▎ 摘　　要

NOVELTY - The layer has a carbon fiber (200) which is grafted with graphene and/or carbon nano tube. The graphene or carbon nano-tube (300) is radially distributed on the surface of the carbon fiber. The diameter of carbon fiber is 6-7 mu m. The length is 1-160 mm, preferably 1-100 mm. The thickness of graphene is 0.35-10 nm. The substrate is soaked in a carbon nanotube solution for 10-200 minutes. The porous substrate is taken out and heated at not less than 850 degrees C. USE - Gas diffusion layer for proton exchange membrane fuel cell used in electric vehicle such as automobile, regional power station and portable device, etc. ADVANTAGE - The proton exchange membrane fuel cell has high energy conversion rate, low temperature starting, and no electrolyte leakage. The method enhances the hydrophobicity of the gas diffusion layer, conductivity and gas transmission performance, so as to improve the electrochemical performance and discharge stability of the fuel cell. The carbon fiber is grafted with graphene and/or carbon nano tube, so that the carbon fiber-based porous substrate is soaked in the graphene oxide solution for 10 minutes to 200 minutes, and under the temperature of greater than or equal to 850 degrees C, and is heated and reduced to obtain the porous substrate of carbon fiber grafted by the graphene-based carbon fiber. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) a proton exchange membrane fuel; and (2) a preparation method of gas diffusion layer of proton exchange membrane fuel. DESCRIPTION OF DRAWING(S) - The drawing shows the schematic diagram of the carbon fiber grafted with graphene and/or carbon nano-tube. Carbon fiber (200) Graphene or carbon nano-tube (300)