Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution
<p>This Thesis is primarily concerned with developing sustainable and cost-efficient methods for applications of hydrogen (H<sub>2</sub>-driven fine chemical synthesis) and production of hydrogen (hydrogen evolution reaction, HER). Using novel catalysts, immobilising these catalyst...
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| Format: | Thesis |
| Language: | English |
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2016
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| _version_ | 1824458710181740544 |
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| author | Zor, C |
| author2 | Grobert, N |
| author_facet | Grobert, N Zor, C |
| author_sort | Zor, C |
| collection | OXFORD |
| description | <p>This Thesis is primarily concerned with developing sustainable and cost-efficient methods for applications of hydrogen (H<sub>2</sub>-driven fine chemical synthesis) and production of hydrogen (hydrogen evolution reaction, HER). Using novel catalysts, immobilising these catalysts, and translating the conventional batch processes to flow processes are the key solutions used for both of these processes.</p> <p>In the first part of this work enzymes are employed as catalysts in fine chemical synthesis. Enzymes are enantio-, regio- and stereoselective, can be used in mild reaction conditions, and can be easily produced in the laboratory. It is possible to electronically couple a hydrogenase to an NAD+ reductase enzyme <em>via</em> conductive carbon particles for NAD<sup>+</sup> to NADH reduction. Thus, enzymes were immobilised on high surface area, porous and electronically conducting commercial carbon particles for H2-driven generation of NADH, an expensive cofactor required by many enzymes to work, in batch. The commercial carbon materials which are conventionally used for metal catalysed hydrogenation reactions were shown to be suitable supports for enzymes used in H<sub>2</sub>-driven biotransformations in batch. In this work, novel carbon nanotube columns (CNCs) were utilised as enzyme supports and flow devices for a range of H<sub>2</sub>-driven biotransformations including ketone reduction and reductive amination reactions. This is the first demonstration of H<sub>2</sub>-driven NADH recycling for selective biotransformations in flow.</p> <p>The second part of this work focuses on HER catalysis. Here, novel WS<sub>2</sub> assemblies were developed as alternatives to expensive and rare platinum catalysts. WS<sub>2</sub> nanostructures were directly grown on multi-wall carbon nanotube (MWCNT) carpets and CNCs for the first time. Preliminary electrochemical studies showed that these assemblies are suitable to be used as HER catalysts, although they require a significant overpotential. This is a promising proof-of-concept demonstration of WS<sub>2</sub>-MWCNT assemblies being used in HER catalysis. A possible future extension of this work would involve using these assemblies in flow.</p> |
| first_indexed | 2024-03-07T01:21:15Z |
| format | Thesis |
| id | oxford-uuid:906cecaf-7470-46aa-8e5b-87bdf4b9455e |
| institution | University of Oxford |
| language | English |
| last_indexed | 2025-02-19T04:30:13Z |
| publishDate | 2016 |
| record_format | dspace |
| spelling | oxford-uuid:906cecaf-7470-46aa-8e5b-87bdf4b9455e2025-01-02T10:12:19ZDedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolutionThesishttp://purl.org/coar/resource_type/c_bdccuuid:906cecaf-7470-46aa-8e5b-87bdf4b9455eNanostructured materialsBiocatalysisHydrogenation ChemistryHydrogen EconomyEnglishORA Deposit2016Zor, CGrobert, NVincent, KDillon, F<p>This Thesis is primarily concerned with developing sustainable and cost-efficient methods for applications of hydrogen (H<sub>2</sub>-driven fine chemical synthesis) and production of hydrogen (hydrogen evolution reaction, HER). Using novel catalysts, immobilising these catalysts, and translating the conventional batch processes to flow processes are the key solutions used for both of these processes.</p> <p>In the first part of this work enzymes are employed as catalysts in fine chemical synthesis. Enzymes are enantio-, regio- and stereoselective, can be used in mild reaction conditions, and can be easily produced in the laboratory. It is possible to electronically couple a hydrogenase to an NAD+ reductase enzyme <em>via</em> conductive carbon particles for NAD<sup>+</sup> to NADH reduction. Thus, enzymes were immobilised on high surface area, porous and electronically conducting commercial carbon particles for H2-driven generation of NADH, an expensive cofactor required by many enzymes to work, in batch. The commercial carbon materials which are conventionally used for metal catalysed hydrogenation reactions were shown to be suitable supports for enzymes used in H<sub>2</sub>-driven biotransformations in batch. In this work, novel carbon nanotube columns (CNCs) were utilised as enzyme supports and flow devices for a range of H<sub>2</sub>-driven biotransformations including ketone reduction and reductive amination reactions. This is the first demonstration of H<sub>2</sub>-driven NADH recycling for selective biotransformations in flow.</p> <p>The second part of this work focuses on HER catalysis. Here, novel WS<sub>2</sub> assemblies were developed as alternatives to expensive and rare platinum catalysts. WS<sub>2</sub> nanostructures were directly grown on multi-wall carbon nanotube (MWCNT) carpets and CNCs for the first time. Preliminary electrochemical studies showed that these assemblies are suitable to be used as HER catalysts, although they require a significant overpotential. This is a promising proof-of-concept demonstration of WS<sub>2</sub>-MWCNT assemblies being used in HER catalysis. A possible future extension of this work would involve using these assemblies in flow.</p> |
| spellingShingle | Nanostructured materials Biocatalysis Hydrogenation Chemistry Hydrogen Economy Zor, C Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution |
| title | Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution |
| title_full | Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution |
| title_fullStr | Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution |
| title_full_unstemmed | Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution |
| title_short | Dedicated carbon scaffolds for next generation hydrogenation chemistry and H2 evolution |
| title_sort | dedicated carbon scaffolds for next generation hydrogenation chemistry and h2 evolution |
| topic | Nanostructured materials Biocatalysis Hydrogenation Chemistry Hydrogen Economy |
| work_keys_str_mv | AT zorc dedicatedcarbonscaffoldsfornextgenerationhydrogenationchemistryandh2evolution |