Photoinduced Charge Transfer and Trapping on Single Gold Metal Nanoparticles on TiO<sub>2</sub>
Mónica Luna, Mariam Barawi, G. M. Sacha, J. Colchero, Micaela Rodríguez-Peña, Shanshan Yang, Xiao Zhao, Yi‐Hsien Lu, Ravi Chandra Chintala, Patricia Reñones, Virginia Altoé, L. Martı́nez, Yves Huttel, Seiji Kawasaki, Alexander Weber‐Bargioni, Víctor A. de la Peña O’Shea, Peidong Yang, Paul D. Ashby, Miquel Salmerón
Abstract
We present a study of the effect of gold nanoparticles (Au NPs) on TiO 2 on charge generation and trapping during illumination with photons of energy larger than the substrate band gap. We used a novel characterization technique, photoassisted Kelvin probe force microscopy, to study the process at the single Au NP level. We found that the photoinduced electron transfer from TiO 2 to the Au NP increases logarithmically with light intensity due to the combined contribution of electron-hole pair generation in the space charge region in the TiO 2 -air interface and in the metal-semiconductor junction. Our measurements on single particles provide direct evidence for electron trapping that hinders electron-hole recombination, a key factor in the enhancement of photo(electro)catalytic activity.