Proton exchange membrane

Okay, so let's say you want to make a toy car that runs on a special kind of energy called hydrogen. In order to make it work, you need to have something called a proton exchange membrane (PEM).

Now, a PEM is kind of like a little wall that separates two different parts of the car's energy system. On one side of the wall, you have a special liquid called hydrogen fuel that's made up of tiny particles called protons. On the other side, you have another liquid called oxygen, which is what the car uses to actually make the energy it needs to run.

But in order for the car to work, you need to somehow get the protons from the hydrogen fuel to move through the wall and join up with the oxygen on the other side. That's where the PEM comes in!

You can think of the PEM like a tiny gatekeeper that only lets protons through. It's made up of special materials that are able to grab onto protons and help them move through the wall. As the protons move through the PEM, they combine with the oxygen on the other side to create a reaction that gives off energy, which is what makes the car move!

So, in short, a proton exchange membrane is a special wall or "gatekeeper" that helps protons from a hydrogen fuel source move through to combine with oxygen and create energy. It's an important part of making things like hydrogen-powered cars work!