{
  "abstract": "Orange hydrogen (H2) is generated through stimulated water–rock reactions, analogous to natural hydrogen formation via serpentinization, and offers a potential pathway for clean H2 production from Fe(II)-bearing minerals and mineral side streams. Here, we investigate orange H2 production based on fayalite slag, an Fe(II)-rich metallurgical waste that has not previously been studied for this purpose. H2 generation from fayalite slag was evaluated in a stirred hydrothermal reactor pressurized with Ar and experiments were carried out at initial pressures of 5, 50, and 100 bar and temperatures of 160 and 230 °C. The highest H2 production was observed at 230 °C and an initial pressure of 5 bar in 1 M KOH (pH 14) after 48 h, reaching 0.45 g H2 kg-1 fayalite slag, corresponding to ⁓7.2% of the theoretical maximum H2 yield. During the reaction, the fayalite content decreased, while magnetite and a K-bearing mica phase formed as secondary products. These secondary phases may have limited further reaction by reducing water access to Fe(II)-bearing regions. This is evidenced by the fact that H2 generation plateaued after 48 h of reaction time. Overall, the results show that fayalite slag is a potential feedstock for orange H2 production under comparatively mild hydrothermal conditions, while also indicating that secondary phase formation and surface passivation are important reaction bottlenecks.",
  "abstract_shown": true,
  "affiliations": [
    "Faculty of Technology, Fiber and Particle Engineering Research Unit, University of Oulu, PO Box 4300, Finland, 90014",
    "Faculty of Science, University of Oulu, P.O. Box 3000, Finland, FI-90014"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Somayeh Karandish Marvasti"
    },
    {
      "affs": [
        1
      ],
      "name": "Rossella Greco"
    },
    {
      "affs": [
        0
      ],
      "name": "Juho Yliniemi"
    },
    {
      "affs": [
        0
      ],
      "name": "Tero Luukkonen",
      "orcid": "0000-0002-1124-775X"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7k6vhrj6hmk50.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009239/v1",
  "fulltext_url": null,
  "id": "7k6vhrj6hmk50",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009239/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",
      "2305|CO2 Sequestration and Geologic Interactions"
    ]
  ],
  "openalex": "W7213975776",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-22",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/7k6vhrj6hmk50.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:21Z",
      "native_id": "10.26434/chemrxiv.15009239",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009239/v2"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "openalex:2305|CO2 Sequestration and Geologic Interactions",
      "subfield": "environmental-science"
    }
  ],
  "title": "Orange hydrogen production with fayalite slag: identifying reaction bottlenecks",
  "title_text": "Orange hydrogen production with fayalite slag: identifying reaction bottlenecks",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:21Z",
  "url": "https://research.draconitic.com/paper/7k6vhrj6hmk50",
  "venue": "ChemRxiv",
  "versions": []
}