Structure and composition of Cu(hkl) surfaces exposed to O2 and emersed from alkaline solutions: Prelude to UHV-EC studies of CO2 reduction at well-defined copper catalysts

摘要: The ability of copper electrodes to catalyze the reduction carbon dioxide better than any single-metal material is now well known. However, it also an established fact that efficient scavenger dry oxygen. Hence, initiation CO_2 reaction at must contend with presence surface oxides spontaneously formed when metal exposed ambient air. In this regard, interfacial structures and compositions Cu(1 0 0), 1 0) 1), before after exposure gaseous oxygen emersion from in mildly alkaline media (pH 8 10), were characterized by a combination electrochemistry electron spectroscopy (low-energy diffraction Auger spectroscopy). affinity low-index planes gas was found decrease order > 1). same reactivity trend exhibited emersed K_2SO_4 solution. initial stages anodic oxidation copper, prior formation bulk oxides, span wide potential window pH-sensitive; within precursory region, submonolayer coverages tended form domains long-range order. At potentials far below anodic-oxidation region (E < −0.90 V), Cu(hkl) are expected mimic those zerovalent copper. These results may bear significant implications generation as identification surface-bound intermediates define electrocatalytic selectivity towards molecular species such CO media.