Synthesis of Catalysts for Energy Application
| dc.contributor.advisor | Ran, Jingrun | |
| dc.contributor.advisor | Kwong, Philip | |
| dc.contributor.author | Talebian Kiakalaieh, Amin | |
| dc.contributor.school | School of Chemical Engineering | |
| dc.date.issued | 2025 | |
| dc.description.abstract | Undoubtedly, the utilization of renewable and carbon-free energy resources is vital to address the rising global energy demand and environmental concerns. In this regard, one of the most environmentally friendly approaches is the photocatalytic process for the direct generation of value-added chemicals and fuels from sustainable solar energy. Realistic applications of this technique rely on the development of high activity, stable, and cheap photocatalysts. Although no ideal photocatalyst has yet been successfully synthesized and applied in large-scale applications, tremendous advancements in materials science, nanotechnology, and the insightful understanding of reaction mechanisms in this area have been achieved over the last few decades. The emergence and application of various advanced in situ characterization techniques to achieve element-, space-, and time-resolved information on charge carrier kinetics is of crucial significance. Most importantly, the atomic scale engineering of photocatalysts is reported as one of the vital approaches to accelerate charge carrier separation and transport, which is considered the bottleneck of the photocatalysis process, to achieve maximum efficiency and selectivity. This thesis focuses on the development of highly active and robust photocatalysts for the sustainable conversion of diverse feedstocks into clean energy and high-value chemicals. The significance, objectives, and scope of this thesis are reported in Chapter 1. Chapter 2 provides a critical review on recent progress and advancements in single atom photocatalysts for photoexcited holes extraction. This review critically investigates the impact of various crucial factors, such as the importance of various metal single atoms and the interaction of active single atoms sites with each other and with support material, on the photocatalyst’s efficiency and selectivity. Additionally, they provide an in-depth discussion of various advanced ex-situ and in-situ characterization techniques. Chapter 3 focuses on the synthesizing of high-performance Ru atom incorporated CdS quantum dots (QDs) using an in situ hot-injection route. The optimized photocatalyst (Ru0.1) exhibits excellent photocatalytic benzyl alcohol conversion rates of H2O2 (8.78 mmol g−1 h−1) and benzaldehyde (11.70 mmol g−1 h−1), respectively. Four different in situ characterization techniques demonstrate that under realistic conditions, the incorporated Ru atoms, with a high oxidation state (+3), effectively attract photo-generated electrons from the bulk to the overall surface of Ru0.1. These directed electron flows also greatly facilitate the transfer of photo-generated holes from the bulk to the surface of Ru0.1, thereby efficiently reducing electron-hole recombination. Furthermore, in situ diffuse reflectance infrared fourier transform spectroscopy, electron spin spectroscopy, and species-trapping experiments reveal possible reaction pathways for H2O2 evolution. Chapter 4 reports the synthesis of an atomic-scale defected HfS2 nanosheets (NSs) combined with CdS nanoparticles (NPs) to form the HfS2-CdS photocatalyst for hydrogen evolution in triethanolamine (5971 μmol g−1h−1) and benzyl alcohol (2419 μmol g−1h−1) aqueous solutions. Various state-of-the-art characterization techniques reveal element-, space-, and time-resolved electron/hole kinetics in HfS2-CdS composites, disclosing that atomic-scale sulphur vacancies (Vs) temporarily trap electrons, thereby facilitating spatiotemporal electron–hole separation and transfer. This work paves the way for the atomic-scale design and synthesis of new 2D-materials-based photocatalysts for sunlight utilization. Chapter 5 introduces an atomically engineered GeS NS/ZnIn2S4 photocatalyst for the direct transformation of raw polyethylene terephthalate (PET) into a variety of organic chemicals (13917μmol g−1) using Earth’s most abundant resources: sunlight, seawater, and air. Advanced ex situ and in situ characterization analyses reveal that sulphur vacancies (Vs) and the electrolyte-assisted polarization effect of seawater play crucial roles in trapping photogenerated electrons and accelerating charge carrier separation, respectively. These effects significantly enhance photocatalytic plastic upcycling efficiency and improve oxidative organic reactions. Chapter 6 exhibits the application of a novel floatable artificial leaf concept using a Ru single-atom loaded ZnIn2S4 photocatalyst (ZIS/R1) for the direct conversion of raw polypropylene (PP) into different value-added chemicals, such as formic acid and acetic acid. Advanced in-situ characterization analyses reveal that Ru single atoms act as a pump, extracting photoexcited electrons from the bulk photocatalyst to the surface and accelerating charge carrier separation. Finally, conclusions, perspectives, and future outlooks are presented in Chapter 7. | |
| dc.description.dissertation | Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2025 | en |
| dc.identifier.uri | https://hdl.handle.net/2440/146362 | |
| dc.language.iso | en | |
| dc.provenance | This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals | en |
| dc.subject | Photocatalysis | |
| dc.subject | single atom catalyst | |
| dc.subject | plastic upcycling | |
| dc.subject | Hydrogen generation | |
| dc.subject | defect engineering | |
| dc.title | Synthesis of Catalysts for Energy Application | |
| dc.type | Thesis | en |
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