WO2008074113A1

WO2008074113A1 - Process of carbons functionalization by the growth of polymeric chains with ion exchange properties for polymer electrolyte fuel cell applications

Info

Publication number: WO2008074113A1
Application number: PCT/BR2007/000354
Authority: WO
Inventors: Marcelo Do Carmo; João Guilherme Rocha POCO; Marcelo Linardi
Original assignee: Instituto Pesquisas Tecnológicas Do Estado De São Paulo - Ipt
Priority date: 2006-12-19
Filing date: 2007-12-19
Publication date: 2008-06-26
Also published as: BRPI0605696E2; BRPI0605696A

Abstract

'PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS', that is related to the electrocatalysts for polymer electrolyte fuel cell technology, related to a chemical activation form of the carbon source surface, like carbon black, performing the growth of polymeric chains with proton exchange properties, and afterward to perform the anchoring of the electrocatalysts nanoparticles like Pt, PtRu and others, or by just a chemical activation of the carbon source surface by chemical oxidant reaction using oxidant agents like chromate ions, dichromate, permanganate, nitrate, halogens, hydrogen peroxide, and others, preferably nitric acid or hydrogen peroxide or its mixtures, or any reagent or technique that are able to produce oxygenated groups in the carbon surface. The main effect of this invention is the improvement of the ion conductivity in the three interfaces, consequently decreasing the ohmic drop of the system.

Description

"PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH

OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR

POLYMER ELECTROLYTE FUEL CELL APPLICATIONS"

FIELD OF THE INVENTION

This invention, which is related to the sector of polymer electrolyte fuel cells electrocatalysts, is related to the chemical activation of the carbons surface, carbons in the form of colloidal particles or other carbon forms, carbon nanotubes and derived from fullerene or graphite, preferably in carbon black form, promoting the creation or growth of ions exchange polymer chains, type sulfonated polystyrene or NAFION^® like, polyaniline, polyacrilate, polymethylmethacrylate, polyethylene, polyvinyl, polymaleic, polyglutamic, polyvinylamine, polyethylamine, polyvinyl 4-alkilpiridinium, po Iy vi nyl be nzil tri met hy lam on ium , polypropylene, polymaleicacidcovinylalkyle-ther, polymaleicacidcoalkene, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, acrilonitrile butadiene styrene, styrene acrilonitrile or polybutylene terephthalate in the carbon source surface or by just a chemical activation of the micro-nanoscopic surface of the carbon source, through oxidation chemical reactions, using oxidant agents like, for no limiting examples, ions chromate, dichromate, permanganate, nitrate, halogens, peroxides and other, preferentially nitric acid or hydrogen peroxide, or their mixtures, or any reagent or technique that are able to produce oxygenated groups in the carbon surface which form carboxylic, alcohol, ketone and ether functional groups, and promote the elimination of "sludges" in its surface and after that, perform the anchor of metals nanoparticles, type Pt, PtRu or other, using any method of state of the art to prepare the dispersed electrocatalysts.

BACKGROUND OF THE INVENTION The currently used methodologies now by the state of the art in the preparation of supported electrocatalysts on powdered carbon , known as carbon black, with high specific area are based on the use of carbon black, as obtained, without any functionalization or chemical activation for subseq uent electrocatalysts preparation . In the a summarized form , the carbon powder, without any treatment, it is impregnated with the solutions of the metal catalysts precursors and then the metal ions are reduced to metal form , occurring the depositions of the metal nanoparticles on the surface of the carbon black. Then , in the catalytic ink preparation , for subsequent manufacture of gas diffusion electrodes, it is added an ionomer solution similar to the polymeric membrane used as electrolyte.

With that type of approach, some problems are found , su ch as the presence of impurities from the reaction or method of the carbon production, which could lead to a non homogeneous distribution of metal nanoparticles in the carbon support during the electrocatalysts preparation , and favors the ageing of catalyst by the sintering of metal nanoparticles.

In the present invention , the surface of different carbons a re grafted with exchange polymeric chains with protons exchange properties, followed by the anchoring of the electrocatalysts nanoparticles of Pt, PtRu and others.

For better understanding of the invention , in the electrocatalysis process of a (proton exchange membrane) P EM fuel cell working with H₂IO₂, the H₂ molecules that will be oxidized should first diffuse in the gas diffusion electrode in the anode side and reach to the electrocatalysts nanoparticles (e.g . Pt), which are homogeneously distributed in the support, generally nanoparticles of carbon black. The H₂ molecules should electrochemically adsorb in the Pt atoms to be oxidized, occurring the release of the electrons that will be conducted to the external system by the carbon support. The formed protons should be conducted from the catalytic site to the electrolyte, which in this case is a proton exchange membrane (for example NAFION^®), to subsequently react with oxygen at the cathode, where the oxygen molecule bond was weakened by the electrocatalyst (usually Pt dispersed in C) present in the cathode, finalizing with the H₂O production. To enhance the protons conduction from the catalytic site to the membrane, usually, Nafion ionomer is added to the catalyst, facilitating the conduction of the protons.

According to these facts, it can be seen that there are three different interfaces that are responsible for an improvement or worsening in the catalytic performance in a PEM fuel cell: a) Interface Pt-C, b) Interface Ionomer-Pt and c) Interface Ionomer-C. Hence, to develop catalysts that could result in a better performance for H₂ oxidation and also for another fuels oxidation, such as methanol and ethanol, the determination of which are the best physical and chemical conditions of these interfaces is necessary. One alternative may be the modification of the carbon support surface with the grafting of protons exchange polymer chains, improving the processes of proton transference in the fuel cell system .

In the present invention, the different carbons are treated with oxidizers agents, preferentially hydrogen peroxide (H₂O₂) or nitric acid (HNO₃), or their mixtures, and then the obtained material, after filtering and drying, it is used as support in the preparation of the eletrocatalysts and of the gas diffusion electrodes, also being able to graft polymeric proton exchangers chains, grafting from the carbon surface, following by the anchorage of the nanoparticles of metals and metallic alloys, type Pt and PtRu and other, producing catalyst or gas diffusion electrodes, as well as the modification of the surface of the carbon support be used for the insertion of polymeric proton exchangers chains (H⁺) to improve the processes of protonic transfers that happen in the use of this catalyst in the cell to fuel.

The invention eliminates impurities from the carbon surface, contributing also to a more homogeneous metal nanoparticles distribution in the carbon support, improves the catalytic activity of the material, and also decreases the probability of nanoparticles sintering, and consequently decreasing the aging of the catalyst. But the main effect of this invention is the improvement of the ion conductivity in the three interfaces, as already described , conseq uently decreasing the ohm ic drop of the system . This occurs d ue the formation of carboxyls, hyd roxyls, ketones, ethers and other groups in the surface of the carbon which , by halosteric effect, the nanoparticles are deposited in a more homogeneous form in the carbon surface, improve the catalytic activity of the material and also red uce the probability of nanoparticles sintering, in other words, red uce the aging of the catalyst.

Alternatively, in the present invention , the surface of a carbon source, that are in colloidal particles form , or other carbon forms such as carbon nanotubes, and derived from fullerene or graphite, preferably in carbon black form , begin ning from this functional groups, it is performed the growth of polystyrene sulfonated polymeric chains, NAFION®, polyaniline, polyacrilate, polymethylmethacrylate, polyethylene, polyvinyl, polymaleic, polyglutamic, polyvinylam ine, polyethylamine, polyvinyl 4- alkilpiridinium , polyvinylbenziltrimethylamonium, polymaleicacidcovinylalkylether, polymaleicacidcoalkene, polypropylene, polyamide, polyacetal , polycarbonate, polyethylene terephthalate, acrilonitrile butadiene styrene, styrene acrilonitrile or polybutylene terephthalate, all these polymer in the sulfonated form or not, through chemical reactions and processes that will be described below. Then, the material obtained is used in the preparation of electrocatalysts and gas diffusion electrodes.

There are technologies, in the state of the art, involving functionalization of carbon black, and the growth of polymer chains on the carbon particles, but none applies to the growth of protons exchange polymers for PEM fuel cells applications.

In the patent present, the treatment with oxidizers agents eliminates the "sludges" presents in the surface of the source of carbon, improving the deposition of the metallic nanoparticles in the surface of the support, and the oxygenated groups that are created in the surface of the carbon cause a better distribution of the nanoparticles in the support surface and also avoid the aging of the catalyst by halosteric effect. In addition, as main beneficial effect, the treatment with oxidizer agent causes the closing of the pores that exist in the surface of the carbon source, pores that are responsible to store the metals nanoparticles, after that, they are completely filled and sunk with the nanoparticles, avoiding that the reagents reach those nanoparticles, causing an expense of noble metal. Hence, the treatment with peroxide, nitric acid or their mixtures causes the block of the micro/nano pores, causing an economy in the use of noble metal for the fuel cell technology.

The patent US 6533859 - Masterbatch of functionalized carbon black and elastomer(s) and articles with component(s) thereof, including tires", refers to the preparation of a pre-rubber mixture composition of at least one of carbon black functionalized with a organic solvent solution or aqueous emulsion of at least one elastomer. The functionalized carbon black for the purposes of that invention preferably contains a functional fraction on its surface to help to promote links between the covalent of functionalized carbon black and the polymer. This manufacture article can be, for example , a tire. However, such document does not refer to the preparation of the catalysts for fuel cells. I n the present invention the goal of the grafted polymeric chains is not to form covalent linkages with any substance, but to enhance the proton conduction in the P EM fuel cell electrode, and by halosteric effect to avoid the sintering and growth of metal nanoparticles.

The U.S. Patent Application 20020014185 - "Surface treated carbon black having improved dispersibility in rubber and compositions of rubber there from having improved processability, rheological and dynamic mechanical properties" is related to a carbon black treated surface causing better d ispersibility in rubber. Th is invention is related to a composition which comprises a combination of carbon black, and at least one treatment agent for the surface treatment selected from the group of quinone compounds, composed of quinoneimine and quinonediimine compounds, as well as procedures to obtain the composition and the use of the carbon black composition in a natural or synthetic polymer, but it is not related to the surface -OH g roups formation . The composition reaches characteristics of g reater d ispersibility and improved mixing of carbon black and better processability of the polymer containing the carbon black. In the present invention , there is not the goal of the formation of such groups, and that patent does not refer to the preparation of the catalysts for PEM fuel cells.

The patent US 6794428 - "Carbon black coupler" - describes the use of a coupler in compositions of rubber filled with the carbon black. The coupler includes an amino group and a thiol group or a polysulphide link and improves the interaction of carbon black and the rubber. In the present invention , there is not the goal of the formation of such groups, or any polysulphide link but rather exchange protons exchange polymer chains. None of the patents found presents results for applications in the preparation of electrocatalysts for fuel cells, and the method developed in those patents are not related to what was developed in the present invention .

The technology of the US 6225412

"Polymerization of a sticky polymer in the presence of the treated carbon black" - is the polymerization of a sticky polymer in the presence of a catalyst under conditions of polymerization , using carbon black as a particulate inert material, and the improvement comprises lead in the polymerization in the presence of a carbon black, which was treated with a sulfur donor or an oxidizer agent. I n the process, the polymerization is carried out only in the presence of carbon black, loaded with sulfur and the chemical insertion of polymer chains on the carbon black surface is not accomplished . In the American process , the goal is included in the polymer which is in the carbon black, with the goal of changing their properties for application in rubber and other materials. I n the present invention , the surface of a carbon source, as a carbon black is carried out the growth of polystyrene sulfonated polymeric chains type, NAFION®, polyaniline, polyacrilate, polymethylmethacrylate, polyethylene , polyvinyl, polymaleic, polyglutamic, polyvinylamine, polyethylamine, polyvinyl 4- alkilpiridinium , polyvinylbenziltrimethylamonium , polymaleicacidcovinylalkylether, polymaleicacidcoalkene , polypropylene, polyam ide, polyacetal, polycarbonate , polyethylene terephthalate , acrilonitrile butad iene styrene , styrene acrilonitrile or polybutylene terephthalate, all these polymer in the sulfonated form or not, and the obtained material is used in the preparation of electrocatalysts for manufacture of gas diffusion electrodes.

The patent US 4661383, "Method for grafting polymers to polytetrafluoroethylene, and grafted composites" - describes a method for growing polymer chains on the surface of PTFE - Polytetrafluoretileno. In the process the graft polymers is performed on the surface of PTFE - polytetrafluoroethylene, whereas in the present invention, it occurs on the surface of the carbon black.

The patent US 61 10994 - "Polymeric products containing modified carbon products and methods of making and using the same" - is a method for improving the dispersion of carbon products in polymers, consisting of the idea that when you add the carbon black into polymers the physical and chemical properties of the final product will be different. In that patent, the process is done by mixing materials and not by grafting on the surface of polymers of carbon, as occurs in the " PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS " object of this patent.

The patent US 4014844 - "Process for grafting polymers on carbon black through free radical mechanism" describes the use of technique of free radical polymerization to grow polymers on carbon black. The technology is aimed at the growth of polymers using monomers type styrene, acrilonitrile, mixture of styrene and acrilonitrile and vinyl acetates. The goal is to prepare these materials for applications such as varnishes, paints, increasing the dispersibility of carbon black, and improves its efficiency as a pigment, as an ultraviolet agent, filling, and antioxidant. In that process there are grafted polymers with different structure from that used in the " PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH I ON EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", which are not proton exchangers and so are not usable for catalysts for fuel cells application .

Thus, the novelty and inventive activity of this invention consists to produce oxygenates groups in the carbon su rface, i n different types of carbon sources, by treating them with oxid izers agents preferably using hydrogen peroxide (H₂O2) or nitric acid (H NO₃) or their mixtures, and then the obtained material, after filtering and drying , it is used as support in the preparation of the electrocatalysts and of the gas d iffusion electrodes. Alternatively, before the catalyst preparation , the surface of the different carbons, after they are treated with the oxidizers agents, it can be created or g rafted of proton polymeric exchangers chains from the oxygenated functional groups created at the carbon surface, followed by anchoring the metal nanoparticles or meta llic alloys as Pt or PtRu and other, hence forming a catalyst or gas d iffusion electrode. The inserted polymeric proton exchanger is used to improve the proton exchange at level of electrocatalyst surface that happens in the microstructure of the fuel cell, being preferably polystyrene sulfonated , other polymer chains can be NAFION ®, polyaniline, polyacrilate, polymethylmethacrylate, polyethylene, polyvinyl, polymaleic, polyglutamic, polyvinylamine, polyethylamine, polyvinyl 4-alkilpiridinium, polyvinylbenziltrimethylamonium, polymaleicacidcovinylalkylether, polymaleicacidcoalkene, polypropylene, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, acrilonitrile butadiene styrene, styrene acrilonitrile, or polybutylene terephthalate. SUMMARY OF THE INVENTION

The "PROCESS OF CARBONS

FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAI NS

WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS," is performed in 5 steps:

• Step 1 -reaction of carbon with oxidizing agent to occur the formation of carboxylic groups, alcohols, ketones, ethers and other oxygenated groups on the carbon surface, followed by filtering, washing the material with water to eliminate the oxidizing agent until pH neutral and even the removal of salts or other products, if any, that may be indicated, for example, by the reaction of the washed waters to reagent Brucine.

Optionally, when the oxidizers agents are dissolved in polar solvents (as for no limiting example, water or alcohols) and apolar (as for no limiting example, benzene, toluene, nitrobenzene, dimethylformamide, chloroform, formaldehyde or their mixtures) for formation carboxylic, alcohols, ketones and ethers groups in the surface of the source of carbon, the process can be followed with filtering, washing of the material with water for elimination of the excess of oxidizer agent and, finally, drying of the product, being proceeded the addition of the metals nanoparticules, being eliminated the other stages of the process

• Step 2-reaction of the formed groups in the surface material obtained in Step 1 with thionyl chloride, DMAP or any reaction activator agent, followed by the elimination of the agent and its remaining solvent and drying the obtained material.

• Step 3-reaction of the obtained material in Step 2 with the initiator agent 4.4 azobiscyanovaleric acid or any AZO initiator agent of polymerization , followed by mixing , filtering , washing and drying the obtained material.

• Step 4-Reaction of the obtained material in Step 3 with the monomers to occur the growth of the polymeric chains on the carbon surface.

• Step 5-Reaction of the obtained material with sulfuric acid or nitric acid and other acids, or their m ixtures, to make the polymer a proton exchanger. Filtering , washing and checking the material obtained .

In details, the process can be described :

Step 1 -reaction of a carbon source with oxidizing agent to occur the formation of carboxylic, alcohols, ketones and / or ethers groups on the surface of the source of carbon followed by filtering, washing with water to eliminate the oxidizing agent until neutral pH and even removal of salts or other products, if any, that may be indicated, for example, by the reaction of waters with reagent Brucine and drying the material .

I n a reactor, containing protective internal coating, external heating , sealing against emissions of greenhouse gases, stirrer and a coupled condenser, the carbon source reacts with an oxidant agent such as nitric acid , hydrogen peroxide, ammonium persulfate, hyd rochloric acid , sulfuric acid or other oxidizing agents such as peroxides, nitrates , bromates, chromates, chlorates, dichromates, perchlorates or permanganates that exist or will exist or their mixtures, preferably n itric acid , dissolved or not in polar solvents such as water, alcohol or apolar solvents as benzene, toluene, nitrobenzene, dimethylformamide, ch loroform, formaldehyde or their m ixtures, in a concentration of 0.1 MoI. L^"1 to 15 MoI. L^"1 , preferably 12 MoI . L^{" 1} , in colloidal particles or other carbon forms, carbon nanotubes and derived from fullerene or graphite, preferably carbon black in the concentration of 0.00001 gl_^"1 to 1000 gl_^"1 , in temperatures ranging between 0 and 250 ° C, preferably 80 ⁰C in the case of nitric acid or 60 ° C in the case of hydrogen peroxide or mixture of both, for up to 100 hours, preferably 24 hours, under agitation from 0 to 8000 rpm, preferably 800 rpm, the positive pressure to 10 psi, preferably atmospheric pressure. During the step is necessary to use the condenser to keep nitric acid in the reaction environment. The solution is withdrawn from the reactor and the carbon black is filtered using an appropriate vacuum filtering, and washed with de-ionized water thoroughly to remove nitrates traces from not reacted HNO₃, or from any oxid izing agents used or their mixtures not responded or even the removal of salts or other products, if any, which affect the performance in the preparation of electrocatalysts. The washing must be done to achieve neutral pH, in the case of the reaction with nitric acid to remove the nitrates, which can be indicated by the reaction of washers waters with reagent Brucine (negative test - colorless - indicates no nitrates). The product obtained is dried in oven with temperatures less than 250 ° C, preferably 1 10 ⁰ C until it is completely dry.

Optionally, when the oxidizers agents are dissolved in polar solvents (as for no limiting example water or alcohols) and apolar (as for no limiting example the benzene, toluene, nitrobenzene, dimethylformamide, chloroform, formaldehyde or their mixtures) for formation of carboxylic, alcohols, ketones and ethers groups in the surface of the carbon source, it should occur in a reactor, containing protective coating, external heating, sealing against emission of gases, agitator and a coupled condenser, in closed atmosphere reacts an oxidizer agent, preferentially nitric acid or hydrogen peroxide or their mixtures, depending on the functional group type wanted to be formed, dissolved in polar solvents and/or apolar in the concentration of 0, 1 Mol/L to 15 Mol/L, preferentially 12 Mol/L, with the carbon source in suspension, of 0,00001 g/L to 10000 g/L, preferentially 17 g/L, in temperature varying between 0 and 25O⁰C , preferentially 8O⁰C in the case of nitric acid use, or 6O⁰C in the case of use of hydrogen peroxide, or intermediate temperature in the case of use of mixture of hydrogen peroxide and nitric acid , d uring 0 at 1 00 hours, preferentially 24 hours, under agitation from 0 to 8.000 rpm , preferentially 800 rpm , to the positive pressure of up to 3 atm , preferentially atmospheric pressure. During the process it is necessary the use of a condenser to maintain the oxidizer agent inside of the reaction atmosphere.

The nitric acid use tends to a la rger formation of carboxylic functional groups (- COOH) and the hydrogen peroxide to a larger formation of alcohols functional groups (- OH) . The mixture of those oxidizers agents should be used when , although interest is in the majority formation of a certain functional group, it is also of interest the formation of the other functional group formed by the other oxid izer, could also be used other oxidizers. The amount and nitric acid concentration , hydrogen peroxide or other oxidizer will depend , also, of the source of carbon used. The difference in the types of superficial groups generated in the surface of the carbon alters the physical-chemical characteristics of the support, causing different possibilities of chemical reactions, and changing the final application of the product. Groups of the acid type COOH , turn acid the surface of the carbon, altering the properties of the carbon for subsequent use as catalysts support, properties that will be different when of the use of carbon with superficial groups of the type-OH in its surface. Besides, the difference in the superficial groups also alters the route of chemical reaction for subsequent growth of polymeric chains grafted in the surface of the carbon . Different superficial groups also alter the d ispersibility of that material in different solvents, then the possibility to vary the use of d ifferent solvents in the method of funcionalization of those carbons. Carbons of high superficial area can be prepared of many forms and broken , usually with the formation of many "sludges" com ing of the method of preparation of those carbons that usually interfere in a negative way for the preparation of supported nanocatalysts in carbon . Chem ical oxidizers treatments in the surface of those carbons tend to decrease or to eliminate those sludges, for the own oxidation or lixiviation of the same ones.

The solution is removed from the reactor and the source of carbon is filtered , for instance in Bϋchner funnel , using appropriate filtration paper and under vacuum , and the solid prod uct is washed exhaustively with water, preferentially with deion ized water for removal of traces of the oxid izer agent residual nitrates from non reacted H NO₃ and or traces resid ual peroxides from non reacted H₂O₂, which affect the preparation of the electrocatalysts. The washing should be accomplished until neutral pH or, in the case of the reaction with nitric acid , total elim ination of the nitrates by the reaction of the wash waters with Brucine reagent.

The obtained prod uct is dried in a oven with temperature to below 25O⁰C, preferentially 1 1 O⁰C, until that it is completely dry and , then , it is directed for preparation of the catalysts by the addition of nanoparticulated metals, usually using pre-developed methods of impregnation of the carbon in aqueous solution of the desired ions, and subsequent metallic reduction of those metallic ions by some reducer agent of the state of the art.

Step 2-reaction of the formed groups in the surface material obtained in Step 1 with thionyl chloride, DMAP or any activator reaction agent, or mixtures, in a reactor, contain ing internal protective coating , external heating , sealing against emissions of greenhouse gases, and a coupled condenser, followed by drying of the material obtained , and disposal of thionyl chloride, DMAP or any activator reaction agent, or mixtures and its remaining solvent. Reacts itself on a protected environment with th ionyl chloride, DMAP or any activator reaction agent, or mixtures, dissolved in organ ic solvent such as benzene, toluene, nitrobenzene, d imethylformamide, chloroform or formaldehyde, benzene preferably in a concentration range of 0.01 MoI. L^{' 1} to 15 MoI. L^'1 , preferably 5 MoI. L^{" 1} , the material obtained from Step 1 , in temperatures ranging between 0 and 250 ⁰C, preferably 85 ⁰C, for 0 to 1 00 hours, preferably 50 hou rs, u nder agitation from 0 to 8000 rpm , preferably 800 rpm , with positive pressure until 1 0 psi, preferably atmospheric pressure. During th is step is necessary the use of condenser to keep th ionyl ch loride, DMAP or any agent of reaction activator, or mixtures within the environment of the reaction . Then , to make the operation of drying and removal of thionyl chloride, DMAP or any agent of reaction activator, or mixtures, and solvent in excess, they are evaporated in a inert gas flow, such as n itrogen or argon , temperature from 0 to 250 ° C, preferably 90 ° C, drying up the material. The obtained prod uct is d ried in oven with temperatures less than 250 ° C, preferably 1 1 0 ° C u ntil it is completely dry, and then is forwarded to the next stage.

Step 3-Reaction of the obtained material in Step 2 with the in itiator agent 4.4 azobiscyanovaleric acid , or any AZO initiator agent of the polymerization , or thei r m ixtures, in a reactor contain ing internal protective coating , external heating , sealing against gas emissions and stirrer. The agent initiator 4.4 azobiscyanovaleric acid , or any AZO agent initiator of the polymerization, or their mixtures, using organic solvent such as benzene, toluene, n itrobenzene, dimethylformamide, chloroform or formaldehyde or their mixtures, preferably chloroform , in a range of concentrations of 1 .0 x 1 0^"4 mol. L^'1 to 15 mol. L^"1 , preferably 0.04 mol. L^"1 , is added to a carbon source from Step 2, in temperatures ranging between 0 and 250 ° C, preferably 25 ° C for 0 to 200 hours, preferably 24 hours, under agitation from 0 to 8000 rpm, preferably 800 rpm, with positive pressure until 10 psi, preferably environment pressure.

The solution is withdrawn from the reactor and the carbon source is filtered using appropriate vacuum filtering, and washed thoroughly with the same solvent used in the reaction for removal of initiator excess that was not reacted , i.e. initiator excess that is not chemically bound to the surface of the carbon source, that could cause the growth of chains outside their carbon surface. The obtained product is dried in oven with temperatures less than 250 ° C, preferably 25 ° C until it is completely dry, and then is forwarded to the next stage.

Step 4-Reaction of the obtained material in Step 3 with monomer to grow the polymer chains on the carbon source surface in a reactor containing internal antacid coating, external heating, sealing against emission of gases and stirrer.

The monomers usable are those trainers of the polymers chains, as polystyrene sulfonated, NAFION®, polyaniline, polyacrilate, polymethylmethacrylate, polyethylene, polyvinyl, polymaleic, polyglutamic, polyvinylamine, polyethylamine, polyvinyl 4-alkilpiridinium, polyvinylbenziltrimethylamonium, polymaleicacidcovinylalkylether, polymaleicacidcoalkene, polypropylene, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, acrilonitrile butadiene styrene, styrene acrilonitrile or polybutylene terephthalate, using water as a solvent, benzene, toluene, nitrobenzene, dimethylformamide, chloroform or formaldehyde or their mixtures, preferably water, in a range of concentrations from 1 to 1 .O x 10⁶ monomers molecules for each group initiator reacted on the surface of carbon, preferably 8, or a ratio of 1 :3 of bulk carbon to monomer, that reacts with the initiator group present on the carbon source surface from Step 3, in temperatures ranging between 0 and 250 ° C, preferably 80 ° C, from 0 to 200 hours, preferably 24 hours, under agitation from 0 to 8000 rpm , preferably 800 rpm, and positive pressure until 10 psi, preferably pressure environment. The protons exchange polymer chains grown from the carbon surface ("graft-from") are created or grafted with pre-synthesized polymer ("graft onto") from any technical and mechanisms available in the state of the art.

Step 5-Reaction of the obtained material from step 4 with sulfuric acid or nitric acid and other acids, or their mixtures, to make the polymer a protons exchanger, followed by filtering, washing and drying the obtained material. Then at the end of step 4, is added to the reactor, aqueous solution of sulfuric acid , or nitric acid and other acids, or their mixtures, in a range of concentrations of 0.001 to 10 mol. L^"1 , preferably 0.5 mol. L^"1 , in temperatures ranging between 0 and 150 ⁰C, preferably 80 ⁰C from 0 to 200 hours, preferably 24 hours, under agitation from 0 to 8000 rpm , preferably 800 rpm, with positive pressure until 10 psi, preferably ambient pressure, to turn the form -SO₃H that is proton exchanger. The solution is withdrawn from the reactor and the carbon source is filtered using appropriate vacuum filtering, and washed thoroughly with the same solvent used in the reaction of step 4 for excess polymer removal that was formed, excess polymer that is not chemically bound to the surface of the carbon. The obtained product is then dried in oven with temperatures less than 250 ° C, preferably 1 1 O ⁰ C until it is completely dry and the process is finalized . The Tables 1 , 2 and 3; and the Figures 1 and 2 present obtained results when made the Stepi in the optional form.

The Table 1 presents the results of the characterization obtained for different supports and the Table 2 the characterization obtained for different catalysts.

The capacitance data in the Table 1 show that the chemical treatment of oxidation reduced the capacitance of the material, increasing its conductivity. The specific surface area is decreased with oxidation.

Table 1 - Characterization data obtained for the different supports

After the inclusion of the metal nanoparticles in the support, it is observed in Table 2 a decrease of the particle size in the materials which support was submitted to the chemical treatment with nitric acid and hydrogen peroxide (as smaller the particle size, better the catalytic efficiency, due to a larger available specific surface area to happen the electrochemical reaction). The functional groups created in the surface of the carbon result in a better distribution of the metallic Pt particles anchored in the surface of the carbon , fact also observed for the materials PtRu. It is observed that the treatment with peroxide forms smaller sizes of metal particles for Pt/C and the treatment with nitric acid forms of smaller size of metal particles for PtRu/C, but very close of the treatment with peroxide.

For the technique of Transmission Electronic Microscopy (TEM) it can be obtained information of the homogeneity of the metal nanoparticles of the electrocatalysts distributed in the carbon black surface, as well as to obtain information on the particle size of supported metals. They were obtained micrographs for the electrocatalysts supported in carbon black without treatment and carbon black treated with H2O2, as shown in the Figure 1 .

Table 2 - Characterization data obtained for the different catalysts

(*) TEM- Transmission Electronic Microscopy

(* *) DRX-Diffraction of X-ray

BRIEF DESCRIPTION OF THE DRAWINGS

The Figure 1 shows micrograph of the catalysts supported in carbon black with chemical treatment of oxidation, and the Figure 2 shows micrograph of the catalysts supported in carbon black without the oxidation treatment. The enlargement scales are suitable in the own micrograph and in each Figure we have two different enlargements for the same material.

Observing the micrographs in the Figures 1 and 2 was its possible to conclude that the nanoparticles of the electrocatalysts supported in carbon black without treatment (Figure 2) show an agglomerated way, in other words, no homogeneous in its surface. Already the nanoparticles supported on carbon black treated with H₂O2 (Figure 1 ) they present a better homogeneity, resulting in a catalysts with larger specific surface area available to occur the adsorption of the combustible reagents. The treatment with peroxide eliminates the present sludge in the carbon black surface, believed to be responsible for the agglomeration of nanoparticles to be supported.

Using the Scherrer equation, it was dear the medium diameter of the crystals of the supported materials. The calculated values are in the Table 2. Those results show that there was a reduction in the of metal particle size of the prepared catalysts after the treatment with nitric acid or hydrogen peroxide, and that means an increase of the available catalytic area and, consequently, a better acting of the catalyst for applications in fuel cells. Results of larger reliability presented by TEM prove that fact, showing the same observed tendency, as it can be observed in the Figures 1 and 2. Tests of commercial catalysts in cells to fuel type PEM for oxidation of H2 / O2

As presented previously, one of the objectives of the creation of functional groups in carbon black surface is it of avoid the nanoparticles to sinterize along the time of use of the catalysts in cell to fuel, reducing its efficiency, in other words, to impede its aging.

They were lifted up polarization curves or applied potential curves (in Volts) versus current density (in Amperes/cm2xgmetal), in unitary cell I model FC25/125 of the company Baltic Fuel Cell GmbH, of 5x5 cm2 of eletrodic area, operand with H₂/ar and with Metanol/ar (fuels usually applied for cells PEMFC and DMFC, respectively, with larger densities of possible potencies).

In the Table 3 the data of obtained potencies of the polarization curves are presented. It was observed that the material that it presented the best catalytic efficiency, that is, better potency value was the material treaty with H₂O₂.

Table 3. Potency data obtained for the materials PtRu/C-H₂O₂ and PtRu/C AND-TEK in cells to fuels unitary operand with H₂/ar and Metanol/ar.

EXAMPLE Step 1- Add 15 grams of carbon black in a glass reactor, coupled to a bath thermostatized and a mechanical stirrer with rod-type propeller, and then add 300 ml_ of concentrate nitric acid 75% to the reactor, and then the system must be closed and a condenser must be coupled to the reactor. This stage of activation is performed at 80 ⁰C for 24 hours with stirring at 800 rpm and atmospheric pressure, then the solution is withdrawn, and the carbon black is filtered and washed thoroughly to remove traces of nitrates until neutral pH. The obtained powder is dried in oven at 110 ⁰C.

Step 2 - Then, 6 grams of the obtained powder is placed in a round bottom flask, with 60 ml_ of benzene and 30 ml_ of thionyl chloride (SOCI2). This stage of activation is performed at 80 ⁰C for 50 hours with stirring at 800 rpm and with atmospheric pressure, and then the solution is evaporated in inert atmosphere. The obtained powder is dried under vacuum.

Step 3 - Then, the obtained powder from Step 2 should be placed in a reactor round bottom flask, together with 100 mL of chloroform and 6 grams of 4.4 azobiscyanovaleric acid. This stage of activation is performed at room temperature for 24 hours with stirring at 800 rpm and atmospheric pressure, and then the remaining solid is filtered. The obtained powder is dried under vacuum.

Step 4 - Then, the obtained powder from step 3 should be placed in a round bottom flask, together with 100 mL of de-ionized water and 18 grams of monomer styrene sulfonic sodium salt. This stage of activation is performed at 80 ° C for 1 hour with stirring at 800 rpm and atmospheric pressure.

Step 5- Then, in the used flask in the step 4, it should be added concentrated sulfuric acid, resulting in a final concentration of acid in the system of 1 mol.L^'1. This stage of activation is performed at 80 ° C for 1 hour with stirring at 800 rpm and atmospheric pressure. The obtained powder is dried under vacuum at 60 ⁰C.

EXAMPLES - (STAGE 1 OPTIONAL)

EXAMPLE 1

5 grams of carbon are added to a reactor of jacketed glass coupled to a termostatized bath and a mechanical agitator with a helix type propeller.

Then 100 mL of hydrogen peroxide of 30° V/V is added to the reactor.

The system is closed and a condenser is coupled to the reactor.

The activation process is accomplished to 6O⁰C by 24 h.

In the next step the solution is removed, the carbon is filtered and washed exhaustively for removal of hydrogen peroxide residues.

The obtained powder is dry in oven to 1 10 ⁰C, being composed of carbon functionalized, where they can be later the polymeric chains be inserted and/or the metals of the catalysts.

EXAMPLE 2.

10 grams of carbon are added to a reactor of jacketed glass coupled to a termostatized bath and a mechanical agitator with type helix propeller.

Then 150 mL of fuming concentrated nitric acid are added to the reactor. The system is closed and a condenser is coupled to the reactor.

The activation process is accomplished 80 ⁰C by 24 h.

Then the solution is removed, the functionalized carbon is filtered and washed exhaustively for removal of nitrate residues.

The obtained powder is dried at 110 ⁰C, where it can be later used to graft polymeric exchanger chains.

Claims

1 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS," characterized by doing the growing of polymer chains with protons exchange properties that are chemically linked in the carbon source surface, performed by 5 steps:

• Step 1 - reaction of the carbon source with oxidizing agent to occur the formation of carboxylic groups, alcohols, ketones, ethers and other on the carbon surface, followed by filtering, washing the material with water to eliminate the oxidizing agent until pH neutral and even the removal of salts or other products, if any, that may be indicated, for example, by the reaction of the washed waters to reagent Brucine, and with the option to use this activated support with oxidation agents preferably nitric acid and hydrogen peroxide as a support for electrocatalysts for polymer electrolyte fuel cell applications.

• Step 3-Reaction of the obtained material in Step 2 with the initiator agent 4.4 azobiscyanovaleric acid or any initiator AZO agent of polymerization, followed by mixing, filtering, washing and drying the obtained material.

• Step 5-Reaction of the obtained material with sulfuric acid or nitric acid and other acids, or their mixtures, to make the polymer a protons conductor or exchanger followed by filtering, washing and checking the material obtained. 2 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 , characterized by the using

5 of a polymer type Nafion®, NAFION ®, polyaniline , polyacrilate , polymethylmethacrylate , polyethylene sulfonated, polyvinyl , polymaleic , polyglutamic, polyvinylamine, polyethylamine, polyvinyl4-alkilpiridinium, polyvinylbenziltrimethylamonium, polymaleicacidcovinylalkyiether, polymaleicacidcoalkene, polypropylene, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, acrilonitrile butadiene styrene , styrene acrilonitrile or polybutylene terephthalate and the used carbon source in the colloidal form and or other forms of carbons like carbon nanotubes, derived from fullerene or graphite.

3 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 2, characterized by the carbon source used is carbon black.

4 - "PROCESS OF CARBONS FUNCTIONALIZATION BY D THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 , characterized by the step 1 , the reaction of carbon source to occur the formation of carboxylic groups, alcohols, ketones, ethers or others in the carbon surface with oxidant 5 agents in polar or apoiar solvents and its mixtures in concentration range from 0, 1 mol.L^"1 to 15 mol.L^"1 from 0,00001 gL^"1 to 1000 gL^'1 with stirring from 0 to 8000 rpm, in a temperature range from 0 to 25O⁰C, during 0 until 100 hours, in a positive pressure of 10 psi, followed by wash, filtering, and dry of the material.

) 5 - "PROCESS OF CARBONS FUNCTIONALIZATION BY

THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 , and 4, characterized by the use of a oxidant agent like nitric acid, hydrogen peroxide, ammonium persulfate, chloridric acid, sulfuric acid or other oxidant agent like peroxides, nitrates, bromates, chromates, chlorates, dichromates, perchlorates e permanganates that exists or its mixtures, dissolved in apolar solvent or not.

6 "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 , 4 and 5, characterized by the use of a oxidant agent like nitric acid, hydrogen peroxide or its mixtures.

7 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 , 4 and 5, characterized by the polar or apolar solvents, water or alcohols or its mixtures like benzene, toluene, nitrobenzene, dimethylformamide, chloroform, formaldehyde or its mixtures.

8 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 and 3, characterized to take the solution and the filtering of the product, washing with distillated water to make the removal of unreacted reagent and nitrates that comes from the HNO₃ activation.

9 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 , characterized with the step 2 to react the product from step 1 with thionyl chloride, DMAP or any reaction activator reagent that exists. 10 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 9, characterized by the use of thionyl chloride, DMAP or any reaction activator reagent that exists, that are dissolved or not in a organic solvent like benzene, toluene, nitrobenzene, dimethylformamide, chloroform, formaldehyde or its mixtures in the concentration from 0.01 to 15 mol.L^"1.

11 "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 and 9, characterized to perform the reaction of the product from the step 2 with thionyl chloride, DMAP or any reaction activator reagent that exists, in a temperature range from 0 to 25O⁰C, during 0 to 100 hours under stirring of 0 to 8000 rpm, under a positive pressure of 10 psi.

12 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 and 9, characterized to perform the an elimination operation of the thionyl chloride excess, DMAP or any reaction activator reagent that exists, and its solvent by evaporation under an inert gas flow in a temperature range from 0 to 25O⁰C e the dry of the material in oven with temperature under 25O⁰C.

13 - "PROCESS OF CARBONS FUNCTIONALIZATION

BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 , characterized by the step 3 which the product that comes from step 2 reacts, during 200 hours, with azo agent 4,4 azobiscyanovaleric, or any agent AZO or initiator polymerization agent that exist or will exist, or its mixtures, dissolved in a organic solvent like benzene, toluene, nitrobenzene, dimethylformamide, chloroform or formaldehyde or its mixtures, in a temperature range from 0 to 250 ⁰C, with stirring from 0 to 8000 rpm, in a positive pressure of 10 psi, followed by wash, filtering, and dry of the material.

14 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 13, characterized by the step 3 which the product that comes from step 2 reacts, during 200 hours, with azo agent 4,4 azobiscyanovaleric, or any agent AZO or polymerization initiator agent that exists, or its mixtures, dissolved in a organic solvent like benzene, toluene, nitrobenzene, dimethylformamide, chloroform or formaldehyde or its mixtures, in a concentration range from 0 ,0001 mol.L^"1 to 15 mol.L/¹.

15 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 13, characterized to take the solution and the filtering of the product, washing with distillated water to make the removal of unreacted AZO reagent, and dry the material in a temperature under 25O⁰C.

16 - "PROCESS OF CARBONS FUNCTIONALIZATION

BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 , characterized by the step 4, until 200 hours, from material obtained in the step 3 with the respective monomers, to perform the growth of the polymeric chains in the carbon surface, in the temperature range from 0 to 25O⁰C, under stirring of 8000 rpm and positive pressure of 10 psi.

17 - "PROCESS OF CARBONS FUNCTIONALIZATION

BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS

APPLICATIONS", according with the claims 1 and 16, characterized to the utilization of the monomer dissolved in water, benzene, toluene, nitrobenzene, dimethylformamide, chloroform or formaldehyde or its mixtures in a monomer concentration range from 1 to 1 .0 x 10⁶ meros for each initiators group in the carbon surface.

1 8 - "PROCESS OF CARBONS FU NCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAI NS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 , characterized by the step 5 to add in the reactor an sulfuric acid water solution, or nitric acid, or other acids, or its mixtures, in a concentration range from 0001 to 10 mol. L^"1 , until 200 hours, in a temperature range from 0 to 25O⁰C, under stirring from 0 to 8000 rpm with a positive pressure of 10 psi to make the polymer a proton exchanger.

1 9 - "PROCESS OF CARBONS FU NCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAI NS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 and 18, characterized to make the solution and the filtering of the prod uct, washing with the same solvent used to remove unreacted monomer and polymers that were produced outside the carbon surface.

20 - "PROCESS OF CARBONS FUNCTIONALIZATION

BY THE GROWTH OF POLYMERIC CHAI NS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claim 1 and 4, characterized by the optional step 1 , the oxidant agents are hydrogen peroxide or nitric acid or its mistures.

21 - "PROCESS OF CARBONS FUNCTIONALIZATION BY TH E GROWTH OF POLYMERIC CHAI NS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the optional step 1 , the oxidant agents are dissolved in polar or apolar solvents or its mixtures in the concentration of 12 mol. L^"1. 22 - "PROCESS OF CARBONS FU NCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the step 1 optional, the carbon source is in the concentration of 17 gL^"1.

23 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the step 1 optional, the operation temperature is 80 ⁰C, in the case of the use of nitric acid.

24 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the step 1 optional, the operation temperature is in a range is 60 ⁰C, in the case of the use of hydrogen peroxide.

25 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the step 1 optional, the operation temperature is in a range of 60 to 8O⁰C, in the case of the use of hydrogen peroxide and nitric acid mixture.

26 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4, characterized by the optional step 1 , the oxidation operation period is 24 hours.

27 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE

PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4, characterized by the step 1 optional, the stirring speed is 800 rpm.

28 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAI NS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the step 1 optional, the operation pressure is positive pressure until 3 atm.

29 - PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4 , characterized by the optional step 1 , the operation pressure is atmospheric pressure.

30 - "PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS", according with the claims 1 and 4, characterized by the step 1 optional, after the reaction the final product is filtered, washed with water to eliminate the oxidizing agent until pH neutral and even the removal of salts or other products, and after that, the product is dried in oven in a temperature under 250⁰C.

31 - PROCESS OF CARBONS FUNCTIONALIZATION BY THE GROWTH OF POLYMERIC CHAINS WITH ION EXCHANGE PROPERTIES FOR POLYMER ELECTROLYTE FUEL CELLS APPLICATIONS, according with the claims 1 and 4 , characterized by in the optional step 1 the product resulting from the oxidation reaction, after the filtering, to be exhaustively washed with distilled water when the agent oxidizer is hydrogen peroxide.