PRODUCTION METHOD FOR ELECTRODE CATALYST, ELECTRODE CATALYST, COMPOSITION FOR FORMING GAS DIFFUSION ELECTRODE, GAS DIFFUSION ELECTRODE, MEMBRANE-ELECTRODE ASSEMBLY (MEA), AND FUEL CELL STACK

摘要

Provided is an electrode catalyst production method capable of obtaining, through an easy operation, an electrode catalyst whose chlorine (Cl) species content has been reliably and sufficiently reduced, even when using as an electrode catalyst raw material an electrode catalyst precursor containing a high concentration of chlorine. The method is to produce an electrode catalyst having a core-shell structure including a support, a core part formed on the support and a shell part formed to cover at least a part of a surface of the core part. The method includes a first step (1) of retaining a liquid containing ultrapure water, a reductant such as a hydrogen-containing gas and an electrode catalyst precursor under at least one stage of a predetermined temperature for a predetermined retention time, such electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined first chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy.