in the synthesis. Furthermore, energy dispersive X-ray spectroscopy (EDX) measurements in line-scan mode were used to investigate the elemental distribution within the structure of the gel (see Fig. 1A-1F), unveiling a slight enrichment of Pt on the surface of the bimetallic PdPt aerogels.These spectroscopic measurements were complemented by electrochemical characterization using CO-stripping as a means to infer the aerogels’ electrochemical surface area (ECSA) and surface composition. While the inferred ECSA values were all ≥70% of what is the expected value based on the aerogels’ web thickness, we observed significant changes in the shape of the hydrogen underpotential deposition (Hupd) that indicate alloy formation on the surface of the aerogels. Additionally, clear trends in the potential position of the CO-oxidation peak as a function of the alloy composition, and in the CO-oxidation charge depending on the CO-adsorption potential (i.e., 0.1 vs. 0.4 V vs. the reversible hydrogen electrode) were found.Lastly, the CO2-reduction activity of these bimetallic PdPt aerogels was tested in our custom, online gas chromatography setup for CO2-electroreduction. Using this approach, the pure palladium aerogel (Pd100) was shown to display Faradaic efficiencies towards CO and formate exceeding 90% at high or low overpotentials, respectively, proving the beneficial effect of the removal of the carbon support on palladium’s CO2 electroreduction selectivity. Meanwhile, the PdPt aerogel alloys featured formate and CO Faradaic efficiencies much lower than those previously reported in Ref. 1, with hydrogen making up the majority of the Faradaic efficiency (see Fig. 1G). Here, the activity towards CO2 electroreduction products was found to decrease with increasing Pt-content, so that on the pure Pt-aerogel (Pt100) hydrogen was the only product. These results are in line with the above-described Pt-enrichment of the alloys’ surfaces, which explains their high activity for the HER reaction and reduced activity for CO2 electroreduction. Figure 1