Probing the Active Surface Sites for CO Reduction on Oxide-Derived Copper Electrocatalysts
Arnau Verdaguer-Casadevall, Christina W Li, Tobias P Johansson, Soren B Scott, Joseph T McKeown, Mukul Kumar, Ifan E L Stephens, Matthew W Kanan, Ib Chorkendorff
Journal of the American Chemical Society 2015 August 12, 137 (31): 9808-11
26196863
CO electroreduction activity on oxide-derived Cu (OD-Cu) was found to correlate with metastable surface features that bind CO strongly. OD-Cu electrodes prepared by H2 reduction of Cu2O precursors reduce CO to acetate and ethanol with nearly 50% Faradaic efficiency at moderate overpotential. Temperature-programmed desorption of CO on OD-Cu revealed the presence of surface sites with strong CO binding that are distinct from the terraces and stepped sites found on polycrystalline Cu foil. After annealing at 350 °C, the surface-area corrected current density for CO reduction is 44-fold lower and the Faradaic efficiency is less than 5%. These changes are accompanied by a reduction in the proportion of strong CO binding sites. We propose that the active sites for CO reduction on OD-Cu surfaces are strong CO binding sites that are supported by grain boundaries. Uncovering these sites is a first step toward understanding the surface chemistry necessary for efficient CO electroreduction.
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