A Cu-Pd alloy catalyst with partial phase separation for the electrochemical CO2 reduction reaction

Abstract

Cu catalysts can convert CO2 through an electrochemical reduction reaction into a variety of useful carbon-based products. However, this capability provides an obstacle to increasing the selectivity for a single product. Herein, we report a simple fabrication method for a Cu-Pd alloy catalyst for use in a membrane electrode assembly (MEA)-based CO2 electrolyzer for the electrochemical CO2 reduction reaction (ECRR) with high selectivity for CO production. When the composition of the Cu-Pd alloy catalyst was fabricated at 6:4, the selectivity for CO increased and the production of multi-carbon compounds and hydrogen is suppressed. Introducing a Cu-Pd alloy catalyst with 6:4 ratio as the cathode of the MEA-based CO2 electrolyzer showed a CO faradaic efficiency of 92.8% at 2.4 Vcell. We assumed that these results contributed from the crystal planes on the surface of the Cu-Pd alloy. The phases of the Cu-Pd alloy catalyst were partially separated through annealing to fabricate a catalyst with high selectivity for CO at low voltage and C2H4 at high voltage. The results of CO-stripping testing confirmed that when Cu partially separates from the lattice of the Cu-Pd alloy, the desorption of *CO is suppressed, suggesting that C–C coupling reaction is favored.