9806
J. Phys. Chem. B 1998, 102, 9806-9811
Enhancement of Electrochemical Hot Electron Injection into Electrolyte Solutions at Oxide-Covered Tantalum Electrodes by Thin Platinum Films Yung-Eun Sung† and Allen J. Bard* Department of Chemistry and Biochemistry, The UniVersity of Texas at Austin, Austin, Texas 78712 ReceiVed: June 23, 1998; In Final Form: October 10, 1998
The previously reported experimental evidence for hot solution-phase electrons generated at Ta2O5-covered Ta electrodes in both acetonitrile and aqueous solutions using electrogenerated chemiluminescence (ECL) and electrochemical measurements was extended by observing the effect of thin Pt films. Hot electron injection was monitored by noting the photoemission following reduction of the thianthrene radical cation (TH•+), signaling the direct formation of the excited state (TH•+ + ehs f TH*), a process that does not occur at a bulk Pt electrode. We report the enhancement of hot electron injection efficiency by a factor of ∼5 by deposition of a thin (
