|A membrane electrode structure suitable for use in a membrane electrode
assembly (MEA) that comprises membrane-affixed metal nanoparticles whose
formation is controlled by a photochemical process that controls
deposition of the metal nanoparticles using a photocatalyst integrated
with a polymer electrolyte membrane, such as an ionomer membrane.
Impregnation of the polymer membrane with the photocatalyst prior to
metal deposition greatly reduces the required amount of metal precursor
in the deposition reaction solution by restricting metal reduction
substantially to the formation of metal nanoparticles affixed on or near
the surface of the polymer membrane with minimal formation of metallic
particles not directly associated with the membrane.