{
  "abstract": "Green ammonia production will be crucial to achieving global net-zero emissions. The current dominant technology for producing ammonia, known as the Haber-Bosch process, requires extreme temperatures and pressures. One promising alternative is mechanocatalysis, where mechanical energy is used to promote reactivity and reduce energy consumption. Ammonia production via mechanocatalysis has recently been demonstrated at the laboratory scale. A deeper understanding of the kinetics and mechanism of this reaction is necessary to facilitate scale-up of this process. However, this is challenging to obtain inside ball mills, the most commonly used devices for mechanocatalysis. Here, we use molecular dynamics simulations to study mechanocatalytic ammonia production. A reactive force field is employed to investigate the effect of applied stress on nitrogen dissociation and hydrogenation on an iron catalyst. We find that the activation energy of the nitrogen dissociation step decreases from 56 kJ/mol in the thermally activated process on Fe(111), to 29 kJ/mol under a normal stress of 5 GPa. For the less reactive Fe(110) surface, the reduction is even more significant, from 117 kJ/mol to 35 kJ/mol. The larger activation volume for Fe(110) than Fe(111) is due to deeper penetration of the nitrogen molecules into the more open surface. The hydrogenation step was also accelerated under applied stress, although the effect was less pronounced than for nitrogen dissociation. These trends are quantified using SATA equation framework, providing the first SATA analysis of mechanochemical ammonia synthesis. We also reveal the atomic-scale mechanism of this stress-enhanced reactivity, which does not require increased defect density in the iron catalyst. The mechanistic analysis reveals that normal stress promotes Fe–N bond formation, which weakens the N–N bond and lowers the activation barrier. This is distinct from non-catalytic mechanochemistry, where normal stress typically inhibits bond-breaking reactions. Nitrogen dissociation can be further accelerated by the application of shear stress, which can promote the reaction at room temperature. These results provide an improved fundamental understanding that could help to guide further improvements in the efficiency of mechanochemical ammonia production.",
  "abstract_shown": true,
  "affiliations": [
    "Mechanical and Industrial Engineering, Universitas Gadjah Mada, Jl. Grafika No. 2, Yogyakarta, Indonesia, 55281",
    "Mechanical Engineering",
    "Imperial College London",
    "University of Bath"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0,
        1,
        2
      ],
      "name": "Muhammad Aulia Rahman",
      "orcid": "0000-0002-3161-123X"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Daniele Dini",
      "orcid": "0000-0002-5518-499X"
    },
    {
      "affs": [
        1,
        2,
        3
      ],
      "name": "James P. Ewen",
      "orcid": "0000-0001-5110-6970"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1rfjmqxwannps.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008447/v1",
  "fulltext_url": null,
  "id": "1rfjmqxwannps",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008447/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1503|Ammonia Synthesis and Nitrogen Reduction"
    ]
  ],
  "openalex": "W7208705112",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-07",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/1rfjmqxwannps.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:17Z",
      "native_id": "10.26434/chemrxiv.15008447",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008447/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1503|Ammonia Synthesis and Nitrogen Reduction",
      "subfield": "catalysis"
    }
  ],
  "title": "Reactive Molecular Dynamics Simulations of Mechanochemical Ammonia Production",
  "title_text": "Reactive Molecular Dynamics Simulations of Mechanochemical Ammonia Production",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:17Z",
  "url": "https://research.draconitic.com/paper/1rfjmqxwannps",
  "venue": "ChemRxiv",
  "versions": []
}