On the mechanism of the electrochemical conversion of ammonia to dinitrogen on Pt(1 0 0) in alkaline environment

Ioannis Katsounaros (Corresponding author), Marta C. Figueiredo, Federico Calle-Vallejo, Hongjiao Li, Andrew A. Gewirth, Nenad M. Markovic, Marc T.M. Koper (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

14 Citations (Scopus)

Abstract

The electrochemical oxidation of ammonia to dinitrogen is a model reaction for the electrocatalysis of the nitrogen cycle, as it can contribute to the understanding of the making/breaking of N–N, N–O, or N–H bonds. Moreover, it can be used as the anode reaction in ammonia electrolyzers for H 2 production or in ammonia fuel cells. We study here the reaction on the N 2 -forming Pt(1 0 0) electrode using a combination of electrochemical methods, product characterization and computational methods, and suggest a mechanism that is compatible with the experimental and theoretical findings. We propose that N 2 is formed via an NH + NH coupling step, in accordance with the Gerischer-Mauerer mechanism. Other N–N bond-forming steps are considered less likely based on either their unfavourable energetics or the low coverage of the necessary monomers. The N–N coupling is inhibited by strongly adsorbed N and NO species, which are formed by further oxidation of NH.

Original languageEnglish
Pages (from-to)82-91
Number of pages10
JournalJournal of Catalysis
Volume359
DOIs
Publication statusPublished - 1 Mar 2018
Externally publishedYes

Keywords

  • Ammonia oxidation
  • Electrocatalysis
  • Nitrogen cycle
  • Physical electrochemistry
  • Single-crystal electrochemistry

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