Thermodynamic Constraints in Using AuM (M = Fe, Co, Ni, and Mo) Alloys as N2 Dissociation Catalysts: Functionalizing a Plasmon-Active Metal

John Mark P. Martirez, Emily A. Carter

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The Haber-Bosch process for NH3 synthesis is arguably one of the greatest inventions of the 20th century, with a massive footprint in agriculture and, historically, warfare. Current catalysts for this reaction use Fe for N2 activation, conducted at high temperatures and pressures to improve conversion rate and efficiency. A recent finding shows that plasmonic metal nanoparticles can either generate highly reactive electrons and holes or induce resonant surface excitations through plasmonic decay, which catalyze dissociation and redox reactions under mild conditions. It is therefore appealing to consider AuM (M = Fe, Co, Ni, and Mo) alloys to combine the strongly plasmonic nature of Au and the catalytic nature of M metals toward N2 dissociation, which together might facilitate ammonia production. To this end, through density functional theory, we (i) explore the feasibility of forming these surface alloys, (ii) find a pathway that may stabilize/deactivate surface M substituents during fabrication, and (iii) define a complementary route to reactivate them under operational conditions. Finally, we evaluate their reactivity toward N2, as well as their ability to support a pathway for N2 dissociation with a low thermodynamic barrier. We find that AuFe possesses similar appealing qualities, including relative stability with respect to phase separation, reversibility of Fe oxidation and reduction, and reactivity toward N2. While AuMo achieves the best affinity toward N2, its strong propensity toward oxidation could greatly limit its use.

Original languageEnglish (US)
Pages (from-to)2940-2949
Number of pages10
JournalACS Nano
Volume10
Issue number2
DOIs
StatePublished - Feb 23 2016

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Keywords

  • Au alloys
  • Haber-Bosch
  • ammonia synthesis
  • heterogeneous catalysis
  • nitrogen dissociation
  • surface plasmon
  • transition metal catalysis

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