ORR activity and stability of carbon supported Pt3Y thin films in PEMFCs
Journal article, 2023

In order to investigate stability of oxygen reduction reaction (ORR) on a Pt3Y thin film under relevant fuel cell conditions, we performed an accelerated stress test (AST) consisting of 3600 potential cycles between 0.4 and 1.4 V at 1 V s−1 in a single proton exchange membrane fuel cell (PEMFC). The ORR activities were evaluated via polarization curves before and after the AST. Electrochemical active surface area (ECSA) was obtained by CO-stripping voltammetry whereas the morphological changes were monitored by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Variations in surface composition and electronic structures were evaluated by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). After AST, the polarization curves show loss of ORR activity in all voltages for both Pt and Pt3Y. Except at very high voltages (E > 0.85 VRHE), the ORR activity of Pt3Y after AST is very close to that of Pt before AST. This correlates well with the results from the deconvolution of Pt-4f XPS spectra where the binding energy of metallic Pt in Pt3Y is comparable to pure Pt (71.22 eV). SEM and TEM images demonstrate that the morphologies of the aged Pt3Y and as-sputtered Pt are similar, whereas EDX results confirm a steady bulk composition of Pt3Y thin films throughout the entire electrochemical test. By correlating all these results, we conclude that the loss of ORR activity for Pt3Y is due to an increase in the thickness of the Pt overlayer which induces a relaxation of the Pt overlayer decreasing the compressive strain effect. For pure Pt, the loss of ORR activity is associated with a growth of the Pt domains associated with Ostwald ripening process.

Platinum rare earth metal alloy

Accelerated stress test

Platinum yttrium thin film

Oxygen reduction reaction

Proton exchange membrane fuel cell

Author

Eva Marra

Royal Institute of Technology (KTH)

Gerard Montserrat Siso

Chalmers, Physics, Chemical Physics

Björn Eriksson

Royal Institute of Technology (KTH)

Björn Lönn

Chalmers, Physics, Chemical Physics

R. W. Lindstrom

Royal Institute of Technology (KTH)

Göran Lindbergh

Royal Institute of Technology (KTH)

Björn Wickman

Chalmers, Physics, Chemical Physics

C. Lagergren

Royal Institute of Technology (KTH)

Electrochimica Acta

0013-4686 (ISSN)

Vol. 472 143436

Material för effektiva och konkurrenskraftiga bränsleceller

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

New fuel cell catalyst materials with nanostructured model electrodes

Swedish Research Council (VR) (2018-03927), 2019-01-01 -- 2022-12-31.

Subject Categories

Other Chemical Engineering

Other Physics Topics

DOI

10.1016/j.electacta.2023.143436

More information

Latest update

11/15/2023