This thesis investigates the synthesis and activation of highly monodisperse Au25(SR)18
-
clusters and bimetallic clusters (AuAg and AuPd) protected with various stabilizers for reduction
and hydrogenation catalytic reactions. The first chapter is the introduction chapter, which
summarizes the literature involving monolayer protected Au clusters, atomically precise Au
clusters, bimetallic clusters, X-ray absorption spectroscopy, research objectives, and organization
and scope. The second chapter describes the synthesis of Au25(SR)18
- clusters protected with
various thiolate stabilizers for nitrophenol reduction catalysis using NaBH4 as a reducing agent.
This chapter also describes the stability of these clusters under reaction conditions using UV-Vis
spectroscopy and MALDI mass spectrometry. The third chapter details the synthesis of carboxylic
acid-protected Au25 clusters using a NaBH4 purification strategy. Here, the knowledge obtained in
the second chapter regarding the exceptional stability of Au25(SR)18
- clusters in the presence of
NaBH4 was used to isolate carboxylic acid protected Au25 clusters from a polydisperse reaction
mixture. The fourth chapter describes the synthesis and activation of mesoporous carbon supported
Au25(SR)18
- clusters for nitrophenol reduction catalysis. Here, thermal removal of thiolate
stabilizers led to the enhancement in the catalytic activity at low calcination temperatures;
however, at higher calcination temperatures activity dropped as particle sintering was observed.
Activation of these clusters on mesoporous carbon support was followed by TEM and X-ray
absorption spectroscopy. The fifth chapter describes the thermal and chemical removal of thiolate
stabilizers from supported Au25(SC8H9)18
- clusters. Here, the removal of thiolate stabilizers and
subsequent growth of Au25 clusters was followed by TEM and EXAFS spectroscopy. The sixth
and seventh chapters describe the synthesis of AuPd and AuAg bimetallic clusters using
Au25(SR)18
- clusters as precursors and their characterization using UV-Vis spectroscopy,
transmission electron microscopy, and X-ray absorption spectroscopy. Here, AuPd bimetallic
clusters were thermally and chemically treated, which resulted in the formation of AuPd bimetallic
nanoparticles with segregated Pd atoms on the surface. AuPd bimetallic nanoparticles were used
for the selective hydrogenation catalysis of allyl alcohol. The last chapter of this thesis includes
final conclusions and possible avenues for future work.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2015-09-2227 |
| Date | 2015 September 1900 |
| Contributors | Scott, Robert W. J. |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
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