Cu-Pd alloy nanoparticles as highly selective catalysts for efficient electrochemical reduction of CO2 to CO

[Display omitted] •Monodisperse Cu-Pd alloy nanoparticles for electrochemical CO2 reduction are fabricated using the colloidal method.•Cu-Pd alloy NP shows totally different catalytic performance form the that of bulk Cu, which only produces CO.•DFT calculation is performed to reveal the effect of the alloying on catalytic activity increase and selectivity changes.•Alloying Pd to Cu increases energy barrier to CO protonation step, which causes suppression of the hydrocarbon production. Although a copper catalyst has very interesting properties in CO2 electroreduction reaction (CO2RR), the high overpotential of this reaction and low selectivity of the catalyst for a single product are major hindrances to catalyst commercialization. In this work, monodisperse Cu-Pd nanoparticles (NPs) with various compositions are synthesized using the colloidal method. These NPs show a totally different catalytic performance than bulk Cu catalysts. Alloying Cu with Pd suppresses hydrocarbon production on the alloy NP catalyst surface. NPs with a 1:1 Cu-Pd ratio show the best catalytic activity for the conversion of CO2 to CO. At -0.9 V (vs. RHE), 87% CO Faradaic efficiency is achieved, as well as a high noble metal mass activity of 47 mA mgPd-1, for CO production. Density functional theory calculations suggest that the energy barrier to the CO* protonation step is increased when Pd is alloyed with Cu; this increase suppresses the reduction of CO2 to hydrocarbons. This result is a significant advance toward selective electrochemical reduction of CO2.