TY - JOUR
T1 - Electron capture and transport by heteropolyanions
T2 - Multi-functional electrolytes for biomass-based fuel cells
AU - Geletii, Yurii V.
AU - Gueletii, Andrei
AU - Weinstock, Ira A.
N1 - Funding Information:
We thank the U.S. Department of Agriculture (FS-FPL-05-JV-11111122-026) for financial support. We also thank Robert Apkarian (The Integrated Microscopy and Microanalytical Facility, Emory University) for HREM data, and Craig L. Hill (Emory University) and Alan Rudie (USDA Forest Service, Forest Products Laboratory) for technical input and administrative support.
PY - 2007/2/1
Y1 - 2007/2/1
N2 - Keggin heteropolyanions (POMs) are evaluated for use as an alternative to H2 in the storage and transfer of electrons from alcohols (ROH) to O2 in biomass-based electrochemical energy-conversion devices. Pt(0) (present as 10 wt.% Pt on C) is used to catalyze the oxidation of alcohols under mild conditions by α-H3PMo12O40 (H31) and H5PV2Mo10O40 (H52). During these reactions, the POMs efficiently "capture" electron equivalents as they are rapidly reduced by intermediates generated during the Pt(0)-catalyzed oxidation of alcohols. Potentiometric data indicate that this results in the two-electron reduction of 1, and in substantial reduction of 2. Kinetic data show that the rate of POM reduction is limited by the rate of ROH activation at Pt. Upon exposure to O2, Pt(0) catalyses rapid oxidation of the reduced solutions of both 1 and 2 to their (nearly) fully oxidized forms. Possible effects of the POMs on the activity of the Pt catalyst were assessed by measuring rates of Pt(0)-catalyzed O2-oxidations of EtOH. Here, as in the anaerobic reduction of POMs, activation of EtOH on Pt(0) is rate limiting. Having demonstrated this, Keggin heteropolyanions were added, and their effects on overall rates quantified. In all cases, inhibition was observed, and the effect was more pronounced for Keggin anions with more positive reduction potentials. While the reactions involved are complex, these observations suggest that under certain conditions POMs may inhibit the rate-limiting activation of EtOH by Pt(0).
AB - Keggin heteropolyanions (POMs) are evaluated for use as an alternative to H2 in the storage and transfer of electrons from alcohols (ROH) to O2 in biomass-based electrochemical energy-conversion devices. Pt(0) (present as 10 wt.% Pt on C) is used to catalyze the oxidation of alcohols under mild conditions by α-H3PMo12O40 (H31) and H5PV2Mo10O40 (H52). During these reactions, the POMs efficiently "capture" electron equivalents as they are rapidly reduced by intermediates generated during the Pt(0)-catalyzed oxidation of alcohols. Potentiometric data indicate that this results in the two-electron reduction of 1, and in substantial reduction of 2. Kinetic data show that the rate of POM reduction is limited by the rate of ROH activation at Pt. Upon exposure to O2, Pt(0) catalyses rapid oxidation of the reduced solutions of both 1 and 2 to their (nearly) fully oxidized forms. Possible effects of the POMs on the activity of the Pt catalyst were assessed by measuring rates of Pt(0)-catalyzed O2-oxidations of EtOH. Here, as in the anaerobic reduction of POMs, activation of EtOH on Pt(0) is rate limiting. Having demonstrated this, Keggin heteropolyanions were added, and their effects on overall rates quantified. In all cases, inhibition was observed, and the effect was more pronounced for Keggin anions with more positive reduction potentials. While the reactions involved are complex, these observations suggest that under certain conditions POMs may inhibit the rate-limiting activation of EtOH by Pt(0).
KW - Alcohol oxidation
KW - Dioxygen
KW - Keggin heteropolyanion
KW - Platinum
KW - Polyoxometalates
UR - http://www.scopus.com/inward/record.url?scp=33846182664&partnerID=8YFLogxK
U2 - 10.1016/j.molcata.2006.08.075
DO - 10.1016/j.molcata.2006.08.075
M3 - Article
AN - SCOPUS:33846182664
SN - 1381-1169
VL - 262
SP - 59
EP - 66
JO - Journal of Molecular Catalysis A: Chemical
JF - Journal of Molecular Catalysis A: Chemical
IS - 1-2
ER -
