Boosting electrocatalytic nitrogen reduction to ammonia in alkaline media

Guangzhe Li, He Lin, Zhefei Pan, Yun Liu, Liang An

Research output: Journal article publicationJournal articleAcademic researchpeer-review

2 Citations (Scopus)

Abstract

Electrochemical ammonia synthesis is a promising alternative technique to traditional Haber-Bosch process, capable of converting nitrogen to ammonia at ambient conditions and can be driven by intermittent energy. However, it generally requires high overpotential for nitrogen dissociation due to the stable triple bonds of nitrogen molecules, resulting in a poor ammonia yield rate. Tailoring the electrolyte-ion composition is a promising approach to facilitate nitrogen dissociation by optimizing the local reaction environment near the electrode toward ammonia production. In this study, the effect of anions in the electrolyte composition on electrocatalytic nitrogen reduction to ammonia is investigated. It is found that a lower onset potential for nitrogen reduction (−0.2 V vs RHE) and a higher ammonia yield rate (6.69 × 10−11 mol cm−2 s−1) are achieved in the electrolyte containing OH anions, compared to singly charged anions of Cl and SCN when using an electrode made of commercial Au/C electrocatalysts. In addition, current density contributed by nitrogen reduction achieved in the high-pH electrolyte (pH ≥ 13) shows around 3-fold increase compared to that in low-pH electrolyte (11 ≤ pH ≤ 12). Such performance enhancement is possibly attributed to the appearance of hydronium ions (H3O+) in high-pH electrolyte, which facilitates nitrogen dissociation by strengthening protonation((Formula presented.)).

Original languageEnglish
Pages (from-to)19634-19644
Number of pages11
JournalInternational Journal of Energy Research
Volume45
Issue number13
DOIs
Publication statusPublished - 25 Oct 2021

Keywords

  • ambient ammonia synthesis
  • anions
  • highly concentrated hydroxide ions
  • hydronium ions
  • nitrogen reduction reaction

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology

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