Title Page
Abstract
Contents
Chapter 1. Overview: Synthesis of noble metal-based intermetallic nanomaterials for electrocatalysis 22
1.1. Noble metal-based intermetallic nanomaterials for electrocatalysis 22
1.2. Synthesis of Pt-based intermetallic nanomaterials 26
1.3. Synthesis of Pd-based and Au-based intermetallic nanomaterials 40
1.4. Dissertation overview 45
1.5. References 48
Chapter 2. Solid-state synthesis of platinum-alloy nanoparticles for oxygen reduction reaction 64
2.1. Introduction 64
2.2. Methods 68
2.3. Results and discussion 74
2.4. Conclusion 118
2.5. References 119
Chapter 3. Practical large-scale synthesis of Pt-Conanoparticles for proton-exchange-membrane fuel cells 130
3.1. Introduction 130
3.2. Methods 133
3.3. Results and discussion 139
3.4. Conclusion 190
3.5. References 192
Bibliography 205
국문 초록 207
Table 2.1. The atomic ratio of Fe and Pt elements in Fe-Pt compound measured by STEM-EDS at five sites. 115
Table 2.2. Comparison of ORR activities of the prepared FePt/rGO catalysts with literature. 116
Table 2.3. The atomic ratio of Co (or Ni) and Pt elements in Co-Pt and Ni-Pt compounds measured by STEM-EDS at three sites. 117
Table 3.1. The atomic ratio of Co and Pt elements in Co-Pt compound measured by STEM-EDS at three sites. 187
Table 3.2. Measured Co:Pt atomic ratios and the Pt loadings of i-CoPt/KB and i-CoPt@Pt/KB by ICP-AES. 188
Table 3.3. Comparison of Pt loadings, MEA mass activities at 0.9 V in H₂-O₂conditions, and the MEA power performances in H₂-air conditions of i-... 189
Figure 1.1. Illustrative images of noble metal-based (a) random alloy, (b) intermetallic alloy, (c) core-shell structure, (d) single-atom alloy, (e) high... 25
Figure 1.2. (a-b) TEM images of the assembled 6 nm-sized PtFe nanoparticles, and (c) XRD patterns of the annealed PtFe nanoparticles with a phase... 33
Figure 1.3. (a) Schematic illustration of the synthesis of L10-FePt nanoparticles by MgO-coating approach....[이미지참조] 34
Figure 1.4. (a) Schematic illustration, and (b) XRD patterns of the thermal evolution of the atomic structure of PtFeAu nanoparticles upon annealing. 35
Figure 1.5. (a) TEM image of PtCo random-alloy nanoparticles. (b) Schematic, and (c) STEM images of an atomically ordered L10-PtCo...[이미지참조] 36
Figure 1.6. (a) STEM image, and (b) XRD pattern of annealed intermetallic PtNiN/KB sample. 37
Figure 1.7. (a) Schematic illustration of the synthesis of L1₂-Pt₃Co nanowires by template-mediated method, and (b) their TEM (top) and HAADF-STEM... 38
Figure 1.8. (a) HAADF-STEM, and high resolution TEM (inset) images of the supported L1₂-Pt₃Co nanoparticles on ZIF-derived carbon Reproduced... 39
Figure 1.9. (a) TEM images of B2-PdCu nanoparticles on carbon support, and A1-PdCu nanoparticles (inset). Reproduced with permission. Copyright... 43
Figure 1.10. (a) TEM images, and (b) XRD patterns of the AuCu nanoparticles with controlled degrees of atomic ordering. 44
Figure 2.1. Schematic illustration of the preparation of Fe-Pt compound by mixing [Fe(bpy)3]2+ complex solution with [PtCl6]2- complex solution.[이미지참조] 81
Figure 2.2. Photographs of (a) FeSO₄ dissolved in water, (b) Fe(bpy)₃SO₄ dissolved in water/ethanol, (c) H2PtCl6 dissolved in ethanol, (d) Fe-Pt...[이미지참조] 82
Figure 2.3. UV-vis absorption spectra of (a) Fe(bpy)₃SO₄, Fe-Pt compound, and H2PtCl6 in water, and (b) Fe-Pt compound continuously diluted in water.[이미지참조] 83
Figure 2.4. (a) XRD patterns, and (b) TEM images for the Fe-Pt compounds obtained from two different pathways. 84
Figure 2.5. (a) TEM image, and (b-d) STEM-EDS mapping of Fe-Pt compound. 85
Figure 2.6. TEM images of Fe-Pt compound annealed under 700 ℃ in Ar atmosphere for 6 h. 86
Figure 2.7. Schematic illustration of the synthesis of L10 -FePt nanoparticles on rGO (FePt/rGO) by thermal decomposition of Fe-Pt compound and...[이미지참조] 87
Figure 2.8. (a) TEM image, and (b) STEM-EDS mapping of the intermediate obtained at 500 ℃. 88
Figure 2.9. (a) XRD patterns, and (b) FTIR data of composite ([Fe(bpy)3][PtCl6]/GO), intermediate (at 500℃), and FePt/rGO.[이미지참조] 89
Figure 2.10. Ex situ TEM images of the samples annealed up to several different temperature. 90
Figure 2.11. Ex situ XRD data of the samples annealed up to several different temperature. 91
Figure 2.12. SEM images of (a-b) composite ([Fe(bpy)3][PtCl6]/GO), and (c-d) FePt/rGO. Scale bar: 1μm.[이미지참조] 92
Figure 2.13. TEM images of (a) composite ([Fe(bpy)3][PtCl6]/GO), and (b) FePt/rGO.[이미지참조] 93
Figure 2.14. (a) STEM image (bright-field), and (b) TEM image of N-doped carbon shells on FePt nanoparticles in 37 wt %-FePt/rGO. 94
Figure 2.15. STEM-EDS (a) mapping, and (b) spectrum of 37 wt %-FePt/rGO. 95
Figure 2.16. (a) Powder XRD pattern, and (b) magnetic hysteresis loop of 37 wt %-FePt/rGO. 96
Figure 2.17. (a) HAADF-STEM image of 37 wt %-FePt/rGO (inset: FFT pattern of the image). (b) An enlarged HAADF-STEM image of 37 wt %-... 97
Figure 2.18. TEM images of (a) 24 wt %-, and (b) 37 wt %-FePt/rGO (size distributions of the nanoparticles are shown in the insets). (c) CV curves and... 98
Figure 2.19. CV curve of 37 wt %-FePt/rGO compared to that of GO. 99
Figure 2.20. (a-b) TEM images, and (c) XRD pattern of 37 wt %-FePt/rGO after air etching. 100
Figure 2.21. (a) ORR polarization curves, (b) Tafel plots, (c) ECSA, and (d) mass activities and specific activities of FePt/rGO catalysts compared with... 101
Figure 2.22. Magnetic hysteresis loop of 24 wt %-FePt/rGO. 102
Figure 2.23. ORR activities of 24 wt %-, and 37 wt %-FePt/rGO catalysts compared with literature. 103
Figure 2.24. CV curves of commercial Pt/C, 24 wt %-, and 37 wt %-FePt/rGO before and after ADT cycling. 104
Figure 2.25. (a) ORR polarization curves, (b) Tafel plots, (c) ECSA, and (d) mass activities and specific activities before and after ADT cycling for the... 105
Figure 2.26. TEM images of 37 wt %-FePt/rGO after ADT cycling. 106
Figure 2.27. STEM image (left), and EDS mapping data (right) of 37 wt %-FePt/rGO after ADT cycling. 107
Figure 2.28. TEM, and STEM-EDS data of (a) Ni-Pt compound, and (b) Co-Pt compound. 108
Figure 2.29. TEM, and STEM-EDS data of (a-b) NiPt/rGO, and (c-d) CoPt/rGO. 109
Figure 2.30. (a) Powder XRD patterns, and (b) ORR polarization curves of NiPt/rGO and CoPt/rGO. 110
Figure 2.31. Mass activities of NiPt/rGO, and CoPt/rGO compared to FePt/rGO, and commercial Pt/C at (a) 0.9 V and (b) 0.95 V. 111
Figure 2.32. TEM images and STEM-EDS mappings of [Fe(terpy)2][PtCl6], and [Fe(phen)3][PtCl6] compounds.[이미지참조] 112
Figure 2.33. (a) TEM images, and (b) XRD patterns of FePt/rGO samples prepared by annealing [Fe(terpy)2][PtCl6], and [Fe(phen)3][PtCl6] compounds...[이미지참조] 113
Figure 2.34. TEM images of FePt nanoparticles on various carbon supports prepared by the decomposition of Fe-Pt compound. 114
Figure 3.1. (a) TEM images, and (b) XRD pattern of Co-Pt compound. 148
Figure 3.2. STEM-EDS mapping data of Co-Pt compound. Scale bar 250 nm. 149
Figure 3.3. Photographic images of the mixtures of (a) Co²+ +PtCl62-, and (b) Co(bpy)32+ +PtCl62-.[이미지참조] 150
Figure 3.4. FTIR spectra of KB, bpy, Co-Pt compound, composite, and i-CoPt/KB. 151
Figure 3.5. (a) SEM, (b) TEM, and (c) STEM images of the composite. 152
Figure 3.6. Schematic illustration of the synthesis of i-CoPt/KB by thermal decomposition of Co-Pt compound on KB. 153
Figure 3.7. (a) SEM, and (b) TEM images (with nanoparticle size distribution) of i-CoPt/KB 154
Figure 3.8. XRD pattern of i-CoPt/KB compared with reference peak positions of L10-CoPt and Pt phases.[이미지참조] 155
Figure 3.9. TEM image of the N-doped carbon shells on a i-CoPt nanoparticle 156
Figure 3.10. STEM-EDS mapping data of i-CoPt/KB. 157
Figure 3.11. HAADF-STEM image of a single i-CoPt nanoparticle in i-CoPt/KB. 158
Figure 3.12. (a) Ex situ XRD data for the samples obtained by annealing the composite at different temperatures. (b) The growth mechanism of i-CoPt... 159
Figure 3.13. TEM and STEM images of the ex situ samples obtained by annealing the composite at different temperatures. 160
Figure 3.14. XPS (a) Pt 4f, and (b) Co 2p spectra of the ex situ samples obtained by annealing the composite at different temperatures. 161
Figure 3.15. Schematic illustration of the activation process applied in this study. The atomic arrangement of Co and Pt is marked by blue and gray colors, respectively. 162
Figure 3.16. (a) TEM, and (b) HADDF-STEM images of i-CoPt@Pt/KB. (c) Pt L₃-edge XANES, (d) Pt EXAFS, (e) Co K-edge XANES, and (f) Co... 163
Figure 3.17. TEM images of (a) air-etched i-CoPt/KB, and (b) i-CoPt@Pt/KB and the size distribution of the nanoparticles. 164
Figure 3.18. XRD data for the samples obtained during the activation of i- CoPt/KB into i-CoPt@Pt/KB. 165
Figure 3.19. (a) Pt L₃-edge XANES, (b) Co K-edge XANES, (c) Pt EXAFS, and (d) Co EXAFS data for the samples obtained during the activation of i-... 166
Figure 3.20. XPS (a) Pt 4f, (b) Co 2p, and (c) N 1s data for the samples obtained during the activation of i-CoPt/KB into i-CoPt@Pt/KB. 167
Figure 3.21. (a) Pt EXAFS, and (b) Co EXAFS data of i-CoPt@Pt/KB compared to Pt/C and Co foil, respectively. 168
Figure 3.22. HAADF-STEM image (left), and the line profile of the outermost layer along the [112] direction (right) of i-CoPt@Pt/KB.[이미지참조] 169
Figure 3.23. XPS (a) Co 2p spectra, and (b) the derived Co/Pt ratio in i-CoPt@Pt/KB by varying incident photon energy from 880 to 1280 eV. 170
Figure 3.24. (a) Photograph of i-CoPt/KB powder synthesized in gram scale. TEM images of (b) i-CoPt/KB synthesized in gram scale, and (c) its activated... 171
Figure 3.25. (a) Half-cell CV curves of i-CoPt@Pt/KB, i-CoPt/KB, and commercial Pt/C. (b) Comparison of ECSA values of i-CoPt@Pt/KB and Pt/C... 172
Figure 3.26. CO stripping data of (a) Pt/C, and (b) i-CoPt@Pt/KB. (c) ECSA of Pt/C and i-CoPt@Pt/KB obtained from H upd and CO stripping. 173
Figure 3.27. Changes in the CV curves of (a) Pt/C, and (b) i-CoPt@Pt/KB after ADT. 174
Figure 3.28. Changes in the ECSA values of Pt/C and i-CoPt@Pt/KB after ADT. 175
Figure 3.29. Changes in the ORR polarization curves of (a) Pt/C, and (b) i-CoPt@Pt/KB after ADT. 176
Figure 3.30. Comparison of (a) CV curves, and (b) ORR polarization curves of the i-CoPt@Pt/KB samples prepared in the typical scale and gram-scale. 177
Figure 3.31. Optimization of the H₂-air fuel cell performances for (a) Pt/C, and (b) i-CoPt@Pt/KB by different ionomer to carbon ratios, respectively. 178
Figure 3.32. EIS data of i-CoPt@Pt/KB and Pt/C at 0.05 Acm-2 at BOT and EOT[이미지참조] 179
Figure 3.33. H₂-air fuel cell performance of i-CoPt@Pt/KB and Pt/C(150kPaabs) at BOT and EOT.[이미지참조] 180
Figure 3.34. Current densities at 0.8 V (left), and peak power densities (right) of i-CoPt@Pt/KB and Pt/C at BOT and EOT. 181
Figure 3.35. Comparison of the power performance (rated power density and specific rated power at 0.67 V) of i-CoPt@Pt/KB with the recently reported... 182
Figure 3.36. Changes in (a) the CV curves, and (b) ECSAs of i-CoPt@Pt/KB and Pt/C after ADT. 183
Figure 3.37. Changes in the mass activities of i-CoPt@Pt/KB and Pt/C after ADT. 184
Figure 3.38. (a) TEM, and (b) STEM images of i-CoPt@Pt/KB after ADT. 185
Figure 3.39. STEM-EDS data of i-CoPt@Pt/KB after ADT. 186