CO oxidation on electrically charged gold nanotips.

We report a study of the oxidation of CO on a gold nanotip in the presence of high electrostatic fields. With the binding energies obtained using density functional theory as a function of the electric field, a simple field-dependent kinetic model based on the Langmuir-Hinshelwood mechanism is set up. We show that the dissociative adsorption of oxygen on gold happens only below a negative critical value of the electric field while the binding of CO on gold is enhanced for positive values. We explain the propagation of a wave observed in field ion microscopy experiments and predict that the oxidation of CO occurs on negatively charged gold clusters.