Welcome to the

Surface Science and Nanocatalysis Research Group

at Lebanon Valley College

 

Current Projects

 

Selectivity Control in Ketone Hydrogenation on Nanoscale Platinum Catalysts

 

Hydrogenations that selectively convert unsaturated ketones to unsaturated alcohols are important catalytic reactions in chemical industries ranging from pharmaceuticals to flavorings.  Optimizing selectivity for these reactions requires detailed understanding of various parameters at a molecular-level.  The goal of our research is to understand how reaction conditions, catalyst properties, and reactant substituent groups influence selectivity for this class of chemical reactions.  Colloidal platinum nanoparticles with well-controlled particle sizes are being synthesized in the 1-10 nm size range and characterized using transmission electron microscopy, mass spectrometry, and chemisorption methods.  Aqueous phase hydrogenations are being performed using selected ketones to measure product formation rates as a function of catalyst particle size, reaction conditions, and reactant structures.  This information is being used to determine kinetic parameters such as turnover frequencies, product yields, selectivities, reaction orders, and apparent activation energies.  Additionally, key adsorbed intermediates are being identified using in-situ infrared spectroscopy.  The outcome of this work will be the relation of reaction pathways to product selectivities at a molecular level.  These research activities will increase the understanding of factors which optimize selectivity in catalytic reactions, leading to better design of catalytic materials.  Furthermore, the proposed research plan of synthesis, characterization, and reaction studies combined with in situ spectroscopic measurements will advance the development of catalysts that lead to more environmentally-friendly processes.  This material is based upon work supported by the National Science Foundation under Grant No. 0719160.

 

2.9 nm PVP-Pt Nanocatalyst

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Elementary Photoreactions for the Synthesis of Amino Acids on a Model Interstellar Surface

 

This research project is investigating the role of elementary photoreactions in amino acid formation within the interstellar medium.  For these experiments, we are taking advantage of a model interstellar surface, highly-oriented pyrolitic graphite, and ultrahigh vacuum surface science techniques to determine mechanisms for synthesis of the amino acids glycine, alanine, and serine.  Photoreactions within nanoscale ice films of amino acid precursors are being initiated using 193 nm light from an ArF excimer laser, and product formation is being determined from post-irradiation temperature-programmed desorption.  In addition, the adsorption and photochemical reactivity of the amino acids glycine, alanine, and serine are being investigated.  The results of this work will aid in understanding mechanisms of photoreactions in confined media, particularly those relevant to the origin of biomolecules in the interstellar medium.  This material is based upon work supported by Research Corporation under Cottrell College Science Award No. 7726.

 

 

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Synthesis, Characterization, and Photocatalytic Activity of Zinc sulfide Nanocrystals Capped by Amino Acids

 

Nanocrystals are being synthesized using solution-based colloidal methods as with selected amino acids as capping agents.  The degradation of p-nitrophenol has been used as an initial test reaction to gauge photocatalytic activity as a function of amino acid structure.  For these experiments, solutions of p-nitrophenol and the ZnS nanocrystals capped with the selected amino acid are being prepared and UV-light at a wavelength of 365 nm is being directed upon the solution.  Concentrations over time are being monitored using UV/Vis spectroscopy.  Initial results clearly indicate that the photocatalytic activity of these synthesized nanocrystals is dependent on the amino acid used as a capping agent.  As a more direct comparison, rate constants are being determined through a pseudo first order kinetic analysis.  Differences in observed rate constants also suggest that photocatalytic behavior of these particles is dependent on the amino acid used as the capping agent.  In continuing studies, we are utilizing these amino acid capped nanocrystals in the photocatalytic oxidation of bilirubin, a reaction of biological significance with regards to the treatment of neonatal jaundice.  Because of the additional question of the side effects that could result during photodynamic therapy, we are also examining the interaction of these synthesized nanocrystals with liver cells.  Cells are being injected with ZnS nanocrystals, and then exposed to UV light.  Changes in the structure of the cell after exposure to UV light are being determined using AFM.  This material is based upon work supported by Merck/AAAS.