표제지
목차
Abstract 9
1. Introduction 11
2. Computational Details 18
3. Result and Discussion 23
3.1. Reaction pathways for steam methane reforming on Ni catalysts 23
3.2. Mechanisms of electrolyte (Na) poisoning 30
3.3. Design of Ni-Based Bimetallic alloy catalysts 40
3.4. Descriptor-Based catalyst screening 56
3.5. Analysis of catalytic activity 60
4. Conclusions 67
Appendix 68
References 73
Table 1. Structure and total energy of all SMR intermediates calculated by gas phase molecule optimization. 25
Table 2. Adsorption energy(△Eads) of all SMR adsorbates on 3×3 Ni(2 1 1).[이미지참조] 26
Table 3. Reaction Energy(△Er) and activation energy(△Ea) of SMR on 3×3 Ni (2 1 1).[이미지참조] 28
Table 4. Adsorption energy(△Eads) of all SMR adsorbates on electrolyte (Na) poisoned 3×3 Ni(2 1 1).[이미지참조] 37
Table 5. Reaction energy(△Er) and activation energy(△Ea) of SMR on electrolyte (Na) poisoned 3×3 Ni (2 1 1) surface.[이미지참조] 38
Table 6. Hierarchical Structures and surface energy of Ni₃M(2 1 1) catalyst. 44
Table 7. Adsorption energy(△Eads) of all SMR adsorbates on 3×6 Ni(2 1 1).[이미지참조] 46
Table 8. Reaction Energy(△Er) and activation energy(△Ea) of SMR on 3×6 Ni (2 1 1).[이미지참조] 47
Table 9. Energy difference between two Na-poisoned structures(△E₁₋₂, eV/atom) on 3×6 Ni₃M(2 1 1), NiM(2 1 1) alloy. (Electrolyte(Na) coverage=0.75)[이미지참조] 50
Table 10. Adsorption energy(△Eads) of all SMR adsorbates on electrolyte (Na) poisoned 3×6 Ni (2 1 1).[이미지참조] 53
Table 11. Reaction Energy(△Er) and activation energy(△Ea) of SMR on electrolyte (Na) poisoned 3×6 Ni (2 1 1).[이미지참조] 54
Table 12. Activation energy(△Eact) of SMR on electrolyte (Na) poisoned 3×6 Ni(2 1 1), Ni₃Co(2 1 1), Ni₃Cu(2 1 1), Ni₃Zn(2 1 1), NiZn(2 1 1) at 600℃.[이미지참조] 63
Figure 1. Production cost (US$/kg H₂) comparison of the selected hydrogen production options. Steam methane reforming(SMR) is most economical hydrogen production... 13
Figure 2. Combined MCEC cell with internal steam methane reformer that produces the higher purity hydrogen(〉98%) with higher efficiency than SMR. 16
Figure 3. Catalyst structure of 3×3 (a) Ni(1 1 1) (b) Ni(2 1 1). 17
Figure 4. DFT calculation for Schrödinger equation solving. 21
Figure 5. The procedure for solving the Kohn-Sham equation. 22
Figure 6. Most favorable paths of Steam Methane Reforming(SMR) on Ni catalyst. 24
Figure 7. SMR activation diagram at (a) Path 1 and (b) Path 2 on 3×3 Ni(2 1 1) catalyst. 29
Figure 8. Electrolyte adsorption energy(△Eads) and Poisoning structure of (a) Na₂O, (b) NaOH and (c) Na on 3×3 Ni (2 1 1) surface.[이미지참조] 31
Figure 9. Methane(CH₄) decomposition energy diagram on 3×3 Ni (2 1 1) poisoned by (a) Na₂O, (b) NaOH and (c) Na. 33
Figure 10. AIMD simulation of (a) K adsorption (b) Na adsorption on 3×3 Ni (2 1 1) at 600℃. 36
Figure 11. SMR gibbs energy diagram on 3×3 Ni (2 1 1) and electrolyte (Na) poisoned 3×3 Ni (2 1 1) at 600℃. 39
Figure 12. (a) Structure of Ni-M bimetallic bulk alloy (Ni₃M, NiM), (b) 3d, 4d, 5d transition metal, (c) Formation energy(△Eform) of Ni-M bimetallic alloy. 41
Figure 13. (a) structure a, (b) structure b of 3×6 Ni₃M(2 1 1) alloy. 43
Figure 14. Na-poisoned (a) structure 1, (b) structure 2 of 3×6 Ni(2 1 1), Ni₃M(2 1 1) and NiM(2 1 1) alloy. 49
Figure 15. Electrolyte(Na) poisoned(coverage=0.75) surface on (a) 3×3 Ni(2 1 1), (b) 3×6 Ni(2 1 1). 51
Figure 16. SMR gibbs energy diagram on 3×3 Ni (2 1 1) and electrolyte (Na) poisoned Ni (2 1 1) at 600℃. 55
Figure 17. Steam methane reforming(SMR) catalyst screening of Ni-based bimetallic alloy. 58
Figure 18. Slab and electrolyte(Na) poisoned structure of Ni₃M(2 1 1), NiM(2 1 1). 59
Figure 19. Catalyst screening diagram and result. 61
Figure 20. SMR gibbs free energy diagram of Na-poisoned Ni(2 1 1), Ni₃Co(2 1 1), Ni₃Cu(2 1 1), Ni₃Zn(2 1 1) and NiZn(2 1 1) at 600℃. 62
Figure 21. Linear relationship of (a) Activation energy(△Ea) of RDS and Carbon adsorption energy(△Eads) (b) Step site DOS near fermi level and Carbon adsorption...[이미지참조] 65
Figure 22. Density of state(DOS) of step site atoms on (a) Ni₃Co(2 1 1) b, (b) Ni₃Cu(2 1 1) b, (c) Ni₃Zn(2 1 1) b and (d) NiZn(2 1 1) structure. 66
Figure 23. The structure of (a) pure CoS₂, (b) Fe-doped CoS₂, and (c)Fe/F-doped CoS₂. 69
Figure 24. Calculated gibbs free energy change diagrams and side-views of OER on (a) pure CoS₂, (b) Fe-doped CoS₂, and (c)Fe/F-doped CoS₂. 71