CN100393456C - Nano polycrystalline noble metal hollow sphere particle chain and preparation method thereof - Google Patents

Abstract

A chain of hollow nanoparticles made of polycrystal noble metal (Au, Pd, or Pt) is prepared through dissolving polyvinyl pyrrolidone in inertial gas and uniform magnetic field while stirring, adding hexahydrated cobalt chloride powder, dropping the aqueous solution of sodium bromohydride, adding the solution of AuCl3, PdCl6 or PtCl6 to obtain coarse product, and purifying.

Description

Nano polycrystalline noble metal hollow sphere particle chain and preparation method thereof

Technical field:

The invention belongs to the technical field of nano particles, in particular to a nano polycrystalline precious metal gold, palladium or platinum hollow sphere particle chain and a preparation method thereof.

Background technique:

Noble metal nanoparticles have strong localized surface plasmon oscillation characteristics in the visible light band, which makes them have a very broad application prospect in biochemical sensing, biomarkers, nano waveguides, etc. In recent years, the research on noble metal nanoparticles has aroused more and more researchers' interest, especially the research on hollow nanoparticles of noble metals is changing with each passing day. application potential. For example, the United States "Science" (Science 298.2176-2179, 2002) reported the preparation technology of noble metal hollow spherical particles, that is, the technology of galvanic replacement reactions; German "Applied Chemistry" (Angew.Chem.Int.Ed.43.1540- 1543, 2004) reported that this electrodisplacement reaction technology can be applied to the system in which cobalt particles react with precursors to generate noble metal palladium hollow sphere particles; German "Advanced Materials" (Adv.Mater.17, 2255-2261, 2005) reported The localized surface plasmon oscillation peaks of gold hollow nanoparticles obtained by reacting with silver nanoparticles as precursors were significantly red-shifted. However, since there is no direction-induced factor in the existing process of preparing noble metal hollow nanoparticles, the noble metal hollow nanoparticles prepared by the electrodisplacement reaction reported in the above literature are all monodisperse systems, and there are common limitations in application, such as It is difficult to handle, does not have an ordered structure, has poor electron transport performance, and poor drug loading capacity. So far, there have been no reports of advanced nanostructures, such as chain-like nanostructures, formed by noble metal hollow sphere nanoparticles.

Invention content:

The purpose of the present invention is to provide a nano polycrystalline precious metal gold, palladium or platinum hollow sphere particle chain and its preparation method, to overcome the shortcomings of the prior art that the hollow sphere nanoparticles are difficult to control and lack of order, and obtain precious metal Ordered chain-like structure of gold, palladium or platinum hollow sphere nanoparticles.

The preparation method of the nano polycrystalline precious metal hollow sphere particle chain of the present invention comprises dissolving polyvinylpyrrolidone (PVP) in water at a stirring speed of 500 to 1500 rpm and an inert atmosphere, and then adding cobalt chloride hexahydrate Powder (CoCl ₂ 6H2O), the PVP concentration in the solution is 0.125～0.25 mmol/liter, the cobalt chloride concentration is 1.5～3.5 mmol/liter; 8～12 milliliters contain 3～6 milligrams of sodium borohydride ( NaBH ₄ ) aqueous solution is added to the above solution at a rate of 3-10 drops/second; it is characterized in that: the above-mentioned process is placed in a uniform magnetic field of 100-300 mTesla; and then the content of 0.3-0.7 mmol A solution of the noble metal source AuCl ₃ ^- , PdCl ₆ ^{4 -} or PtCl ₆ ^2- with a pH value of 6 to 8; the crude product is purified to obtain the noble metal gold (Au), palladium (Pd) or platinum (Pt) chains of nano hollow spheres.

The product can be dissolved in ethanol for preservation.

The nano polycrystalline noble metal hollow sphere particle chain of the present invention is characterized in that polycrystalline noble metal particles with a diameter of 25nm to 70nm are connected to form a chain structure with a chain length of 500nm to 5000nm; the noble metal includes gold (Au), Palladium (Pd) or Platinum (Pt).

The method of the present invention is different from the noble metal hollow particles prepared in the absence of an external magnetic field in the prior art: the cobalt colloid solution precursor formed by reducing cobalt chloride with _NaBH will not form a chain nanostructure without an external magnetic field, but It is a monodisperse form, so that the noble metal Au, Pd or Pt hollow spherical particles formed in the further reaction also present a monodisperse state, rather than a chain structure; while the present invention induces the cobalt colloid by applying an external magnetic field when preparing the cobalt colloid solution of the precursor. The particles form a chain-like nanostructure precursor, so that the noble metal Au, Pd or Pt hollow sphere particles formed in further reactions can maintain the chain-like characteristics of the precursor; this kind of noble metal hollow sphere particle chain nanostructure has not been reported so far , This kind of structural regulation of noble metal hollow sphere nanoparticles by using an external magnetic field has not been reported. Compared with monodisperse noble metal hollow sphere nanoparticles, the noble metal hollow sphere particle chain has many unique potential properties, such as better structural order, easy handling, enhanced electron transport performance, and greater drug loading capacity. , these potential properties make it have far-reaching application prospects in the fields of nanoelectronic devices, molecular sensors and bio-loading.

Description of drawings:

Fig. 1 is the transmission electron microscope photograph of the product gold hollow sphere particle chain of embodiment 1 of the present invention;

Fig. 2 is a single transmission electron microscope photograph of a gold hollow sphere particle chain;

Fig. 3 is a high-resolution transmission electron microscope photograph of a gold hollow sphere particle chain;

Fig. 4 is the electron diffraction picture of gold hollow sphere particle chain;

Fig. 5 is an X-ray energy scatter spectrogram of a chain of gold hollow spheres.

Fig. 6 is the single transmission electron micrograph of the product palladium hollow sphere particle chain of embodiment 2 of the present invention;

Fig. 7 is the high-resolution transmission electron microscope photo of the palladium hollow sphere particle chain;

Fig. 8 is the electron diffraction photograph of palladium hollow sphere particle chain;

Fig. 9 is the X-ray energy scattering spectrum of the palladium hollow sphere particle chain.

Fig. 10 is a single transmission electron micrograph of the product platinum hollow sphere particle chain of Example 3 of the present invention;

Figure 11 is a high-resolution transmission electron microscope photo of platinum hollow sphere particle chains;

Fig. 12 is the electron diffraction photograph of platinum hollow sphere particle chain;

Fig. 13 is an X-ray energy scatter spectrum of a chain of platinum hollow spheres.

Fig. 14 is the transmission electron micrograph of comparative example 1 product monodisperse gold hollow sphere particle;

Fig. 15 is a high-resolution transmission electron micrograph of monodisperse gold hollow sphere particles.

Fig. 16 is the transmission electron micrograph of comparative example 2 product monodisperse palladium hollow sphere particles;

Fig. 17 is a high-resolution transmission electron micrograph of monodisperse palladium hollow sphere particles.

Fig. 18 is the transmission electron micrograph of comparative example 3 product monodisperse platinum hollow sphere particles;

Fig. 19 is a high-resolution transmission electron micrograph of monodisperse platinum hollow sphere particles.

Detailed ways:

Example 1: Preparation of polycrystalline Au hollow sphere particle chains with an average size of 50 nanometers

First configure the precursor colloidal solution A for preparing noble metal hollow ball chains. The steps are: under an inert atmosphere—nitrogen gas is used in this example, 200 mg of PVP is ultrasonically dissolved in 20 ml of water, and then 11.9 mg of CoCl ₂ 6H2O is weighed. into this solution. This solution is transferred in the three-neck flask of 100ml capacity, inserts the stirring plate of mechanical stirrer from the bottle mouth in the middle, nitrogen is led into from the next bottle mouth, and a dropping funnel is put on the other bottle mouth. The entire reaction system was placed in a uniform magnetic field of 200 mTesla. Hold for 15 minutes at a mechanical stirring speed of 1000 rpm. Another 5 mg of NaBH ₄ was dissolved in 10 ml of water and quickly transferred to the dropping funnel. Then within 1 minute, this NaBH _aqueous solution was added dropwise into the three-necked flask at a constant speed to obtain a dark brown colloidal solution, and continued to stir for 5 minutes under nitrogen protection, and then stirred under nitrogen atmosphere for later use.

Then configure gold source solution C, the steps are: take 5ml of 0.1M HAuCl ₃ solution, neutralize it with 1M KOH solution to pH = 7.0, and then dilute to 20ml.

After rinsing the above-mentioned dropping funnel with a small amount of water for 3 times, use it to add the prepared gold source solution C to the above-mentioned precursor colloidal solution A within 1 minute to obtain a dark blue colloidal solution, and continue stirring for 30 minutes under a nitrogen atmosphere. After standing for 5 minutes, the product was purified.

The purification steps are as follows: centrifuge the obtained dark blue colloidal solution at 2400rpm for 10 minutes in a centrifuge, discard the supernatant, redissolve the precipitate with an equal amount of water, and centrifuge at 2400rpm for 10 minutes; repeat this 3 times, the obtained The precipitate was dissolved with 1ml of absolute ethanol, and it was still a dark blue colloidal solution.

Add 2 to 3 drops of the above colloidal solution onto the carbon-coated copper grid used for electron microscope testing. After the solvent is completely volatilized, place the carbon-coated copper grid loaded with the product on a JOEL2100 high-resolution microscope with an accelerating voltage of 200,000 volts. Photographed under a transmission electron microscope. Fig. 1 is a transmission electron micrograph of a gold hollow sphere particle chain, and it can be seen that the average length of the gold hollow sphere chain is 2 microns; Fig. 2 is a single TEM photo of a gold hollow sphere particle chain, and it can be seen that the hollow sphere particles are spherical and basically the same in size , with a diameter of 50±10nm; Figure 3 is a high-resolution photo of a hollow sphere on the chain, Figure 4 is its electron diffraction pattern, the lattice fringes of Au in multiple directions appearing in Figure 3 and the ring in Figure 4 The shape diffraction pattern shows that the product is a polycrystalline nanomaterial; Figure 5 is its X-ray energy scattering analysis diagram, in which it can be seen that except for the background signal of the substrate copper mesh (that is, the position of Cu marked in the figure), only The signal of single element Au (ie the position of Au marked in the figure). It can be seen that the product of this example is a chain of polycrystalline Au hollow spheres with an average size of 50 nanometers. It can be seen that the precursor colloidal solution A, under the induction of an external magnetic field, makes the product of the electric displacement reaction exhibit an ordered chain-like nanostructure.

Example 2: Preparation of polycrystalline Pd hollow sphere particle chains with an average size of 50 nanometers

Preparation of palladium source solution D: Weigh 88.66mg of PdCl ₂ , dissolve it in 10ml of 1M HCl, neutralize with 1M KOH solution to pH=7.0, and then dilute to 20ml.

Using the same operation and method as in Example 1, the configured palladium source solution D was added dropwise to the colloidal precursor A used for the preparation of hollow ball chains, and mechanical stirring was continued for 30 minutes under an inert atmosphere to obtain a black colloidal solution . The purification steps are the same as in Example 1, and finally dissolved in 1 ml of absolute ethanol to form a black colloidal solution.

Sample testing and data processing methods are the same as in Example 1. Figure 6 is a transmission electron microscope photo of a single Pd hollow sphere chain. It can be seen from the photo that the Pd hollow sphere particles on the chain are spherical, basically the same size, and the diameter is 50±10nm; Figure 7 is a high-resolution photo of the interior of a hollow sphere on the chain , Figure 8 is its electron diffraction pattern, the lattice fringes of Pd in multiple directions appearing in Figure 7 and the annular diffraction pattern in Figure 8 indicate that the product is a polycrystalline nanomaterial; Figure 9 is its X-ray Energy scatter analysis diagram, in which it can be seen that in addition to the background signal of the substrate copper network (that is, the position of Cu marked in the figure), it only contains the signal of a single element Pd (that is, the position of Pd marked in the figure). It can be seen that the product of this example is a chain of polycrystalline Pd hollow spheres with an average size of 50 nanometers.

Example 3: Preparation of polycrystalline Pt hollow sphere particle chains with an average size of 40 nanometers

Prepare platinum source solution E: weigh 0.24g of H ₂ PtCl ₆ ·6H ₂ O and dissolve it in 10ml of water, add dropwise 1M KOH solution to neutralize to pH=7.0, and then dilute to 20ml.

Using the same operation and method as in Example 1, the configured platinum source solution E was added dropwise to the colloidal precursor solution A used for the preparation of hollow ball chains, and mechanical stirring was continued for 30 minutes under an inert atmosphere to obtain a black colloidal solution . The purification method is the same as in Example 1, and finally dissolved in 1 ml of absolute ethanol to form a black colloidal solution.

Sample testing and data processing methods are the same as in Example 1. Figure 10 is a transmission electron microscope photo of a single Pd hollow sphere chain. It can be seen from the photo that the Pt hollow sphere particles on the chain are spherical, most of the particles are of the same size, and the diameter is 40±10nm, and the diameter of a very few particles exceeds 60nm; The high-resolution photo of the intersection of the two hollow spheres above, Figure 12 is its electron diffraction pattern, the lattice fringes of Pt in multiple directions appearing in Figure 11 and the ring-shaped diffraction pattern in Figure 12 indicate that the product is multi- Crystalline nanomaterials; Figure 13 is its X-ray energy scattering analysis diagram, in which it can be seen that the background signal except for the background signal of the substrate copper mesh (that is, the position of Cu marked in the figure) and the background signal of the carbon film coated on the substrate copper mesh (that is, the position marked C in the figure), only the signal containing a single element Pt (that is, the position marked Pt in the figure). It was concluded that the product was a chain of polycrystalline Pt hollow spheres with an average size of 40 nm.

In the above embodiments of the present invention, an external magnetic field is used in the process of configuring the precursor colloid solution. The results show that in the presence of an external magnetic field, the product prepared by using colloidal colloid as the precursor of the electrodisplacement reaction is a chain-like nanostructure of polycrystalline noble metal gold, palladium or platinum hollow sphere particles. The situation when no magnetic field is applied during the preparation of the precursor colloid solution is illustrated below through three sets of comparative examples.

Comparative Example 1: Preparation of monodisperse polycrystalline Au hollow spherical particles with an average size of 50 nm

Configure precursor colloid solution B for preparing monodisperse noble metal hollow spheres, the steps are: cancel the uniform magnetic field around the reaction device in the process of preparing precursor A in Example 1, and other operations are the same as in Example 1, and deep For the brown colloidal solution, continue to mechanically stir for 5 minutes under an inert atmosphere.

Prepare the gold source solution with the same method as in Example 1, and use the same operation and method as in Example 1 to add the configured gold source solution dropwise to the precursor colloid solution B used for the preparation of noble metal hollow spheres, continue Stir mechanically under an inert atmosphere for 30 minutes to obtain a black colloidal solution. After standing for 5 minutes, the product was purified.

The purification steps are as follows: centrifuge the obtained dark blue colloidal solution at 3000rpm for ten minutes in a centrifuge, discard the supernatant, redissolve the precipitate with an equal amount of water, and centrifuge at 3000rpm for ten minutes; repeat this 3 times, the obtained The precipitate was dissolved with 1ml of absolute ethanol, and it was still a dark blue colloidal solution.

Add 2 to 3 drops of the above colloidal solution onto the carbon-coated copper grid used for electron microscope testing. After the solvent is completely volatilized, place the carbon-coated copper grid loaded with the product on a JOEL2100 high-resolution microscope with an accelerating voltage of 200,000 volts. Photographed under a transmission electron microscope. Figure 14 is a transmission electron microscope photo. It can be seen from the photo that the Au hollow spherical particles are monodisperse, with an average diameter of 50 ± 20 nm; Fig. 15 is a high-resolution photo of the edge of an Au hollow spherical particle. The lattice fringes of Au in three directions indicate that it is a polycrystalline nanomaterial. It was concluded that the product was monodisperse polycrystalline Au hollow spherical particles with an average size of 50 nm. It can be seen that in the absence of an external magnetic field, the precursor colloidal solution B will not be induced during the configuration process, so that the product of the next step of the electro-displacement reaction exhibits a disordered monodisperse nanostructure.

Comparative Example 2: Preparation of monodisperse polycrystalline Pd hollow spherical particles with an average size of 35 nm

Prepare the Pd source according to the method of Example 2, use the same operation and method as Comparative Example 1, add it dropwise in the precursor colloid solution B for preparing noble metal hollow spheres, and continue to mechanically stir for 30 minutes under an inert atmosphere. A black colloidal solution was obtained. The purification method was the same as in Comparative Example 1, and the product was dissolved in 1 ml of absolute ethanol to form a black colloidal solution.

Sample testing and data processing methods are the same as in Comparative Example 1. Figure 16 is its transmission electron microscope photo. It can be seen from the photo that the Pd hollow spherical particles are monodisperse, with an average diameter of 35 ± 10nm; Fig. 17 is a high-resolution photo of the interior of a Pd hollow spherical particle. The lattice fringes of Pd in the direction indicated that it is a polycrystalline nanomaterial. It can be seen that the product is monodisperse polycrystalline Pd hollow spherical particles with an average size of 35 nm.

Comparative Example 3: Preparation of monodisperse polycrystalline Pt hollow spherical particles with an average size of 30 nm

Prepare the Pt source according to the method of Example 3, use the same operation and method as Comparative Example 1, add it dropwise in the precursor colloid solution B for preparing noble metal hollow spheres, and continue to mechanically stir for 30 minutes under an inert atmosphere. A black colloidal solution was obtained. The purification method was the same as in Comparative Example 1, and the product was dissolved in 1 ml of absolute ethanol to form a black colloidal solution.

Sample testing and data processing methods are the same as in Comparative Example 1. Figure 18 is its transmission electron microscope photo. It can be seen from the photo that the Pt hollow spherical particles are monodisperse, with an average diameter of 30 ± 10nm; Fig. 19 is a high-resolution photo of the interior of a Pd hollow spherical particle. The lattice fringes of Pt in the direction indicated that it is a polycrystalline nanomaterial. It can be seen that the product is a monodisperse polycrystalline Pt hollow spherical particle with an average size of 30 nanometers.

The above three comparative examples show that in the absence of an external magnetic field, the product prepared by using cobalt colloid as the precursor of the electrodisplacement reaction is a monodisperse nanostructure of polycrystalline precious metal gold, palladium or platinum hollow spherical particles.

Comprehensive analysis description:

In the reaction of the present invention, the cobalt colloid is used as the precursor of the electro-displacement reaction to prepare hollow-structure granular nano-polycrystalline precious metal gold, palladium or platinum hollow spheres and hollow sphere chain nanomaterials. The shape of the particles in the cobalt colloid directly determines the external shape of the final product. In the presence of an external magnetic field, the particles in the cobalt colloid will be induced by the external magnetic field to form an ordered structure, and the product of the electric displacement reaction will obtain an orderly arrangement of noble metal hollow sphere particle chains, reflecting the induction effect of the external magnetic field; When there is no external magnetic field, the particles in the cobalt colloid will not be induced by the external field, and the product of the electrodisplacement reaction will obtain monodisperse noble metal hollow sphere nanoparticles, maintaining the disordered state of the particles in the cobalt colloid.

Claims (2)

1. the preparation method of a nano-polycrystalline noble-metal hollow ball particle chain, be included under 500～1500 revolutions per seconds the mixing speed and inert atmosphere, polyvinylpyrrolidone is dissolved in the water, add the cobalt chloride hexahydrate powder again, make polyvinylpyrrolidone concentration in the solution be 0.125～0.25 mM/liter, cobalt chloride concentration be 1.5～3.5 mMs/liter; The speed of 8～12 milliliters of aqueous solution that contain 3～6 milligrams of sodium borohydrides with 3～10 droplets/second is joined in the above-mentioned solution; It is characterized in that: said process is in the uniform magnetic field of 100～300 milli teslas; The pH value that adds content then and be 0.3～0.7 mM is 6～8 noble metal source AuCl ₃ ^-, PdCl ₆ ^4-Or PtCl ₆ ^2-Solution; Crude product is purified, promptly obtain the nano-hollow ball particle chain of its Precious Metals-Gold, palladium or platinum.

2. nano-polycrystalline noble-metal hollow ball particle chain is characterized in that by diameter being that the polycrystalline noble-metal particle of 25nm～70nm connects into the chain structure that chain length is 500nm～5000nm; Described noble metal comprises gold, palladium or platinum.

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