Directly observe the behavior of the platinum in a fuel cell

Directly observe the behavior of the platinum in a fuel cell


The combustible batteries with a proton exchange membrane bring into play electrochemical reactions to convert hydrogen into electricity
. Platinum, used as a catalyst, plays a crucial role in this process by accelerating the chemical reactions involved. The experiments carried out in the laboratory on a “model” assembly show a good durability of the platinum in the long term. This is unfortunately no longer the case when trying to get closer to the operating conditions of a fuel cell where you can see a faster degradation of the catalyst. An observation which strongly limits the deployment of this technology which is however promising on a large scale.

In this study, CNRS scientists from the Charles Gerhardt Institute (CNRS/ University of Montpellier/ ENSCM), in collaboration with scientists from the European Synchrotron (ESRF) in Grenoble and a team from the Interuniversity Research and Research Center Material engineering (CNRS/Toulouse INP/University of Toulouse), sought to highlight the origin of this degradation by directly observing the behavior of the platinum in a fuel cell in operation.

To achieve this, the researchers used, among other analysis techniques, the diffraction of very intense at high energy X -ray generated by the extremely brilliant source of ESRF. This technique allowed them to follow in real time the evolution of the crystalline structure of the platinum during the operation of the battery (operating), and in a non-intrusive way.

The results show that, contrary to what was known in laboratory model conditions, the platinum to the cathode of a fuel cell undergoes multiple transitions between its metal phase and a very unstable amorphous phase, and this for tensions to perfectly identified battery terminals. This process induces a strong acceleration of the dissolution of the platinum, which explains the decrease in its sustainability.

Highlighting this phenomenon, the object of an article in the review Nature Communicationsmakes it possible to consider new platinum stabilization strategies, inviting to act at the level of the material itself, or at the control scale of the fuel cell system, in order to avoid critical tensions identified by the study.

Writer: CCDM

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