NOVELTY - Carbon supported catalyst membrane preparation involves dispersing metal acetate tetrahydrate and alkyl halide in 20 ml water ultrasonically for 30 minutes to obtain an ionic liquid solution. The obtained ionic liquid is mixed with potassium tetrahydroborate ultrasonically in saturated argon or nitrogen gas atmosphere, and then refluxed under sealed conditions with magnetic stirring at 60 degrees C to give another solution. The formed solutions are mixed uniformly with magnetic stirring at 60-100 degrees C for 1 hour to obtain carbon carrier nanofilm.    USE - Method for preparing carbon supported catalyst membrane for use in fuel cells (all claimed).    ADVANTAGE - The method prepares the carbon supported catalyst membrane in a simple manner with enhanced oxygen reduction activity and good alcohol electro-oxidation catalytic activity on large scale.    DETAILED DESCRIPTION - Carbon supported catalyst membrane preparation involves dispersing metal acetate tetrahydrate and alkyl halide in 20 ml water ultrasonically for 30 minutes to obtain an ionic liquid solution. The obtained ionic liquid is mixed with potassium tetrahydroborate ultrasonically in saturated argon or nitrogen gas atmosphere, and then refluxed under sealed conditions with magnetic stirring at 60 degrees C to give another solution. The formed solutions are mixed uniformly with magnetic stirring at 60-100 degrees C for 1 hour to obtain carbon carrier nanofilm. The obtained carbon carrier nanofilm is cooled at 40 degrees C after adding palladium (II) chloride solution for 30 minutes to obtain carbon-loading type palladium nanoparticles colloidal membrane. The carbon loaded colloidal membrane is cooled at room temperature, washed with ethanol, and then dried at room temperature for 12 hours to give the carbon supported catalyst membrane. The metal is a transition metal selected from iron, cobalt or nickel.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic transmission electron microscopic image of the carbon supported catalyst membrane.