# PEM electrolyzer - How does platinum reduce activation energy?

• HelloCthulhu
In summary, the conversation discusses the use of platinum in PEM electrolyzers and its role in reducing activation energy for the dissociation of H2O. The operating specs for the electrolyzer are also provided, as well as a previous attempt to calculate the volumetric flowrate and mass of water electrolyzed during the process. It is mentioned that platinum is used for electrodes due to its resistance to oxidation and its catalytic properties, which can lower the activation energy for certain processes.
HelloCthulhu
I've been researching pem electrolyzers, but still don't understand how to mathematically express how platinum reduces the activation energy necessary to dissociate H2O. I've seen the Arrhenius equation solved before, but didn't understand how to get the values for it. Here are the operating specs for the electrolyzer:

https://www.fuelcellstore.com/manuals/horizon-mini-pem-electrolyzer-instructions-fcsu-010.pdf

- Input Voltage: 1.8V ~ 3V (D. C.)

- Input Current: 0.7A

- Hydrogen production rate: 7ml per minute at 1A

- Oxygen production rate: 3.5ml per minute at 1A

In a previous post, I tried to figure out what the volumetric flowrate would be. Not sure if the mass is necessary to find the activation energy, but I'll include it anyway:

2H2O —> 2H2 + O2

3.5 ml O2/min = 0.00015625 M O2(STP)

0.0003125 H2O(l) →0.0003125 H2(g)/1A*min + 0.00015625O2(g)/1A*min
0.0003125M H2O *18 g = 0.005625 g/1A*min H2O

Any help is greatly appreciated!

Platinum does not reduce activation energy it is only used for electrodes because it resists oxidation better then other materials.

Miloje said:
Platinum does not reduce activation energy it is only used for electrodes because it resists oxidation better then other materials.

It is not that simple - platinum black has some catalytic properties which make it perfect for electrode material, as when used most processes work with lower overpotential. And - as it is a case with catalysis - it works by lowering activation energy.

HelloCthulhu and Astronuc

## 1. How does a PEM electrolyzer work?

A PEM electrolyzer is a type of electrolysis device that uses a proton exchange membrane (PEM) as the electrolyte. It works by passing an electric current through water, splitting it into hydrogen and oxygen gas through a process called electrolysis.

## 2. What is the purpose of platinum in a PEM electrolyzer?

Platinum is used as a catalyst in a PEM electrolyzer to reduce the activation energy needed for the electrolysis reaction to occur. This means that less energy is required to split the water molecules, making the process more efficient.

## 3. How does platinum reduce activation energy in a PEM electrolyzer?

Platinum has a high catalytic activity, meaning it can speed up chemical reactions without being consumed in the process. In a PEM electrolyzer, platinum acts as a surface for the water molecules to attach to, making it easier for them to break apart and form hydrogen and oxygen gas.

## 4. Is platinum the only catalyst that can be used in a PEM electrolyzer?

No, platinum is not the only catalyst that can be used in a PEM electrolyzer. Other materials such as nickel, palladium, and gold can also be used as catalysts. However, platinum is often preferred due to its high catalytic activity and stability in harsh environments.

## 5. What are the advantages of using a PEM electrolyzer with platinum?

Using platinum as a catalyst in a PEM electrolyzer has several advantages. It allows for a faster and more efficient electrolysis process, resulting in higher yields of hydrogen and oxygen gas. Platinum is also resistant to corrosion and can operate at high temperatures, making it a durable and long-lasting catalyst for the electrolyzer.