Oxygen reduction reaction kinetics on a Pt thin layer electrode in AEMFC
Journal article, 2022

The study of the catalytic activity in a fuel cell is challenging, as mass transport, gas crossover and the counter electrode are generally interfering. In this study, a Pt electrode consisting of a thin film deposited on the gas diffusion layer was employed to study the oxygen reduction reaction (ORR) in an operating Anion Exchange Membrane Fuel Cell (AEMFC). The 2D Pt electrode was assembled together with a conventional porous Pt/C counter electrode and an extra Pt/C layer and membrane to reduce the H2 crossover. Polarization curves at different O2 partial pressures were recorded and the resulting reproducible ORR activities were normalized with respect to the active surface area (ECSA), obtained by CO stripping. As expected, decreasing the O2 partial pressure results in a negative shift in open circuit voltage (OCV), cell voltage and maximum attainable current density. For cell voltages above 0.8 V a fairly constant Tafel slope of 60 mV dec−1 was recorded but at lower voltages the slope increases rapidly. The observed Tafel slope can be explained by a theoretical model with an associative mechanism where charge- and proton-transfer steps are decoupled, and the proton transfer is the rate-determining step. A reaction order of 1 with respect to O2 was obtained at 0.65 V which corresponds well with the mechanism suggested above. Based on the obtained catalyst activities, the electrode performance is comparable to good porous electrodes found in the field. The methodology presented in this study is expected to be useful in future kinetic studies of other catalysts for AEMFC.

Anion exchange membrane fuel cells

Oxygen reduction reaction kinetics

Platinum thin film

Author

Eva Marra

Royal Institute of Technology (KTH)

Henrik Grimler

Royal Institute of Technology (KTH)

Gerard Montserrat Siso

Chalmers, Physics, Chemical Physics

R. W. Lindstrom

Royal Institute of Technology (KTH)

Björn Wickman

Chalmers, Physics, Chemical Physics

Göran Lindbergh

Royal Institute of Technology (KTH)

C. Lagergren

Royal Institute of Technology (KTH)

Electrochimica Acta

0013-4686 (ISSN)

Vol. 435 141376

Material för effektiva och konkurrenskraftiga bränsleceller

Swedish Foundation for Strategic Research (SSF) (EM16-0060), 2018-01-16 -- 2022-12-31.

Subject Categories

Inorganic Chemistry

Other Chemical Engineering

Other Chemistry Topics

DOI

10.1016/j.electacta.2022.141376

More information

Latest update

10/27/2023