WO2012123435A1 - Platinium/silver noble metal single wall hollow nanoparticles and their preparation process - Google Patents

Platinium/silver noble metal single wall hollow nanoparticles and their preparation process Download PDF

Info

Publication number
WO2012123435A1
WO2012123435A1 PCT/EP2012/054319 EP2012054319W WO2012123435A1 WO 2012123435 A1 WO2012123435 A1 WO 2012123435A1 EP 2012054319 W EP2012054319 W EP 2012054319W WO 2012123435 A1 WO2012123435 A1 WO 2012123435A1
Authority
WO
WIPO (PCT)
Prior art keywords
nanoparticles
nanoparticle
single wall
noble metal
silver
Prior art date
Application number
PCT/EP2012/054319
Other languages
French (fr)
Inventor
Víctor FRANCO PUNTES
Edgar Emir GONZÁLEZ
Original Assignee
Fundació Privada Institut Català De Nanotecnologia
Institució Catalana De Recerca I Estudis Avançats
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fundació Privada Institut Català De Nanotecnologia, Institució Catalana De Recerca I Estudis Avançats filed Critical Fundació Privada Institut Català De Nanotecnologia
Publication of WO2012123435A1 publication Critical patent/WO2012123435A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/50—Silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold
    • B01J35/23—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/0547—Nanofibres or nanotubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/0553—Complex form nanoparticles, e.g. prism, pyramid, octahedron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0466—Alloys based on noble metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/921—Alloys or mixtures with metallic elements
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/02—Inorganic compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/0087—Galenical forms not covered by A61K9/02 - A61K9/7023
    • A61K9/0092—Hollow drug-filled fibres, tubes of the core-shell type, coated fibres, coated rods, microtubules or nanotubes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/51—Nanocapsules; Nanoparticles
    • A61K9/5107—Excipients; Inactive ingredients
    • A61K9/5115—Inorganic compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/51—Nanocapsules; Nanoparticles
    • A61K9/5192—Processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2301/00—Metallic composition of the powder or its coating
    • B22F2301/25—Noble metals, i.e. Ag Au, Ir, Os, Pd, Pt, Rh, Ru
    • B22F2301/255—Silver or gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2304/00—Physical aspects of the powder
    • B22F2304/05—Submicron size particles
    • B22F2304/054—Particle size between 1 and 100 nm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to the field of nanoparticles, more particularly to noble metal nanoparticles with well defined hollow interiors.
  • the invention relates to noble metal nanoparticles with a multiple wall and with a hollow interior, the process to obtain them as well to the use as catalyst. It also relates to Pt/Ag single wall hollow interior nanoparticles, the process to obtain them, as well as to their uses.
  • noble metal nanoparticles have been extensively studied owing to their interesting optical, electronic and catalytic properties.
  • the introduction of hollows into their interiors could offer some properties, such as resonant cavities, increased surfaces areas or reduced density.
  • Nanoparticles obtained by galvanic replacement reaction present an alloy of the metals all over the structure.
  • other approach to produce noble metal nanoparticles has been described by Xiaohu et al. "Au- Ag alloy nanoporous nanotubes" Nano Research, 2009, vol. 2, pag. 386-393. In this document, it is described the obtention of bimetallic nanoporous nanotubes by dispersion in water of silver nanoparticles containing
  • CAB cetyltrimethylammonium bromide
  • ascorbic acid under magnetic stirring and at 40°C, followed by the addition of a salt of Au.
  • CAB cetyltrimethylammonium bromide
  • the sample is mixed with nitric acid. Unfortunately, the pores distribution and size of the nanoparticles obtained are irregular and the particles show signs of fragmentation and structural damage, suggesting that by this method, nanoparticles with sufficient quality can not be obtained.
  • Nanoparticles of Pt/Ag have been produced by the method described in Gao et al. "Bimetallic Ag-Pt hollow nanoparticles: synthesis and tunable surface plasmon resonance", Scripta Materialia, 2007, Vol. 57, pag 687, but when the nanoparticles are formed, the platinum nucleates in form of islands which growth in the surface without the alloying. So, the nanoparticle is not a smooth alloy.
  • Chen et al. “Optical properties of Pd-Ag and Pt-Ag nanoboxes synthesized via galvanic replacement reactions", Nano Lett.
  • an aspect of the invention relates to a Pt/Ag single wall nanoparticle with a hollow interior, wherein the nanoparticle has at least two dimensions at the nanoscale, particularly the nanoparticle has all three dimensions at the nanoscale, where the nanoscale is the range about 1 nm to about 100 nm. Particularly, the nanoparticle has a size from 5 nm to 100 nm, more
  • This Pt/Ag nanoparticle is of a
  • Another aspect of the invention relates to a process for the preparation of Pt/Ag single wall nanoparticles as defined above at room temperature, the process comprising the steps of: a) adding benzyldodecyldimethylammonium chloride in a molar concentration from 3 x10 "2 M to 4 x10 "2 M in an aqueous medium comprising nanoparticles of silver, b) adding a salt of platinum in a molar concentration from 0,05 x 10 "2 to 4 x10 "2 M, particularly from 3 x 10 "2 to 4 x10 "2 M, and c) isolating the obtained nanoparticles.
  • the salt of platinum is not soluble in water.
  • the Pt/Ag single wall nanoparticles are homogeneous, namely are nanoparticles with a
  • nanoparticles obtainable by the process defined above also form part of the invention.
  • noble metal nanoparticles with multiple walls and with a hollow interior comprising two or three noble metals, the walls with a structure based on a layer of noble metals with a high concentration of one of the noble metals both in the exterior and interior face surfaces of the walls, and an alloy of two metals with specific features in the space between the two layers of the wall, advantageously are more stable than nanoparticles made of a simple metallic alloy all over the wall.
  • the reason lies on the high chemical stability of the metal which is in a high concentration in the external faces of the wall.
  • the highly concentrated in the faces noble metal is gold, as it is an inert metal, the nanoparticles are particularly suitable for their use in biological environments.
  • an aspect of the present invention relates to a noble metal nanoparticle with multiple walls and with a hollow interior, the nanoparticle comprising two or three noble metals, wherein each one of the walls comprises a layer of noble metals, with a concentration of one of the noble metals equal to or higher than 85%, both in the exterior and interior face surfaces of the walls, and an alloy of a first and a second noble metals in the space between the two layers of the wall, wherein the second noble metal has a higher reduction potential than the first noble metal, and the first and the second noble metals have different diffusion coefficients, and wherein the noble metal of the layer is made of the second noble metal or of a third noble metal.
  • Another aspect of the present invention relates to a process for the preparation of bimetallic nanoparticles at room temperature comprising the steps of: a) adding cetyltnmethylammonium bromide and ascorbic acid into an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 30 ⁇ to 100 ⁇ and with a flow rate from 20 ⁇ /min to 50 ⁇ /min, wherein the second noble metal has a higher reduction potential than the first noble metal, and wherein the first and the second noble metals have different diffusion coefficients, and c) isolating the obtained nanoparticles.
  • the bimetallic nanoparticles obtainable by the process defined above also form part of the invention.
  • Another aspect of the present invention relates to a process for the
  • trimetallic nanoparticles comprising carrying out the process for the preparation of bimetallic nanoparticles and further comprising adding before step c) a salt of a third noble metal in a molar concentration from 3.5x10 "3 M to 4x10 "3 M and with a flow rate from 200 ⁇ /min to 270 ⁇ /min.
  • a salt of a third noble metal in a molar concentration from 3.5x10 "3 M to 4x10 "3 M and with a flow rate from 200 ⁇ /min to 270 ⁇ /min.
  • Another aspect of the present invention relates to a process for the preparation of trimetallic nanoparticles having two or more cavities at room temperature comprising the steps of: a) adding cetyltrimethylammonium bromide or a mixture of cetyltrimethylammonium bromide and ascorbic acid into an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 3.5x10 " M to 4x10 "3 M,
  • the trimetallic nanoparticles having two or more cavities obtainable by the process defined above also forms part of the invention.
  • the trimetallic nanoparticles have the two or more cavities uniformly distributed.
  • Another aspect of the present invention refers to the use of any of the nanoparticles disclosed above as a catalyst.
  • nanoparticles can also be used as fuel cells, drug delivery carrier, sensor or plasmon resonators.
  • Another aspect of the present invention refers to the use of any of the nanoparticles disclosed above as a catalyst or drug delivery carrier.
  • the process of the invention ensures the formation of pores with control in the size and localization. This may be an important condition for its use as carrier and delivery system, on the other hand allows a fine modulation of the optical response. Accordingly, another aspect of the invention relates to a process for the preparation of bimetallic nanoparticles in the form of nanocages at room temperature the process comprising the steps of: a) adding
  • benzyldodecyldimethylammonium chloride in a molar concentration from 3 x 10 "2 M to 3.5 x 10 "2 M in an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 1 .4 x10 "4 M to 3 x10 "4 M and with a flow from 100- to 200 ⁇ /min, herein the second noble metal has a higher reduction potential than the first noble metal, and wherein the first and the second noble metals have different diffusion coefficients, and c) isolating the obtained nanoparticles.
  • the bimetallic nanoparticles in the form of nanocages obtainable by the process as defined above.
  • another aspect of the present invention relates to the use of Pt/Ag nanoparticles, in particular, in form of nanocages, nanoboxes or nanotubes, more particularly in form of nanocages, as defined above as a drug delivery carrier, as catalytic cathode in fuel cells or as a catalyst in oxidation reactions.
  • This aspect can also be formulated as a method of use of the mentioned nanoparticles as a drug delivery carrier, as catalytic cathode in fuel cells or as a catalyst in oxidation reactions.
  • This aspect can also be formulated as a method of use of the mentioned nanoparticles as catalytic cathodes in fuel cells. It can be prepared a colloidal solution of AuAg nanoparticles, in particular blue colour. For its preparation, Au nanocages are prepared. The gold nanocage may be prepared by the method explained in the Example 10 of this document. The gold nanoparticle may be prepared also by other methods known in the art. It is also prepared oxidized polyvinylpyrrolidone (PVP). For its preparation PVP is oxidized during two days in the presence of air. Other method known in the art for oxidizing the polyvinylpyrrolidone may also be used.
  • PVP polyvinylpyrrolidone
  • FIG. 1 shows a Transmission electron microscopy (TEM) image of double walled nanocubes Au/Ag.
  • FIG. 2 shows an Energy-dispersive X-ray spectroscopy (EDX) map of double walled nanocubes Au/Ag.
  • EDX Energy-dispersive X-ray spectroscopy
  • FIG 3 shows a schematic representation of double walled nanocubes with an open window.
  • FIG. 4 shows a TEM image for Pt-Ag nanoboxes.
  • FIG. 5 shows a TEM image of Au-Ag nanocages.
  • FIG. 6 show a schematic representation of a trimetallic Pd-Au-Ag triple walled nanocubes with five cavities
  • Pt/Ag single wall nanoparticles with a hollow interior of the invention are part of the invention.
  • the process is carried out at room temperature, and comprises the steps of: a) adding benzyldodecyldimethylammonium chloride until obtaining a molar concentration from 3 x 10 "2 M to 4 x 10 "2 M in an aqueous medium comprising nanoparticles of silver, b) adding a non-water soluble salt of platinum until obtaining a molar concentration from 0,05 x 10 "2 M to 4 x10 "2 M, particularly from 3 x 10 "2 M to 4 x 10 "2 M, in the aqueous medium, and isolating the obtained nanoparticles.
  • the salt of platinum is not soluble in water.
  • the salt of platinum is PtCI 2 .
  • PtCI 2 provides a high standard potential, favoring the inherent reactivity in addition to its insolubility in water, aspect that allows a kinetic control on reaction via a sustained release of Pt ions in the reacting mixture. It is known that PtCI 2 is soluble in HCI or ammonia, so, with the use of
  • amphyphilic/tensioactives/surfactant molecules as
  • BDAC benzyldodecyldimethylammonium chloride
  • the wall ot the Pt/Ag single wall nanoparticles with a hollow interior as defined above has a thickness from 3 to 10 nm, particularly of around 5 nm.
  • the nanoparticle of silver is a nanocube and, consequently, the obtained nanoparticle is a nanobox.
  • the nanoparticle of silver is a nanowire and the obtained nanoparticle is a nanotube.
  • the Pt/Ag single wall nanoparticles are homogeneous.
  • Pt/Ag single wall nanoparticles with a hollow interior in form of nanoboxes or in form of nanotubes obtainable by this process also form part of the invention.
  • Pt/Ag nanotubes show a great potential in their use as catalytic agents. Particularly, with Pt/Ag nanotubes it is not necessary having an additional substrate to form the catalytic cathode.
  • the salt of platinum is H 2 PtCI 6 .
  • H 2 PtCI 6 appear a formation of Pt-Ag nanocages with porous symmetrically distributed.
  • the isolation of the obtained nanoparticles can be carried out by conventional methods known to those skilled in the art, such as by filtration or
  • another aspect of the present invention relates to a noble metal nanoparticle with multiple walls and with a hollow interior, the nanoparticle comprising two or three noble metals, wherein each one of the walls comprises a layer of a noble metals with a concentration of one of the noble metals equal to or higher than 85% both in the exterior and interior face surfaces of the walls, and an alloy of a first and a second noble metals in the space between the two layers of the wall, wherein the second noble metal has a higher reduction potential than the first noble metal, and the first and the second noble metals have different diffusion coefficients, and wherein the noble metal of the layer is made of the second noble metal or of a third noble metal.
  • the layer of noble metals has a concentration of one of the noble metals equal to or higher than 90%, more preferably, metals equal to or higher than 95%, still more preferably equal to or higher than 97%, and even still more preferably equal to or higher than 99%.
  • nanoparticle refers to a particle with at least two dimensions at the nanoscale, particularly with all three dimensions at the nanoscale, where the nanoscale is the range about 1 nm to about 100 nm.
  • the “nanoparticle” refers to a particle with at least two dimensions at the nanoscale, this two dimensions being the cross-section of the nanoparticle.
  • the term "size” refers to a characteristic physical dimension.
  • the size of the nanoparticle corresponds to the diameter of the nanoparticle.
  • the size of the nanoparticle corresponds to the diameter of the cross-section of the
  • a size of a set of nanoparticles can refer to a mode of a distribution of sizes, such as a peak size of the distribution of sizes.
  • noble metal refers to metals that are resistant to corrosion and oxidation in moist air. Examples of noble metal are palladium, silver, platinum and gold.
  • multiple walls refers to at least a double wall, for example double wall, triple wall or quadruple wall.
  • hollow interior refers to the presence of one or more cavities in the interior of the nanoparticle, such as two, three, four or five cavities.
  • metal alloy refers to a homogeneous mixture of two or more metals, wherein each of the metals may be in different or equal amounts.
  • homogeneous as used herein is understood according to the common understanding of the term. Namely, in the context of composite metals, it relates to an alloy of metals which forms a solid solution, i.e., to a homogeneous mixture of two or more than two metals.
  • a “homogeneous Pt-Ag nanoparticle” is a nanoparticle with a single phase alloy between silver and platinum.
  • a “solid solution” is a solid-state solution of one or more solutes in a solvent. Such a mixture is considered a solution rather than a compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single homogeneous phase.
  • the nanoparticle of the invention refers to a nanobox, nanotube or a nanocage.
  • the nanobox, nanotube or nanocage may have different morphologies depending on the sacrificial template, which can have different shapes such as cubes, spheres, wires, rods, prisms and so on.
  • the term "nanobox” as used herein, refers to nanoparticles with hollow interior and solid walls, or with one pore in one of the walls.
  • nanoparticles refers to nanoparticles with hollow interior and porous walls and/or porous corners.
  • nanotubes refers to cylindrical nanoparticles with porous walls or solid walls.
  • sacrificial template refers to nanoparticles that participate as reactant and are partially or totally consumed during the process.
  • the final product takes the same shape as the template, aspect that allows controlling the geometry of the hollow structure.
  • the first novel metal is silver.
  • the second and third noble metals are selected from the group consisting of gold, platinum, and palladium.
  • the nanoparticle is a bimetallic double walled nanoparticle and has an opening giving access to the hollow interior.
  • the nanoparticle is a Au/Ag double walled nanocube. This nanoparticle is shown in FIG. 1 .
  • FIG 2 shows the metalic distribution of the nanoparticle of FIG. 1 .
  • the nanoparticle is a Au/Ag double walled nanosphere.
  • the nanoparticle is a double walled nanotube.
  • opening giving access to the hollow interior refers to a hole that allows direct access to the interior of the nanoparticle.
  • a schematic representation of this access is shown in FIG. 3.
  • the nanoparticle is a trimetallic double wall nanoparticle nanoparticle and has an opening giving access to the hollow interior.
  • the nanoparticle is Pd/Au/Ag double walled nanocube.
  • the inventors have development trimetallic nanoparticles with interior cavities, symmetrically distributed in the nanoparticles.
  • the nanoparticle is a trimetallic nanoparticle having two or more cavities such as two, four or five central cavities.
  • the nanoparticle is a trimetallic nanoparticle having two or more cavities such as two, four or five central cavities.
  • nanoparticle is Pd/Au/Ag triple walled with five cavities. A schematic representation of this nanoparticle is shown in FIG. 6.
  • cavities refers to interior voids surrounded by only one wall of noble metals in the centre symmetrically distributed.
  • the term cavities does not include the gaps between the walls or the gaps around the cavities.
  • the bimetallic nanoparticles as defined above may be prepared by a process carried out at room temperature comprising the steps of: a) adding
  • cetyltrimethylammonium bromide and ascorbic acid into an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 30 ⁇ to 100 ⁇ and with a flow rate from 20 ⁇ /min to 50 ⁇ /min, wherein the second noble metal has a higher reduction potential than the first noble metal, and wherein the first and the second noble metals have different diffusion coefficients, c) isolating the obtained nanoparticles.
  • room temperature refers to a temperature between 20°C to 30°C, for example 25°C.
  • Hydrochloric acid may be optionally added in step a.
  • the trimetallic nanoparticles as defined above may be prepared by a process comprising carrying out the process of the second aspect of the present invention and further comprising adding before step c) a salt of a third noble metal in a molar concentration from 3.5x10 "3 M to 4x10 "3 M and with a flow rate from 200 ⁇ /min to 270 ⁇ /min.
  • the third noble metal has a lower reduction potential than the second noble metal, thereby a nanocage is obtained. In another particular embodiment, the third noble metal has a higher reduction potential than the second noble metal, thereby a nanobox is obtained.
  • Example 8 Production of trimetallic Pd-Au-Ag triple walled nanocubes with five cavities

Abstract

Noble metal nanoparticles and their preparation process. It is provided homogeneous Pt/Ag single wall nanoparticles with a hollow interior, as well to the process for their preparation, and the uses of the nanoparticles as drug delivery carrier, catalytic cathode in fuel cells, or catalyst in oxidation reactions.

Description

PLATINIUM/SILVER NOBLE METAL SINGLE WALL HOLLOW
NANOPARTICLES AND THEIR PREPARATION PROCESS
The present invention relates to the field of nanoparticles, more particularly to noble metal nanoparticles with well defined hollow interiors. In particular, the invention relates to noble metal nanoparticles with a multiple wall and with a hollow interior, the process to obtain them as well to the use as catalyst. It also relates to Pt/Ag single wall hollow interior nanoparticles, the process to obtain them, as well as to their uses. BACKGROUND ART
In recent years, noble metal nanoparticles have been extensively studied owing to their intriguing optical, electronic and catalytic properties. For most of the nanoparticles, the introduction of hollows into their interiors could offer some properties, such as resonant cavities, increased surfaces areas or reduced density.
Many attempts have been performed in order to produce noble metal nanoparticles with hollow interiors, but all of them present limited industrial applications since its preparation is either complicated or not reproducible. Thus, hollow metal nanostructures have been described by Xianmao et al. "Galvanic replacement reaction: a simple and powerful route to hollow and porous metal nanostructures" J. Nanoengineering and Nanosystems, vol. 221 , part N, pp. 1 -14. These nanoparticles are prepared by galvanic replacement. Unfortunately, the process needs relatively high temperatures (of about 100°C). The high temperature needed for the reaction implies a high energy cost. Additionally, by galvanic replacement in this condition is difficult to scale up the process for the production of large amounts of nanoparticles. Nanoparticles obtained by galvanic replacement reaction present an alloy of the metals all over the structure. On the other hand, other approach to produce noble metal nanoparticles has been described by Xiaohu et al. "Au- Ag alloy nanoporous nanotubes" Nano Research, 2009, vol. 2, pag. 386-393. In this document, it is described the obtention of bimetallic nanoporous nanotubes by dispersion in water of silver nanoparticles containing
cetyltrimethylammonium bromide (CTAB) and ascorbic acid, under magnetic stirring and at 40°C, followed by the addition of a salt of Au. For dealloying the sample is mixed with nitric acid. Unfortunately, the pores distribution and size of the nanoparticles obtained are irregular and the particles show signs of fragmentation and structural damage, suggesting that by this method, nanoparticles with sufficient quality can not be obtained.
Nanoparticles of Pt/Ag have been produced by the method described in Gao et al. "Bimetallic Ag-Pt hollow nanoparticles: synthesis and tunable surface plasmon resonance", Scripta Materialia, 2007, Vol. 57, pag 687, but when the nanoparticles are formed, the platinum nucleates in form of islands which growth in the surface without the alloying. So, the nanoparticle is not a smooth alloy. Similarly, in Chen et al. "Optical properties of Pd-Ag and Pt-Ag nanoboxes synthesized via galvanic replacement reactions", Nano Lett. 5, 2058 (2005), nanoboxes produced by galvanic replacement of Ag nanocubes dispersed in water with Na2PtCI4 is disclosed. However, it is reported that Pt does not readily undergo solid-solid diffusion with Ag at temperatures below 900 K (626.85 °C). Thus, at the reaction conditions Pt and Ag do not alloy, and the nanobox formed after replacement of Ag with Pt is composed of distinct Pt nanoparticles. So, the nucleation and growth of Pt particles on the Ag nanocube results in the formation of rough, noncrystalline nanobox walls that collapse upon further addition of Pt salt.
Document US200500561 18A1 discloses the preparation of single wall nanoparticles with a hollow interior, wherein the wall is made of platinum and silver. Particularly, in Example 1 1 single wall Pt/Ag nanotubes are prepared by refluxing silver nanowires with Pt(CH3COO)2 in water solution.
Nevertheless, it is stated that compared to Au/Ag nanotubes, the walls of Pt/Ag nanotubes seemed to be rougher and primarily composed of discrete nanoparticles, and that the wall of Pt/Ag nanotubes could not effectively be reconstructed to form a highly crystalline structure.
Thus, from what is known in the art, there is a need of a simple process allowing for the preparation of Pt-Ag nanoparticles with homogeneous alloy between silver and platinum. Additionally, it is derived that the development of noble metal nanoparticles with a multiple wall and with an hollow interior at room temperature as well as the development of porous nanoparticles with regular pores is still of great interest.
SUMMARY OF THE INVENTION
Inventors have found a process to produce Pt/Ag nanoparticles with homogeneous alloy between silver and platinum at room temperature, the Pt/Ag nanoparticles having a single wall. Platinum silver nanoparticles of this kind are very difficult to produce due to the deficiency of interdiffusion between Pt and Ag, which is a fundamental issue in the process of epitaxial growth. Thus, an aspect of the invention relates to a Pt/Ag single wall nanoparticle with a hollow interior, wherein the nanoparticle has at least two dimensions at the nanoscale, particularly the nanoparticle has all three dimensions at the nanoscale, where the nanoscale is the range about 1 nm to about 100 nm. Particularly, the nanoparticle has a size from 5 nm to 100 nm, more
particularly from 30 nm to 100 nm. This Pt/Ag nanoparticle is of a
homogeneous Pt/Ag alloy.
Another aspect of the invention relates to a process for the preparation of Pt/Ag single wall nanoparticles as defined above at room temperature, the process comprising the steps of: a) adding benzyldodecyldimethylammonium chloride in a molar concentration from 3 x10"2 M to 4 x10"2 M in an aqueous medium comprising nanoparticles of silver, b) adding a salt of platinum in a molar concentration from 0,05 x 10"2 to 4 x10"2 M, particularly from 3 x 10"2 to 4 x10"2 M, and c) isolating the obtained nanoparticles. Particularly the salt of platinum is not soluble in water. As mentioned above, the Pt/Ag single wall nanoparticles are homogeneous, namely are nanoparticles with a
homogeneous alloy between silver and platinum. The nanoparticles obtainable by the process defined above also form part of the invention.
This process allows controlling the ratio between Pt and Ag in the alloy with high morphological and structural quality, and production at industrial scale. On the other hand, the production of homogeneous Pt-Ag hollow structures by the process of the invention, allowing minimizing the consumption of the expensive metal Pt, is a strategic contribution to materials with high catalytic activity. Additionally, the process is advantageous since it is carried out at room temperature, which results in a more cost-effective process. Also, Pt nanoparticles alloyed with Ag, not composed of distinct Pt nanoparticles, exhibit in some cases a higher catalytic activity than pure Pt. Consequently, a more efficient and cost-effective product is obtained. This fact is considered an important contribution to the art since the production of of Pt-Ag hollow structures known in the art had limited use mainly due to higher capital costs as a consequence of the use of high temperatures and the higher
consumption of Pt, as a consequence of nucleation and growth of Pt discrete nanoparticles.
Inventors have also found that noble metal nanoparticles, with multiple walls and with a hollow interior comprising two or three noble metals, the walls with a structure based on a layer of noble metals with a high concentration of one of the noble metals both in the exterior and interior face surfaces of the walls, and an alloy of two metals with specific features in the space between the two layers of the wall, advantageously are more stable than nanoparticles made of a simple metallic alloy all over the wall. The reason lies on the high chemical stability of the metal which is in a high concentration in the external faces of the wall. Particularly, when the highly concentrated in the faces noble metal is gold, as it is an inert metal, the nanoparticles are particularly suitable for their use in biological environments.
Therefore an aspect of the present invention relates to a noble metal nanoparticle with multiple walls and with a hollow interior, the nanoparticle comprising two or three noble metals, wherein each one of the walls comprises a layer of noble metals, with a concentration of one of the noble metals equal to or higher than 85%, both in the exterior and interior face surfaces of the walls, and an alloy of a first and a second noble metals in the space between the two layers of the wall, wherein the second noble metal has a higher reduction potential than the first noble metal, and the first and the second noble metals have different diffusion coefficients, and wherein the noble metal of the layer is made of the second noble metal or of a third noble metal. The process for the production of these nanoparticles with noble metal layers at room temperature makes possible the scale up the process to a large production scale. Thus, another aspect of the present invention relates to a process for the preparation of bimetallic nanoparticles at room temperature comprising the steps of: a) adding cetyltnmethylammonium bromide and ascorbic acid into an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 30 μΜ to 100 μΜ and with a flow rate from 20 μΙ/min to 50 μΙ/min, wherein the second noble metal has a higher reduction potential than the first noble metal, and wherein the first and the second noble metals have different diffusion coefficients, and c) isolating the obtained nanoparticles. The bimetallic nanoparticles obtainable by the process defined above also form part of the invention.
Another aspect of the present invention relates to a process for the
preparation of trimetallic nanoparticles, comprising carrying out the process for the preparation of bimetallic nanoparticles and further comprising adding before step c) a salt of a third noble metal in a molar concentration from 3.5x10"3 M to 4x10"3 M and with a flow rate from 200 μΙ/min to 270 μΙ/min. The trimetallic nanoparticles obtainable by the process defined above also form part of the invention.
It has also been found that it can be increased the level of complexity of the nanoparticles with respect to the simple interior hollow of double walls nanoparticles. This geometric pattern, which is formed by cavities
symmetrically distributed, can be obtained by a second process of carving. The process allows having a better control of the interior morphology of the nanoparticles.
Therefore another aspect of the present invention relates to a process for the preparation of trimetallic nanoparticles having two or more cavities at room temperature comprising the steps of: a) adding cetyltrimethylammonium bromide or a mixture of cetyltrimethylammonium bromide and ascorbic acid into an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 3.5x10" M to 4x10"3 M,
c) waiting for a period from 20 to 30 minutes, d) adding
cetyltrimethylammonium bromide and ascorbic acid, e) adding a salt of a third noble metal in a molar concentration from 55 μΜ to 100 μΜ, and f) isolating the obtained nanoparticles. The trimetallic nanoparticles having two or more cavities obtainable by the process defined above also forms part of the invention. The trimetallic nanoparticles have the two or more cavities uniformly distributed.
Another aspect of the present invention refers to the use of any of the nanoparticles disclosed above as a catalyst.
These nanoparticles can also be used as fuel cells, drug delivery carrier, sensor or plasmon resonators.
Another aspect of the present invention refers to the use of any of the nanoparticles disclosed above as a catalyst or drug delivery carrier.
When preparing bimetallic nanoparticles in the form of nanocages, the process of the invention ensures the formation of pores with control in the size and localization. This may be an important condition for its use as carrier and delivery system, on the other hand allows a fine modulation of the optical response. Accordingly, another aspect of the invention relates to a process for the preparation of bimetallic nanoparticles in the form of nanocages at room temperature the process comprising the steps of: a) adding
benzyldodecyldimethylammonium chloride in a molar concentration from 3 x 10"2 M to 3.5 x 10"2 M in an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 1 .4 x10"4 M to 3 x10"4 M and with a flow from 100- to 200 μΙ/min, herein the second noble metal has a higher reduction potential than the first noble metal, and wherein the first and the second noble metals have different diffusion coefficients, and c) isolating the obtained nanoparticles. It also forms part of the invention the bimetallic nanoparticles in the form of nanocages obtainable by the process as defined above.
On the one hand, the existence of pores in nanocages makes possible to load through the pores chemical compounds that can be delivered in a controlled manner.
Therefore, another aspect of the present invention relates to the use of Pt/Ag nanoparticles, in particular, in form of nanocages, nanoboxes or nanotubes, more particularly in form of nanocages, as defined above as a drug delivery carrier, as catalytic cathode in fuel cells or as a catalyst in oxidation reactions. This aspect can also be formulated as a method of use of the mentioned nanoparticles as a drug delivery carrier, as catalytic cathode in fuel cells or as a catalyst in oxidation reactions.
Finally, it is known that the durability under cycling regimes in systems of proton exchange membrane fuel cells is one of the most important problems that must be resolved. When platinum nanoparticles are used as cathode, amorphous carbon clusters are utilized as support. Unfortunately, the corrosion of the support limits the duration and efficiency of the system. Due at its high surface area, advantages offered by its morphology, and the facility to be aligned and assembled in 2D configurations, the Pt/Ag nanoparticles in form of nanotubes of the invention can be used for its implementation as catalytic cathode in fuel cells. Thus, it is also an aspect of the present invention the use of Pt/Ag nanoparticles as defined above in form of nanotubes as catalytic cathodes in fuel cells. This aspect can also be formulated as a method of use of the mentioned nanoparticles as catalytic cathodes in fuel cells. It can be prepared a colloidal solution of AuAg nanoparticles, in particular blue colour. For its preparation, Au nanocages are prepared. The gold nanocage may be prepared by the method explained in the Example 10 of this document. The gold nanoparticle may be prepared also by other methods known in the art. It is also prepared oxidized polyvinylpyrrolidone (PVP). For its preparation PVP is oxidized during two days in the presence of air. Other method known in the art for oxidizing the polyvinylpyrrolidone may also be used.
It is also considered an aspect of the present invention a process for the preparation of a colloidal solution of Pt/Ag nanoparticles of blue colour which comprises the steps of:
a) adding between 0.5 ml and 1 ml of oxidized polyvinylpyrrolidone with a molar concentration between 1 .5 M and 2.5 M, to an aqueous medium comprising the gold nanocages; b) leaving to stand the solution at least during one day; and c) removing the supernatant.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a Transmission electron microscopy (TEM) image of double walled nanocubes Au/Ag.
FIG. 2 shows an Energy-dispersive X-ray spectroscopy (EDX) map of double walled nanocubes Au/Ag.
FIG 3 shows a schematic representation of double walled nanocubes with an open window.
FIG. 4 shows a TEM image for Pt-Ag nanoboxes.
FIG. 5 shows a TEM image of Au-Ag nanocages.
FIG. 6 show a schematic representation of a trimetallic Pd-Au-Ag triple walled nanocubes with five cavities
DETAILED DESCRIPTION OF THE INVENTION
As mentioned above, Pt/Ag single wall nanoparticles with a hollow interior of the invention, as well as their preparation process, are part of the invention. Also as mentioned above, the process is carried out at room temperature, and comprises the steps of: a) adding benzyldodecyldimethylammonium chloride until obtaining a molar concentration from 3 x 10"2 M to 4 x 10"2 M in an aqueous medium comprising nanoparticles of silver, b) adding a non-water soluble salt of platinum until obtaining a molar concentration from 0,05 x 10"2 M to 4 x10"2 M, particularly from 3 x 10"2 M to 4 x 10"2 M, in the aqueous medium, and isolating the obtained nanoparticles. Particularly the salt of platinum is not soluble in water.
This process leads to the mentioned Pt/Ag nanoparticles where the Pt mass is extremely reduced and high index planes -highly reactive low coordinated Pt atoms- for increased reactivity, stabilized. Particularly, a stable
homogeneous alloy between silver and platinum coated by a thin layer of platinum is formed, the nanoparticles having a very high catalytic activity.
In a particular embodiment of this process, the salt of platinum is PtCI2. The
PtCI2 provides a high standard potential, favoring the inherent reactivity in addition to its insolubility in water, aspect that allows a kinetic control on reaction via a sustained release of Pt ions in the reacting mixture. It is known that PtCI2 is soluble in HCI or ammonia, so, with the use of
amphyphilic/tensioactives/surfactant molecules as
benzyldodecyldimethylammonium chloride (BDAC) in aqueous media it is possible to create a chemical environment to solubilise the salt slowly. Under these conditions, the diffusion of platinum in silver is favored and it leads to the formation of a homogeneous alloy.
In a particular embodiment, the wall ot the Pt/Ag single wall nanoparticles with a hollow interior as defined above has a thickness from 3 to 10 nm, particularly of around 5 nm.
In an embodiment of the process for the preparation of Pt/Ag single wall nanoparticles with a hollow interior as defined above, the nanoparticle of silver is a nanocube and, consequently, the obtained nanoparticle is a nanobox. In another particular embodiment of the same process, the nanoparticle of silver is a nanowire and the obtained nanoparticle is a nanotube. As mentioned above, the Pt/Ag single wall nanoparticles are homogeneous. Pt/Ag single wall nanoparticles with a hollow interior in form of nanoboxes or in form of nanotubes obtainable by this process also form part of the invention. As mentioned above, like with Pt/Ag nanocages, Pt/Ag nanotubes show a great potential in their use as catalytic agents. Particularly, with Pt/Ag nanotubes it is not necessary having an additional substrate to form the catalytic cathode.
In another preferred embodiment, the salt of platinum is H2PtCI6. With H2PtCI6 appear a formation of Pt-Ag nanocages with porous symmetrically distributed.
The isolation of the obtained nanoparticles can be carried out by conventional methods known to those skilled in the art, such as by filtration or
centrifugation.
Also as mentioned above, another aspect of the present invention relates to a noble metal nanoparticle with multiple walls and with a hollow interior, the nanoparticle comprising two or three noble metals, wherein each one of the walls comprises a layer of a noble metals with a concentration of one of the noble metals equal to or higher than 85% both in the exterior and interior face surfaces of the walls, and an alloy of a first and a second noble metals in the space between the two layers of the wall, wherein the second noble metal has a higher reduction potential than the first noble metal, and the first and the second noble metals have different diffusion coefficients, and wherein the noble metal of the layer is made of the second noble metal or of a third noble metal. Preferably, the layer of noble metals has a concentration of one of the noble metals equal to or higher than 90%, more preferably, metals equal to or higher than 95%, still more preferably equal to or higher than 97%, and even still more preferably equal to or higher than 99%. The term "nanoparticle" as used herein, refers to a particle with at least two dimensions at the nanoscale, particularly with all three dimensions at the nanoscale, where the nanoscale is the range about 1 nm to about 100 nm. Particularly, when the nanoparticle is substantially rod-shaped with a substantially circular cross-section, such as a nanowire or a nanotube, the "nanoparticle" refers to a particle with at least two dimensions at the nanoscale, this two dimensions being the cross-section of the nanoparticle.
As used herein, the term "size" refers to a characteristic physical dimension. For example, in the case of a nanoparticle that is substantially spherical, the size of the nanoparticle corresponds to the diameter of the nanoparticle. In the case of a nanoparticle that is substantially rod-shaped with a substantially circular cross-section, such as as nanowire or a nanotube, the size of the nanoparticle corresponds to the diameter of the cross-section of the
nanoparticle. In the case of a nanoparticle that is substantially box-shaped, such as a nanocube, a nanobox, or a nanocage, the size of the nanoparticle corresponds to the maximum edge length. When referring to a set of nanoparticles as being of a particular size, it is contemplated that the set of nanoparticles can have a distribution of sizes around the specified size. Thus, as used herein, a size of a set of nanoparticles can refer to a mode of a distribution of sizes, such as a peak size of the distribution of sizes.
The term "noble metal" as used herein, refers to metals that are resistant to corrosion and oxidation in moist air. Examples of noble metal are palladium, silver, platinum and gold.
The term "multiple walls" as used herein, refers to at least a double wall, for example double wall, triple wall or quadruple wall. The term "hollow interior" as used herein, refers to the presence of one or more cavities in the interior of the nanoparticle, such as two, three, four or five cavities.
The term "metallic alloy" as used herein, refers to a homogeneous mixture of two or more metals, wherein each of the metals may be in different or equal amounts.
The term "homogeneous" as used herein is understood according to the common understanding of the term. Namely, in the context of composite metals, it relates to an alloy of metals which forms a solid solution, i.e., to a homogeneous mixture of two or more than two metals. Thus, a "homogeneous Pt-Ag nanoparticle" is a nanoparticle with a single phase alloy between silver and platinum. A "solid solution" is a solid-state solution of one or more solutes in a solvent. Such a mixture is considered a solution rather than a compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single homogeneous phase. The nanoparticle of the invention refers to a nanobox, nanotube or a nanocage. The nanobox, nanotube or nanocage may have different morphologies depending on the sacrificial template, which can have different shapes such as cubes, spheres, wires, rods, prisms and so on. The term "nanobox" as used herein, refers to nanoparticles with hollow interior and solid walls, or with one pore in one of the walls.
The term "nanocages" as used herein, refers to nanoparticles with hollow interior and porous walls and/or porous corners.
The term "nanotubes" as used herein, refers to cylindrical nanoparticles with porous walls or solid walls.
The term "sacrificial template" as used herein, refers to nanoparticles that participate as reactant and are partially or totally consumed during the process. The final product takes the same shape as the template, aspect that allows controlling the geometry of the hollow structure.
In a preferred embodiment of the first aspect of the invention, the first novel metal is silver. In another preferred embodiment of the first aspect, the second and third noble metals are selected from the group consisting of gold, platinum, and palladium.
In another preferred embodiment the nanoparticle is a bimetallic double walled nanoparticle and has an opening giving access to the hollow interior. In a particular embodiment of this aspect the nanoparticle is a Au/Ag double walled nanocube. This nanoparticle is shown in FIG. 1 . FIG 2 shows the metalic distribution of the nanoparticle of FIG. 1 . In other particular embodiment of this aspect the nanoparticle is a Au/Ag double walled nanosphere. In another particular embodiment of this aspect the nanoparticle is a double walled nanotube.
The sentence "opening giving access to the hollow interior" refers to a hole that allows direct access to the interior of the nanoparticle. A schematic representation of this access is shown in FIG. 3.
In other preferred embodiment of the first aspect of the invention the nanoparticle is a trimetallic double wall nanoparticle nanoparticle and has an opening giving access to the hollow interior. In a particular embodiment, the nanoparticle is Pd/Au/Ag double walled nanocube.
To increase the levels of complexity in the double walled nanoparticles with hollow interior the inventors have development trimetallic nanoparticles with interior cavities, symmetrically distributed in the nanoparticles.
In a preferred embodiment of the first aspect of the invention the nanoparticle is a trimetallic nanoparticle having two or more cavities such as two, four or five central cavities. In a particular embodiment of this aspect, the
nanoparticle is Pd/Au/Ag triple walled with five cavities. A schematic representation of this nanoparticle is shown in FIG. 6.
The term "cavities" as used herein refers to interior voids surrounded by only one wall of noble metals in the centre symmetrically distributed. The term cavities does not include the gaps between the walls or the gaps around the cavities.
The bimetallic nanoparticles as defined above may be prepared by a process carried out at room temperature comprising the steps of: a) adding
cetyltrimethylammonium bromide and ascorbic acid into an aqueous medium comprising nanoparticles of a first noble metal, b) adding a salt of a second noble metal in a molar concentration from 30 μΜ to 100 μΜ and with a flow rate from 20 μΙ/min to 50 μΙ/min, wherein the second noble metal has a higher reduction potential than the first noble metal, and wherein the first and the second noble metals have different diffusion coefficients, c) isolating the obtained nanoparticles.
The term "room temperature" as used in the present invention, refers to a temperature between 20°C to 30°C, for example 25°C. Hydrochloric acid may be optionally added in step a.
Hydrochloric acid improves quality surface, smoothness, regularity and monodispersity of the nanoparticle. The trimetallic nanoparticles as defined above, may be prepared by a process comprising carrying out the process of the second aspect of the present invention and further comprising adding before step c) a salt of a third noble metal in a molar concentration from 3.5x10"3 M to 4x10"3 M and with a flow rate from 200 μΙ/min to 270 μΙ/min.
In a particular embodiment, the third noble metal has a lower reduction potential than the second noble metal, thereby a nanocage is obtained. In another particular embodiment, the third noble metal has a higher reduction potential than the second noble metal, thereby a nanobox is obtained.
Throughout the description and claims the word "comprise" and variations of the word, are not intended to exclude other technical features, additives, components, or steps. Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention. The following examples and drawings are provided by way of illustration, and they are not intended to be limiting of the present invention. Reference signs related to drawings and placed in parentheses in a claim, are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim. Furthermore, the present invention covers all possible combinations of particular and preferred embodiments described herein. EXAMPLES Example 1 : Production of bimetallic Au-Ag double walled nanoboxes
In Mili Q water (2ml) at room temperature under magnetic stirring, silver nanocubes (200 μΙ_, 7 nM) were added. The silver nanocubes were prepared as the method described in Skrabakak et al. "Nature Protocols", 2007, vol. 2, 2182-2190 and stabilized with polyethylene glycol. Immediately after Cetyl Trimethyl Ammonium Bromide (CTAB) (1 .4 10"2 M) and L- ascorbic acid (1 .4 10-4 M) were added, the two products dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (5.5 10"5 mM) was injected with syringe pump a flow of 30 μΙ/min. After 10 min the product was centrifuged at 14000 rpm and was washed several times with water to eliminate the residues of the synthesis.
Example 2: Production of bimetallic Au-Ag double walled spheres
In Mili Q water (2 ml) at room temperature under magnetic stirring, silver nanospheres (250 μΙ, 7 nM) were added. The silver nanospheres were prepared as the method described in Kim et al. "J. Phys. Chem. C", 2008, vol. 1 12, 7872-7876. Immediately after CTAB (1 ml, 0.1 M) and L- ascorbic acid (10 μΙ, 0.1 M) were added, the two products dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (4 ml, 0.1 mM) was injected with syringe pump a flow of 300 μΙ/min. The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis.
Example 3: Production of trimetallic Pd-Au-Ag double walled nanoboxes
In Mili Q water (2 ml) at room temperature under magnetic stirring, silver nanocubes (250 μΙ, 7 nM) were added. The silver nanocubes were prepared as the method described in Kim et al. "J. Phys. Chem. C", 2008, vol. 1 12, 7872-7876. Immediately after CTAB (1 ml, 0.1 M) and L- ascorbic acid (10 μΙ, 0.1 M) were added, the two products dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (4 ml, 0.1 mM) was injected with syringe pump a flow of 300μΙ/Γηϊη. Immediately after Na2PdCI4 (4 ml) was injected with syringe pump a flow of 300 μΙ/min.The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis. The sample was re-dispersed in Mili-Q water (18.2 ΜΩ cm) for storage until use.
Example 4: Production of bimetallic Au-Ag double walled nanocages
In Mili Q water (2 ml) at room temperature under magnetic stirring, silver nanocubes (250 μΙ, 7 nM) were added. The silver nanocubes were prepared as the method described in Kim et al. "J. Phys. Chem. C", 2008, vol. 1 12, 7872-7876. Immediately after, benzyldodecyldimethylammonium chloride (BDAC) (1 ml, 0.1 M) was added dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (500-1000 μΙ, 1 mM) was injected with syringe pump a flow of 45 μΙ/min.The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis. The sample was re-dispersed in Mili-Q water (18.2 ΜΩ cm) for storage until use. Example 5: Production of bimetallic Pt-Ag single walled nanoboxes
In Mili Q water (2 ml) at room temperature under magnetic stirring, silver nanocubes (250 μΙ. 7 nM) were added. The silver nanocubes were prepared as the method described in Kim et al. "J. Phys. Chem. C", 2008, vol. 1 12, 7872-7876. Immediately after, BDAC (1 ml, 0.1 M) dissolved in water Mili-Q, and an aqueous solution of PtCI2 (2 ml, 10 mM) were added. The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis. The sample was re-dispersed in Mili-Q water (18.2 ΜΩ cm) for storage until use. Example 6: Production of bimetallic Au-Ag double walled nanotubes
In Mili Q water (2.8 ml) at room temperature under magnetic stirring, silver nanowires (0.28 ml, 7 nM) were added. Immediately after CTAB (1 .4 ml, 0.1 M) and ascorbic acid (0.013 ml, 0.1 M) were added, the two products dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (3 ml, 0.01 mM) was injected with syringe pump a flow of 225 μΙ/min, then an aqueous solution of H2AuCI4 (2.3 ml, 1 mM) was injected with syringe pump a flow of 172 μΙ/min and finally H2AuCI4 (0.2 ml, 10 mM) was injected with syringe pump a flow of 15μΙ/Γηίη. The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis. The sample was re-dispersed in Mili-Q water (18.2 ΜΩ cm) for storage until use. Example 7: Production of bimetallic Pt-Ag nanotubes
In Mili Q water (2 ml) at room temperature under magnetic stirring, silver nanowires (1 ΟΟμΙ, 7 nM) were added. Immediately after BDAC dissolved in water (1 ml, 0.1 M) was added. An aqueous solution of PtCI2 (200μΙ, 10mM) was added drop by drop. The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis. The sample was re-dispersed in Mili-Q water (18.2 ΜΩ cm) for storage until use.
Example 8: Production of trimetallic Pd-Au-Ag triple walled nanocubes with five cavities
In Mili Q water (2ml) at room temperature under magnetic stirring, silver nanocubes (250μΙ, 7 nM) were added. Immediately after CTAB (1 ml, 0.1 M) and ascorbic acid (10 μΙ, 0.1 M) were added, the two products dissolved in water Mili-Q. An aqueous solution of Na2PdCI4 (400 μΙ, 1 mM) was injected with syringe pump a flow of 300 μΙ/min. Twenty minutes after an CTAB (1 ml, 0.1 M) and ascorbic acid (10 μΙ, 0.1 M) were added, the two products dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (400 μΙ, 1 mM) was injected with syringe pump a flow of 300 μΙ/min.
Example 9: Production of bimetallic Au-Ag hybrid nanotubes
In Mili Q water at room temperature under magnetic stirring, silver nanowires
(100 μΙ_, 7 nM) were added. Immediately after BDAC (3 10"2 M) was added dissolved in water Mili-Q. An aqueous solution of H2AuCI4 (1 .4 10"5 M) was injected with syringe pump a flow of 0.075 μΙ/min, then an aqueous solution of H2AuCI4 (1 .4 10"4 M) was injected with syringe pump a flow of 0.075 μΙ/min. The product was centrifuged at 200 rpm and was washed several times with water to eliminate the residues of the synthesis. The sample was re-dispersed in Mili-Q water (18.2 ΜΩ cm) for storage until use.
Example 10: Production of a blue color
In Mili Q water (2 ml) at room temperature under magnetic stirring, silver nanocubes (250μΙ, 7 nM) were added. Immediately after BDAC dissolved in water (1 ml, 0.1 M) was added. An aqueous solution of H2AuCI4 (600 μΙ, 1 mM) was injected with syringe pump a flow of 45 μΙ/min. When the resonance peak of the colloid show 800 nm in a spectrophotometer UV-vis the product was centrifuged at 14000 rpm. The supernatant was removed. Distillated water (1 ml) was added. Then oxidised polyvinylpyrrolidone was added (2 M, 0.5 ml) settling the solution al least one day and finally removing the supernatant.

Claims

1 . A homogeneous Pt/Ag single wall nanoparticle with a hollow interior, wherein the nanoparticle has at least two dimensions at the nanoscale, where the nanoscale is the range about 1 nm to about 100 nm.
2. The homogeneous Pt/Ag single wall nanoparticle according to claim 1 , wherein the nanoparticle has all three dimensions at the nanoscale.
3. The homogeneous Pt/Ag single wall nanoparticle according to any one of claims 1 -2, with a size from 5 nm to 100 nm.
4. The homogeneous Pt/Ag single wall nanoparticle according to any one of claims 1 -2, with a size from 30 nm to 100 nm.
5. The homogeneous Pt/Ag single wall nanoparticle according to any one of claims 1 -4, which is in form of a nanobox.
6. The homogeneous Pt/Ag single wall nanoparticle according to any one of claims 1 -4, which is in form of a nanotube.
7. A process for the preparation of Pt/Ag single wall nanoparticles as defined in any one of claims 1 -4 at room temperature, the process comprising the steps of:
a) adding benzyldodecyldimethylammonium chloride in a molar concentration from 3 x10"2 M to 4 x10"2 M in an aqueous medium comprising nanoparticles of silver,
b) adding a salt of platinum in a molar concentration from 0,05 x 10"2 M to 4 x 10"2 M,
c) isolating the obtained nanoparticles.
8. The process according to claim 7, wherein the molar concentration of the salt of platinum in step b) is from 3 x 10"2 M to 4 x 10"2 M.
9. The process according to any one of claims 7-8, wherein the salt of platinum is not soluble in water.
10. The process according to claim 9, wherein the salt of platinum is PtCI2.
1 1 . The process according to any one of claims 7-10, wherein the
nanoparticle of silver is a nanocube and the obtained nanoparticle is a nanobox.
12. The process according to any one of claims7-10, wherein the nanoparticle of silver is a nanowire and the obtained nanoparticle is a nanotube.
13. Use of the Pt/Ag single wall nanoparticle as defined in any one of claims 1 -6 as drug delivery carrier, catalytic cathode in fuel cells or as catalyst in oxidation reactions.
14. Use of the Pt/Ag single wall nanoparticle as defined in claim 6 as catalytic cathode in fuel cells.
PCT/EP2012/054319 2011-03-14 2012-03-13 Platinium/silver noble metal single wall hollow nanoparticles and their preparation process WO2012123435A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP11158024 2011-03-14
EP11158024.7 2011-03-14

Publications (1)

Publication Number Publication Date
WO2012123435A1 true WO2012123435A1 (en) 2012-09-20

Family

ID=44675885

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2012/054319 WO2012123435A1 (en) 2011-03-14 2012-03-13 Platinium/silver noble metal single wall hollow nanoparticles and their preparation process

Country Status (1)

Country Link
WO (1) WO2012123435A1 (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9410007B2 (en) 2012-09-27 2016-08-09 Rhodia Operations Process for making silver nanostructures and copolymer useful in such process
JP2016530676A (en) * 2013-11-01 2016-09-29 エルジー・ケム・リミテッド Fuel cell and manufacturing method thereof
EP2990138A4 (en) * 2013-06-07 2017-01-11 LG Chem, Ltd. Hollow metal nanoparticles
WO2017072701A1 (en) * 2015-10-27 2017-05-04 Fondazione Istituto Italiano Di Tecnologia Method for the preparation of metal oxide hollow nanoparticles
CN111554946A (en) * 2020-04-23 2020-08-18 广东道氏云杉氢能科技有限公司 Pt alloy with high HOR catalytic activity and preparation method and application thereof
CN111850528A (en) * 2020-07-10 2020-10-30 南京大学 Anti-oxidation and anti-vulcanization protection method for surface of nano silver wire
US20230294076A1 (en) * 2022-03-16 2023-09-21 Honda Motor Co., Ltd. Synthesis of bimetallic structures for use as catalysts

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050056118A1 (en) 2002-12-09 2005-03-17 Younan Xia Methods of nanostructure formation and shape selection
US20070056659A1 (en) * 2003-03-14 2007-03-15 Mirkin Chad A Triangular nanoframes and method of making same
WO2011101837A1 (en) * 2010-02-16 2011-08-25 The Provost, Fellows, Foundation Scholars, And The Other Members Of Board, Of The College Of The Holy And Undivided Trinity Of Queen Elizabeth, Near Dublin Substrate for surface enhanced raman spectroscopy

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050056118A1 (en) 2002-12-09 2005-03-17 Younan Xia Methods of nanostructure formation and shape selection
US20070056659A1 (en) * 2003-03-14 2007-03-15 Mirkin Chad A Triangular nanoframes and method of making same
WO2011101837A1 (en) * 2010-02-16 2011-08-25 The Provost, Fellows, Foundation Scholars, And The Other Members Of Board, Of The College Of The Holy And Undivided Trinity Of Queen Elizabeth, Near Dublin Substrate for surface enhanced raman spectroscopy

Non-Patent Citations (13)

* Cited by examiner, † Cited by third party
Title
AN K ET AL: "Synthesis and biomedical applications of hollow nanostructures", NANO TODAY, ELSEVIER, AMSTERDAM, NL, vol. 4, no. 4, 1 August 2009 (2009-08-01), pages 359 - 373, XP026349294, ISSN: 1748-0132, [retrieved on 20090722] *
BANSAL V ET AL: "Galvanic replacement mediated synthesis of hollow Pt nanocatalysts: Significance of residual Ag for the H2 evolution reaction", ELECTROCHEMISTRY COMMUNICATIONS, ELSEVIER, AMSTERDAM, NL, vol. 11, no. 8, 1 August 2009 (2009-08-01), pages 1639 - 1642, XP026436911, ISSN: 1388-2481, [retrieved on 20090623], DOI: 10.1016/J.ELECOM.2009.06.018 *
CHEN ET AL.: "Optical properties of Pd-Ag and Pt-Ag nanoboxes synthesized via galvanic replacement reactions", NANO LETT., vol. 5, 2005, pages 2058, XP009152777
CHEN JINGYI ET AL: "Facile synthesis of gold-silver nanocages with controllable pores on the surface", JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, AMERICAN CHEMICAL SOCIETY, WASHINGTON, DC; US, vol. 128, no. 46, 22 November 2006 (2006-11-22), pages 14776 - 14777, XP007918675, ISSN: 0002-7863, [retrieved on 20061028], DOI: 10.1021/JA066023G *
DAMIAN AHERNE ET AL: "From Ag Nanoprisms to Triangular AuAg Nanoboxes", ADVANCED FUNCTIONAL MATERIALS, WILEY - V C H VERLAG GMBH & CO. KGAA, DE, vol. 20, no. 8, 23 April 2010 (2010-04-23), pages 1329 - 1338, XP001554195, ISSN: 1616-301X, DOI: 10.1002/ADFM.200902030 *
GAO ET AL.: "Bimetallic Ag-Pt hollow nanoparticles: synthesis and tunable surface plasmon resonance", SCRIPTA MATERIALIA, vol. 57, 2007, pages 687, XP022176485, DOI: doi:10.1016/j.scriptamat.2007.06.049
GAO ET AL: "Bimetallic Ag-Pt hollow nanoparticles: Synthesis and tunable surface plasmon resonance", SCRIPTA MATERIALIA, ELSEVIER, AMSTERDAM, NL, vol. 57, no. 8, 28 July 2007 (2007-07-28), pages 687 - 690, XP022176485, ISSN: 1359-6462, DOI: 10.1016/J.SCRIPTAMAT.2007.06.049 *
JINGYI CHEN ET AL: "Optical Properties of Pd?Ag and Pt?Ag Nanoboxes Synthesized via Galvanic Replacement Reactions", NANO LETTERS, ACS, WASHINGTON, DC, US, vol. 5, no. 10, 1 January 2005 (2005-01-01), pages 2058 - 2062, XP009152777, ISSN: 1530-6984 *
KIM ET AL., J. PHYS. CHEM. C, vol. 112, 2008, pages 7872 - 7876
METRAUX G S ET AL: "Triangular nanoframes made of gold and silver", NANO LETTERS, ACS, WASHINGTON, DC, US, vol. 3, no. 4, 1 April 2003 (2003-04-01), pages 519 - 522, XP007918677, ISSN: 1530-6984, [retrieved on 20030315], DOI: 10.1021/NL034097+ *
SKRABAKAK ET AL., NATURE PROTOCOLS, vol. 2, 2007, pages 2182 - 2190
XIANMAO ET AL.: "Galvanic replacement reaction: a simple and powerful route to hollow and porous metal nanostructures", J. NANOENGINEERING AND NANOSYSTEMS, vol. 221, pages 1 - 14
XIAOHU ET AL.: "Au- Ag alloy nanoporous nanotubes", NANO RESEARCH, vol. 2, 2009, pages 386 - 393

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9410007B2 (en) 2012-09-27 2016-08-09 Rhodia Operations Process for making silver nanostructures and copolymer useful in such process
US9776173B2 (en) 2013-06-07 2017-10-03 Lg Chem, Ltd. Hollow metal nanoparticles
EP2990138A4 (en) * 2013-06-07 2017-01-11 LG Chem, Ltd. Hollow metal nanoparticles
EP2998269A4 (en) * 2013-11-01 2016-12-07 Lg Chemical Ltd Fuel cell and method for manufacturing same
US9614227B2 (en) 2013-11-01 2017-04-04 Lg Chem, Ltd. Fuel cell and method of manufacturing same
JP2016530676A (en) * 2013-11-01 2016-09-29 エルジー・ケム・リミテッド Fuel cell and manufacturing method thereof
WO2017072701A1 (en) * 2015-10-27 2017-05-04 Fondazione Istituto Italiano Di Tecnologia Method for the preparation of metal oxide hollow nanoparticles
US10814313B2 (en) 2015-10-27 2020-10-27 Fondazione lstituto Italiano Di Tecnologia Method for the preparation of metal oxide hollow nanoparticles
CN111554946A (en) * 2020-04-23 2020-08-18 广东道氏云杉氢能科技有限公司 Pt alloy with high HOR catalytic activity and preparation method and application thereof
CN111554946B (en) * 2020-04-23 2022-05-17 广东泰极动力科技有限公司 Pt alloy with high HOR catalytic activity and preparation method and application thereof
CN111850528A (en) * 2020-07-10 2020-10-30 南京大学 Anti-oxidation and anti-vulcanization protection method for surface of nano silver wire
US20230294076A1 (en) * 2022-03-16 2023-09-21 Honda Motor Co., Ltd. Synthesis of bimetallic structures for use as catalysts
US11766660B1 (en) * 2022-03-16 2023-09-26 Honda Motor Co., Ltd. Synthesis of bimetallic structures for use as catalysts

Similar Documents

Publication Publication Date Title
Li et al. Architecture and preparation of hollow catalytic devices
Zhao et al. The synthesis and electrochemical applications of core–shell MOFs and their derivatives
Feng et al. Self‐templating approaches to hollow nanostructures
US11471939B2 (en) Methods of nanostructure formation and shape selection
Yu et al. The design and synthesis of hollow micro‐/nanostructures: present and future trends
Zhu et al. Engineering ordered and nonordered porous noble metal nanostructures: synthesis, assembly, and their applications in electrochemistry
WO2012123435A1 (en) Platinium/silver noble metal single wall hollow nanoparticles and their preparation process
Yang et al. Mesoporous nano/micro noble metal particles: synthesis and applications
Hu et al. Fabrication and application of inorganic hollow spheres
Zhang et al. Noble‐metal nanocrystals with concave surfaces: synthesis and applications
Banadaki et al. Recent advances in facile synthesis of bimetallic nanostructures: An overview
Bhol et al. Modern chemical routes for the controlled synthesis of anisotropic bimetallic nanostructures and their application in catalysis
JP5543021B2 (en) Preparation method of core-shell magnetic alloy nanoparticles
Zhang et al. Fabrication of Au@ Ag core–shell nanoparticles using polyelectrolyte multilayers as nanoreactors
WO2009044146A1 (en) Metal nanoparticles
KR20110040006A (en) Nanorattle structure and process for preparing the same
Koo et al. Pore-engineered silica nanoreactors for chemical interaction-guided confined synthesis of porous platinum nanodendrites
Eid et al. Nanoarchitectonic metals
KR101168653B1 (en) Process for Preparing Nanodendrites
KR101368404B1 (en) Metal nanoparticles and method for preparing the same
Lu et al. Synthesis and property studies of hollow nanostructures
Du et al. Origin of symmetry breaking in the seed-mediated growth of bi-metal nano-heterostructures
Zhan Synthetic architecture of integrated nanocatalysts with controlled spatial distribution of metal nanoparticles
CN111112640A (en) Method for regulating and controlling Yolk-shell nano structure
Janssen et al. Separating Growth from Nucleation for Facile Control over the Size and Shape of Palladium Nanocrystals

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12709312

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12709312

Country of ref document: EP

Kind code of ref document: A1