Gold Nanoparticle-Functionalized Carbon Nanotubes for Light-Induced Electron Transfer Process

Abstract

The modified electronic properties at the heterojunctions of Au nanoparticle-decorated single-walled carbon nanotubes (SWNTs) have been utilized for photoinduced electron transfer by anchoring a photoactive molecule, namely ruthenium trisbipyridine (Ru(bpy)32+). A unidirectional electron flow was observed from the excited state of Ru(bpy)32+ to carbon nanotubes when the chromophores were linked through Au nanoparticles (SWNT−Au−Ru2+). In contrast, photoinduced electron transfer was not observed from the excited state of Ru(bpy)32+ neither to SWNT nor Au nanoparticles when these components were linked directly. The charge equilibration occurring at the SWNT−Au heterojunctions, due to the differences in electrochemical potentials, result in the formation of a localized depletion layer at the bundled carbon nanotube walls, which may act as acceptor sites of electrons from *Ru(bpy)32+. The charge separation in SWNT−Au−Ru2+ nanohybrids was sustained for several nanoseconds before undergoing recombination, maki...