Electrocatalytic Oxidation of Ammonia on Transition-Metal Surfaces: A First-Principles Study
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- 作者：Jeffrey A. Herron ; Peter Ferrin ; Manos Mavrikakis
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：July 2, 2015
- 年：2015
- 卷：119
- 期：26
- 页码：14692-14701
- 全文大小：378K
- ISSN：1932-7455
文摘
We investigate the catalytic electro-oxidation of ammonia on model close-packed surfaces of Au, Ag, Cu, Pd, Pt, Ni, Ir, Co, Rh, Ru, Os, and Re to derive insights for the reaction mechanism and evaluate the catalysts based on their energy efficiency and activity in the context of their application in fuel cells. Two mechanisms, which are differentiated by their N鈥揘 bond formation step, are compared: (1) a mechanism proposed by Gerischer and Mauerer, whereby the N鈥揘 bond formation occurs between hydrogenated NHx adsorbed species, and (2) a mechanism in which N鈥揘 bond formation occurs between N adatoms. The results of our study show that the mechanism proposed by Gerischer and Mauerer is kinetically preferred and that the formation of N adatoms poisons the surface of the catalyst. On the basis of a simple Sabatier analysis, we predict that Pt is the most active monometallic catalyst followed by Ir and Cu, whereas all other metal surfaces studied here have significantly lower activity. We conclude by outlining some design principles for bimetallic alloy catalysts for NH3 electro-oxidation.