Campisi Dario, Lamberts Thanja, Dzade Nelson Y, Martinazzo Rocco, Ten Kate Inge Loes, Tielens Alexander G G M
Leiden Observatory, Leiden University, Niels Bohrweg 2, Leiden 2333 CA, The Netherlands.
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2300 RA, The Netherlands.
ACS Earth Space Chem. 2022 Aug 18;6(8):2009-2023. doi: 10.1021/acsearthspacechem.2c00084. Epub 2022 Jul 27.
Understanding how to catalytically break the C-H bond of aromatic molecules, such as polycyclic aromatic hydrocarbons (PAHs), is currently a big challenge and a subject of study in catalysis, astrochemistry, and planetary science. In the latter, the study of the breakdown reaction of PAHs on mineral surfaces is important to understand if PAHs are linked to prebiotic molecules in regions of star and planet formation. In this work, we employed a periodic density functional theory along with Grimme's D4 (DFT-D4) approach for studying the adsorption of a sample of PAHs (naphthalene, anthracene, fluoranthene, pyrene, coronene, and benzocoronene) and fullerene on the [010] forsterite surface and its defective surfaces (Fe-doped and Ni-doped surfaces and a MgO-Schottky vacancy) for their implications in catalysis and astrochemistry. On the basis of structural and binding energy analysis, large PAHs and fullerene present stronger adsorption on the pristine, Fe-doped, and Ni-doped forsterite surfaces than small PAHs. On a MgO-Schottky vacancy, parallel adsorption of the PAH leads to the chemisorption process (C-Si and/or C-O bonds), whereas perpendicular orientation of the PAH leads to the catalytic breaking of the aromatic C-H bond via a barrierless reaction. Spin density and charge analysis show that C-H dissociation is promoted by electron donation from the vacancy to the PAH. As a result of the undercoordinated Si and O atoms, the vacancy acts as a Frustrated Lewis Pair (FLP) catalyst. Therefore, a MgO-Schottky vacancy [010] forsterite surface proved to have potential catalytic activity for the activation of C-H bond in aromatic molecules.
了解如何催化断裂芳香族分子（如多环芳烃，PAHs）的碳氢键，目前是一个巨大的挑战，也是催化、天体化学和行星科学领域的研究课题。在行星科学中，研究PAHs在矿物表面的分解反应对于理解PAHs是否与恒星和行星形成区域的益生元分子有关至关重要。在这项工作中，我们采用周期性密度泛函理论结合格林姆的D4（DFT-D4）方法，研究了PAHs样本（萘、蒽、荧蒽、芘、 coronene和苯并 coronene）以及富勒烯在[010]镁橄榄石表面及其缺陷表面（铁掺杂和镍掺杂表面以及MgO肖特基空位）上的吸附情况，以探讨它们在催化和天体化学方面的意义。基于结构和结合能分析，大型PAHs和富勒烯在原始、铁掺杂和镍掺杂的镁橄榄石表面上的吸附比小型PAHs更强。在MgO肖特基空位上，PAH的平行吸附会导致化学吸附过程（C-Si和/或C-O键），而PAH的垂直取向会通过无势垒反应导致芳香族碳氢键的催化断裂。自旋密度和电荷分析表明，空位向PAH的电子捐赠促进了C-H键的解离。由于硅和氧原子的配位不足，该空位起到了受阻路易斯对（FLP）催化剂的作用。因此，MgO肖特基空位[010]镁橄榄石表面被证明对芳香族分子中碳氢键的活化具有潜在的催化活性。
