METAL-SUPPORTED CATALYST, BATTERY ELECTRODE, AND BATTERY

A metal-supported catalyst, a battery electrode, and a battery, each having both excellent catalytic activity and durability. The metal-supported catalyst includes: a carbon carrier; and platinum particles serving as catalyst metal particles supported on the carbon carrier, wherein the platinum particles contain pure platinum particles and platinum alloy particles, wherein a proportion of a weight of the pure platinum particles to a sum of the weight of the pure platinum particles and a weight of the platinum alloy particles is 15% or more and 61% or less, and wherein a ratio of a proportion of a nitrogen atom content to a carbon atom content measured by elemental analysis using a combustion method, to a proportion of a nitrogen atom content to a carbon atom content measured by X-ray photoelectron spectroscopy, is 1.05 or more.