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MM: Fachverband Metall- und Materialphysik
MM 63: Computational Materials Modelling - Electronic Structure of Complex Materials
MM 63.5: Vortrag
Donnerstag, 19. März 2020, 18:30–18:45, IFW A
Addressing the conflict of locating solvated electrons in alkali metal doped zeolites — •Debalaya Sarker1,2, Sergey V. Levchenko1,2, and Matthias Scheffler2 — 1Skolkovo Institute of Science and Technology, Moscow, RU — 2Fritz-Haber-Institut der MPG, Berlin, DE
Doping faujasite Y (FAU-Y), a nanoporous aluminosilicate zeolite, with alkali metal atoms M (Na, K, Cs, etc.) is a promising way to produce outstanding basic catalysts. The dopants, along with extraframework metal atoms, often form M4+3 clusters inside zeolite pores: leaving the valence electron of the dopant solvated and available for catalysis. Despite extensive experimental efforts, the distribution of the dopants and solvated electrons remains debated till date [1,2]. Combining a cluster expansion model, parameterized with extensive PBE+vdW calculations, and ab initio atomistic thermodynamics, we address this issue. Further, the electronic structure is calculated with hybrid HSE06 functional for low-energy configurations. We find that at temperatures >850 K Na atoms in NaY zeolites with two extraframework atoms per unit cell on average redistribute so that areas with lower and higher local concentrations emerge. The redistribution is driven by increased configurational disorder at both higher and lower concentrations. This explains why solvated electrons can be located inside both small and large cages in NaY, reconciling experiments assigning the solvated electrons to a particular pore type.
[1] A. R. Armstrong et al., J. Am. Chem. Soc. 117, 9087 (1995).
[2] W. Louisfrema et al., Molecular Simulation 41, 1371 (2015).