The platinum group metals (PGMs), in general, are excellent choices to trigger the hydrogen evolution reaction (HER), which is, however, a significant side reaction in any non-HER cathodic electrocatalytic reactions using the aqueous electrolyte, including the electrocatalytic CO2 reduction reaction (CO2RR) in this study. For this reason, many pioneering research works using Cu-based alloys for CO2RR opted for doped metals with positive H binding energy (&gt; 0.5 eV) to avoid HER. This comes with a penalty, however. Because these “safer” metals often inherit weak binding strength to the almost ubiquitous *CO reaction intermediate, the alloyed catalysts naturally lean towards making CO and formate-based products, defeating the purpose of using copper-based catalysts to produce energy-intensive hydrocarbons (HCs) in the first place. Indeed, by its chemical nature, the PGM species may induce stronger *CO binding to potentially benefit HCs formation through CO2RR. However, from the perspective of interfacial catalysis, two general questions arise 1) how the PGM-Cu structures shall be optimized to limit the kinetically faster HER intrinsically, and 2) how the PGM moiety shall be anchored to help but not “disturb” the copper from making selective HCs?<br/>In this work, we show that, compared to the parent Cu-only catalysts, a family of single-atom Pd- and Pt-Cu alloy catalysts have been developed to achieve more than one magnitude higher CO2 to HCs conversion rates and significantly suppressed selectivity to HER. Notably, a dilute amount of PGM associated with copper does not automatically guarantee the observed benefit described above. Avoiding the formation of PGM clusters, even tiny ones, is critical for a proper catalytic PGM-Cu interface design. Upon extension of our findings of single-atom PGM alloys on polycrystalline Cu particles to shape-selective Cu (cube and octahedra), we found that the Cube-Pd1Cu SAA and Octa- Pd1Cu SAA specifically enhances the CH4 and C2H4 formation rates respectively without altering the intrinsic selectivity of their parent Cube-Cu(111) and Octa-Cu(100) samples. This is particularly important because Cu is the only known element to versatilely catalyze the formation of HCs (especially C2+) through CO2RR.

Engineering the PGM-Cu catalytic interfaces to promote electrochemical CO2R without triggering HER

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