WO2019136822A1

WO2019136822A1 - Core-shell type gold-ruthenium oxide nano-composite material and preparation method therefor

Info

Publication number: WO2019136822A1
Application number: PCT/CN2018/079280
Authority: WO
Inventors: 倪卫海; 叶洋; 李月; 邹微微; 谢皓; 赵飞; 朱海飞
Original assignee: 苏州大学
Priority date: 2018-01-11
Filing date: 2018-03-16
Publication date: 2019-07-18
Also published as: CN108237223A; CN108237223B

Abstract

A core-shell type gold-ruthenium oxide nano-composite material, comprising gold nanoparticles in a core and ruthenium oxide coated on the outside thereof, the molar ratio of the gold nanoparticles to the ruthenium oxide being 1:0.2-0.8. The preparation method for the core-shell type gold-ruthenium oxide nano-composite material comprises steps of: adjusting the pH of a gold-containing solution to 8-12, and adding an organic solution of ruthenium acetylacetonate and then uniformly mixing the same, the gold-containing solution comprising gold nanoparticles, a cationic surfactant, and water, the concentration of the cationic surfactant in the gold-containing solution being 0.05 × 10-3 to 1.5 × 10-3 mol/L; and carrying out a hydrothermal reaction in the mixed solution at 100-120°C to obtain a core-shell type gold-ruthenium oxide nano-composite material.

Description

Core-shell type gold-yttria nano composite material and preparation method thereof

Technical field

The invention relates to the technical field of nano material preparation, in particular to a core-shell type gold-yttria nano composite material and a preparation method thereof.

Background technique

Due to the many special properties of ruthenium oxide (RuO ₂ ), such as metal conductivity, chemical and thermal stability, catalytic activity, electrochemical redox properties and field emission reactions, studies on both crystalline and amorphous yttrium oxide It has important theoretical and practical significance. In electrical terms, yttrium oxide thin films have important application value in integrated circuits, membrane resistors, ferroelectric thin films and high temperature superconducting thin films. In terms of catalysis, cerium oxide is an active component in chlor-alkali industrial electrodes, and is also an important substance for electrolysis of water to produce hydrogen, photocatalytic reduction of CO ₂ and oxidized CO sensing. In the application of energy storage and conversion devices, barium hydroxide is an essential element of the Pt-Au electrode for removing methanol fuel cells similar to CO poisoning. In addition, due to its surface redox ion pair and ultra-high tantalum capacitance, RuO ₂ ·H ₂ O itself is an extremely important electrode material for electrochemical supercapacitors.

Nanocomposites are composed of two or more nanomaterials and are widely recognized for their unique properties and process applications. The core-shell structure and the dumbbell-shaped structure are most famous in the nanocomposite structure, and have better optical, magnetic and catalytic properties than the material of the single component. There are no reports on the nanocomposite structure of core-shell gold and yttria. At present, the research on the composite structure of gold and yttrium oxide is mostly to deposit cerium oxide particles on the surface of gold nanoparticles.

Summary of the invention

In order to solve the above technical problems, an object of the present invention is to provide a core-shell type gold-cerium oxide nano composite material and a preparation method thereof, and synthesize a core-shell type gold-yttria nanometer by a simple one-step method under high temperature hydrothermal synthesis conditions. The composite material has simple operation, high repetition rate, high yield of the synthesized product, and easy control of its morphology and shell thickness.

The present invention provides a core-shell type gold-yttria nanocomposite comprising gold nanoparticles of a core and cerium oxide coated on the outside thereof, and the molar ratio of gold nanoparticles to cerium oxide is 1:0.2-0.8.

Further, the ratio of the diameter of the core composed of the gold nanoparticles to the thickness of the shell composed of ruthenium oxide in the core-shell type gold-yttria nanocomposite is 1:0.5-2.

Further, the gold nanoparticles are gold nanorods having a diameter of 10-30 nm and a length of 50-80 nm.

Further, the core-shell type gold-yttria nanocomposite has a rod shape with a diameter of 20-30 nm and a length of 60-140 nm.

Further, the ultraviolet-visible-near-infrared absorption spectrum absorption peak wavelength of the core-shell type gold-yttria nanocomposite is between 800 and 1300 nm.

In the present invention, the gold nanoparticles and the ruthenium oxide are connected to each other by a coordination bond. The colloidal gold core is coated in the yttrium oxide shell structure, and the shell layer is a homogeneous structure rather than a particle, and the yield of the composite material is high, and the morphology and shell thickness are easily controlled.

The invention also provides a preparation method of the above core-shell type gold-yttria nano composite material, comprising the following steps:

(1) adjusting the pH of the gold-containing solution to 8-12, and then adding an organic solution of cesium acetylacetonate, which comprises gold nanoparticles, a quaternary ammonium salt-based cationic surfactant, and water, and then mixing. The concentration of the quaternary ammonium salt type cationic surfactant in the gold-containing solution is 0.05×10 ^-3 -1.5×10 ^-3 mol/L;

(2) The solution obtained by mixing the step (1) is hydrothermally reacted at 100 to 120 ° C to obtain a core-shell type gold-yttria nanocomposite.

Further, in the step (1), the gold nanoparticles are gold nanorods.

Further, in the step (1), the molar ratio of the gold nanoparticles to the quaternary ammonium salt-based cationic surfactant is 1:0.08-2.4.

Further, in the step (1), the quaternary ammonium salt-based cationic surfactant is cetyltrimethylammonium bromide or tetraoctyl ammonium bromide.

In the step (1), the quaternary ammonium salt type cationic surfactant can act as a stabilizer, and the cationic surfactant adsorbs on the surface of the gold nanorod to form a bilayer to make the gold nanorod particles positively chargeable, and is electrostatically repelled. The action and surfactant steric hindrance maintains its stability in aqueous solution and prevents agglomeration of gold nanoparticles in solution. In the subsequent reaction process, the gold nanoparticles become the nucleation center of the hydrolysis of acetylacetone oxime under the action of surfactant, and form a nano-cerium oxide shell layer. The surface of the nano-cerium oxide surface reduces the surface energy on the surface of the gold nanoparticle, forming a core-shell type gold-yttria nanocomposite structure. After the reaction, the cationic surfactant present in the system can prevent the agglomeration of the core-shell gold-yttria nanocomposite.

Adjusting the amount of cationic surfactant added can make the morphology and structure of the final product well controlled. Taking cetyltrimethylammonium bromide (CTAB) as an example, the surface of gold nanoparticles adsorbs Br ^- and Cl ^- ions, the gold atoms on the surface of gold nanoparticles are considered to be negatively charged. The positively charged amino group in the CTAB molecule is tightly bound to the surface of gold due to electrostatic interaction, forming an internal molecular layer. Since the hydrophobic carbon chain cannot be dispersed in water, another layer of CTAB molecules is formed, the hydrophobic carbon chain of the molecular layer points to the inside, and interacts with the hydrophobic carbon chain of the inner molecular layer, while the hydrophilic amino group of the head Point to the outside. The presence of such a bilayer of gold nanoparticle surface can be determined by measuring the thickness. The CTAB bilayer can be destroyed by reducing the concentration of CTAB in the solution below the critical micelle concentration, adding an organic solvent, increasing the salt concentration in the solution, or other external stimuli.

The CTAB bilayer on the surface of gold nanoparticles affects the attraction of gold nanorods to nano-cerium oxide. The concentration of CTAB in the control solution regulates the CTAB bilayer on the surface of gold nanorods, and regulates the ease of adsorption of cerium oxide on the surface of gold nanoparticles, so that the morphology and structure of the final product are well controlled.

Further, in the step (1), the molar ratio of the ruthenium acetylacetonate to the gold nanoparticles in the gold-containing solution is 0.2 to 0.8:1. Changing the amount of cerium acetylacetonate added controls the thickness of the cerium oxide shell layer in the final product.

Further, in the step (1), the concentration of cerium acetylacetonate in the organic solution is 0.1 × 10 ^-3 - 0.5 × 10 ^-3 mol / L.

Further, in the step (1), the organic solvent used in the organic solution is one or more of methanol, ethanol, isopropanol and acetone.

Further, in the step (1), the pH is adjusted with an aqueous solution of a base, and preferably, the base is sodium hydroxide.

Further, in the step (2), the reaction is carried out in a hydrothermal reaction vessel.

Further, in the step (2), the reaction time is 5 to 30 hours. Preferably, the reaction time is 8-12 h. More preferably, the reaction time is 10 h.

The acetylacetonate hydrazine is hydrolyzed under the pH and reaction temperature conditions disclosed in the present invention to form nano cerium oxide, and the nano cerium oxide surface atom has a large bond-level deletion, thereby generating a large surface energy, and the nano cerium oxide is in the gold nanometer. Under the attraction of the rod, the surface yttrium oxide atom uses gold atoms as surface ligands on the surface of the gold nanorods to reduce the surface energy, forming a core-shell type gold-yttria nanocomposite structure.

With the above solution, the present invention has at least the following advantages:

The invention is based on the hydrolysis technology of acetylacetonate hydrazine in an aqueous phase at a high temperature to prepare a cerium oxide shell structure. The core-shell composite material is completed in the next step of high temperature hydrothermal synthesis, which greatly reduces energy loss and is more suitable for mass production. The solvent used in the synthesis process is water and a small amount of organic solvent, which is safe and non-toxic; the cerium source is a cerium salt containing an organic ligand, and the synthesized shell is a homogeneous structure rather than a granule. The method can be extended to other similar precious metal and oxide systems, and can be used as a universally applicable method for preparing core-shell composite materials.

The preparation method of the invention has the advantages of simple operation, high repetition rate, high yield of the synthesized product, easy control of the morphology and shell thickness of the composite material, low cost of the synthesized product, and easy industrial production.

The core-shell type gold-yttria nanocomposites prepared by the method of the invention have a significantly improved thermal stability, and the ultraviolet-visible-near-infrared absorption spectrum of the composite structure is red-shifted and absorbed compared to a single gold nanoparticle. The peak is located in the near-infrared region and has unique optical and magnetic properties. It has a good application prospect in the biomedical field and the catalytic field. Conventional methods for regulating gold nanoparticles can achieve high yields of synthetic gold nanorods by localized surface plasmon resonance (LSPR) response wavelengths ranging from 500-900 nm in the near-infrared region (750) through structural (size and morphology) regulation. -1400 nm) High yield synthesis of gold nanomaterials cannot be achieved. The core-shell gold-yttria nanocomposites exhibit local reddensity of surface plasmon resonance (LSPR), making the core-shell gold-yttria nanocomposite structure a high-yield synthetic gold nanomaterial with localized An effective method for surface plasmon resonance (LSPR) in the near-infrared region.

The above description is only an overview of the technical solutions of the present invention, and the technical means of the present invention can be more clearly understood and can be implemented in accordance with the contents of the specification. Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

DRAWINGS

Figure 1 is a scanning electron microscope image of a gold nanorod;

2 is a scanning electron microscope image of a gold nanorod/yttria core-shell nanostructure prepared in Example 3 of the present invention;

3 is an ultraviolet-visible-near-infrared absorption spectrum of gold nanorods and gold nanorods/yttria core-shell nanostructures prepared in Examples 1, 2 and 3 of the present invention;

4 is an X-ray diffraction (XRD) pattern of a gold nanorod/yttria core-shell composite structure prepared in Example 3 of the present invention.

Detailed ways

The specific embodiments of the present invention are further described in detail below with reference to the drawings and embodiments. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Example 1

(1) 10 ml of colloidal gold (rod-like) stabilized with cetyltrimethylammonium bromide was taken, centrifuged at 7,500 rpm for 32 minutes in a centrifuge, and centrifuged twice to remove excess surfactant. Then, 2 ml of deionized water was added for dispersion to obtain a concentrated colloidal gold solution.

(2) Take 1 ml of concentrated colloidal gold solution, add 6.470 ml of water, then add 0.1 mol/L of cetyltrimethylammonium bromide aqueous solution 10 μl, then add sodium hydroxide aqueous solution to adjust the pH of the solution. The value is 8.

(3) Add 0.05mL of acetylacetone oxime in methanol solution (the concentration of acetylacetonate in methanol solution is 0.02mol/L, the concentration of acetylacetonate in the reaction solution is 1×10 ^-3 mol/L), and the reaction during the addition The system remains mixed evenly.

(4) After the methanol solution of acetylacetonate ruthenium is added, the solution is transferred to a hydrothermal reaction kettle, and the reaction kettle is transferred to a drying oven at a temperature of 100 ° C for about 10 hours to obtain a gold nanorod/cerium oxide nucleus. Shell-type nanostructures with a yield of 95%.

Example 2

(2) Take 1 ml of concentrated colloidal gold solution, add 6.470 ml of water, then add 0.1 mol/L of cetyltrimethylammonium bromide aqueous solution 30 μl, then add sodium hydroxide aqueous solution to adjust the pH of the solution. The value is 10.

(3) Add 0.1mL of acetylacetone oxime in methanol (the concentration of acetylacetonate in methanol solution is 0.02mol/L, the concentration of acetylacetonate in the reaction solution is 2×10 ^-3 mol/L), and the reaction during the addition. The system remains mixed evenly.

(4) After the methanol solution of acetylacetonate ruthenium is added, the solution is transferred to a hydrothermal reaction kettle, and the reaction vessel is transferred to a drying oven at a temperature of 110 ° C for about 10 hours to obtain a gold nanorod/cerium oxide core. Shell-type nanostructures with a yield of 96%.

Example 3

(2) Take 1 ml of concentrated colloidal gold solution, add 6.470 ml of water, then add 0.1 mol/L of cetyltrimethylammonium bromide aqueous solution 50 μl, then add sodium hydroxide aqueous solution to adjust the pH of the solution. The value is 12.

(3) Add 0.25 mL of acetylacetone oxime in methanol (concentration of acetylacetone oxime in methanol solution is 0.02 mol/L, concentration of acetylacetonate in the reaction solution is 5×10 ^-3 mol/L), and react during the addition. The system remains mixed evenly.

(4) After the methanol solution of acetylacetonate ruthenium is added, the solution is transferred to a hydrothermal reaction kettle, and the reaction kettle is transferred to a drying oven at a temperature of 120 ° C for about 10 hours to obtain a gold nanorod/cerium oxide nucleus. Shell-type nanostructures with a yield of 95%.

In the above embodiment of the present invention, the colloidal gold used in the step (1) is a gold nanorod, which is prepared by a seed crystal method, and the specific preparation method is described in the literature: Wu Jian, metal nanoparticle assembly and surface plasmon enhanced optics. Characteristics Research [D], Shanghai Jiaotong University, 2015. Figure 1 is a scanning electron microscope image of a gold nanorod. 2 is a scanning electron microscope image of a gold nanorod/yttria core-shell nanostructure prepared in Example 3 of the present invention. Comparing Fig. 1 and Fig. 2, it was found that after the reaction, the surface of the gold nanorod was successfully coated with a shell of cerium oxide having a length of 60-70 nm and a diameter of 20-30 nm.

3 is an ultraviolet-visible-near-infrared absorption spectrum of gold nanorods (AuNR) and gold nanorods/cerium oxide core-shell nanostructures (AuNR@RUO ₂ ) prepared in Examples 1, 2 and 3 of the present invention, It can be seen that after the gold nanorods are coated with yttrium oxide shells, the maximum absorption peak is red-shifted from about 870 nm to a maximum of about 1050 nm, and the local surface plasmon resonance (LSPR) is in the near-infrared region. Nanorod/yttria core-shell nanostructures have the potential to achieve localized surface plasmon resonance (LSPR) of gold nanomaterials in the near-infrared region.

4 is an X-ray diffraction (XRD) pattern of a gold nanorod/yttria core-shell composite structure prepared in Example 3 of the present invention. Figure 4 shows the XRD lines of the AuNR@RuO ₂ nanostructures after calcination at 300 ° C and 500 ° C for 6 h. The XRD results show that the shell structure of AuNR@RuO ₂ composite is RuO ₂ .

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. It should be noted that those skilled in the art can make some improvements without departing from the technical principles of the present invention. And modifications and variations are also considered to be within the scope of the invention.

Claims

A core-shell type gold-yttria nanocomposite characterized by comprising: a gold nanoparticle comprising a core and a cerium oxide coated on the outside thereof, the molar ratio of the gold nanoparticle to the cerium oxide being 1:0.2 -0.8.
The core-shell type gold-yttria nanocomposite according to claim 1, wherein the core of the core-shell type gold-yttria nanocomposite has a diameter of a core composed of gold nanoparticles and a thickness of a shell composed of ruthenium oxide. The ratio is 1:0.5-2.
The core-shell type gold-yttria nanocomposite according to claim 1, wherein the core-shell type gold-yttria nanocomposite has a rod shape and a diameter of 20-30 nm and a length of 60-140 nm.
The method for preparing a core-shell type gold-cerium oxide nanocomposite according to any one of claims 1 to 3, comprising the steps of:

(1) adjusting the pH of the gold-containing solution to 8-12, and then adding an organic solution of cesium acetylacetonate, which comprises gold nanoparticles, a quaternary ammonium salt-based cationic surfactant, and water, and then mixing. The concentration of the quaternary ammonium salt-based cationic surfactant in the gold-containing solution is 0.05×10 -3 -1.5×10 -3 mol/L;

(2) The solution obtained by mixing the step (1) is hydrothermally reacted at 100 to 120 ° C to obtain the core-shell type gold-yttria nanocomposite.
The preparation method according to claim 4, wherein in the step (1), the molar ratio of the gold nanoparticles to the quaternary ammonium salt-based cationic surfactant is 1:0.08-2.4.
The preparation method according to claim 4, wherein in the step (1), the quaternary ammonium salt-based cationic surfactant is cetyltrimethylammonium bromide or tetraoctyl ammonium bromide.
The preparation method according to claim 4, wherein in the step (1), the molar ratio of cerium acetylacetonate to the gold nanoparticles in the gold-containing solution is from 0.2 to 0.8:1.
The preparation method according to claim 4, wherein in the step (1), the organic solvent used in the organic solution is one or more of methanol, ethanol, isopropanol and acetone.
The preparation method according to claim 4, wherein in the step (2), the reaction time is 5 to 30 hours.