NOVELTY - Catalyst assembly comprises (a) a substrate with a substrate base and a number of substrate fibers extending in the longitudinal direction of the substrate base, where the substrate base includes a metal, and the number of substrate fibers contains an oxide of the metal (90 wt.% or is greater), and (b) a catalyst film contacting at least one portion of the substrate, where the catalyst film includes a first catalyst layer (104) of atoms, a second atomic layer exposed to the catalyst and a number of intermediate atomic layers between the first and the second atomic layers of the catalyst.    USE - The catalyst assembly is useful for proton exchange membrane fuel cell applications.    ADVANTAGE - The method: includes at least one treatment of coating of nano-particle to improve catalyst-substrate interactions and/or to promote the rate of the catalyst to obtain improved durability/corrosion resistance, and to promote formation of desired facets on the catalyst; and potentially reduces electronic- and structural effects on the oxide layer, thus enabling improved interaction of the catalyst with the underlying oxide layer.    DETAILED DESCRIPTION - Catalyst assembly comprises (a) a substrate with a substrate base and a number of substrate fibers extending in the longitudinal direction of the substrate base, where the substrate base includes a metal, and the number of substrate fibers comprise an oxide of the metal ( greater than or equal to 90 wt.%, based on the total weight of the number of substrate fibers); and (b) a catalyst film contacting at least one portion of the substrate, where the catalyst film includes a first catalyst layer (104) of atoms, a second atomic layer exposed to the catalyst and a number of intermediate atomic layers between the first and the second atomic layers of the catalyst, and where the total number of atomic layers of the catalyst is 2-20. An INDEPENDENT CLAIM is also included for forming the catalyst assembly comprising depositing the catalyst film onto the substrate, which includes the substrate base and number of substrate fibers extending in the longitudinal direction of the substrate base, where the substrate base is a metal, and the number of substrate fibers includes the oxide of the metal.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of an electrode assembly with a catalyst layer.    Catalyst-coated membrane (100)    Gas diffusion electrode (100')    Proton exchange membrane (102)    Catalyst layer (104)    Gas diffusion layer (106)