Fabrication of the carbon paper by wet-laying of ozone-treated carbon fibers with hydrophilic functional groups

Carbon papers (CPs) have been widely investigated as a gas diffusion layer for high performance fuel cells. Herein we report the fabrication of the CP by wet-laying of ozone-treated carbon fibers (CFs) with hydrophilic functional groups. To improve the dispersion of CFs in water, the surface of the CFs was modified by the ozone treatment. The surface of the ozone-treated CFs contains hydrophilic functional groups such as C–O, CO and O–CO, which have been characterized by X-ray photoelectron spectroscopy. The negative charge of CFs determined by zeta potential was significantly increased after the ozone treatment, and the value was linearly decreased upon increasing ozone-treated time. Since ozone-treated CFs were better dispersed in aqueous solution than bare CFs, the CP prepared by a wet-laying process of ozone-treated CFs have higher porosity and gas permeability than that from bare CFs. In addition, the prepared CP from ozone-treated CFs showed better performance in I–V measurement of the single cell than those from bare CFs because of their high gas permeability.