@article{Markiewicz:2015:10.1016/j.electacta.2015.04.066,
author = {Markiewicz, M and Zalitis, C and Kucernak, A},
doi = {10.1016/j.electacta.2015.04.066},
journal = {Electrochimica Acta},
pages = {126--136},
title = {Performance measurements and modelling of the ORR on fuel cell electrocatalysts - the modified double trap model},
url = {http://dx.doi.org/10.1016/j.electacta.2015.04.066},
volume = {179},
year = {2015}
}

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TY  - JOUR
AB  - Experimental results for the ORR (oxygen reduction reaction) in perchloric acid for ultra low loading Pt/Celectrodes have been fitted to a number of different ORR mechanisms. These were accomplished as afunction of temperature (280–330 K), oxygen partial pressure(0:01 < po2p0o2< 1) and potential (0.3–1.0V vs.RHE). A reaction exponent for oxygen of 1  0.1 across the potential range 0.3–0.85V vs. RHE is confirmed.From the experimental results it is clear that the surface becomes increasingly blocked towards the ORRas overpotential increases (i.e. as the potential decreases from 0.6 to 0.3 V vs. RHE). The double trap model[J.X. Wang, J. Zhang, R.R. Adzic, J. Phys. Chem. A, 111 (2007) 12,702] fails to account for this observation,although we have produced a modified version to include the formation of OOHad intermediates. Theseintermediates block the electrode at larger overpotentials and lead to a decrease in electrocatalystperformance compared to a Tafel type approximation. Furthermore these intermediates can lead to theformation of hydrogen peroxide at large overpotentials, an experimental observation which is currentlypoorly described by models.The decreased activity at large overpotentials suggests that blocking of active catalyst sites may be asimportant to catalyst activity in an operating fuel cell as the absolute performance of the electrode in thelow overpotential region as typically measured on an RDE. It may also offer an explanation to theincreased losses seen in fuel cell electrodes at lower catalyst loadings – i.e. the loses, which are typicallyascribed to increased mass transport loses, may instead result from decreased electrocatalyticperformance at high overpotentials.
AU  - Markiewicz,M
AU  - Zalitis,C
AU  - Kucernak,A
DO  - 10.1016/j.electacta.2015.04.066
EP  - 136
PY  - 2015///
SN  - 1873-3859
SP  - 126
TI  - Performance measurements and modelling of the ORR on fuel cell electrocatalysts - the modified double trap model
T2  - Electrochimica Acta
UR  - http://dx.doi.org/10.1016/j.electacta.2015.04.066
UR  - http://hdl.handle.net/10044/1/28893
VL  - 179
ER  - 

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