Theoretical evaluation of M/H-magadiite and Al modified M/H-[Al]-magadiites single-atom catalysts (M = Ag, Au, Pd, and Pt)

• Published in: Surface science Vol. 748; p. 122541
• Main Authors: Tôrres, Monize F., Santos, Márcio F., Silva, Bruna Nádia N., Saqlain, Muhammad Adnan, Antunes, Florence P.N., Pastore, Heloise O., Leitão, Alexandre A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2024
• Subjects: DFT; Electronic barriers; H-magadiite; Single-atom; H-magadiite; DFT; Electronic barriers; Single-atom
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2024.122541

•The M/H-magadiite and M/H-[Al]-magadiites catalysts (M = Ag, Au, Pt, Pd) were simulated by DFT calculations.•The Au/H-magadiite and Ag/H-magadiite models were more stable at the hydroxyl groups.•Pt/H-magadiite structure stabilized inside the silicon rings of the silicate, offering the strongest charge interaction and lower adsorption energy.•The presence of an extra H atom was responsible to accommodate each metal single-atom in the M/H-[Al]-magadiites.•MEP calculations in the Ag/H-magadiite, Au/H-magadiite and Pd/H-magadiite suggested the high possibility of metal sintering.
This work intends to simulate the interaction of metal single-atom(s) supported on surfaces of H-magadiite (H4Si14O30) and Al substituted H-[Al]-magadiites (H5AlSi13O30), hereafter called M/H-magadiite and M/H-[Al]-magadiite (M = Ag, Au, Pt, Pd), using DFT calculations (PBE and PBE-D3 functionals). Three distinct positions were defined in all surfaces to optimize each simulated model: “hydroxyl”, “edge” and “cavity”. The Au/H-magadiite and Ag/H-magadiite models were more stable at the “hydroxyl” sites. Meanwhile, in the aluminated surfaces, the presence of an extra hydrogen atom (here called Hextra, located in the “edge” region) was responsible for a more stable situation of these metal atoms. On the other hand, the Pd and Pt single-atoms present in H-magadiite and H-[Al]-magadiites showed greater interaction with all the sites, compared to the Au- and Ag- models. Based on the binding energies and other electronic calculations, the aluminol site at H-[Al]-magadiites has the best capacity to support metal species. For example, the Pt/H-[Al]-magadiite showed the lowest binding energy (-2.64 eV for PBE and -2.93 eV for PBE-D3), the strongest charge interaction and the smallest Pt – Hextra distance (1.55 Å). The migration barriers (PBE) in Ag/H-magadiite, Au/H-magadiite, and Pd/H-magadiite were lower than 21.50 kJ·mol−1, suggesting the high possibility of metal sintering. For all the cases, the PBE-D3 overestimated the barriers. Contrarily, the Pt/H-magadiite structures stabilized in the “cavity” region, inside the silicon rings of the silicate, and presented a migration barrier greater than 200 kJ·mol−1. These calculations offered the first indications of the behavior of single-atoms, which will serve as the basis for a broader description, in future works, of the migration of metal species in the Al-models simulated here, as well as for modeling single-atom catalysts that can be used in stable conditions.