2891 results about "Electrocatalyst" patented technology

The invention relates to platinum-coated particles useful as fuel cell electrocatalysts. The particles are composed of a noble metal or metal alloy core at least partially encapsulated by an atomically thin surface layer of platinum atoms. The invention particularly relates to such particles having a palladium, palladium alloy, gold alloy, or rhenium alloy core encapsulated by an atomic monolayer of platinum. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

In a solid polymer fuel cell series, various circumstances can result in the fuel cell being driven into voltage reversal. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pass current during fuel starvation, reactions other than fuel oxidation may take place at the fuel cell anode, including water electrolysis and oxidation of anode components. The latter may result in significant degradation of the anode. Such fuel cells can be made more tolerant to cell reversal by promoting water electrolysis over anode component oxidation at the anode. This can be accomplished by incorporating a catalyst composition at the anode to promote the water electrolysis reaction, in addition to the typical anode electrocatalyst for promoting fuel oxidation.

The present invention relates to controlled growth of carbon nanotube (CNT) arrays via chemical vapor deposition (CVD) using novel porous anodic aluminum oxide (AAO) templates, which have been seeded with transition metal catalysts. The resulting CNT bundles may be dense and long and can be used for numerous applications. Further, the porous AAO templates and the CNTs grown thereby, can be functionalized and used for separation of chemical species, hydrogen storage, fuel cell electrocatalyst and gas flow membranes, other catalytic applications, and as a bulk structural material.

High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The preferred manufacturing process involves the initial oxidation of the carbon nanostructures followed by immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means and the nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. Subsequent film growth may be performed via the initial quasi-underpotential deposition of a non-noble metal followed by immersion in a solution comprising a more noble metal. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

Disclosed is an electrocatalyst for fuel cells, in which a porous carbon material including pores having a diameter smaller than a kinetic diameter of carbon monoxide is used as a support body and contact probability between an activated metal and carbon monoxide is decreased, thereby preventing fuel cell performance from being degraded by carbon monoxide. The electrocatalyst is obtained by adsorbing 10-80 parts by weight of an activated metal to 20-90 parts by weight of a porous support body, characterized in that the porous support body has a total surface area of 200-2,500 m<2>/g including an outer surface thereof and an inner surface of pores thereof, and has a plurality of pores penetrating into an interior of the support body with an average diameter of 2-15 nm and a total volume of 0.4-2.0 m<3>/g, and the activated metal is alloyed with 20-95 at % of platinum and 5-80 at % of one metal selected from among Ru, Sn, Os, Rh, Ir, Pd, V, Cr, Co, Ni, Fe and Mn. As for such an electrocatalyst, carbon monoxide does not fundamentally come in contact with the activated metal adsorbed to the inner surface of the pores of the support body, thereby minimizing degradation of fuel cell performance, thus overcoming fuel-feeding problems.

High-stability, self-protecting particles encapsulated by a thin film of a catalytically active noble metal are described. The particles are preferably nanoparticles comprising a passivating element having at least one metal selected from the group consisting of columns IVB, VB, VIB, and VIIB of the periodic table. The nanoparticle is preferably encapsulated by a Pt shell and may be either a nanoparticle alloy or a core-shell nanoparticle. The nanoparticle alloys preferably have a core comprised of a passivating component alloyed with at least one other transition metal. The core-shell nanoparticles comprise a core of a non-noble metal surrounded by a shell of a noble metal. The material constituting the core, shell, or both the core and shell may be alloyed with one or more passivating elements. The self-protecting particles are ideal for use in corrosive environments where they exhibit improved stability compared to conventional electrocatalyst particles.

The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen.

The invention relates to a nano carbon doped electrocatalyst for a fuel cell, and application of the nano carbon doped electrocatalyst. The electrocatalyst is prepared by adopting the steps of: complexing a nitrogen-containing and/or boron-containing organic precursor and a transition metal salt to form a composite; adding nano carbon as a carrier, and heating and reacting a mixture by adopting a microwave radiation method; and after the reaction is complete, filtering and drying, placing a product obtained after the reaction in an inert atmosphere and/or reducing atmosphere, and treating at a high temperature of 500-1500 DEG C to obtain the nano carbon doped electrocatalyst. The nano carbon doped electrocatalyst is very low in cost, high in activity and stability and excellent in anti-poisoning capacity.

The invention discloses a preparation method of a ferro-nickel bi-metal hydroxide of a sheet structure on foamed nickel through in-situ growth, and belongs to the field of electrochemistry. Nickel nitrate hexahydrate, iron nitrate nonahydrate, urea, ammonium fluoride and foamed nickel are adopted as main raw materials, and an electrocatalyst through water electrolysis oxygen production is successfully prepared. The sheet structure of the catalyst supplies abundant active sites, due to existence of substrate foamed nickel, the electrical conductivity is enhanced, and when the hydroxide is adopted as the electro-catalysis oxygen production catalyst, the excellent catalysis activity is shown. The activity of a traditional non-noble metal material under an oxygen evolution reaction (OER) in analkaline electrolyte is not ideal. Accordingly, the OER catalysis performance of the non-noble metal material under the alkaline condition is improved, and the method is of great significance in solving the fossil fuel energy crisis. Nickel and iron earth reserve volumes are quite abundant, the OER catalytic performance of the ferro-nickel bi-metal hydroxide of the sheet structure under the alkaline condition is excellent, and the hydroxide is a catalytic material with the wide prospect.

The invention discloses core/shell type catalyst particles comprising a M_core/M_shell structure with M_core=inner particle core and M_shell=outer particle shell, wherein the medium diameter of the catalyst particle (d_core+shell) is in the range of 20 to 100 nm, preferably in the range of 20 to 50 nm. The thickness of the outer shell (t_shell) is about 5 to 20% of the diameter of the inner particle core of said catalyst particle, preferably comprising at least 3 atomic layers. The core/shell type catalyst particles, particularly the particles comprising a Pt-based shell, reveal a high specific activity. The catalyst particles are preferably supported on suitable support materials such as carbon black and are used as electrocatalysts for fuel cells.

The present invention provides a bimodal porous carbon capsule with a hollow core and a mesoporous shell structure, which can be employed as an electrocatalyst support for a fuel cell; electrocatalysts for the fuel cell using the bimodal porous carbon capsule, and a method of preparing the same. The electrocatalyst according to the present invention has higher catalysis activity as compared with the Pt—Ru or Pt catalyst supported by the conventional carbon black, so that the performance of the fuel cell is enhanced, and it can be easily prepared in an aqueous solution state. According to the present invention, the porous carbon support employed as the support for the catalyst has excellent conductivity and a high surface area, so that the loaded catalyst can be prepared with a smaller amount than that of the conventional carbon black. Further, metal particles having an extremely fine size of 2˜3 nm are uniformly distributed on the support, so that the area of an active site at which catalysis reaction is performed is increased, thereby increasing the catalyst activity with respect to the oxidation reaction of the fuel such as methanol, ethanol, hydrogen, etc. Also, a fine pore of a porous carbon support secures a fuel dispersing passage, so that the fuel including alcohol such as methanol, ethanol or the like, hydrogen, etc. can be easily transferred and dispersed, thereby efficiently performing its oxidation-reduction reaction. On the other hand, an air electrode can efficiently function as the catalyst due to the same principle.

Processes, techniques, and compositions used to fabricate high performance solid acid fuel cell membrane electrode assemblies are disclosed. The techniques include preparing the solid acid electrolyte material, depositing the electrolyte membrane, depositing the electrocatalyst layer, preparing the electrodes, fabricating the gas seals, and constructing the membrane electrode assembly.

The invention described concerns an anode electrode comprising a hydrogen storage material/alloy and a high energy density metal. In addition a hydrogen electrocatalyst may be added to increase the hydrogen reaction rate. The high energy density metal is selected from a group consisting of Al, Zn, Mg and Fe, or from a combination of these metals. A method of production of an electrode comprising a hydrogen storage alloy and a high energy density metal is also described. The method comprises sintering or binding a high energy density metal powder and/or hydrogen storage alloy into at least one thin street, and calendaring or pressing said sheet forming the electrode. The anode electrode may be used in metal hydride batteries and metal air fuel cells.

A method and apparatus for coating an ion-exchange membrane or fluid diffusion layer with a catalyst layer for use in an electrochemical fuel cell is disclosed, the method comprising the steps of electrostatically charging a catalyst slurry to yield an electrostatically-charged catalyst slurry, and applying the electrostatically-charged catalyst slurry onto a first surface of the ion-exchange membrane or fluid diffusion layer to form a first catalyst layer on the first surface.

A nanofibrous catalyst and method of manufacture. A precursor solution of a transition metal based material is formed into a plurality of interconnected nanofibers by electro-spinning the precursor solution with the nanofibers converted to a catalytically active material by a heat treatment. Selected subsequent treatments can enhance catalytic activity.

The invention provides an electrocatalyst with a cobalt-based multi-stage nano-composite structure for oxygen production by electrolysis of water and a preparation method of the electrocatalyst. The preparation method comprises the following steps: dissolving cobalt nitrate hexahydrate, urea and ammonium fluoride in deionized water to obtain a precursor solution; transferring the precursor solution into a hydrothermal reactor; adding carbon fiber paper; enabling basic cobalt carbonate nanowires to grow on the carbon fiber paper through solvothermal reaction; after finish of reaction, naturally cooling; then taking out a product; washing and drying to obtain a carbon fiver paper loaded basic cobalt carbonate nanowire composite structure; by taking powdered sulfur as the raw material, preparing a carbon fiber paper loaded cobalt sulfide nanowire composite structure through low-temperature sulfuration reaction under the condition of an inert gas; and finally, electroplating the surface of the carbon fiber paper loaded cobalt sulfide nanowire composite structure with a layer of cobalt hydroxide nanosheets by use of the electrochemical deposition method so as to obtain the electrocatalyst with the cobalt-based multi-stage nano-composite structure for oxygen production by electrolysis of water. As the sulfide and the hydroxide of transition metal cobalt are adopted as the catalyst, in comparison with noble metals, the cost of the catalyst is lowered.