TECHNOLOGY FOCUS - ELECTRONICS - Preferred Device: The fuel cell component comprises a bipolar plate. The fuel cell component comprise a substrate comprising a metal, a polymeric material and/or electrically conductive composite material.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: The fuel cell component is rinsed to remove nanoparticles which are not adhered to the fuel cell component, before drying the coating. An aqueous solution containing a polyelectrolyte polymer is applied to the fuel cell component and polyelectrolyte polymer is adhered to the fuel cell component, before submerging in the bath. A coating material (II) is applied to the polyelectrolyte polymer adhered to the component. The fuel cell bipolar plate is immersed in a pretreatment solution, and grease and contaminants are removed. The plate is rinsed in a bath (I) of deionized water and bath (II) of deionized water. The plate is immersed in an aqueous solution of a polyelectrolyte polymer (I). The plate is rinsed in bath (III) of deionized water, and polyelectrolyte polymer (I) which is not adhered to plate is removed. The plate is then rinsed a bath (IV) of deionized water. The plate is immersed in a dispersion (II) comprising a coating material (II), nanoparticles and an alcohol. The plate is rinsed in a bath (IV) of deionized water and the coating material (II) which is not adhered to the polyelectrolyte polymer (I). The plate is immersed in a bath (V) of deionized water. The plate is dried, and processed fuel cell bipolar plate is obtained. A multi layer of nanoparticles having thickness of 100 nm is formed on the fuel cell component by repeatedly immersing the fuel cell component on the bath.Preferred Agent: The dispersion agent comprises an alcohol. The nanoparticle dispersion agent comprises an organic solvent which forms a solution with water.Preferred Composition: The content of alcohol in the liquid phase is 30 vol.%. The liquid phase further comprises water (0.1-70 vol.%). The coating material (II) comprises anionic functional groups to the polyelectrolyte polymer so that the anionic functional groups and the cationic functional groups form an ionic bond. The coating material (II) further comprises gold, silver, ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum, rare earth metal, their alloys, polymeric carbon or graphite, and a material derived from siloxane.Preferred Particles: The nanoparticles comprises siloxane or silicon dioxide. The nanoparticles have particle size of 2-100 nm. The nanoparticles comprise inorganic or organic materials and hydrophilic side chains. The nanoparticles comprise inorganic material (in wt.%) (10-70), hydrophilic material (5-70), and organic side chains having a functional group (0-50). The nanoparticles comprise amino, sulfonate, sulfate, sulfite, sulfonamide, sulfoxide, carboxylate, polyol, polyether, phosphate and/or phosphonate group. The functional group of the organic side chain is epoxy, acryloxy, methacryloxy, glycidyloxy, allyl, vinyl, carboxyl, mercapto, hydroxyl, amide or amino, isocyano, hydroxy or silanol groups. The nanoparticles comprise silicon dioxide, hafnium oxide, zirconium oxide, aluminum oxide, tin oxide, tantalum oxide, niobium oxide, molybdenum oxide, iridium oxide, ruthenium oxide, metastable oxynitride, non-stoichiometric metal oxide, oxynitride or their derivatives. The nanoparticles comprise Si-O group, polar group and Si-R group, where R is (un)saturated carbon chain. The polar group is hydroxyl, halide, carboxyl, ketonic or aldehyde functional groups. The molar ratio of Si-R group and Si-O group is 1/8-1/2. The nanoparticles are derived from a material of formula (1). The content of nanoparticles in the bath is 0.2-5 wt.%.R1-R6 = H, oxygen, chlorine, or 1-4C (un)saturated carbon chain, and at least one of R1-R6 is a carbon chain with at least one carbon atom.Preferred Compound: The alcohol is methanol, ethanol or propanol. Preferred Polymer: The polyelectrolyte polymer comprises a cationic functional group and an anionic functional group. The polyelectrolyte polymer (I) comprises a copolymer of acrylamide and quaternary ammonium salt, polyamido amine, polyallylamine hydrochloride, epoxy based azo polymer or acrylic acid based azo polymer.