JP2019039026A - Visible-light plasmonic alloy nanoparticle, method for manufacturing same and applications thereof - Google Patents

Abstract

To provide a visible-light plasmonic alloy nanoparticle, method for manufacturing same and applications thereof.SOLUTION: The present invention relates to a visible-light plasmonic alloy nanoparticle, method for manufacturing same and applications thereof, satisfying the followings (1)-(3): (1) the alloyed nanoparticle is an alloy constituted with elements A and B, in which the element A is one or more selected from a group consisting of groups 8-11 of the periodic table and the element B is one or more selected from a group consisting of groups 12-14 of the periodic table, (2) the composition ratio of the element A and the element B in the alloy nanoparticle is 60:40-40:60, and (3) the alloyed nanoparticle has a crystal structure in which respective atomic layers of element A and element B can be confirmed to laminate alternately if viewed in any of 3 directions orthogonal to one another in a three-dimensional space of an orthogonal coordinate system defined by x, y and z axes.SELECTED DRAWING: None

Description

  The present invention relates to a visible light plasmonic alloy nanoparticle, a production method thereof, and an application thereof.

  When gold (Au) becomes spherical fine particles (nanoparticles) having a nanometer size, green light is absorbed by a collective oscillation phenomenon of free electrons called localized surface plasmon resonance (LSPR). Moreover, since blue light is absorbed by the transition between Au bands, red is exhibited by absorbing green and blue light in sunlight. Since the green light absorbed by LSPR is localized on the Au nanoparticle surface as near-field light, photons can be locally collected by LSPR as if the funnel collects liquid. Therefore, interaction between near-field light and adsorbed molecules, such as molecular sensing by surface-enhanced Raman scattering (SERS) and fluorescence enhancement of dye molecules, is an attractive research target. In recent years, it has attracted attention as a phenomenon that can improve low-grade light with low energy density such as sunlight, and its application in the fields of energy creation and energy saving is also being actively studied.

The absorption wavelength by LSPR is called “plasma frequency” and shifts by a short wavelength as the carrier density of the substance increases. Usually, metal carrier density (free electron density) n is large (n≈10 ²³ cm ⁻³ ), and the plasma frequency is in the ultraviolet region. A conductive oxide such as indium tin oxide (ITO) has a smaller carrier density (n≈10 ²¹ cm ⁻³ ) than a metal, and thus the plasma frequency is in the near infrared light region. Among them, gold (Au), silver (Ag), and copper (Cu) are few exceptions having a plasma frequency in the visible region. The light in the visible region is an extremely important wavelength region that induces intramolecular electronic transition, charge transfer from ligand to central metal (LMCT), interband transition, etc. for organic molecules, metal complexes or inorganic semiconductors. Nevertheless, practically, the visible light plasmonic material that can increase the efficiency of these transition processes is Au, Ag, or a solid solution alloy thereof.

  However, while Au has high chemical stability, it is expensive. Ag has a higher electric field strength than Au, but has problems in terms of chemical stability such as low oxidation resistance.

  Note that Cu has a lower oxidation resistance than Ag, and further, the light absorption band resulting from the interband transition largely overlaps with the absorption band by LSPR, so that it is difficult to apply as a visible light plasmonic material.

  In recent years, the plasma frequency has been controlled by making metal nanoparticles such as palladium (Pd) and aluminum (Al), which have plasma frequency in the ultraviolet region, into anisotropic shapes such as nanosheets, nanoplates, and nanorods. Attempts have been made to impart visible light responsiveness (Patent Documents 1 and 2, Non-Patent Documents 1 and 2, etc.). However, since the metal nanoparticles are not essentially materials having a plasma frequency in the visible region, there is a concern that the visible light responsiveness may be lost when the shape is changed by a large energy due to heat or the like.

  Thus, in spite of various approaches being attempted, no metal (alloy) material having a plasma frequency in the visible region has been found in addition to Au, Ag and Cu. is there.

  By the way, in Patent Document 3, palladium alloy nanoparticles are produced by reacting a metal having a positive potential with respect to a standard oxidation-reduction potential of -1.2 V or a metal complex thereof, a phosphorus-palladium compound, and an organic ligand. It has been reported that it can be done.

Special Table 2008-532097 (International Publication No. 2006/096255) JP 2011-232384 JP 2016-56431 A

Nat. Nanotech. 2011, 4, 28., “Freestanding Palladium Nanosheets with Plasmonic and Catalytic Properties” ACS Photonics 2014, 1, 538., “Robust and Versatile Light Absorption at Near Infrared Wavelengths by Plasmonic Aluminum Nanorods”

  An object of the present invention is to provide a visible light plasmonic alloy nanoparticle, a production method thereof, and an application thereof.

  The present inventor conducted intensive studies to solve the above-described problems. As a result, alloy nanoparticles of palladium (Pd) and indium (In) absorb light in the visible region by localized surface plasmon resonance (LSPR). I found out. The PdIn alloy nanoparticles are an alloy composed of approximately 1: 1 Pd atoms and In atoms, and are defined by a B2 type crystal structure similar to cesium chloride (CsCl), ie, x, y, and z axes. The three-dimensional space of the orthogonal coordinate system has a crystal structure in which atomic layers of Pd and In are alternately stacked when viewed from any of three directions orthogonal to each other (see, for example, FIG. 11). Based on this finding, further studies have been made to complete the present invention.

  That is, the present invention provides the following visible light plasmonic alloy nanoparticles, a production method thereof, and uses thereof.

Item 1. Visible light plasmonic alloy nanoparticles satisfying the following (1) to (3);
(1) The alloy nanoparticles are an alloy composed of an element A and an element B, the element A is one or more elements selected from the group consisting of groups 8 to 11 of the periodic table, and the element B is It is one or more elements selected from the group consisting of Groups 12-14 of the periodic table.
(2) The composition ratio of element A and element B in the alloy nanoparticles is 60:40 to 40:60, and (3) the alloy nanoparticles are orthogonal coordinates defined by the x, y, and z axes. In the three-dimensional space of the system, it has a crystal structure in which it can be confirmed that the atomic layers of the element A and the element B are alternately stacked when viewed from any of three directions orthogonal to each other.

Item 2. The visible light plasmonic material according to Item 1, further satisfying the following (4):
(4) When the alloy nanoparticles have a Fermi energy of 0 eV, the alloy nanoparticles have a band (d band) mainly composed of d orbitals in a region of −1.5 eV or less, and −1.5 eV to 2.0 eV. The region has a band (sp band) mainly including s and p orbitals that hardly include d orbitals.

  Item 3. Item 3. The visible light plasmonic alloy nanoparticles according to item 1 or 2, wherein the crystal structure of the alloy nanoparticles is a B2-type crystal structure.

  Item 4. Element A is one or more (especially 1 to 3) elements selected from the group consisting of Groups 8 to 11 and Periods 4 to 6 of the periodic table, and Element B is elements 12 to 14 of the periodic table. Item 4. The visible light plasmonic alloy nanoparticles according to any one of Items 1 to 3, which are one or more elements (particularly 1 to 3 elements) selected from the group consisting of a group and a second to sixth periods.

  Item 5. Element A is one or more (particularly 1 to 3) elements selected from the group consisting of Groups 10 to 11 and Periods 4 to 5 of the periodic table, and Element B is elements 12 to 13 of the periodic table. Item 5. The visible light plasmonic alloy nanoparticles according to Item 4, which are one or more elements (particularly 1 to 3 elements) selected from the group consisting of a group and a third to fifth period.

  Item 6. Item 6. The element A according to any one of Items 1 to 5, wherein the element A is one or more elements selected from the group consisting of palladium and nickel, and the element B is one or more elements selected from the group consisting of indium and cadmium. Visible light plasmonic alloy nanoparticles.

  Item 7. Item 7. The visible light plasmonic alloy nanoparticles according to Item 6, wherein the element A is palladium and the element B is indium.

  Item 8. A visible light plasmonic material comprising the visible light plasmonic alloy nanoparticles according to any one of Items 1 to 7.

  Item 9. Item 9. Use in one or more applications selected from the group consisting of pigments, dyes, plasmon sensing devices, plasmon enhancement devices, plasmon photoelectric conversion devices, imaging devices, plasmon optical devices, drug delivery systems, and thermotherapy. Visible light plasmonic material.

  Item 10. The method for producing visible light plasmonic alloy nanoparticles according to any one of Items 1 to 7, wherein the element A or a phosphorus compound thereof, the element B or a compound thereof, and an organic ligand are reacted. Manufacturing method.

  Since the visible light plasmonic alloy nanoparticles of the present invention absorb light in the visible region by localized surface plasmon resonance (LSPR), the substance itself is essentially a metal (alloy) material having a plasma frequency in the visible region. It is a completely new visible light plasmonic material that has never existed.

  Here, “essentially the substance itself” means that the isotropic shape (such as a sphere) does not have a plasma frequency in the visible region as in Patent Documents 1 and 2 and Non-Patent Documents 1 and 2. However, the anisotropic shape does not control the plasma frequency and give visible light responsiveness, but even the isotropic shape has plasma vibration in the visible region as the original property of the substance. Means having a number.

  The visible light plasmonic alloy nanoparticles of the present invention have high chemical stability and can be produced at low cost. For example, B2 type-PdIn alloy nanoparticles are an alloy containing about half of Pd with high chemical stability, and thus are considered to have higher chemical stability than Ag with low oxidation resistance. Since it is also an alloy containing about half of inexpensive In, the raw material cost can be suppressed to about 25% of Au.

  The visible light plasmonic alloy nanoparticles of the present invention are useful as a visible light plasmonic material, and can be a promising alternative to Au and Ag used in a wide range of fields such as plasmon sensing devices and plasmon enhancement devices.

The TEM image of the Pd-P nanoparticle obtained by manufacture examples 1-4 is shown. The TEM images of the Pd—P nanoparticles of Production Examples 1 to 4 correspond to a to d in FIG. The TEM image of the PdIn nanoparticle obtained in Examples 1-4 is shown. The TEM images of the PdIn nanoparticles of Examples 1 to 4 correspond to a to d in FIG. It is a measurement result of the powder X-ray diffraction (PXRD) of the PdIn nanoparticle obtained in Examples 1-4. It is a measurement result of the visible and near-infrared absorption spectrum of the PdIn nanoparticle obtained in Examples 1-4. It is the result of having measured the absorption peak of LSPR by dispersing the B2-type-PdIn alloy nanoparticles obtained in Example 3 in solvents having different refractive indexes. It is the schematic diagram which showed the electronic structure (state density distribution of the Fermi level vicinity) characteristic to the metal solid which consists of an element of the 8th-10th group, the 11th group, and the 12th-14th group of a periodic table. The state density distribution near the Fermi level of Pd nanoparticles (Pd ₅₆₁ ) calculated in Test Example 4 is shown. The state density distribution of the PdIn nanoparticles (Pd ₃₂₉ In ₃₁₂ ) calculated in Test Example 4 near the Fermi level is shown. The state density distribution near the Fermi level of PdIn nanoparticles (Pd ₃₁₂ In ₂₇₅ ) calculated in Test Example 4 is shown. The state density distribution near the Fermi level of Au nanoparticles (Au ₅₆₀ ) calculated in Test Example 4 is shown. In the B2-type PdIn, the Pd atomic layer is viewed from any of the three directions orthogonal to each other (for example, the x, y, and z axis directions) in the three-dimensional space defined by the x, y, and z axes. And In atomic layers are alternately stacked.

  Hereinafter, the present invention will be described in detail.

  In this specification, the expression “comprising” includes the concepts of “comprising”, “consisting essentially of”, and “consisting of”.

1. Visible light plasmonic alloy nanoparticles Visible light plasmonic alloy nanoparticles mean alloy nanoparticles that absorb light in the visible region by localized surface plasmon resonance (LSPR) (having a plasma frequency in the visible region).

  The visible light plasmonic alloy nanoparticles of the present invention are (1) an alloy composed of an element A and an element B, and the element A is one or more elements selected from the group consisting of Groups 8 to 11 of the periodic table Element B is one or more elements selected from the group consisting of Groups 12 to 14 of the periodic table. (2) The composition ratio of Element A and Element B in the alloy nanoparticles is 60:40 to 40:60, and (3) the alloy nanoparticles are element A and element B when viewed from any of the three directions orthogonal to each other in the three-dimensional space of the orthogonal coordinate system defined by the x, y, and z axes. It has the crystal structure which can confirm that each of these atomic layers are laminated | stacked alternately.

  The element A is preferably one or more (especially 1 to 3) elements (metal elements) selected from the group consisting of Groups 8 to 11 and 4 to 6 in the periodic table. Specifically, Iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), Examples include silver (Ag) and gold (Au). Among them, more preferably one or more elements (particularly 1 to 3 elements) selected from the group consisting of Groups 10 to 11 and Periods 4 to 5 of the periodic table, and more preferably from the group consisting of Pd and Ni. One or more (especially one) element selected, particularly preferably Pd.

  The element B is preferably one or more (particularly 1 to 3) elements selected from the group consisting of Groups 12 to 14 and 2 to 6 periods of the periodic table, and specifically zinc (Zn). , Cadmium (Cd), mercury (Hg), boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), carbon (C), silicon (Si), germanium (Ge) , Tin (Sn), and lead (Pb). Among them, more preferably one or more (especially 1 to 3) elements selected from the group consisting of Groups 12 to 13 and 3 to 5 of the periodic table, and more preferably indium (In) and cadmium ( One or more (especially one) element selected from the group consisting of Cd), and particularly preferably In.

  The reason why the visible light plasmonic alloy nanoparticles of the present invention are composed of the element A and the element B is as follows. The elements in the 8th to 11th groups (element A) and the elements in the 12th to 14th groups (element B) The p-orbital of the element B extending in the three axis directions of the orthogonal coordinate axis forms a simple cubic lattice, and the element A enters the position of the body center, so that the crystal structure of the alloy consisting of cesium chloride (CsCl) type This is because it is considered that a B2 type crystal structure corresponding to the crystal structure of FIG. For example, see FIG. Moreover, the electronic structure of the alloy which consists of a group 8-11 element (element A) of a periodic table and a group 12-14 element (element B) is the 11th group single element (Cu, Ag, and so on) in the meantime. This is because it is considered that an electronic structure similar to that of Au (existing visible light plasmonic material) is easily obtained. For example, see FIG.

  The composition ratio of element A and element B in the alloy nanoparticles is preferably 58:42 to 42:58, more preferably 56:44 to 44:56, and particularly preferably 54:46 to 46:54. It is.

  Specific examples of alloy nanoparticles include AlFe, AlCo, AlNi, AlRu, AlRh, AlPd, AlIr, AlPt, CoGa, NiZn, NiGa, NiIn, CuZn, CuPd, CuIn, ZnAg, ZnPt, ZnAu, GaRh, PdCd, PdIn, AgCd, CdAu and the like can be mentioned, among which PdCd, PdIn and the like are preferable, and PdIn is more preferable.

  The alloy nanoparticles have a crystal structure, and in the three-dimensional space of the orthogonal coordinate system defined by the x, y, and z axes, the atomic layer of element A and the atoms of metal B are seen from any of the three directions orthogonal to each other. It has a crystal structure in which it can be confirmed that the layers are alternately stacked. In particular, it is typically preferable to have a B2 type crystal structure corresponding to a cesium chloride (CsCl) type crystal structure. In the case of the B2 type crystal structure, for example, the atomic layer of element A and the atomic layer of metal B are alternately stacked in the x, y and z axis directions, in other words, [100], [010] and [001]. I can confirm that. For example, see FIG.

  When the electronic structure in the vicinity of the Fermi level is calculated by density functional theory (DFT) calculation, the visible light plasmonic alloy nanoparticles of the present invention have a region of −1.5 eV or less when the Fermi energy is 0 eV (particularly, It is preferable to have a band mainly composed of d orbits (d band) in a range of −4.5 eV to −1.5 eV. Moreover, it is preferable to have a band (sp band) mainly composed of s and p orbitals that hardly include d orbitals in a region of −1.5 eV to 2.0 eV (particularly, a region of −1.5 eV to 0 eV). For example, see Test Example 4.

  The average particle diameter of the visible light plasmonic alloy nanoparticles of the present invention is usually 1 nm to 1000 nm, preferably 1 to 500 nm, more preferably 1 nm to 100 nm, and particularly preferably 3 nm to 50 nm. The standard deviation is usually 0.1 nm to 10 nm. The relative standard deviation is usually 5-15%. Thus, the average particle diameter, standard deviation, and relative standard deviation can be measured by the methods described in the examples.

  The visible light plasmonic alloy nanoparticles of the present invention absorb light in the visible region (wavelength: 360 to 830 nm (for example, see JIS Z 8120)) by localized surface plasmon resonance (LSPR), in other words, It has the characteristic of having a plasma frequency in the visible region. Specifically, the alloy nanoparticles have a peak top of the absorption wavelength in a region of 360 to 830 nm. It is useful as a visible light plasmonic material.

2. Method for Producing Visible Light Plasmonic Alloy Nanoparticles Visible light plasmonic alloy nanoparticles of the present invention can be produced by reacting element A or its phosphorus compound, element B or its compound, and an organic ligand. it can.

2.1 Element A or its phosphorus compound element A is one or more metals selected from the group consisting of Groups 8 to 11 of the periodic table described above. The phosphorus compound is a compound containing element A and phosphorus, and can be produced according to or according to a known method. As a typical example, when the element A is Pd, Pd or a phosphorus compound thereof is obtained by a known method (for example, Small, 2011, vol. 7, p.469-473, Nano Res., 2011, vol.4, p.83). -91, Dalton Trans., 2013, vol.42, p.12667-12674, Chem. Commun., 2014, Advance Article DOI: 10.1039 / C4CC03282A, Chem. Mater., 2014, vol.26, p.1056-1061 ) For reference.

  There is no restriction | limiting in particular as a composition ratio (element A: P) of the element A and phosphorus atom in the phosphorus compound of the element A, What is necessary is just to adjust suitably according to the target alloy nanoparticle. In general, the composition ratio of element A and phosphorus atom (element A: P) is usually in the range of 10:90 to 90:10, and preferably in the range of 50:50 to 90:10. , 60:40 to 80:20 is more preferable. The composition ratio between the element A and the phosphorus atom can be measured by fluorescent X-ray analysis (XRF).

  The average particle diameter of the element A or its phosphorus compound is in a desired range (usually in the range of 1 nm to 1000 nm, preferably 1 nm to 500 nm, more preferably 2 nm to 100 nm, particularly preferably 3 nm to 50 nm. Yes.) The average particle diameter can be measured from a photograph taken with a transmission electron microscope. As a measuring method, 200 particles are randomly extracted (sample number n = 200), the diameter of each particle is measured, and the average of the diameters can be calculated.

2.2 Element B or its compound element B is one or more elements selected from the group consisting of Groups 12-14 of the periodic table described above. The compound is an organic or inorganic compound containing the element B and can be produced according to or according to a known method.

  Examples of the compound of element B include a complex of carboxylic acid compound and element B; a complex of amine compound and element B; a complex of sulfonic acid compound and element B; a complex of phosphine compound and element B; And a complex of a chelate ligand and an element B; an organometallic compound of the element B; and an inorganic salt of the element B (a halide, carbonate, nitrate, sulfate, etc. of the element B). Among these, a complex of a carboxylic acid compound and an element B and an inorganic salt of the element B are particularly preferable. Examples of the carboxylic acid compound in the complex of the carboxylic acid compound and element B (carboxylic acid metal complex) include the types of carboxylic acid compounds described in the following organic ligands. When the element B is In as the compound of the element B, for example, indium (III) chloride, indium (III) acetate, and the like can be given.

  The element B or a compound thereof may be used alone or in combination of two or more. Element B and its compounds may be used in combination.

  Element B or a compound thereof may be solid or liquid. In the case of a solid, the shape is not particularly limited. For example, powder or granule can be used, and a commercially available product can be used.

  As an average particle diameter of the metal B or its compound, the range of 50 nm-5 mm is mentioned, for example, Preferably it is 50 nm-500 micrometers, More preferably, it is the range of 50 nm-50 micrometers. As the average particle diameter, a median diameter (50% cumulative diameter) obtained from the number average distribution can be adopted. The number average distribution of particle sizes can be easily determined by various commonly used measurement methods such as laser diffraction, dynamic light scattering, centrifugal sedimentation, electrical detector method, and image analysis. .

  There is no restriction | limiting in particular as the usage-amount of the element B or its compound, What is necessary is just to adjust suitably with the target alloy nanoparticle. For example, in terms of element A in element A or its phosphorus compound, it is usually 0.5 to 100 moles per mole of element A (the sum of the number of moles of each element when two or more kinds of element A). 1 to 50 mol is preferable, and 2 to 20 mol is more preferable.

  Here, when synthesizing the phosphorus compound of element A, the yield is assumed to be 100%, and the amount of element A (for example, palladium (II) acetylacetonate, etc.) used in the synthesis is calculated from the amount of element. The amount of A can be converted. Also, prepare a solution of the phosphorus compound of element A, obtain the concentration of element A in the solution by atomic absorption spectrometry (AAS) or high frequency inductively coupled plasma emission spectroscopy (ICP-AES), and convert the amount of element A You can also.

2.3 Organic Ligand The organic ligand may be an organic compound that forms a bond with a metal atom or adsorbs to the nanoparticle surface. For example, organic oxygen compounds such as alcohol compounds, carbonyl compounds, carboxylic acid compounds, ether compounds, ester compounds; organic nitrogen compounds such as amine compounds, ammonium compounds, nitrile compounds, isocyanide compounds; thiol compounds, thioether compounds, thioester compounds, sulfoxides Organic sulfur compounds such as compounds, sulfone compounds and sulfonic acid compounds; organic phosphorus compounds such as phosphine compounds, phosphine oxide compounds, phosphinic acid compounds and phosphonic acid compounds; organic silicon compounds such as silane compounds and silanol compounds; Oligomer, polymer) and the like. Of these, organic oxygen compounds and organic nitrogen compounds are preferable, and carboxylic acid compounds and amine compounds are more preferable.

  The carboxylic acid compound is not particularly limited as long as it is an organic compound having a carboxylic acid group. For example, oleic acid, myristoleic acid, palmitoleic acid, sapienoic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, linoleic acid, eicosadienoic acid, docosadienoic acid, linolenic acid, pinolenic acid, eleeolic acid Stearic acid, medic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid, boseopentaenoic acid, eicosapentaenoic acid, ozbond acid, sardine acid, tetracosapentaenoic acid, docosahexaenoic acid, nisic acid C8-24 unsaturated aliphatic carboxylic acids such as stearic acid, arachidic acid, palmitic acid, myristic acid, lauric acid, capric acid, caprylic acid, 1-adamantanecarboxylic acid, etc. Carboxylic acid; cumic acid, 4-butyl Aromatic carboxylic acids Ikikosanto thereof. The carboxylic acid compound may be a linear, branched or non-aromatic carboxylic acid having an aliphatic chain. Among these, carboxylic acids having 8 to 24 carbon atoms are preferable, carboxylic acids having 16 to 20 carbon atoms are more preferable, and olein is preferable from the viewpoints of suppressing aggregation and fusion of nanoparticles, improving dispersibility in a solvent, and boiling point. Acid, linoleic acid, stearic acid, arachidic acid, palmitic acid and palmitoleic acid are more preferred, and oleic acid is particularly preferred.

  The amine compound is not particularly limited as long as it is an organic compound having an amino group. For example, unsaturated amines having 8 to 24 carbon atoms such as oleylamine and linoleylamine; saturated amines having 8 to 24 carbon atoms such as stearylamine, myristylamine and adamantylamine; aromatics such as 4-isopropylaniline and 4-butylaniline Examples include amines. The amine compound may be a linear, branched or non-aromatic cyclic amine with an aliphatic chain. Among these, amines having 8 to 24 carbon atoms are preferable, amines having 16 to 20 carbon atoms are more preferable, amines having 16 to 20 carbon atoms are more preferable, from the viewpoint of suppressing aggregation and fusion of nanoparticles, improving dispersibility in a solvent, and boiling point. Railamine, stearylamine, arachidylamine, palmitylamine and palmitolylamine are more preferred, and oleylamine is particularly preferred.

  Only one kind of organic ligand may be used, or two or more kinds may be mixed and used. In particular, it is preferable to use both a carboxylic acid compound and an amine compound.

  There is no restriction | limiting in particular as the usage-amount of an organic ligand, What is necessary is just to adjust suitably with the target alloy nanoparticle. For example, in terms of element A in element A or its phosphorus compound, the amount is usually 0.1 mol to 400 mol with respect to 1 mol of element A (the total number of moles of each element when element A is two or more). Yes, 0.5 mol to 300 mol is preferable, and 1 mol to 250 mol is more preferable.

  Moreover, the usage-amount of an organic ligand is the element B in the element B or its compound, for example, and 1 mol of said element B (when the element B is 2 or more types, the total number of moles of each element) Usually, it is 0.1 mol-400 mol, 0.5 mol-300 mol are preferable, and 1 mol-200 mol are more preferable.

  The organic ligand can be added in an excess amount as a solvent more than the element A or its phosphorus compound, or the element B or its compound.

  If necessary, an organic solvent may be further added to the organic ligand. The organic solvent preferably has a boiling point higher than the reaction temperature and is stable. For example, the organic solvent has 1 to 30 carbon atoms such as 1-octadecene, octadecane, eicosane, dodecylbenzene, tetradecylbenzene, octyl ether, squalene, etc. The following hydrocarbon solvents can be used.

  The amount of the organic solvent used is usually 0.1 to 100 parts by weight, preferably 0.5 to 50 parts by weight, and preferably 1 to 20 parts by weight with respect to 1 part by weight of the organic ligand. Part by weight is more preferred.

2.4 Reaction Conditions The method for producing visible light plasmonic alloy nanoparticles of the present invention includes a step of reacting element A or its phosphorus compound, element B or its compound, and an organic ligand.

  Typically, by heating the element A or its phosphorus compound, the element B or its compound, and an organic ligand, alloy nanoparticles of the element A and the element B can be produced. As heating temperature, it is 260 degreeC or more normally, Preferably it is the range of 280 degreeC-350 degreeC, More preferably, it is the range of 300 degreeC-330 degreeC. The reaction time is not particularly limited, and is usually about 30 minutes to 6 hours, preferably 1 to 3 hours. The reaction can be carried out in an atmosphere of an inert gas such as nitrogen, helium, argon, or xenon.

  Among these, the method for producing palladium alloy nanoparticles can be carried out, for example, according to or in accordance with the description in Patent Document 3 (Japanese Patent Laid-Open No. 2016-56431).

3. Applications of Visible Light Plasmonic Alloy Nanoparticles The visible light plasmonic alloy nanoparticles of the present invention absorb light in the visible region by localized surface plasmon resonance (LSPR). It becomes a metal (alloy) material having a number. Therefore, it is useful as a visible light plasmonic material.

  The visible light plasmonic alloy nanoparticles of the present invention are used in a wide range of fields such as pigments, dyes, plasmon sensing devices, plasmon enhancement devices, plasmon photoelectric conversion devices, imaging devices, plasmon optical devices, drug delivery systems, and thermotherapy. be able to. Specifically, for example, enhanced Raman scattering (SERS) measuring device, chip enhanced Raman spectroscopy (TERS), surface enhanced infrared spectroscopy (SEIRAS) measuring device, total reflection illumination fluorescence microscope (TIRF), fluorescence enhancement, photoelectric conversion device And photocatalyst efficiency enhancement, near-field light microscope, optical waveguide, laser, optical filter, light modulator, photonic crystal, metamaterial and the like. It can be a promising material that can replace Au and Ag that have been used as visible light plasmonic materials.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these.

Production Examples 1 to 4 (Preparation of Pd—P nanoparticles having different average particle diameters)
Pd—P nanoparticles having different average particle diameters were prepared according to the description in Examples of Patent Document 3 (Japanese Patent Laid-Open No. 2016-56431). The results are shown in Table 1. The transmission electron microscope (TEM) images of ad in FIG. 1 correspond to the Pd—P nanoparticles prepared in Production Examples 1 to 4, respectively.

  Each Pd-P nanoparticle is amorphous, and its average particle size, standard deviation, and relative standard deviation are randomly extracted from 200 TEM images of Pd-P nanoparticles (number of samples). n = 200), and the diameter of each particle was measured. The particle diameters of the Pd—P nanoparticles in Production Examples 1 to 4 were all monodispersed.

Production Example 5 (Preparation of Pd nanoparticles)
Pd nanoparticles were prepared as described in the literature (Nano Res., 2011, vol.4, p.83-91).

  The average particle diameter, standard deviation, and relative standard deviation of the Pd nanoparticles of Production Example 5 were measured in the same manner as described above. The results are shown in Table 1.

Example 1 (Production of B2 type-PdIn alloy nanoparticles)
In a 100 mL three-necked flask equipped with a condenser, a thermometer and a septum, 0.5 mmol of Pd—P nanoparticles having an average particle size of 3.3 nm obtained in Production Example 1 (Pd atom conversion), 2 mmol of indium powder, 10 mmol of oleylamine, Then, 10 mmol of oleic acid was added, and in order to remove the existing oxygen and moisture in the reaction solution, vacuum degassing was performed at 80 ° C. for 30 minutes while stirring the solution. Thereafter, the inside of the reaction vessel was set to a nitrogen atmosphere, and the temperature was raised to 300 ° C., followed by stirring at the same temperature for 3 hours to produce PdIn nanoparticles.

  The reaction solution was cooled to room temperature, chloroform was added thereto, and the mixture was separated into a supernatant and a precipitate by centrifugation. In order to remove excess organic substances in the supernatant, ethanol was added as a poor solvent, and further purified by centrifugation to obtain PdIn nanoparticles as a precipitate. The PdIn nanoparticles could be redispersed in chloroform.

  A TEM image of the PdIn nanoparticles obtained in Example 1 is shown in FIG. The average particle diameter, standard deviation, and relative standard deviation were obtained by randomly extracting 200 particles from a TEM image of PdIn alloy nanoparticles (sample number n = 200) and measuring the diameter of each nanoparticle. The results are shown in Table 2.

Examples 2 to 4 (Production of B2 type-PdIn alloy nanoparticles)
PdIn nanoparticles were obtained using the same method as in Example 1, except that the Pd—P nanoparticles with different average particle diameters obtained in Production Examples 2 to 4 were used, respectively, except that the reaction temperatures shown in Table 2 were used. Manufactured.

  TEM images of the PdIn nanoparticles obtained in Examples 2 to 4 are shown in FIG. In all cases, the shape was spherical. Their average particle diameter, standard deviation and relative standard deviation were determined in the same manner as in Example 1. The results are shown in Table 2.

Example 5 (Production of B2 type-PdIn alloy nanoparticles)
In a 100 mL three-necked flask equipped with a condenser, a thermometer, and a septum, 0.5 mmol of Pd nanoparticles having an average particle diameter of 15 nm obtained in Production Example 5 (Pd atom conversion), 1.0 mmol of indium chloride, 100 mmol of oleylamine, and olein 10 mmol of acid was added, and degassed under reduced pressure at 80 ° C. for 30 minutes while stirring the solution in order to remove the existing oxygen and moisture in the reaction solution. Thereafter, the inside of the reaction vessel was set to a nitrogen atmosphere, and the temperature was raised to 300 ° C., followed by stirring at the same temperature for 3 hours to produce PdIn nanoparticles.

  The reaction solution was cooled to room temperature, chloroform was added thereto, and the mixture was separated into a supernatant and a precipitate by centrifugation. In order to remove excess organic substances in the supernatant, ethanol was added as a poor solvent, and further purified by centrifugation to obtain PdIn nanoparticles as a precipitate. The PdIn nanoparticles could be redispersed in chloroform.

  The PdIn nanoparticles obtained in Example 5 were spherical from the TEM image. The average particle size, standard deviation, and relative standard deviation were determined in the same manner as in Example 1. The results are shown in Table 2.

Test Example 1 (Measurement of powder X-ray diffraction; confirmation of B2 type crystal structure)
When the powder X-ray diffraction (PXRD) of the PdIn nanoparticles obtained in Examples 1 to 4 was measured, the pattern of the diffraction peak was attributed to the cubic B2 (cesium chloride) type alloy phase. From this, it was confirmed that all the nanoparticles obtained in Examples 1 to 4 were B2 type-PdIn alloy nanoparticles (a to d in FIG. 3). See FIG. 11 for the crystal structure.

Test Example 2 (Visible and near infrared absorption spectrum; measurement of LSPR absorption peak)
A chloroform solution of the B2-type PdIn nanoparticles obtained in Examples 1 to 4 was prepared, and an ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectrum was measured. The results (correlation between the wavelength of light and the absorption intensity) are shown in FIGS. In any case, an absorption peak was confirmed in the visible region of 500 to 800 nm. As the particle size of the B2-type-PdIn alloy nanoparticles increased, an increase in absorption peak intensity and a long wavelength shift of the peak top were observed, confirming a tendency characteristic of localized surface plasmon resonance (LSPR).

Test Example 3 (Refractive Index Sensitivity Measurement; Verification of LSPR Absorption Peak)
In order to experimentally verify that the absorption peak observed in the visible region in Test Example 2 is caused by LSPR, the refractive index sensitivity was measured. The medium (solvent) in which the B2-type PdIn alloy nanoparticles obtained in Example 3 are dispersed is (i) n-hexane (refractive index n = 1.37), (ii) cyclohexane (n = 1.42). , (Iii) chloroform (n = 1.44), (iv) toluene (n = 1.48) and (v) o-dichlorobenzene (refractive index n = 1.55). -NIR absorption spectrum was measured. The result is shown in FIG.

  From this spectrum, it was observed that the peak top of the absorption peak shifted with a longer wavelength as the refractive index of the solvent increased. FIG. 5 (2) is a diagram showing the relationship between the refractive index of the solvent used in FIG. 5 (1) and the peak top wavelength, and a clear primary relationship was confirmed between the two. The gradient in this linear expression is called refractive index sensitivity, and the refractive index sensitivity of the B2-type PdIn alloy nanoparticles of Example 3 was 52.3 nm / RIU. The value of the refractive index sensitivity was equivalent to that of Au and Ag, which are existing visible light plasmonic materials.

  From the above results, it was confirmed that the absorption peak confirmed in the visible region in FIG. 4 of Test Example 2 was caused by LSPR.

  Similar results are obtained for the B2-type PdIn alloy nanoparticles obtained in Examples 1, 2, 4 and 5.

  From this, it was experimentally confirmed that the B2 type-PdIn alloy nanoparticles obtained in Examples 1 to 5 were visible light plasmonic materials.

Test Example 4 (Density Functional Theory (DFT) Calculation; Derivation of Electronic Structure)
The electronic structure (state density distribution (DOS)) in the vicinity of the Fermi level of the B2-type PdIn alloy was derived by theoretical calculation. The calculation was carried out by an original calculation program GCEED using the real space grid method based on the density functional theory described in the literature (J. Comput. Phys. 2014, Vol.265, p.145-155). GCEED employs a method of directly calculating numerical values of the Khon-Sham equation based on the difference method on a real space grid. The grid width was 0.25 mm, and LDA was used for the functional. Inner-shell electrons other than Au 5d ¹⁰ 6s ¹ , Pd 4d ¹⁰ , In 4d ¹⁰ 5S ² 5p ¹ are obtained using the fhi98PP program described in the literature (Comput. Phys. Commun. 1999, Vol. 119, p. 67-98). Replaced by pseudopotential by Martins method. For the Troullier-Martins method, reference was made to the literature (Comput. Phys. Commun. 1999, Vol.119, p.67-98). In addition, DOS near the Fermi level of Pd and Au to be compared was calculated using the same method as for the B2-type PdIn alloy.

The structure of the PdIn nanoparticles used in the calculation is a ridged cube with the number of constituent atoms Pd ₃₂₉ In ₃₁₂ and Pd ₃₁₂ In ₂₇₅ , and is described in the literature (Russ. Metall., 1980, Vol.4, p.192-194). It was created using the lattice constant described. The structure of the Pd nanoparticles was a cubic octahedron having Pd _{561 as} the constituent atoms, and was created using the lattice constant described in the literature (Crystal Structures, 1963, Vol. 1, p.7-83). For Au nanoparticles, refer to the literature (J. Phys. Chem. A, 2014, Vol. 118, p. 11317-11322), and the number of constituent atoms Au _{560 obtained by} removing one vertex atom from an icosahedron. The structure of was adopted.

  The results obtained by the above calculation method are shown in FIGS.

  In the DOS of Pd nanoparticles (FIG. 7), a wide single distribution (circle 1) continues from around the Fermi level (0 eV) to about −5 eV, and the s band and d band are hardly separated.

  In the PdIn nanoparticles (FIGS. 8 and 9), the difference in the electronic structure due to the difference in structure is hardly recognized, and the peak position (circled circle 2) is a position where the energy is deep (−4.5 to −1.5 eV). ). From there, take a structure with a tail extending to the vicinity of the Fermi level (circle 3). That is, in the case of PdIn nanoparticles, the distribution derived from Pd d electrons and In sp electrons (circled 2) and the distribution derived from Pd s electrons and In sp electrons (circled 3) are − The structure is separated at a boundary of about 1.5 eV.

  For the Au nanoparticles (FIG. 10), only the DOS of the occupied orbit is shown, but it can be seen that the sp band and the d band are separated around −1.5 eV as in the case of the PdIn nanoparticles.

  Therefore, it was found that the electronic state of the PdIn alloy is more similar to Au (Group 11) than Pd (Group 10).

<Discussion>
From the above results, it was confirmed that the PdIn alloy nanoparticles have a B2 type crystal structure in which Pd atoms and In atoms are substantially 1: 1. In addition, it was confirmed that the PdIn alloy nanoparticles are visible light plasmonic materials because absorption due to localized surface plasmon resonance (LSPR) exists in the visible light region.

  Further, from the calculation data of the state density distribution of PdIn alloy nanoparticles (Test Example 4), in order for the alloy nanoparticles to have the characteristics of a visible light plasmonic material, −1.5 eV or less when Fermi energy is 0 eV. A band consisting mainly of d orbitals (d band) in the region of, and a band consisting of mainly s and p orbitals (sp band) containing almost no d orbitals in the region of −1.5 eV to 2.0 eV. It is considered important to have

  The visible light plasmonic alloy nanoparticles of the present invention are essentially a metal (alloy) material whose substance itself has a plasma frequency in the visible region, and is a completely new visible light plasmonic material that has never existed before. Therefore, it can be a promising alternative material for Au and Ag used in a wide range of fields such as plasmon sensing devices and plasmon enhancement devices.

Claims (10)

Visible light plasmonic alloy nanoparticles satisfying the following (1) to (3);
(1) The alloy nanoparticles are an alloy composed of an element A and an element B, the element A is one or more elements selected from the group consisting of groups 8 to 11 of the periodic table, and the element B is It is one or more elements selected from the group consisting of Groups 12-14 of the periodic table.
(2) The composition ratio of element A and element B in the alloy nanoparticles is 60:40 to 40:60, and (3) the alloy nanoparticles are orthogonal coordinates defined by the x, y, and z axes. In the three-dimensional space of the system, it has a crystal structure in which it can be confirmed that the atomic layers of the element A and the element B are alternately stacked when viewed from any of three directions orthogonal to each other. The visible light plasmonic material according to claim 1, further satisfying the following (4):
(4) When the alloy nanoparticles have a Fermi energy of 0 eV, the alloy nanoparticles have a band (d band) mainly composed of d orbitals in a region of −1.5 eV or less, and −1.5 eV to 2.0 eV. The region has a band (sp band) mainly including s and p orbitals that hardly include d orbitals. The visible light plasmonic alloy nanoparticles according to claim 1 or 2, wherein the crystal structure of the alloy nanoparticles is a B2 type crystal structure. Element A is one or more elements selected from the group consisting of Groups 8 to 11 and Periods 4 to 6 of the Periodic Table, and Element B is Groups 12 to 14 and Periods 2 to 6 of the Periodic Table The visible light plasmonic alloy nanoparticles according to any one of claims 1 to 3, which are one or more elements selected from the group consisting of: Element A is one or more elements selected from the group consisting of Groups 10 to 11 and Periods 4 to 5 of the Periodic Table, and Element B is Groups 12 to 13 and Periods 3 to 5 of the Periodic Table The visible light plasmonic alloy nanoparticles according to claim 4, which are one or more elements selected from the group consisting of: The element A is one or more elements selected from the group consisting of palladium and nickel, and the element B is one or more elements selected from the group consisting of indium and cadmium. Visible light plasmonic alloy nanoparticles. The visible light plasmonic alloy nanoparticles according to claim 6, wherein the element A is palladium and the element B is indium. A visible light plasmonic material comprising the visible light plasmonic alloy nanoparticles according to claim 1. The method according to claim 8, which is used in one or more applications selected from the group consisting of a pigment, a dye, a plasmon sensing device, a plasmon enhancement device, a plasmon photoelectric conversion device, an imaging device, a plasmon optical device, a drug delivery system, and a thermotherapy. The visible light plasmonic material described. It is a manufacturing method of the visible light plasmonic alloy nanoparticle in any one of the said Claims 1-7, Comprising: The said element A or its phosphorus compound, the element B or its compound, and an organic ligand are made to react. A manufacturing method including a process.