| AVS 61st International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS-WeM |
| Session: | Nanoscale Catalysis and Surface Chemistry |
| Presenter: | Paolo Reyes, University of California Irvine |
| Authors: | P. Reyes, University of California Irvine Y. Liu, University of California Irvine J.C. Hemminger, University of California Irvine |
| Correspondent: | Click to Email |
We will describe methods to generate TiO2 nanoparticles supported on HOPG substrates. We then utilize photoelectrochemical deposition to selectively decorate the TiO2 particles with metal nanoparticles. These samples are easily amenable to characterization with SEM and TEM imaging as well as electron spectroscopy surface analysis methods. The introduction of noble metals adsorbed on TiO2 substrates can affect the intrinsic catalytic properties of the metal oxide, however previous research has been focused on single species of adsorbed noble metals (e.g. Pt, Au, Co, etc.) and the result impact on the photocatalytic activity. Typical effects from noble metals include lowering the band-gap requirement of TiO2 (3.2 eV) in order for electron excitement from the valence band to the conduction band to occur. Our current research focuses on the fabrication and study of two or more noble metal nanoparticle species loaded onto TiO2 particle arrays and to observe the impact on the catalytic activity, chemistry, electromagnetic field enhancements. The presence of two or more noble metal species may affect the catalytic properties of TiO2 in interesting ways, such as Au nanoparticles allowing visible light to be absorbed, and Pt particles allowing more efficient photo-chemistry in degrading pollutants. In this work, we photodeposit Pt and Au particles onto TiO2 particles situated on highly oriented pyrolitic graphite (HOPG). Au and Pt particles are found to be on average 4.7 nm in diameter. Preliminary experiments on bi-metallic loaded particles have been conducted in order to study photocatalytic properties via pollutant degradation rate. Methylene Blue (MB), a common organic dye, is used to observe photocatalytic activity of these particles through UV-induced photo-degradation. Bare TiO2 particles are known to be photoactive, however the introduction of noble metal species show an increase of MB degradation over time. We are currently observing MB degradation rates with dual-loaded TiO2 nanoparticles. Previous work in our group has proven that polarized Raman spectroscopy performed on Ag nanoparticle arrays yields a significant increase in signal
1. Wei Luo, W. Van der Veer, P. Chu, D. L. Mills, R. M. Penner, and J.C. Hemminger, Journal Of Physical Chemistry C, 2008. : p. 11609-11613.
This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences through grant number: DE-FG02-96ER45576