Electrode catalyst for fuel cell, method of preparing the same, and membrane electrode assembly and fuel cell including electrode catalyst

An electrode catalyst for a fuel cell which includes alloy particles comprising an alloy of a Group 8 metal and a Group 9 metal, a method of preparing the same, a membrane electrode assembly including the electrode catalyst, and a fuel cell including the membrane electrode assembly. In an embodiment the alloy particles have a core-shell structure (50); i) the core (51) comprises the Group 8 metal, but does not comprise the Group 9 metal; and the shell (53) comprises the alloy of the Group 8 metal and the Group 9 metal; or ii) the core (51) comprises the alloy of the Group 8 metal and the Group 9 metal; and the shell (53) comprises the Group 9 metal, but does not comprise the Group 8 metal.