Ab initio modelling and investigation of the effects of magnesium oxide surface modifications on single atom catalysis systems

Download

AydogaKallem_Tez_280223.pdf

Date

2023-1-23

Author

Kallem, Aydoğa

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

342
views

234
downloads

An emerging technology, namely Single Atom Catalysts (SACs) have the potential to bridge the positive characteristics of both heterogenous and homogenous catalysts. In order to create more efficient SACs, it is necessary to understand the metal support interaction (MSI) at the molecular level, which seriously affects the performance of SACs. In this study, the effects of surface modifications on the catalytic performance of SACs were examined via Density Functional Theory (DFT) to gain a deeper understanding of the underlying mechanisms from first principles. Firstly, MgO(100) and MgO(110) surfaces were doped with the Li, Ca, C, Al, Cr, Ni, and N impurity atoms, and the effects of the doped local environment on the Ir SACs were investigated. In the second part of the study, MgO(100) monolayer was modeled as a single-layer film on the Ag(100) and TiN(100) substrates, and the effects of the support systems on the performance of Ir and Rh SACs were analyzed. As a measure of the performance adsorption characteristics of the probe molecule CO was chosen. Adsorption energy, electronic density of states, charge density, and bond order analysis tools were used to characterize CO adsorption. Our results show that adsorption energy/geometry, charge density and bond order values of the Ir/Rh SACs can be affected by both impurity atoms and by the surface atoms which are modified by the impurity atoms or ultrathin film supports. Modified surfaces affected the SACs performances at different levels, these differences were reflected in the adsorption energy/geometry and bond length values of the CO molecule. Hybrid electronic states formed by the Ir/Rh, heteroatoms, and surface oxygen atoms near the Fermi energy level were observed to both alter the occupied and unoccupied electronic states of the CO molecule. The study provides a comprehensive investigation in terms of catalytic performance tuning of SACs by examining the differences and common aspects of various SACs systems.

Subject Keywords

Single atom catalysts, Surface modifications, Impurity atoms, Ultrathin film, Ir metal atom, Rh metal atom, Metal support interaction

URI

https://hdl.handle.net/11511/102554

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

AB initio modelling of materials proper ties for catalytic and device applications Şensoy, Mehmet Gökhan; Toffoli, Hande; Toffoli, Daniele; Department of Physics (2017) The first-principles computations based on density functional theory is used to study the adsorption properties and the activation of CO, CO2 and H2O on gamma-Al2O3(100) surface. A systematic study has been conducted to identify the most stable adsorption sites for both mono- and di-atomic Pt clusters. Several stable adsorption geometries have been identified for the species as well as introduces their interaction with Pt clusters and the support. In this context, analysis of the adsorption properties allow...
In situ atom trapping of Bi on W-coated slotted quartz tube flame atomic absorption spectrometry and interference studies KILINÇ, ERSİN; BAKIRDERE, Sezgin; AYDIN, FIRAT; Ataman, Osman Yavuz (2013-11-01) Analytical performances of metal coated slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) and slotted quartz tube in situ atom trapping flame atomic absorption spectrometry (SQT-AT-FAAS) systems were evaluated for determination of Bi. Non-volatile elements such as Mo, Zr, W and Ta were tried as coating materials. It was observed that W-coated SQT gave the best sensitivity for the determination of Bi for SQT-FAAS and SQT-AT-FMS. The parameters for W-coated SQT-FAAS and W-coated SQT-AT-FAAS ...
First principles investigation of hydrogen storage in intermetallic systems Kınacı, Alper; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2007) The design and production of efficient metal-hydrides for hydrogen storage is a long standing subject. Over the years, many different types of intermetallic hydride systems were studied and some of them came out to be operable. However, none of them meet all the storage criteria perfectly. In this study, total energies, hydrogen storage capacity and stability of AB (A = Al, Be, Cu, Fe, Ni, Sb, V and B = Ti) type intermetallics were investigated with the goal of spotting a potential hydrogen storage material...
Surface energy and excess charge in (1x2)-reconstructed rutile TiO2(110) from DFT plus U calculations Unal, Hatice; METE, ERSEN; Ellialtıoğlu, Süleyman Şinasi (2011-09-09) Physically reasonable electronic structures of reconstructed rutile TiO2(110)-(1x2) surfaces were studied using density functional theory (DFT) supplemented with Hubbard U on-site Coulomb repulsion acting on the d electrons, the so called DFT + U approach. Two leading reconstruction models proposed by Onishi and Iwasawa [Surf. Sci. Lett. 313, 783 (1994)] and Park and coworkers [Phys. Rev. B 75, 245415 (2007)] were compared in terms of their thermodynamic stabilities.
Design optimization of rocket nozzles in chemically reacting flows Yumusak, M.; Eyi, Sinan (2012-07-30) The objective of this study is to develop a reliable and efficient design tool that can be used in chemically reacting flows. The flow analysis is based on the axisymmetric Euler and the finite rate chemical reaction equations. The finite rate chemistry model includes eight species and eleven reaction equations. These coupled equations are solved by using Newton's method. Both the numerical and the analytical methods are used to calculate the Jacobian matrices. Sensitivities are evaluated by using the adjoi...

Citation Formats

A. Kallem, “Ab initio modelling and investigation of the effects of magnesium oxide surface modifications on single atom catalysis systems,” M.S. - Master of Science, Middle East Technical University, 2023.