Ideal octahedral geometry leads to poor H2 evolution performance: Theoretical insights on reaction intermediates of cobalt-pentapyridyl molecular catalyst

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dc.authoridGurdal, Yeliz/0000-0002-6245-891X
dc.authoridKiser, Ayas/0000-0001-8422-2687
dc.contributor.authorKiser, Ayas
dc.contributor.authorGurdal, Yeliz
dc.date.accessioned2026-02-27T07:32:49Z
dc.date.available2026-02-27T07:32:49Z
dc.date.issued2025
dc.description.abstractThe type and coordination of ligands surrounding water reduction photo-catalysts affect the H2 production reaction pathway. In this respect, we examined two successive reductions followed by two protonations mechanism of H2 evolution reaction catalyzed by Cobalt-based pentapyridyl molecular catalyst in an aqueous solution employing Ab-initio Molecular Dynamics (AIMD), Density Functional Theory (DFT), and Free Energy Perturbation Theory. Each intermediate step of the H2 evolution reaction mechanism was simulated to determine the allowable spin states and solvent response surrounding the reaction center of the catalyst. A single electron transfer to the catalyst, leading to a singlet spin state, induces a conformational change in the water molecule in the first solvation shell, facilitating the formation of a Co-proton bond. Subsequent to the second electron transfer, the Co center acquires the proton from this water molecule, while the remaining OH- ion diffuses swiftly through the solvent. The first protonation step was determined to continue adopting a quartet spin state. Due to the catalyst's cage-like structure around the Co center, following the second protonation, H2 forms; however, it fails to diffuse from the reaction center into the solvent, suggesting the importance of maintaining an open structure around the Co center when designing ligand structures for water- splitting catalysts. The first and the second reduction free energies were calculated as -2 eV and -1.3 eV, respectively.
dc.description.sponsorshipScientific and Technological Research Council of Turkiye (TUBITAK); TUBITAK 3501 Career Development Program [120Z240]
dc.description.sponsorshipY.G. expresses gratitude to the Scientific and Technological Research Council of Turkiye (TUBITAK) for its support. This research was funded under the TUBITAK 3501 Career Development Program (Grant No. 120Z240) . The computational studies detailed in this paper were carried out using resources provided by the TUBITAK ULAKBIM High Performance and Grid Computing Center (TRUBA) in Turkiye.
dc.identifier.doi10.1016/j.ijhydene.2025.01.285
dc.identifier.endpage873
dc.identifier.issn0360-3199
dc.identifier.issn1879-3487
dc.identifier.startpage864
dc.identifier.urihttp://dx.doi.org/10.1016/j.ijhydene.2025.01.285
dc.identifier.urihttps://hdl.handle.net/20.500.14669/4352
dc.identifier.volume106
dc.identifier.wosWOS:001424854600001
dc.indekslendigikaynakWeb of Science
dc.language.isoen
dc.publisherPergamon-Elsevier Science Ltd
dc.relation.ispartofInternational Journal of Hydrogen Energy
dc.relation.publicationcategoryMakale - Uluslararas� Hakemli Dergi - Kurum ��retim Eleman�
dc.rightsinfo:eu-repo/semantics/closedAccess
dc.snmzKA_20260302
dc.subjectWater splitting
dc.subjectHydrogen evolution reaction
dc.subjectAb-initio Molecular Dynamics
dc.subjectDensity Functional Theory
dc.subjectReduction free energy
dc.titleIdeal octahedral geometry leads to poor H2 evolution performance: Theoretical insights on reaction intermediates of cobalt-pentapyridyl molecular catalyst
dc.typeArticle

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