Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction
In the first part of the thesis, a series of first row transition metal complexes have been synthesized in order to study their mechanism and efficiency as a H2 evolution catalyst. The H2 produced can served as an alternative clean fuel to tackle the issue on climate change. A comprehensive chara...
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| Other Authors: | |
| Format: | Thesis-Doctor of Philosophy |
| Language: | English |
| Published: |
Nanyang Technological University
2020
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| Online Access: | https://hdl.handle.net/10356/139947 |
| _version_ | 1811684264631074816 |
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| author | Ho, Xian Liang |
| author2 | Richard D. Webster |
| author_facet | Richard D. Webster Ho, Xian Liang |
| author_sort | Ho, Xian Liang |
| collection | NTU |
| description | In the first part of the thesis, a series of first row transition metal complexes
have been synthesized in order to study their mechanism and efficiency as a H2
evolution catalyst. The H2 produced can served as an alternative clean fuel to tackle the
issue on climate change. A comprehensive characterisation of the electrochemical and
spectroscopic properties of these complexes has been performed. The efficiency and
the mechanism of these materials and complexes have been studied.
In Chapter 3, the effects of the first coordination sphere on H2 evolution was
explored. A new Co and Ni tetraamido macrocyclic ligand (TAML) complexes were
synthesised and their reactivity for electrocatalytic proton reduction were studied. The
metal complexes have been extensively characterized with various spectroscopic
techniques. The Co TAML complex appeared to be active for electrocatalytic H2
evolution initially. However, detailed mechanistic studies revealed that Co
nanomaterials were responsible for the catalysis.
In Chapter 4, the effect of the second coordination sphere modification on H2
evolution activity was explored. An active Ni salicylaldimine catalyst was synthesized
and found to be able to incorporate into a molecular photocatalytic H2 evolution system
with [IrIII(ppy)2(dtbbpy)(]PF6) (ppy = 2-phenylpyridinato; dtbbpy = 4,4’-di-tert-butyl-
2,2’-bipyridine, [Ir]+) as a light-harvester and triethylamine (TEA) as a sacrificial
electron donor and reductive quencher. This new Ni complex possess a pair of
peripheral ether arms in the second coordination sphere of the molecule. Various
spectroscopic techniques such as nanosecond transient absorption spectroscopy (TAS),
transient emission spectroscopy (TES) and, electron paramagnetic resonance (EPR),
supported by intermediate isolation studies and density functional theory (DFT)
calculations suggest the possible influence of balancing ligand redox noninnocence and
second coordination sphere effects to effect H2 evolution activity.
In the second part of the thesis, the surface modification on oxide-derived
copper (OD-Cu) and its influence on the products distribution of CO2 reduction on Cu
were investigated. In Chapter 6 of the thesis, it was found that the majority of the
crystal facets in the polycrystalline OD-Cu can dictate the major products formed and
can greatly reduce the overpotentials for CO2 reduction. |
| first_indexed | 2024-10-01T04:25:52Z |
| format | Thesis-Doctor of Philosophy |
| id | ntu-10356/139947 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T04:25:52Z |
| publishDate | 2020 |
| publisher | Nanyang Technological University |
| record_format | dspace |
| spelling | ntu-10356/1399472023-02-28T23:40:49Z Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction Ho, Xian Liang Richard D. Webster School of Physical and Mathematical Sciences webster@ntu.edu.sg Science::Chemistry In the first part of the thesis, a series of first row transition metal complexes have been synthesized in order to study their mechanism and efficiency as a H2 evolution catalyst. The H2 produced can served as an alternative clean fuel to tackle the issue on climate change. A comprehensive characterisation of the electrochemical and spectroscopic properties of these complexes has been performed. The efficiency and the mechanism of these materials and complexes have been studied. In Chapter 3, the effects of the first coordination sphere on H2 evolution was explored. A new Co and Ni tetraamido macrocyclic ligand (TAML) complexes were synthesised and their reactivity for electrocatalytic proton reduction were studied. The metal complexes have been extensively characterized with various spectroscopic techniques. The Co TAML complex appeared to be active for electrocatalytic H2 evolution initially. However, detailed mechanistic studies revealed that Co nanomaterials were responsible for the catalysis. In Chapter 4, the effect of the second coordination sphere modification on H2 evolution activity was explored. An active Ni salicylaldimine catalyst was synthesized and found to be able to incorporate into a molecular photocatalytic H2 evolution system with [IrIII(ppy)2(dtbbpy)(]PF6) (ppy = 2-phenylpyridinato; dtbbpy = 4,4’-di-tert-butyl- 2,2’-bipyridine, [Ir]+) as a light-harvester and triethylamine (TEA) as a sacrificial electron donor and reductive quencher. This new Ni complex possess a pair of peripheral ether arms in the second coordination sphere of the molecule. Various spectroscopic techniques such as nanosecond transient absorption spectroscopy (TAS), transient emission spectroscopy (TES) and, electron paramagnetic resonance (EPR), supported by intermediate isolation studies and density functional theory (DFT) calculations suggest the possible influence of balancing ligand redox noninnocence and second coordination sphere effects to effect H2 evolution activity. In the second part of the thesis, the surface modification on oxide-derived copper (OD-Cu) and its influence on the products distribution of CO2 reduction on Cu were investigated. In Chapter 6 of the thesis, it was found that the majority of the crystal facets in the polycrystalline OD-Cu can dictate the major products formed and can greatly reduce the overpotentials for CO2 reduction. Doctor of Philosophy 2020-05-22T13:10:44Z 2020-05-22T13:10:44Z 2020 Thesis-Doctor of Philosophy Ho, X. L. (2020). Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/139947 10.32657/10356/139947 en This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). application/pdf Nanyang Technological University |
| spellingShingle | Science::Chemistry Ho, Xian Liang Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction |
| title | Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction |
| title_full | Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction |
| title_fullStr | Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction |
| title_full_unstemmed | Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction |
| title_short | Development of molecular catalysts for H2 evolution and modified copper catalyst for CO2 reduction |
| title_sort | development of molecular catalysts for h2 evolution and modified copper catalyst for co2 reduction |
| topic | Science::Chemistry |
| url | https://hdl.handle.net/10356/139947 |
| work_keys_str_mv | AT hoxianliang developmentofmolecularcatalystsforh2evolutionandmodifiedcoppercatalystforco2reduction |