Abstract: The present invention prevents a flooding phenomenon by a simple method and receives a relatively small influence by a proton transfer in the catalyst layer so as to provide an MEA having an excellent power generation performance. An MEA of the present invention has an anode catalyst layer and a cathode catalyst layer on surfaces of the polymer electrolyte membrane and catalyst loaded particles are included in the anode catalyst layer and the cathode catalyst layer. It is a feature of the present invention that the cathode catalyst layer has more catalysts in a surface region than in a boundary region with the polymer electrolyte membrane in the thickness direction, whereas the anode catalyst layer has more catalysts in a boundary region than in a surface region in the thickness direction.

Abstract: The present invention prevents a flooding phenomenon by a simple method and receives a relatively small influence by a proton transfer in the catalyst layer so as to provide an MEA having an excellent power generation performance. An MEA of the present invention has an anode catalyst layer and a cathode catalyst layer on surfaces of the polymer electrolyte membrane and catalyst loaded particles are included in the anode catalyst layer and the cathode catalyst layer. It is a feature of the present invention that the cathode catalyst layer has more catalysts in a surface region than in a boundary region with the polymer electrolyte membrane in the thickness direction, whereas the anode catalyst layer has more catalysts in a boundary region than in a surface region in the thickness direction.

Abstract: This invention provides a manufacturing method of an MEA in which electrode catalyst layers adhere sufficiently to a polymer electrolyte membrane and the fringe area of the polymer electrolyte membrane has no large waviness to cause a gas seal problem when used in a fuel cell. The method includes preparing a pair of transfer sheets each having an electrode catalyst layer on one surface of a substrate, arranging the transfer sheets in such a way that the electrode catalyst layers, respectively, face both surfaces of the polymer electrolyte membrane and the fringe area of the polymer electrolyte layer is exposed, and hot pressing the transfer sheets together with the interposed polymer electrolyte membrane, and has a feature that pressure applied during the hot pressing in a certain area is 0.5-2.0 MPa (referred to as PA) and pressure applied in the other area is a value 1-3 times smaller than PA.