THEORETICAL STUDY OF H2O2 ADSORPTION ON Fe- AND N-DOPED (TiO2)5 , (TiO2)6 NANOCLUSTERS

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Chapter 1: Introduction

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1-1) Nanomaterials

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1-2) TiO₂ Compounds

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1-3) Doping

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   1-3-1) Cation-Doped TiO₂

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   1-3-2) Anion-Doped TiO₂

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1-4) Objectives of the Present Thesis

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Chapter 2:Literature Review

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Chapter 3:Theoretical Background

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3-1) Density Functional Theory (DFT)

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3-2) Hybrid Functionals

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   3-2-1) B3LYP Methods

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3-3) Basis Sets

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   3-3-1) Double Zeta Basis Set

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   3-3-2) Polarization Basis Functions

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   3-3-3) Basis Set Superposition Errors (BSSEs)

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3-4) Theory of Atoms in Molecules (AIM)

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3-5) Natural Bond Orbitals (NBO)

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3-6) Density of State

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3-7) Computational Details of the Present Research

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Chapter 4:Results and Discussion

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4-1) (TiO₂)_n n=5,6 Nanoclusters

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4-1-1) Structural Optimization

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   4-1-2) Formation Energy

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   4-1-3) Electronic Structures of Doped (TiO₂)_n n=5,6

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4-2) Interaction of (TiO₂)_n n=5,6 Nanoclusters with Hydrogen Peroxide

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   4-2-1) Geometrical Structures

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   4-2-2) Interaction Energies of the Complexes

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   4-2-3) Atoms in Molecules Topological Parameters of the Complexes

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   4-2-4) Natural Bond Orbital (NBO) Analysis

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4-3) Conclusions

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References

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Appendix

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Abstract and Title page in Persian

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Table 4.1 Structural data of doped (TiO₂)₅ nanoclusters;

            spin  multiplicity, dipole moment and average bond lengths (d_av)

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Table 4.2 Structural data of doped (TiO₂)₆ nanoclusters;

spin multiplicity, dipole moment and Average bond lengths (d_av)

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Table 4.3Formation energy of (TiO₂)_n n=5,6 for different position

of dopant atoms. ( eV)

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Table 4.4 HOMO and LUMO energies of pure and doped nanoclusters, HOMO-LUMO energy gap (E_g), Fermi energy (E_fermi)

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Table 4.5 Bond length between titanium and oxygen of H₂O₂ (d_Ti-O), oxygen of cluster and hydrogen of H₂O₂ (d_O-H), oxygen and oxygen in H₂O₂ (d_O-O), bond angles of  oxygen-hydrogen-oxygen (∠OHO), and dihedral angle of H₂O₂ in most stable complexes as well as isolate H₂O₂

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Table 4.6 Adsorption energies (DE_ad) as well as the

counterpoise corrected interaction energies (DE_corr) and the BSSE

values for most stable complexes (all values are in kcal mol^-1 )

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Table 4.7 Calculated adsorption energies for N-, Fe-doped and undoped (TiO₂)_n n=5,6 nanoclusters. (kcal mol^-1)

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Table 4.8Topological parameters at BCP of O…M (M= Fe,Ti) and H…X (X= O,N ). Parameters: ρ ( r ),electron density; Ѳ ρ ( r ), Laplacian; H ( r ), electron energy density; and – , ratio of potential to kinetic electron energy density. (au)

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Table 4.9Correlation between electron density and Ti…O and H…O bonds which has created in adsorption site

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Table 4.10 Charge transfer (CT, e)  and NBO second-order interaction energy (E², kcal mol^-1)  for the corresponding donor-acceptor orbital interactions of H₂O₂ adsorption on N-doped (TiO₂)_n  n=5,6 nanoclusters

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Table 4.11 Charge transfer (CT, e)  and NBO second-order interaction energy (E², kcal mol^-1)  for the corresponding donor-acceptor orbital interactions of H₂O₂ adsorption on Fe-doped (TiO₂)_n  n=5,6 nanoclusters

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Fig4-1) Different position for doping in pure (TiO₂)_n n=5,6nano-

clusters. The letters b, t, and f denote bridge, terminal and

              front sites, respectively

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Fig 4-2) Optimized geometries of Fe- and N-doped (TiO₂)₅ nanoclusters. The blue atom belong to nitrogen, green for iron, grey for titanium and red for oxygen

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Fig 4-3) Optimized geometries of Fe- and N-doped (TiO₂)₆ nanoclusters. The blue atom belong to nitrogen, green for iron, grey for titanium and red for oxygen

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Fig 4-4)Variation of formation energy forpure and doped (TiO₂)_n n=5,6 nanoclusters

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Fig 4-5) The schematic digram of the mechanism of the N- and Fe-doped (TiO₂)_n n=5,6 nanoclusters. e and h refer to electron and hole, respectively

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Fig 4-6)HOMO visualization (left) and total density of states (right) of (TiO2)_n n=5,6 nanostructures. The dashed line represents the position of the Fermi level. The DOS of undoped cluster,N-dopedandFe-doped are shown by Black, blue and red curves, respectively

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Fig 4-7)Natural charge distribution of the undoped and Fe-

               doped (TiO₂)_n  n=5,6 nanoclusters

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Fig 4-8)Most stable optimized geometries for the interaction of Fe-doped (TiO₂)₅  and pure nanoclusters with H₂O₂

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Fig 4-9)Most stable optimized geometries for the interaction of N-doped (TiO₂)₅  and pure nanoclusters with H₂O₂

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Fig 4.10)Most stable optimized geometries for the interaction of Fe-doped (TiO₂)₆  and pure nanoclusters with H₂O₂

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Fig 4.11)Most stable optimized geometries for the interaction of

N-doped (TiO₂)₆  and pure nanoclusters with H₂O₂

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Fig 4.12)Relationship of the electron density with Ti…O and H…O bond distance

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