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Kenneth J. Klabunde

Bio

Dr. Kenneth J. Klabunde is the founder of NanoScale Corporation. He is a University Distinguished Professor in the Department of Chemistry at Kansas State University where he oversees an extensive research program in materials chemistry. Dr. Klabunde is internationally recognized for his work in catalysis, nanoparticles, and destructive adsorbents. He has presented over 150 lectures in the U.S. and abroad, has published 500 scientific papers in these areas, and holds 20 related patents. In 1998, he was the recipient of the American Chemical Society’s Midwest Award for Outstanding Achievements in Chemistry. Dr. Klabunde has served on several editorial boards, including Critical Reviews in Surface Chemistry, Chemistry of Materials, and Nanostructured Materials. His latest book, Nanoscale Materials in Chemistry, was published in August, 2001, and the Second Edition in 2009.

As NanoScale Corporation founder and technical leader, he has helped assemble a world-class technical team in the field of reactive nanoparticles and advanced materials. Dr. Klabunde received his B.A. in Chemistry from Augustana College and his Ph.D. degree in Chemistry from the University of Iowa.

Size Focusing of Nanoparticles by Thermodynamic Control through Ligand Interactions. Molecular Clusters Compared with Nanoparticles of Metals

Abstract

Ligand capped metal entities come in two sizes; (1) molecular clusters of 10 – 200 metal atoms, and (2) nanoparticles of 2000 – 10000 metal atoms. In numerous cases, certain “magic sizes” have been found to be most accessible and stable; clusters of 25, 38, 55, 102 atoms and nanoparticles of 3500 – 5000 atoms or 4 – 5 nm. The most familiar and studied system is that of gold (metal) and thiol (ligand). Herein the methods of synthesis of these gold clusters vs gold nanoparticles are carefully compared. In the cluster case, an important intermediate is (Au+ ‑SR)n polymer, which is not the case in the synthesis of nanoparticles either from metal (vapor) atoms or metal ions. Also, it is shown that thiol can act as both a reductant (Au3+ Au1+), and as an oxidant (Au0 Au1+). The thermodynamic forces responsible for the favored formation of certain size clusters and nanoparticles are proposed, including a discussion of surface energies of smaller vs. larger gold particles and how thiol can attack surface atoms in the 4 – 5 nm size range. Finally, it is demonstrated that thiol oxidation of Au0 surface atoms leads to Au+ ‑SR surface species plus hydrogen gas, quantitatively.