1191 results about "Oxygen reduction reaction" patented technology

A bio-implantable electrochemical cell system for active implantable medical devices. In one embodiment, the fuel cell includes an electrode structure consisting of immobilized anode and cathode enzymes deposited on nanostructured high-surface-area metal nanowires or carbon nanotube electrodes. The anode enzyme comprises immobilized glucose oxidase and the cathode enzyme comprises immobilized laccase. Glucose is oxidized at the surface of the anode and oxygen is reduced at the surface of the cathode. The coupled glucose oxidation-oxygen reduction reactions provide a self-generating current source. In another embodiment, the nanowires or carbon nanotubes, along with the adjacent surface anode and cathode electrodes, are coated with immobilized glucose oxidase and immobilized laccase containing biocolloidal substrates, respectively. This results in the precise construction of an enzyme architecture with control at the molecular level, while increasing the reactive surface area and corresponding output power by at least two orders of magnitude.

The invention discloses a simple method of using foam nickel as a substrate to prepare a three-dimensional graphene-carbon nitrogen nanotube composite. Effective composite of three-dimensional graphene and carbon nanotubes is realized by directly growing the carbon nanotubes on the surface of the three-dimensional graphene by means of the two-step chemical vapor deposition technique, and functionalization of a carbon-based three-dimensional structure is realized by introducing nitrogen-doped atoms into the carbon nanotubes. Compared with other methods for preparing the three-dimensional graphene-carbon nitrogen nanotube composite, the method has the advantages of simplicity in preparation process, low cost, high product conductivity, large specific surface area and the like. The three-dimensional graphene-carbon nitrogen nanotube composite obtained by the method has excellent performances in terms of catalysis oxygen reduction reaction, electrochemical capacitors, electrochemical biological sensing, super-hydrophobic oleophylic foams and the like, and has high potential application values in terms of ionic cells, drug transmission, microreactors and the like.

A method for making a carbon-metal-nitrogen oxygen reducing cathode catalyst, the method comprising mixing a carbon source with a transition metal precursor to form a metal precursor loaded carbon substrate; adding a nitrogen precursor compound to the metal precursor loaded carbon substrate to form a carbon-metal-nitrogen precursor; and pyrolyzing the carbon-metal-nitrogen precursor in a closed vessel, thereby forming an oxygen reducing cathode catalyst. The carbon-metal-nitrogen catalyst requires no precious metal such as Pt, and also provides benefits such as controlled deposition of catalytically active nitrogenous compounds that can increase the catalytic activity of the catalyst when compared to gaseous deposition of nitrogen to the surface of the carbon support.

The invention discloses a method for preparing a carbon nanofiber-based non-noble-metal catalyst through oxidation improved electrostatic spinning in the technical field of carbon nanofibers and fuel cell catalysts. The method disclosed by the invention comprises the following steps: dissolving at least one transition metal salt and polyacrylonitrile in a solvent to form a precursor solution; carrying out electrostatic spinning on the precursor solution under certain parameter conditions to obtain iron-containing polyacrylonitrile nanofibers; and heat treating the iron-containing polyacrylonitrile nanofibers in an atmosphere containing a small amount of oxidizing gas to obtain carbon nanofibers containing transition metal and nitrogen element and improved by the small amount of oxidizing gas. According to the method, the cost of the raw materials is low, the operation is convenient and controllable, the operation is easy, the surface structure of the catalyst can be regulated and controlled, and the prepared oxidation improved carbon nanofiber based non-noble-metal catalyst has good catalytic activity on oxygen reduction reaction. The whole preparation process can be combined with a traditional carbon fiber technique, and the method has a prospect that large scale and industrialization of the non-noble metal catalyst can be realized.

This invention relates to a method for fabricating solid-state alkaline polymer Zn-air battery, which consists of a zinc-gel anode, an air cathode electrode, and alkaline polymer electrolyte. The formulation of said zinc gel anode is similar to that of alkaline Zn-MnO2 battery. The zinc gel anode contains a mixture of electrolytic dendritic zinc powders, KOH electrolyte, gelling agent and small amount of additives. The air cathode electrode is made by carbon gas diffusion electrode, which comprises two layers, namely gas diffusion layer and active layer. The active layer on the electrolyte side uses a high surface area carbon for oxygen reduction reaction and potassium permanganate and MnO2 as catalysts for oxygen reduction. The diffusion layer on the air side has high PTFE content to prevent KOH electrolyte from weeping or climbing. Due to adequate amount of fresh air and oxygen supply, the air cathode electrode can run continuously. Theoretically, the polymer zinc-air battery is an accumulator if the cell has sufficient zinc powder and electrolyte, and the air cathode plays the role of energy transfer.

The invention relates to a non-metallic bi-functional oxygen catalyst for graphene/nickel iron type hydrotalcite as well as a preparation method and electric catalytic application thereof to oxygen evolution reaction and oxygen reduction reaction in an alkaline medium. The catalyst takes a micelle as a template, and under the hydrothermal and reducing conditions, the nickel iron type hydrotalcite is assembled onto graphene in sequence to form a spherical porous graphene oxide/nickel iron type hydrotalcite compound. The method comprises the following steps: dispersing graphene oxide and metal salt in the micelle, introducing an alkali source, synthesizing the graphene oxide/nickel iron type hydrotalcite compound under the hydrothermal conditions, and performing hydrazine hydrate reduction on an obtained product to obtain the catalyst. The catalyst prepared by the method has high oxygen evolution and oxygen reduction catalytic activity, good stability and excellent methanol tolerance under the alkaline conditions and is low in cost of raw materials used, simple in preparation method, easy to operate and convenient for large-scale production.

The invention relates to a method for preparing nitrogen doping hollow carbon nanocages, which comprises the following steps that: (1) basic magnesium carbonate or magnesium carbonate is taken to be added into a reaction tube and is uniformly dispersed, then the reaction tube is placed in a tube furnace, air in the tube furnace is extracted, inert gases are filled into the tube furnace, under the condition of 10-500sccm of inert gases, the temperature of the tube furnace is increased to 650-1,100 DEG C, then the inert gas flow is guided into steam which contains carbon (C) and nitrogen (N), and after reacting for 5-240min, the temperature of the tube furnace is reduced to a room temperature; and (2) powder in the reaction tube is collected, put into hydrochloric acid or sulfuric acid solution to be soaked for 5-720min, filtered, cleaned by deionized water and dried, so a nitrogen doping hollow carbon nanocage is obtained. The nitrogen doping hollow carbon nanocage which is produced by the method has the advantages of high specific surface area, large pore volume, high mesoporous ratio, good graphitization degree and the like, and is a metal-free oxygen reduction reaction catalyst with excellent performance.

A new class of releasable corrosion inhibiting materials for protective coatings, methods of making the same, methods of using the same, and coatings containing the same are provided. The materials comprise one or more corrosion inhibitors that are chemically anchored to the surface of a particle having an aluminum oxyhydroxide surface through a carboxylate bond. The carboxylate/aluminum-oxyhydroxide-surface bond breaks under corrosion-causing conditions (for example the presence of high levels of hydroxide ions generated by the cathodic oxygen reduction reaction on metals such as iron and aluminum) thereby allowing the corrosion inhibitors to detach from the particle surface when corrosion is present.

The present invention relates to an efficient, non-metal, N-doped porous carbon electrocatalyst for oxygen reduction reaction and a process for the preparation of using g-C₃N₄ as a nitrogen precursor, metal organic frameworks (MOF) as a carbon template having high specific surface area, large number of active sites and large pore volume.

The present invention is made to provide a carbon catalyst capable of preventing the coarsening of particles of nanoshell structure of carbon which causes reduction in activity for oxygen reduction reaction. The carbon catalyst is produced by the steps of: preparing a carbon precursor polymer; mixing a transition metal or a compound of the transition metal into the carbon precursor polymer; spinning the mixture of the carbon precursor polymer and the transition metal or the compound of the transition metal into fibers; and carbonizing the fibers.

The invention discloses a ZIF-8-derived hollow Fe/Cu-N-C type oxygen reduction catalyst and a preparation method and application thereof. The preparation comprises (1) preparation of a precursor ZIF-8material; (2) preparation of a precursor Fe(OH)3-Cu(OH)2@ZIF-8 material of the catalyst; and (3) preparation of an oxygen reduction electrocatalyst of an iron/copper, nitrogen co-doped carbon material. The invention adopts ZIF-8 as a precursor, uses inexpensive CuCl2.2H2O and FeCl3.6H2O as metal sources, and adopts a high-temperature calcination method to prepare a Fe/Cu-N-C hollow structure catalyst having high catalytic activity for oxygen reduction reaction, which has comparable ORR performance in alkaline media to that of Pt-based catalysts, and has higher stability and methanol resistance. In addition, the invention has low raw material prices, rich sources and simple preparation processes, is conducive to large-scale production, and can be applied to fuel cells or metal air batteries.

Platinum (Pt)-based alloys are effective catalysts for oxygen reduction reaction (ORR) or fuel oxidation in proton exchange membrane fuel cells (PEMFCs). A wet-chemical approach for preparing monodisperse Pt₃Ni, Pt₃Co and Pt₃Fe nanocubes and Pt₃Ni nanoctahedra which are terminated with {100} and {111} facets, respectively, were developed. Such nanoscaled electrocatalysts supported on carbon black with controlled shape, e.g., octahedral configuration, is provided. ORR activity on the Pt₃Ni nanoctahedra is ˜5.1 fold higher than that of nanocubes with a similar size, and their C-supported samples are highly active with respect to commercial Pt/C.

The invention relates to an iron and nitrogen co-doped carbon-oxygen reduction catalyst, and a preparation method and application thereof. Fe/Zn bimetallic ZIF with elemental gradient distribution isprepared to prepare an iron and nitrogen co-doped carbon-oxygen reduction catalyst by pyrolysis and carbonization as a precursor, in order to improve the utilization rate of active sites, optimize thepore structure and further enhance the catalytic activity. The iron and nitrogen co-doped carbon-oxygen reduction catalyst prepared by the invention can efficiently catalyze the oxygen reduction reaction and exhibits better oxygen reduction catalytic activity and electrochemical stability than the commercial Pt/C catalyst. The preparation method is simple and controllable, has short cycle, abundant raw material reserves and low cost, and can realize large-scale production.

The invention relates to a solid oxide fuel cell, in particular to medium temperature solid oxide fuel cell cathode material and application thereof. Being calculated by a weight percentage, the cathode material consists of 40-99 percent of perovskite-type composite oxides, 1-30 percent of CeO2 doped with rare earth oxides, and 0-59 percent of electrolyte material; the electrolyte material refers to ZrO2 stabilized by 5-20 mol percent of Y2O3 and / or ZrO2 stabilized by 5-20 mol percent of Sc2O3. The invention can change the structure of the active components of the cathode material, can improve the activity of the catalytic oxygen reduction reaction of the cathode material, can accelerate the dissociative adsorption of oxygen on the surface of the cathode material, the diffusion of oxygen species on the surface of the cathode material, the transmission process of the oxygen species in a three-phase bounded domain, charge transfer, and other electrochemical processes, and can increase the activity of the cathode of the solid oxide fuel cell.

The present invention discloses a simple and easily scalable process for preparation of two potentially value added carbonaceous materials from graphene. The invention further discloses simultaneous preparation of graphene quantum dots (GQDs,) and porous graphene (pGr) from graphene. The invention further relates to nitrogen doped porous graphene having excellent activity towards electrochemical oxygen reduction reaction (ORR).

Metal-free fuel cell cathodes having a catalytic layer of vertically-aligned, nitrogen-doped carbon nanotubes (VA-NCNTs) are provided. The fuel cell cathodes comprise a cathode body, a binder layer attached to an outer surface of the cathode body, and the catalytic layer, which is supported by the binder layer. The binder layer may comprise a composite of a conductive polymer and doped or undoped nonaligned carbon nanotubes. In a method for forming the fuel cell cathodes, the VA-NCNTs may be formed by pyrolysis of a metalorganic compound and integration of the nanotubes with nitrogen. The binder layer is applied, and the resulting supported nanotube array may be attached to the cathode body. Fuel cells comprising the fuel cell cathodes are provided. The fuel cell cathodes comprising VA-NCNTs demonstrate superior oxygen-reduction reaction performance, including for electrocatalytic activity, operational stability, tolerance to crossover effects, and resistance to CO poisoning.

The invention discloses a nitrogen-doped porous graphite-like carbon nanosheet as well as preparation and electrocatalytic application thereof. The carbon nanosheet has a flaky morphology, and is richin nitrogen doping amount, large in pore volume, high in mesoporous ratio, and highly graphitized as a whole. According to the preparation of the carbon nanosheet, a metal oxide nanosheet of manganese is taken as a template, a metal organic framework material is taken as a carbon source, a sandwich-type sandwich composite structure precursor material is formed by the template and the carbon source, the precursor material is pyrolyzed in an atmosphere without water or oxygen, the template is removed through acid treatment, the obtained product after the removal of the template is mixed with anitrogen source, and annealing is performed again to prepare the carbon nanosheet. A preparation method has the advantages that the raw materials are easy to obtain, the preparation is simple, the production cost is low, the macro preparation is easy to implement and the like, and provides a universal synthetic route for preparing a two-dimensional doped porous carbon material with high degree ofgraphitization from the metal organic framework material. At the same time, the invention also discloses the application of the nitrogen-doped porous graphite-like carbon nanosheet with a high specific surface and a rich mesoporous structure and as a metal-free catalyst to high-efficiency electrocatalytic oxygen reduction reactions.

The invention belongs to the technical field of the preparation of iron oxide magnetofluids and particularly relates to an aqueous reduction based synthesis method of superparamagnetic ferroferric oxide nanoparticles. According to the aqueous reduction based synthesis method, an inorganic metal water-soluble compound (ferric salt) serves as an iron source, a reducing compound and a stabilizer which can be coordinated with iron serve as raw materials, and reduction reaction is carried out in an aqueous solution to generate the ferroferric oxide magnetofluid in situ. The aqueous reduction based synthesis method provided by the invention has the advantages of mild reaction condition and good repeatability, is easy to operate and safe, and the ferroferric oxide nanoparticles prepared by adopting the aqueous reduction based synthesis method overcome the defects that the ferroferric oxide particles prepared by adopting the traditional aqueous co-precipitation method are easy to agglomerate, can not be dispersed uniformly and are affected in application. The ferroferric oxide nanoparticles with stable performance are prepared successfully by adopting the aqueous reduction based synthesis method, and the ferroferric oxide nanoparticles have good biocompatibility, can form the magnetofluid in an aqueous solution and can be widely applied to the biomedical fields of magnetic resonance imaging, magnetofluid thermotherapy, cell separation, protein separation, DNA purification, immunodetection, magnetically targeted medicine carriers.