134 results about "Catalyst nanoparticles" patented technology

Although nanoparticles capable of providing an extremely large active surface area have highly marked advantages, when a PEFC electrode utilizing nanoparticles is used for a prolonged period of time, the catalyst nanoparticles on carrier of the PEFC electrode because of the nano-size thereof migrate and aggregate together to result in a rapid loss of activity. Thus, there is a demand for inhibition of the above aggregation so as to prevent any drop of catalytic activity. According to the present invention the aggregation of nanoparticles can be inhibited by catalyst nanoparticles containing Pt wherein a porous matter containing an inorganic oxide is disposed on the surface of the catalyst nanoparticles. When use is made of nanoparticles whose surface has undergone specific modification, excellent activity can be realized. Therefore, there are provided surface-modified nanoparticles and catalyst and further a PEFC electrode utilizing these nanoparticles.

Techniques for controlling the size and / or distribution of a catalyst nanoparticles on a substrate are provided. The catalyst nanoparticles comprise any species that can be used for growing a nanostructure, such as a nanotube, on the substrate surface. Polymers are used as a carrier of a catalyst payload, and such polymers self-assemble on a substrate thereby controlling the size and / or distribution of resulting catalyst nanoparticles. Amphiphilic block copolymers are known self-assembly systems, in which chemically-distinct blocks microphase-separate into a nanoscale morphology, such as cylindrical or spherical, depending on the polymer chemistry and molecular weight. Such block copolymers are used as a carrier of a catalyst payload, and their self-assembly into a nanoscale morphology controls size and / or distribution of resulting catalyst nanoparticles onto a substrate.

The methods, apparatus and systems disclosed herein concern ordered arrays of carbon nanotubes. In particular embodiments of the invention, the nanotube arrays are formed by a method comprising attaching catalyst nanoparticles 140, 230 to polymer 120, 210 molecules, attaching the polymer 120, 210 molecules to a substrate, removing the polymer 120, 210 molecules and producing carbon nanotubes on the catalyst nanoparticles 140, 230. The polymer 120, 210 molecules can be attached to the substrate in ordered patterns, using self-assembly or molecular alignment techniques. The nanotube arrays can be attached to selected areas 110, 310 of the substrate. Within the selected areas 110, 310, the nanotubes are distributed non-randomly. Other embodiments disclosed herein concern apparatus that include ordered arrays of nanotubes attached to a substrate and systems that include ordered arrays of carbon nanotubes attached to a substrate, produced by the claimed methods. In certain embodiments, provided herein are methods for aligning a molecular wire, by ligating the molecular wire to a double stranded DNA molecule.

A catalyst material for carbon nanotube synthesis includes a uniform dispersion of host particles on a substrate. The host particles themselves include catalyst nanoparticles that are effective to catalyze nanotube syntheses reactions and provide nucleation sites. Methods for preparing catalyst materials include co-sputtering a catalytic species and a host species to form a precursor thin film on a substrate, followed by an oxidation reaction of the precursor thin film in air. The precursor thin film can be patterned on the substrate to limit the locations of the catalyst material to well-defined areas. Methods for nanotube synthesis employ CVD in conjunction with the catalyst materials of the invention. During the synthesis, the catalyst nanoparticles catalyze carbon nanotubes to grown from a carbon-containing gas.

A system for synthesizing carbon nanotubes (CNT) on a fiber material includes a surface treatment system adapted to modify the surface of the fiber material to receive a barrier coating upon which carbon nanotubes are to be grown, a barrier coating application system downstream of the surface treatment system adapted to apply the barrier coating to the treated fiber material surface, and a barrier coating curing system downstream of the barrier coating application system for partially curing the applied barrier coating to enhance reception of CNT growth catalyst nanoparticles.

The invention relates to the environmental protection field of flue gas treatment of gas-fired boilers, in particular to a surface deposition honeycomb flue gas denitration catalyst and a preparation method thereof. The catalyst comprises a honeycomb framework which takes clay, soot dust or slag as a substrate; TiO2 is taken as an active carrier; WO3 and V2O5 serving as active ingredients are loaded on the TiO2 active carrier, and are uniformly distributed in the honeycomb framework; and the catalyst comprises the following components in percentage by weight: 60-80 percent of clay, soot dust or slag, 13-33 percent of TiO2, 1-5 percent of WO3 and 0.1-2 percent of V2O5. By transferring an ignition lost transition carrier, highly dispersion of catalyst nanoparticles on a molding catalyst pore cannel and an outer surface is realized, and the utilization ratio and catalytic activity of the active ingredients are increased greatly.

A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

An organically complexed nanocatalyst composition is applied to or mixed with coal prior to or upon introducing the coal into a coal burner in order to catalyze the removal of coal nitrogen from the coal and its conversion into nitrogen gas prior to combustion of the coal. This process leads to reduced NOx production during coal combustion. The nanocatalyst compositions include a nanoparticle catalyst that is made using a dispersing agent that can bond with the catalyst atoms. The dispersing agent forms stable, dispersed, nano-sized catalyst particles. The catalyst composition can be formed as a stable suspension to facilitate storage, transportation and application of the catalyst nanoparticles to a coal material. The catalyst composition can be applied before or after pulverizing the coal material or it may be injected directly into the coal burner together with pulverized coal.

An apparatus (50) and method is provided for growing a network of common diameter nanotubes (24). The apparatus comprises chemically functionalizing a portion (16) of a substrate (12); anchoring catalyst nanoparticles (22), each having substantially the same diameter, on the portion (16) of the substrate (12); and growing overlapping carbon nanotubes (24), each having substantially the same diameter, on the catalyst nanoparticles (22).

Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. A method includes A method, includes fabricating a cantilever structure having a vertically aligned nanostructure including: forming a doped layer at a first side of a substrate; depositing an etch mask layer on a second side of the substrate; forming a plurality of alignment marks that are coupled to the first side of the substrate; depositing a catalyst nanoparticle at a deterministic site that is coupled to the doped layer; growing the vertically aligned nanostructure at the deterministic site with the catalyst nanoparticle; depositing a first protective layer that surrounds at least a portion of the vertically aligned nanostructure; patterning the first protective layer to define an outline of a cantilever body; transferring the outline of the cantilever body from the first protective layer into the doped layer to form the cantilever body from the doped layer; depositing a second protective layer that coats at least a portion of a surface of the cantilever body; patterning the etch mask layer to define an outline of a relieved volume; transferring the outline of the relieved volume from the etch mask layer into the second side of the substrate to remove the relieved volume from the substrate, where the cantilever body is not removed.

A membrane electrode assembly (MEA) for a fuel cell comprising a catalyst layer and a method of making the same. The catalyst layer can include a plurality of catalyst nanoparticles, e.g., platinum, disposed on buckypaper. The catalyst layer can have 1% or less binder prior to attachment to the membrane electrode assembly. The catalyst layer can include (a) single-wall nanotubes, small diameter multi-wall nanotubes, or both, and (b) large diameter multi-wall nanotubes, carbon nanofibers, or both. The ratio of (a) to (b) can range from 1:2 to 1:20. The catalyst layer can produce a surface area utilization efficiency of at least 60% and the platinum utilization efficiency can be 0.50 gPt / kW or less.

A system for synthesizing carbon nanotubes (CNT) on a fiber material includes a surface treatment system adapted to modify the surface of the fiber material to receive a barrier coating upon which carbon nanotubes are to be grown, a barrier coating application system downstream of the surface treatment system adapted to apply the barrier coating to the treated fiber material surface, and a barrier coating curing system downstream of the barrier coating application systems for partially curing the applied barrier coating to enhance reception of CNT growth catalyst nanoparticles.