Electrocatalytic instability of platinum surface towards ammonia oxidation reaction

Abstract

Understanding of the deactivation mechanism of Pt electrocatalysis towards the ammonia oxidation reaction (AOR) to dinitrogen is the core of the successful introduction of the nitrogen energy cycle, which can be used as a source of hydrogen fuels. Herein, we study AOR electrocatalysis on NOx-adsorbed polycrystalline Pt electrodes, i.e. NO, NO2− and NO3−, and find that all the NOx species can significantly deteriorate the catalytic activity of Pt. Combined stationary/transient voltammograms reveal that the poisonous NOx species are produced by NH3 oxidation on the bare Pt surface, but the adsorbed NOx species can be transformed to N2 by the Langmuir-Hinshelwood mechanism with *NO as a key intermediate.