CO oxidation on palladium field emitter: kinetic oscillations and bistability

CO oxidation on Pd field emitter was studied by means of field electron microscopy (FEM) in a temperature range between 350 and 450 K. The complicated phenomena of kinetic oscillations in the reaction rate and bistability were found to be well reflected in the electron emission current. Subsurface oxygen, the driving species of the oscillations, was found to form preferentially on the {110} regions from where the oscillations start. Under the reaction conditions, the CO dissociation was unavoidable and it was found to affect the reaction kinetics. Sometimes, the imaging process was complicated by the formation of subsurface oxygen that leads to the appearance of very bright regions and by the CO dissociation process that leads to partial poisoning of the surface by the formed carbon.