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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 31, Number 8
BKCSDE 31(8)
August 20, 2010 

The Interfacial Nature of TiO2 and ZnO Nanoparticles Modified by Gold Nanoparticles
Yeji Do, Jae Soo Choi, Seoq K Kim, Youngku Sohn*
Interfacial electronic structure, X-ray photoelectron spectroscopy, Au-modification, TiO2, ZnO
The surfaces of TiO2 and ZnO nanoparticles have been modified by gold (Au) nanoparticles by a reduction method in solution. Their interfacial electronic structures and optical absorptions have been studied by depth-profiling X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy, respectively. Upon Au-modification, UVvis absorption spectra reveal a broad surface plasmon peak at around 500 nm. For the as-prepared Au-modified TiO2 and ZnO, the Au 4f7/2 XPS peaks exhibit at 83.7 and 83.9 eV, respectively. These are due to a charge transfer effect from the metal oxide support to the Au. For TiO2, the larger binding energy shift from that (84.0 eV) of bulk Au could indicate that Au-modification site of TiO2 is different from that of ZnO. On the basis of the XPS data with sputtering depth, we conclude that cationic (1+ and 3+) Au species, plausibly Au(OH)x (x = 1-3), commonly form mainly at the Au- TiO2 and Au-ZnO interfaces. With Ar+ ion sputtering, the oxidation state of Ti dramatically changes from 4+ to 3+ and 2+ while that (2+) of Zn shows no discernible change based on the binding energy position and the full-width at half maximum (FWHM).
2170 - 2174
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