Gas Diffusion Layer (GDL) is a very important supporting material in a MEA, the heart of a fuel cell. GDL serves as a connect bridge between MEA and graphite plate, and the main functions of GDL include the followings:


A gas diffused pathway from flow channels to the catalyst layer.
Help removing by-produced water outside of the catalyst layer and prevent flooding.
Keep some water on surface for conductivity through the membrane.
Heat transfer during cell operation.
Provide enough mechanical strength to hold MEA from extension caused by water absorbance.