Dear Franklin Uriel Parás Hernández

I hope you are doing well. I have some experience in PEM fuel cell. as they are working in the same concept. PEM fuel cell utilize H2 and O2 and produce power and water, electrolyser use power and water and produce H2 and O2. in PEM fuel cell these two plates should be able to do two main jobs. first of all, they should deliver or collect the exerted current to the system and transfer it to the active material. which means they should have good electrical conductivity. with respect to this fact, some material are using as the outer layer of this section it can be prepared from graphite plate, stainless steel and so on. second, they play role as a part to diffuse gas and distribute it on the surface of electroactive materials (electro catalyst) to increase the kinetic of electrochemical and electron transition reactions. in Electrolyser case they should deliver water and electron to the system and collect the produced gas. in this regard they may composed of several layers. usually the outer layers which are the current collectors, and composed of rigid conductive material like graphite plate or SS sheets, they are square, rectangle or circle plates with two hole that deliver or collect gas from one side to the other side. when you face the outer layer from outside then you can see an square (or other symmetry), having two hole on the top and bottom corner. in the other side of this square, you will have channels that carved on the surface of plate to carry gas from entering hole toward exit hole (see the attached image). after this rigid plate, you will have a porous flexible and conductive sheet. I usually used carbon cloth for PEM fuel cell. it can deliver electron to the electrochemical reaction that should happen inside the cell, because it is conductive. in addition it is located on top of channels that gas flows inside these channels. as far as it is porous, gas will diffuse all around this sheet and will reach to the electrocatalyst. all these layer will stack on each other and they need to be sealed to prevent leaking reactants and products to out.

Dear Hossein Ghafarian-Zahmatkesh :

Thank you for your answer sir.

I understood one important thing. I have changed my geometry, and I located the collecting gas channels of these plates in contact with the Gas Diffusion Layers.

Now it make sens that the produced gases are gonna diffuse to the collector plates, and exit through the channels.

I have another question though: in the water electrolyzer configurations, for the cathode side (H2 production), there is also an inlet and an oulet ?

If so, What is this inlet for ?

And speaking of the materials: as I understand, one set of the most used materials could be :

Membrane: Nafion Dupont

Cathode electrocatalyst: Platinum? or Platinum sustained on a carbon substrate/layer ?

Anode Electrocatalyst: Iridium? or IrO2 ?

Cathode's GDL: Carbon paper ? or layer made of carbon cloth, or carbon fleece ? Which one is more conveninent ?

Anode's GDL: Titanium? is this the standard option? What kind of titanium must be ?

Collector plates: Is stainless steel the best option? It is also graphite used ? Titanium as well ?

I appreciate your answer :)

My best regards !

Hi Franklin Uriel Parás Hernández

I have dismantled some Hydrogen generator from well known companies. It would be a good idea if you can find a used and failed hydrogen generator, because it absolutely would be helpful to understand the design of electrolyzer cell. just keep in mind that there different types of electrolyzers, some of them need alkali solution to produce H2, some of them use purified water for gas generating. regarding your question,

first, inlet for cathode side of electrolyzer, I should say, according to my experience about dismantling electrolyzer, they had no inlet for cathode side. As I said in my previous comment, I manufactured stack fuel cell, and in fuel cell you need inlet for H2 and O2 gases. the image that I attached is a bipolar plate used in fuel cell. you can search on google about bipolar plate or cathode site bipolar plate for electrolyzer and you will see different design for gas canal distribution on bipolar plate used in electrolizer.

second, as you have mentioned one of the most commercial membrane used in this type of energy convertor, is Nafion. I think Dupont is a well known brand. electrocatalyst for cathode is mostly Pt/C which is commercially available. for the anode side I am not sure, but it should a composite of rare metal (may be a mix of Pt-irO/c).

GDL can be made of carbon clothe, carbon paper ( I know just these two candidate). In my opinion, cathode and anode GDL are the same, because both should diffuse gas and collect or deliver electron. Only difference for the cathode and anode side, is refer to the electroactive materials (electrocatalyst), because they catalyze two different electrochemical reaction, so they need to have different bond gap, and electrochemical properties.

regarding bipolar plate, I believe SS sheets is the most economic option because it is easy for operation. for example, you can create gas canal on the surface of thin SS sheet just by putting it under a mold and press it. but if you want to make a graphite bipolar plate, you need a super precise machinery with a precision in the range of less than 10 Micrometer. because those gas canal should be carved on the surface of graphite using a tiny drill bit and it needs so much time compare to press of SS sheet.

In addition, SS is much more solid and they are not fragile, compare to graphite plate which crashes like a biscuit.

I have forgotten another point about bipolar plates, they should have good heat transfer conductivity. as chemical reaction happened in fuel cell, for sure when you have a stack of several cells back to back, the chemical reaction release heat, and this heat should be managed. in low power cell, it is done by air colling. but in higher power, it is done using liquid circulation.

But I am not sure about electrolyzer because as long as it is operating, water goes inside and it can help managing heat transfer.

cheers

Dear Hossein Ghafarian-Zahmatkesh

Thanks for your answer sir.

I will modify my design and maybe come back with updates.

Great day sir ! :)

Dear Sir Franklin Uriel Parás Hernández , I am currently working on a PEM electrolyzer project too, and have encountered some challenges while attempting to generate the polarization plot. I would be truly grateful if you could spare a few moments from your schedule to take a look and possibly guide me through the issue.