PETR 31 |
| Essentially every scheme for photochemical water splitting requires a catalyst, commonly noble metal, to convert the single-electron transfer events, inherent to light induced processes, into multi-electron transfer molecular products. For hydrogen evolution this process is believed to occur via electron transfer from reducing radicals followed by proton consumption from water. The details of this process however, are still not known. We attach probe molecules to the surface of silver nanoparticles from a recently proposed synthesis (Evanoff & Chumanov, J. Phys. Chem. B 2004, 108, 13948) and using surface enhanced Raman scattering follow the changes on the particles during the catalysis. The probe reports on the state of the particle, its overpotential, surface charge, residual ions on the surface, and the effect of pH on the particle, and the probe, as the catalysis progresses. The catalytic hydrogen evolution starts only after complete reduction of residual silver ions; the overpotential that accumulates on the particles then approaches -0.5 V vs. NHE. |
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2nd Symposium on Hydrogen from Renewable Sources and Refinery Applications
1:00 PM-5:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 222, Oral
Division of Petroleum Chemistry |