Pattern Formation during CO Electrooxidation on Thin Pt Films Studied with Spatially Resolved Infrared Absorption Spectroscopy

Infrared absorption spectroscopy in the attenuated total reflection configuration is utilized to obtain spatially resolved information on the metal liquid interface under reaction conditions. This is demonstrated with in situ infrared measurements of the CO coverage on thin Pt films during CO electrooxidation under galvanostatic control conditions. The formation of two stationary domains exhibiting different CO coverages is observed. The relative sizes of the domains adjust with the applied current while the density of adsorbed CO molecules in each domain is independent of it.