Catalyst for electrodes, composition for forming gas diffusion electrode, gas diffusion electrode, membrane electrode assembly, and fuel cell stack

Abstract

This catalyst for electrodes comprises: a porous carbon support which has nanopores having a pore diameter of from 1 nm to 20 nm; and a plurality of catalyst particles which are supported by the support. The catalyst particles contain Pt (zerovalent), and are supported by both inner portions and outer portions of the nanopores of the support. If an analysis of the particle size distribution of the catalyst particles is performed using three-dimensional reconstructed images obtained through a STEM-based electron tomography measurement, the proportion of the catalyst particles supported by the inner portions of the nanoparticles is 50% or more; at least one nanopore is formed in a cubic image having a side of from 20 nm to 50 nm, said cubic image being obtained from a three-dimensional reconstructed image of a catalyst aggregate; and this nanopore has the shape of a continuously extending interconnected pore.