Exploration of catalysis activation emergency as a function of gold nanoparticle surface morphology

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (p. 45).The application of rippled gold nanoparticles with bi-ligand surface morphology as a catalyst was tested. The hydrolysis of 2,4-dinitrophenyl acetate (DNPA) served as the catalytic reaction being analyzed and the bi-ligand composition used was 16-mercaptohexadecanoic acid to imidazole thiol (MHA to IT). The influence of temperature on catalytic reaction of DNPA with the MHA: IT system was tested for ligand rations of 2:1, 1:2, and 1:1 by monitoring the catalytic system on a UV-VIS spectrometer. Catalytic rate constants were obtained and found to increase with increased temperature. The measured catalytic rate constants were greatest overall for the 1:1 system, followed by the 1:2 system, and lastly the 2:1 system. The activation energy for each ligand-ratio system was measured and found to be 22.17 kJ/mol for the 2:1 system, 14.7 kJ/mol for the 1:2 system, and 26.52 for the 1:1 system. The 2:1 and 1:2 systems followed the trend of lower activation energy values for systems with faster rates; however the 1:1 system did not fit this trend as it resulted in the highest activation energy value as well as the fastest reaction rates.by Cristina F. Stefanescu.S.B