Journal Title
Title of Journal: Electrocatalysis
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Abbravation: Electrocatalysis
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Authors: Sebastian Proch Kensaku Kodama Shuhei Yoshino Naoko Takahashi Naohiko Kato Yu Morimoto
Publish Date: 2016/05/19
Volume: 7, Issue: 5, Pages: 362-375
Abstract
Nanoparticulate platinum on carbon as oxygen reduction electrocatalyst suffers from two major drawbacks namely low specific activity of the Pt particles and corrosion instability of the carbon support under hydrogen starvation conditions reverse current degradation Both issues can be tackled by Pt thin films on TiO2 support Platinum films were synthesized on commercially available Nbdoped bulk TiO2 electrodes via electrodeposition from Ar bulk amounts and COsaturated solutions monolayer amounts The platinized electrodes were tested for ORR activity in a voltammetric fashion and the fieldfree semiconductor properties were evaluated by a combination of Xray photoelectron spectroscopy XPS spectroscopic ellipsometry SE photoelectron yield spectroscopy PYS electrochemical impedance spectroscopy EIS and bulk conductivity measurements The deposition of bulk amounts of Pt leads to a situation where the catalytic activity is directly correlated to the conductivity of the electrode Raising the majority carrier density in the Nbdoped TiO2 via proton intercalation in aqueous HClO4 or glycol drastically increased the activity In case of monolayer deposits COterminated deposition intercalation has practically no effect on activity Thus the hypothesis is formed that unfavorable electronic interaction of the TiO2 support with small amounts of platinum drastically reduces ORR activity an effect which is not observed for monolayer amounts of Pt deposited on goldToo Much Interaction The oxygen reduction activity of bulk amounts of Pt deposited on Nbdoped TiO2 can be significantly improved by raising the carrier density via proton intercalation Such treatment has no effect if monolayer amounts are deposited This observation is attributed to unfavorable Pt/TiO2 interactions for minute amounts of Pt
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