In fuel cells hydrogen (H2) is ionized in the anode and is transformed into H+ and e-.
Then H+ moves through the electrolyte membrane towards the cathode, where O2 is flushed. In the meantime, the electrons move from the anode (where they separated from H2) towards the cathode, producing an electron flux, i.e. regenerating an electrical current. In the cathode O2 first captures the electrons and then react with H+ to produce water (and heat).
What I am asking here is: how elemental H2 is forced to separate into two H+ and two e-? I have read that this happens in the anode, but I did not understand how it happens.
Cheers,
Michele
In a fuel cell, the process of hydrogen (H2) ionization occurs at the anode. This process involves the separation of hydrogen molecules into hydrogen ions (H+) and electrons (e-). The ionization of hydrogen is facilitated by the presence of a catalyst, typically platinum or another suitable material, at the anode.
Here's a step-by-step explanation of how the ionization of hydrogen occurs:
Overall, the presence of a catalyst at the anode enables the dissociation of hydrogen molecules into hydrogen ions and electrons, facilitating the flow of ions and electrons through the fuel cell to generate electricity.
Thank you for the explanation Mona.
However I continue in having problems in understanding how a neutral atom can be forced, without energy, to abandon its only electron. Why should hydrogen do this?
You say that hydrogen bonds with the catalyst surface, and this is the link missing for me. How can hydrogen bond with the catalist? More: once it is bond with the catalyst surface, why hydrogen should move towards the electrolitic membrane and not remaining on the catalyst surface?
The last question is: why electrons should move in the circuit, producing an electric current, before H+ is moved towards the chatode? What does attract electrons to the cathode?
Cheers,
michele
Hydrogen breaks into the H+ and e- because the catalyst which I am assuming is a Pt catalyst lowers the activation energy of this dissociation process to below the threshold present in the cell environment, thus the hydrogen bond breaks and separates.
Thanks Kanav. I am just aking myself (and to the experts of Researchgate) how is it possible for a catalyst like Pt to force hydrogen in loosint its only electron. It has not to be an easy choice to remain electron-free!
I understand that this can happen during normal chemical reactions, but in these cases (e.g., during oxidation) the electron of hydrogen is grabbed by oxygen, who has a great hunger of electrons. In the case of Pt, electron is simply set free.
michele
So from my understanding, the H2 first adsorbs on the surface of the platinum. This act causes energy of interaction to be generated, this in turn aids the Pt to break the hydrogen bond between the atoms. The adsorption is the main phenomena that can be called the first step in the process of the H2 bond breaking
Thanks agai Kanav. Due to my poor expertise in the field, I continue to not understand how it is possible to separate an electron from its reference proton. Your explanation replaces H2 into 2H, but they are still two neutral atoms. How from this condition it is possible to move towards an electron + proton separate pair?
Ok i'll try to put this in a simpler way. So you are correct that the H2 goes to 2H, but not as two separate atoms, just like how its almost impossible to have nascent oxygen unless very high up in the atmosphere nascent H is also not present. Instead look at it like H-H and in this pair the electrons from each of the hydrogens balance each other out. Then with the addition of the catalyst this bond breaks releasing energy. Since this energy is generally heat energy ( you can see Pt mesh usually heats up and glows red). Now hydrogen as an atom can only stabilise and gain an electron in the presence of a metal atom to form a stable metal hydride, so it shuffles between two states of instability ( H+ and H), since there is a bond between the platinum and hydrogen, the H+ tends to be retained at the catalyst( probably due to the hydrogen bonding being strong to a proton?) and the electron is transferred as electricity.
This is the best and only explanation I have from material I can find on the internet. Apart from this maybe only someone who works with pt and hydrogen on a daily basis will be able to clear or correct.
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