Structural flexibility dictates reactivity of single-atom catalysts
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arXiv
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| Autori principali: | , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| _version_ | 1866917337637060608 |
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| author | Planer, Jakub Hrůza, Dominik Lesovský, Tadeáš Jabeen, Ayesha Čechal, Jan Jakub, Zdeněk |
| author_facet | Planer, Jakub Hrůza, Dominik Lesovský, Tadeáš Jabeen, Ayesha Čechal, Jan Jakub, Zdeněk |
| contents | Unravelling the origins of single-atom catalyst reactivity is a central challenge in heterogeneous catalysis research. A key question is whether the activity arises solely from atomic isolation or from distinct structural and electronic configurations of the single atoms. Here, we use precisely defined Fe-N$_3$ and Fe-N$_4$ model catalyst sites synthesized on an inert support to quantify the effect of coordination geometry on chemical reactivity. Both the Fe-N$_3$ and Fe-N$_4$ models have the same electronic configuration (high-spin Fe$^{2+}$ with S=2), and even their d-orbital occupancies and positions with respect to Fermi level are almost identical. Despite this electronic similarity, the adsorption energy of CO differs by more than 0.6 eV between the Fe-N$_3$ and Fe-N$_4$ sites, as indicated by density functional theory computations and confirmed by atomically-resolved scanning tunneling microscopy experiments. We trace this reactivity difference to the structural flexibility of the Fe-N$_3$ sites, which allows strengthening of the Fe 3d$_{xz/yz}$-CO 2$π$* back-bonding by lifting the Fe atom from the -N$_3$ plane. These results demonstrate that coordination geometry plays a crucial role in defining the reactivity of single-atom catalysts, and that such effects cannot be predicted by analysis of the sites' electronic structures alone. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_12424 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Structural flexibility dictates reactivity of single-atom catalysts Planer, Jakub Hrůza, Dominik Lesovský, Tadeáš Jabeen, Ayesha Čechal, Jan Jakub, Zdeněk Materials Science Unravelling the origins of single-atom catalyst reactivity is a central challenge in heterogeneous catalysis research. A key question is whether the activity arises solely from atomic isolation or from distinct structural and electronic configurations of the single atoms. Here, we use precisely defined Fe-N$_3$ and Fe-N$_4$ model catalyst sites synthesized on an inert support to quantify the effect of coordination geometry on chemical reactivity. Both the Fe-N$_3$ and Fe-N$_4$ models have the same electronic configuration (high-spin Fe$^{2+}$ with S=2), and even their d-orbital occupancies and positions with respect to Fermi level are almost identical. Despite this electronic similarity, the adsorption energy of CO differs by more than 0.6 eV between the Fe-N$_3$ and Fe-N$_4$ sites, as indicated by density functional theory computations and confirmed by atomically-resolved scanning tunneling microscopy experiments. We trace this reactivity difference to the structural flexibility of the Fe-N$_3$ sites, which allows strengthening of the Fe 3d$_{xz/yz}$-CO 2$π$* back-bonding by lifting the Fe atom from the -N$_3$ plane. These results demonstrate that coordination geometry plays a crucial role in defining the reactivity of single-atom catalysts, and that such effects cannot be predicted by analysis of the sites' electronic structures alone. |
| title | Structural flexibility dictates reactivity of single-atom catalysts |
| topic | Materials Science |
| url | https://arxiv.org/abs/2603.12424 |