Unraveling the Mechanism of Higher Alcohol Production on the Ordered PdCu ₃ Nanointermetallic Surface during CO ₂ Electroreduction

For advancing electrochemical CO 2 reduction, it is crucial to design efficient catalysts with high activity and selectivity for a particular product. Engineering structure at the atomic level by controlled synthesis strategies can effectively tune the product selectivity by optimizing the binding energy of the key intermediates involved in the reaction. Here, we demonstrate a morphology-controlled (spherical and cubic) synthesis route for PdCu 3 -ordered intermetallic nanoparticles without using any external strong reducing agent. Structurally ordered cubic PdCu 3 with predominantly (100) facets exhibits higher selectivity for ethanol (Faradaic efficiency (FE): 44.2%) and n -propanol (FE: 17.0%; formation rate: 39.99 μmol h −1 cm −2 mg −1 ) from CO 2 compared to spherical PdCu 3 with (111) facets (ethanol FE: 32.7%; n -propanol FE: 9.46%). Incorporating the electrode-electrolyte interactions, the ab initio calculations highlight the key C—C coupling step enabling the formation of C 2+ products. The active Pd sites, depending on their presence and absence on the surface of PdCu 3 (100) facets, significantly influence the C—C coupling barrier by controlling CO* and OCCOH* binding. In contrast, this barrier remains unaffected on (111) facets due to the Pd arrangement. This further establishes the important role of alloying Pd with Cu in rationally tailored surfaces for higher alcohol synthesis.