Alfons Baiker

Bio: Alfons Baiker is an academic researcher from ETH Zurich. The author has contributed to research in topics: Catalysis & Enantioselective synthesis. The author has an hindex of 83, co-authored 978 publications receiving 42903 citations. Previous affiliations of Alfons Baiker include University of Vienna & Paul Scherrer Institute.

Oxidation of Alcohols with Molecular Oxygen on Solid Catalysts

Abstract: ion from a primary OH group of glyc-erol. 223,231 A similar mechanism was proposed manyyears ago for alcohol oxidation on Pt/C, involving asecond step, the transfer of a hydride ion to the Ptsurface (Scheme 11). 8,87,237 We consider it more feasible that the rate-deter-mining step is the cleavage of the C-H bond at theR-carbon atom. A similar mechanism is now generallyaccepted for Au electrodes (Scheme 12). 238 Despite thestructural differences between Au nanoparticles andan extended Au electrode surface, there are alsosimilarities, such as the critical role of aqueousalkaline medium and the absence of deactivation dueto decomposition products (CO and C x H y frag-ments). 239,240 An important question is the nature of active siteson Au nanoparticles. Electrooxidation of ethanol onAu nanoparticles supported on glassy carbon re-quired the partial coverage of Au surface by oxides. 241 Another analogy might be the model proposed for COoxidation. 219,242,243 According to this suggestion, theactive site consists of an ensemble of metallic Auatoms and a cationic Au

A new hydrosol of gold clusters. 1. Formation and particle size variation

Abstract: Aqueous reduction of hydrogen tetrachloroaurate(III) with alkaline tetrakis(hydroxymethyl)phosphonium chloride yields gold in an ultrafinely divided form as a stable colloidal hydrosol, with mean metal-cluster diameter between 1 and 2 nm, without the need for large organic stabilizing molecules. The ultraviolet-visible extinction spectrum is very similar to those of other gold colloids of similar dimensions and includes a weak plasmon feature. Dispersions with characteristics of yet finer clusters are prepared using lower initial concentrations of Au3+ ions. Boiling the sols in the presence of appropriate colloidal stabilizers (ionic and/or polymeric) is a route to coarser (3-10 nm particle diameter) gold hydrosols. © 1993 American Chemical Society.

NOx Storage−Reduction Catalysis: From Mechanism and Materials Properties to Storage−Reduction Performance

Abstract: 4.1. Noble Metals 4058 4.1.1. Platinum 4059 4.1.2. Palladium 4060 4.1.3. Bimetallic Systems 4060 4.2. Storage Components 4061 4.2.1. Earth Alkaline Metals 4061 4.2.2. Alkali Metals 4065 4.3. Supports 4065 4.3.1. Single Oxides 4065 4.3.2. Mixed Oxides 4067 4.4. Promoters 4069 4.5. Preparation Methods 4071 4.6. Influence of Remote Control 4073 5. Influence of Exhaust Gas Composition 4074 5.1. Reducing Gas 4074 5.2. Water 4077 5.3. Carbon Dioxide 4077 5.4. Impact of Soot 4079 6. Theoretical and Surface Science Studies 4079 6.1. Theoretical Studies 4079 6.2. Studies on Well-Defined Model Catalysts 4082 7. Reactor Configuration 4082 8. Conclusions and Outlook 4086 9. Acknowledgments 4087 10. References 4087

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

The Chemistry and Applications of Metal-Organic Frameworks

Abstract: Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.