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47008-GB5
Functionalized Surfaces as Templates for In Situ Formation of Gold Nanoparticle Catalyst

Krisanu Bandyopadhyay, University of Michigan - Dearborn

In the recent years, synthesis of gold nanoparticles with size less than 10 nm immobilized on solid support has seen remarkable growth due to their unusual catalytic properties. Although different synthesis strategies, like direct deposition-precipitation or surface-capping methods are explored for achieving a specific size range for these nanostructures; factors controlling size, shape, and interparticle spacing as well as their structure-activity relationship are still poorly understood. Thus, there is a considerable interest for investigating a general preparative route to engineer aggregation-resistant gold nanoparticles for catalytic applications. The present research is using organized assemblies of polyethylenimine (PEI) silane to generate gold   nanoparticles for electro-catalytic oxidation of methanol. The present research also aims to understand the effect of reaction conditions to control the structure of the resulting Au nanoparticles. X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) are used to monitor the chemical and structural development of these nanostructures. Preliminary results show that uniform gold nanoparticles of size ~ 5.8 ± 1.6 nm are generated on silicon surface. Au nanoparticle arrays are also generated on glass and Indium tin oxide (ITO) coated glass substrates. Currently, we are working on understanding the nucleation and growth process of these nanoparticles in different experimental conditions. These nanoparticle arrays also showed catalytic activity towards methanol oxidation.

The use of in situ generated Au nanoparticle arrays for catalytic oxidation of methanol is just the starting point of our exploration of model catalytic building blocks. The present methodology will further be extended to in situ generation of other catalytically active metal nanoparticles like Pt, Ag and bimetallic nanoparticles like Au-Ag, Pt-Au etc. This present study can also be applied to create complex, higher-order functional structure of nanoparticles and patterning of surface in the nanometer scale.

The principal investigator and the undergraduate students are responsible for the execution of the present research project. Currently, they are pursuing the project and playing a major role in day to day research activities by performing different experiments for advancing the project forward. The undergraduate researchers are involved in mastering the experimental protocols, participating in interpretation and planning of experiments, co-author articles, and presenting their work in scientific meetings.

The present proposed research has provided ample opportunity for undergraduate students to work in the emerging area of nano-structured catalyst. This study involves the use of AFM, recently funded by NSF to PI at the University of Michigan-Dearborn and XPS facility in the Electron Microbeam Analysis Laboratory (EMAL) at the University of Michigan-Ann Arbor campus. Apart from the use of microscopy, electrochemical techniques like impedance spectroscopy and cyclic voltammetric measurements with corresponding data analysis is useful for students to understand the fundamentals of electron transfer process at the electrode and also to model the interfacial phenomena associated with it. This is an excellent opportunity for any undergraduate student to get research experience beneficial for future research endeavor. As a broader outcome, the present research helped the principal investigator to sustain a contemporary and challenging research program with active participation of undergraduates’ at the Department of Natural Sciences, UM-Dearborn.

The impact of the project is visible from number of poster and oral presentations by the PI and undergraduate students at the American Chemical Society (ACS) National Meeting (April 6 – 10, 2008, New Orleans, LA, March 25 – 29, 2007, Chicago, IL), Annual Argonne Symposium for Undergraduates in Science, Engineering and Mathematics, (2007 and 2006, Argonne National Laboratory, Argonne, IL), Meeting of Minds, Oakland University (May 16, 2008) and Annual Student Poster Session, Department of Natural Sciences, UM-Dearborn (April 18, 2008). In addition, very recently, two students made poster presentations at the International 82nd American Chemical Society Colloid and Surface Science (ACS CSS) Symposium (June 15-18, 2008), and in SoftMatt-2008, Student Research Symposium on Soft Materials (June 19th 2008), at the North Carolina State University, Raleigh, NC. One of the students, Natalie Wasio won the first place in "SoftMatt 2008, Student Research Symposium" for her poster and received an award of $500. Based on the results obtained so far, a paper has already been submitted for publication and three more are under preparation.

This was one of the first projects in the principal investigator’s (PI’s) laboratory as a faculty member at the University of Michigan-Dearborn. The present proposed research is currently supporting the principal investigator’s effort to initiate research in a very contemporary and increasingly important area. Moreover, the present research would help the PI to build a comprehensive nanotechnology/material science program at the Department of Natural Sciences, UM-Dearborn which encompasses the interest and follow the needs of both students and other faculty members.

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