Fuel cell membrane electrode assemblies (MEAs) typically include carbon paper gas diffusion layers (GDLs) bonded to, coated on, or laminated to the anode and cathode catalysts and membrane layers.  The five-layer construction can be made in several ways, however often the catalysts are attached to the membrane to form a catalyst coated membrane (CCM).  The was diffusion layers with micro porous layer (MPL) are then attached to the catalyst coated membrane to form the membrane electrode assembly. 
Often the bond between the catalyst and microporous layer side of the gas diffusion layer is a weak spot in the construction in terms of desirably securing the gas diffusion layer and catalyst coated membrane together.  Furthermore, even if the bond between the microporous layer and catalyst is relatively strong it is also possible that the bond between the microporous layer and gas diffusion layer fibers is not adequate to hold together the components.  For this reason, it can be advantageous to adhesively bond the gas diffusion layer to the catalyst coated membrane in such a manner that the adhesive is touching the gas diffusion layer carbon fibers and thusly creating a strong bond.