posted on 2014-02-12, 00:00authored byByron
H. Farnum, Zachary A. Morseth, Alexander M. Lapides, Adam J. Rieth, Paul G. Hoertz, M. Kyle Brennaman, John M. Papanikolas, Thomas J. Meyer
Interfacial
electron transfer to and from conductive Sn-doped In2O3 (ITO) nanoparticles (NPs) in mesoporous thin
films has been investigated by transient absorption measurements using
surface-bound [RuII(bpy)2(dcb)]2+ (bpy is 2,2′-bipyridyl and dcb is 4,4′-(COOH)2-2,2′-bipyridyl). Metal-to-ligand charge transfer excitation
in 0.1 M LiClO4 MeCN results in efficient electron injection
into the ITO NPs on the picosecond time scale followed by back electron
transfer on the nanosecond time scale. Rates of back electron transfer
are dependent on thermal annealing conditions with the rate constant
increasing from 1.8 × 108 s–1 for
oxidizing annealing conditions to 8.0 × 108 s–1 for reducing conditions, presumably due to an enhanced
electron concentration in the latter.