Modification of gas diffusion layer in proton exchange membrane fuel cellusing polymethyl methacrylate as a pore-forming agent

Fuel cells are on the verge of competing with fossil fuels and other energy sources to produce cleanelectricity in a variety of sectors. Due to their high efficiency of energy conversion, quick start-up,simple design, low working temperature, and compatibility with the environment, proton exchangemembrane (PEM) fuel cells have attracted enormous attention among the different types of fuel cells[۱]. The gas diffusion layer (GDL), which usually consists of a macroporous substrate and amicroporous layer, is inserted between the catalyst layer and bipolar plate of the PEM fuel cell and hasmultifaceted roles as shown in Fig. ۱. In fact, GDL is a porous component that plays a vital role inmass, heat, and electricity transfer [۲].The GDL is produced by different fabrication processes using carbon or metal-based materials, whichleads to the emergence of different characteristics in it. Among these characteristics, porosity and poresize distribution significantly affect other characteristics of the GDL, including permeability ofreactants and by-products, ohmic resistance, water formation profile, thermal conductivity, etc. If thepore size distribution is uneven, the mass transfer of air (as reactant) will be blocked. So GDL withgood pore size distribution is very important for the management of water and gas in the PEM fuelcell. Increasing the porosity facilitates supply of reactants but also reduces electrical and thermalconductivity and mechanical properties. Therefore, porosity should be optimal to provide an effectivepermeability of the reactants and keep the electrical and thermal conductivity as well as mechanicalproperties at a high level [۳].