(Invited) Electrocatalysis of Ammonia Oxidation Reaction on Pt(100) in Alkaline Solutions

The oxidation of ammonia is an essential process in the nitrogen cycle, with important applications in energy conversion ("ammonia electrolysis"), environmental protection (removal of ammonia from waste streams), electrosynthesis (hydroxylamine production via nitrate or nitric oxide reduction) or sensors (ammonia sensors for a wide range of applications). The conversion of ammonia to nitrogen gas, which is the desirable process in most of these applications, is typically difficult to achieve even though N₂ is thermodynamically the most favorable product. Among the three basal planes of platinum, Pt(100) is unique in converting ammonia selectively to nitrogen. This presentation deals with the mechanism of the ammonia oxidation on the Pt(100) single-crystal electrode in alkaline solutions, investigated by basic electrochemical methods coupled with in-situ infrared spectroscopy and online electrochemical mass spectrometry. Our study particularly focuses on the nature of the adsorbed intermediate species and thereby on their role in the N-N coupling and in the observed deactivation.

Acknowledgments
This research was supported by a Marie Curie International Outgoing Fellowship within the 7th European Community Framework Programme to Ioannis Katsounaros under Award IOF-327650, and by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division.