Quasi-homogeneous gold and bimetallic nanoparticle catalysts

The research in this thesis involves the synthesis and characterization of nanoparticle catalysts for oxidation reactions. It includes two projects: 1) polymer-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts for alcohol oxidation reactions, and 2) oxidative stabilities and catalytic activities of thiolate- and dithiolate-protected Au monolayer-protected clusters (MPCs).n the first project, alcohol oxidations under mild conditions using polyvinylpyrrolidone (PVP)-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts in aqueous solutions have been investigated. The catalytic activities of the nanoparticles towards the oxidation of benzyl alcohol, 1-butanol, 2-butanol, 2-buten-1-ol and 1,4-butanediol indicate that bimetallic 1:3 Au:Pd nanoparticles have higher catalytic activities than Au, Pd and other bimetallic AuPd nanoparticles, and that selectivities towards specific products can often be tuned using bimetallic particles. In addition, advantages and disadvantages for the use of such nanoparticle catalysts as mild, environmentally-friendly oxidation catalysts have been examined. This work has recently been published in the Journal of Catalysis.In the second project, 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs have been synthesized and their thermal stability, oxidative stability in the presence of oxygen and cyanide anions have been studied. These systematic investigations reveal the stability of Au MPCs can be tuned by choosing different thiolate ligands and oxidation conditions. Partially-oxidized thiolate-protected Au MPCs which have substrate-accessible surfaces and are stabilized by residual thiolate ligands show indications they will be promising catalysts. The catalytic activities of 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs for catalytic 4-nitrophenol reduction with sodium borohydride were investigated, and all the Au MPCs showed high catalytic activity for this reaction