CN110182856A - A kind of preparation method of double shells hollow ball-shape nickel cobaltate nano particles - Google Patents

Abstract

The invention relates to a method for preparing double-shell hollow spherical nickel cobaltate nanoparticles, which belongs to the technical field of nanomaterial preparation. The method uses D-xylose as a carbon source, disperses it in isopropanol solution, and adds Cobalt nitrate hexahydrate and nickel nitrate hexahydrate, after a period of solvothermal reaction, form amorphous carbonaceous microspheres containing cobalt ions and nickel ions, and after a certain annealing rate, double-shell hollow spherical nickel cobaltate nanoparticles can be obtained , In addition, nickel cobalt oxide nanoparticles with different internal structures can be obtained by adjusting the annealing rate. Compared with traditional templates or acid etching methods, the present invention has the advantages of low cost, simple operation, and environmental friendliness, and the prepared double-shell hollow spherical nickel cobaltate nanoparticles have obvious mesoporous structure, are not easy to agglomerate, and crystallize Good performance, large specific surface area, high surface chemical activity, good electrochemical performance and gas sensing characteristics, and has potential application value in the fields of supercapacitors and gas sensors.

Description

A kind of preparation method of double-shell hollow spherical nickel cobalt oxide nanoparticles

technical field

The invention belongs to the technical field of nanomaterial preparation, and in particular relates to a method for preparing double-shell hollow spherical nickel cobaltate nanoparticles. The hollow structure exhibits good electrochemical and gas-sensing properties in the fields of supercapacitors and gas-sensing sensors.

Background technique

In recent years, hollow particles have aroused great interest. Due to their internal space, low density, large specific surface area, strong stability and surface permeability, they are widely used in catalysis, photoelectric sensors, drug delivery carriers, and photonic crystals. , energy storage devices and nanochemical reactions have important application prospects. Today, the best way to prepare a well-formed hollow structure consists of coating the desired material on a removable template, or transforming it with preformed particles according to different principles (chemical displacement method, Kirkendall effect, acid-base etching, etc.) generate. Although there have been many remarkable examples of successful preparation of hollow structures, such as Fe ₂ O ₃ , NiO, ZnO, SnO ₂ and other hollow structure particles, the above preparation process generally requires multi-step reactions or acid treatment, the process is complicated, the preparation cost is high and It is easy to cause environmental pollution. Therefore, it is still of great academic significance and application value to explore and develop new methods for the simple, environmentally friendly, and rapid synthesis of hollow-structured particles.

Nickel cobaltate is a spinel-like mixed valence oxide, in which nickel has two and three valences, occupying octahedral positions in the structure, and cobalt also has two and three valences, occupying tetrahedral and octahedral positions , because nickel cobaltate has two pairs of redox pairs, the electrons have low activation energy from one atom to another in multivalent substances, therefore, it shows superior conductivity and electrocatalytic activity, at least NiO and Co ₃ Twice that of O ₄ , these characteristics are very beneficial to the improvement of electrochemical and gas-sensing performance. Previous studies have also used various methods to improve the performance of the material itself, including shape design, doping, and compounding with other substances. There are many types of these preparation methods, including physical methods and chemical methods. Impurities, so chemical methods are mainly used at present. It is worth mentioning that the materials prepared by hydrothermal synthesis have the advantages of hierarchical structure, small particle size, high purity, light agglomeration and narrow particle size distribution. And because the special hierarchical structure has the advantages of large specific surface area and many active sites, it shows potential application value in various fields. A lot of effort has been put into the development of nickel cobaltate with hierarchical structure. Hu et al. used ZIF-67 as a template to synthesize hierarchical double-shell Co ₃ O ₄ /NiCo ₂ O ₄ nanocages using a multi-step chemical synthesis method (Han Hu, Buyuan Guan, Baoyu Xia, and Xiong Wen (David )Lou,Designed Formation of Co ₃ O ₄ /NiCo ₂ O ₄ Double-Shelled Nanocages with Enhanced Pseudocapacitive and Electrocatalytic Properties, J.Am.Chem.Soc.2015,137,5590-5595); Li et al. Methods Monodisperse NiCo ₂ O ₄ mesoporous microspheres were prepared and applied in lithium-ion battery negative electrodes (Jingfa Li, Shenglin Xiong, Yurong Liu, Zhicheng Ju, and YitaiQian, High Electrochemical Performance of Monodisperse NiCo ₂ O ₄ Mesoporous Microspheres as an Anode Material for Li-Ion Batteries, ACSAppl.Mater.Interfaces 2013,5,981-988984); Jiang et al. used cobalt nitrate hexahydrate and nickel nitrate hexahydrate as raw materials and P123 as auxiliary surfactant to prepare NiCo ₂ O ₄ Nanowires (Hao Jiang, Jan Mab and Chunzhong Li, Hierarchical porous NiCo ₂ O ₄ nanowires for high-rate supercapacitors, Chem. Commun, 2012, 48, 4465–4467). However, in the above synthesis process, the morphology of the obtained product is relatively simple, and these preparation processes have disadvantages such as high cost, cumbersome operation, and environmental pollution.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the shortcomings of the background technology and provide a method for preparing double-shell hollow spherical nickel cobaltate nanoparticles with simple operation, environmental protection and low production cost.

The concrete technical scheme that the present invention takes is as follows:

A method for preparing double-shell hollow spherical nickel cobalt oxide nanoparticles, comprising the following steps:

The first step is to prepare the precursor of nickel cobaltate by solvothermal method. Using an appropriate amount of isopropanol solution as a solvent, a certain amount of carbon source, cobalt source and nickel source with a molar ratio of 2:1 are sequentially added to the above solvent to form Uniformly mixed solution, wherein the carbon source, cobalt source, and nickel source are xylose, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate respectively. Form carbon spheres, and finally form a carbonaceous microsphere precursor containing a large amount of Ni ²⁺ and Co ²⁺ ;

The second step is the annealing process of the carbonaceous microsphere precursor. Put the sample prepared in the first step into the crucible and put it in the muffle furnace, raise the temperature to 350-450 ° C, keep it for 1-3 hours, and finally, in 5-10 Under different annealing rates such as ℃/min, nickel cobalt oxide nanoparticles with different structures were formed.

Further, firstly mix 1-2 mmol D-xylose powder with 30 ml of isopropanol, then add Ni(NO ₃ ) ₂ ·6H ₂ O and Co(NO ₃ ) ₂ ·6H ₂ O to the above In the solution, the molar ratio of Ni(NO ₃ ) ₂ 6H ₂ O to Co(NO ₃ ) ₂ 6H ₂ O is 1:2. After stirring evenly, transfer it to a 50ml reaction kettle and seal it at 150℃-200℃ Solvothermal reaction, the reaction lasts for 20-24h; After the reaction is completed and left at room temperature, the precipitate in the solution is centrifuged twice with water and ethanol, 5000 rpm for 5-8 minutes, and finally placed in a drying oven at 60°C for drying , to obtain amorphous carbonaceous microspheres adsorbing a large amount of Ni ²⁺ and Co ²⁺ ; then, annealing was performed on the above samples.

Further, during the annealing process, when the annealing rates are 5°C/min, 7°C/min, and 10°C/min, solid, single-shell, and double-shell spherical nickel cobaltate nanoparticles can be obtained respectively, forming Nickel cobalt oxide nanospheres with different structures.

The present invention has following beneficial effects:

1. Simple operation, one-pot process, no need to separate precursors.

2. Synthesize nickel cobaltate nanoparticles with excellent structure, double-shell hollow spherical hierarchical structure, not easy to agglomerate, good crystallinity, large specific surface area and high chemical activity, and a large number of surface contacts between particles.

3. The cost is low, all the common chemical experimental drugs are used in the experiment, and the price is low.

Description of drawings:

Fig. 1 is the scanning photo figure of the solid spherical carbonaceous microsphere precursor prepared in embodiment 1.

Fig. 2 is the transmission photo figure of the solid spherical carbonaceous microsphere precursor prepared in embodiment 1.

Fig. 3 is the scanning photo figure of the solid spherical nickel cobalt oxide nanosphere prepared in embodiment 2.

Fig. 4 is the transmission picture figure of the solid spherical nickel cobalt oxide nanosphere prepared in embodiment 2.

Figure 5 is a scanning photo of the single-shell hollow spherical nickel cobaltate nanospheres prepared in Example 3.

Figure 6 is a transmission photo of the single-shell hollow spherical nickel cobaltate nanospheres prepared in Example 3.

Figure 7 is a scanning photo of the double-shell hollow spherical nickel cobaltate nanospheres prepared in Example 4.

Figure 8 is a transmission photo of the double-shell hollow spherical nickel cobaltate nanospheres prepared in Example 4.

Fig. 9 is the X-ray diffraction pattern of the samples prepared in Examples 1, 2, 3, and 4.

Detailed ways

Implementation example 1:

Stir and mix 1.5 mmol D-xylose powder with 30 ml isopropanol, then add 0.5 mmol Ni(NO ₃ ) ₂ ·6H ₂ O and 1 mmol Co(NO ₃ ) ₂ ·6H ₂ O to the above solution, stirred evenly, transferred to a 50 ml reaction kettle, sealed, placed in an oven at 180°C, and the reaction continued for 24 hours. After the reaction is completed, the solution is centrifuged and cleaned, water and ethanol are centrifuged twice, and then dried and collected to obtain a solid spherical carbonaceous microsphere precursor. The scanning photo and transmission photo are shown in Figure 1 and Attached Figure 1 respectively. figure 2.

Example 2:

The sample prepared in Example 1 was annealed, the sample was put into a crucible and placed in a muffle furnace, and the temperature was raised to 450°C at a heating rate of 5°C/min, and kept for 2h to obtain solid spherical NiCo ₂ O ₄ nanospheres. The scanning photo and the transmission photo are shown in accompanying drawing 3 and accompanying drawing 4 respectively.

Example 3:

As in Example 2, the sample prepared in Example 1 was annealed, but the heating rate was changed to 7 ° C / min, and other conditions were unchanged, and a single-layer shell hollow spherical NiCo ₂ O ₄ nanosphere was obtained. The scanning photo and See accompanying drawing 5 and accompanying drawing 6 respectively for transmission picture figure.

Example 4:

As in Example 2, the sample prepared in Example 1 was annealed, but the heating rate was changed to 10°C/min, and other conditions were unchanged, to obtain a double-shell hollow spherical NiCo ₂ O ₄ nanosphere, its scanning photo and See accompanying drawing 7 and accompanying drawing 8 respectively for transmission picture figure.

The X-ray diffraction patterns of samples prepared in Examples 1, 2, 3, and 4 are shown in Figure 9. It can be seen that only the precursor has no obvious diffraction peaks, confirming the amorphous nature of the carbon-containing microsphere precursors, and after annealing, the NiCo ₂ O ₄ nanocomposites at different annealing rates have similar diffraction peaks and diffraction The peaks can correspond to the standard card (JCPDS:20-0781) of the face-centered cubic phase NiCo ₂ O ₄ , and there are no other miscellaneous peaks, indicating that the NiCo ₂ O ₄ samples are all pure phases after different annealing rates.

Claims (3)

1. a kind of preparation method of double shells hollow ball-shape nickel cobaltate nano particles, comprising the following steps:

The first step, solvent-thermal method prepares cobalt acid nickel precursor, using suitable aqueous isopropanol as solvent, by a certain amount of carbon source and Molar ratio is that cobalt source, the nickel source of 2:1 is added sequentially in above-mentioned solvent, forms homogeneous mixture solotion, wherein carbon source, cobalt source, nickel Source is respectively xylose, Nickelous nitrate hexahydrate, cabaltous nitrate hexahydrate, when solution is with 150 DEG C of -200 DEG C of progress thermal responses, due to wood Sugar monomer is polycondensed into karyomorphism into carbon ball, and ultimately forms comprising a large amount of Ni²⁺、Co²⁺Carbonaceous microballoon presoma；

Sample made from the first step is fitted into crucible as in Muffle furnace to the annealing process of carbonaceous microballoon presoma by second step, It is warming up to 350-450 DEG C, heat preservation 1-3h finally under the different annealing rate such as 5-10 DEG C/min, forms the cobalt of different structure Sour nano nickel particles.

2. a kind of preparation method of double shells hollow ball-shape nickel cobaltate nano particles according to claim 1, feature exist In 1-2 mmoles D- xylose powder and 30 milliliters of isopropanols being stirred first, then by Ni (NO₃)₂·6H₂O and Co (NO₃)₂· 6H₂O is added in above-mentioned solution, Ni (NO₃)₂·6H₂O and Co (NO₃)₂·6H₂The molar ratio of O is 1:2, after mixing evenly, is turned It moves in 50 milliliters of reaction kettles and seals, 150 DEG C of -200 DEG C of solvent thermal reactions react and continue 20-24h；Reaction is completed to stand room temperature Afterwards, the water of precipitating in solution and ethyl alcohol are respectively centrifuged twice, 5000 revs/min centrifugation 5-8 minutes, be finally placed in 60 DEG C of drying It is dried in case, obtains and adsorb a large amount of Ni²⁺、Co²⁺Amorphous carbonaceous microballoon；Then, above-mentioned sample is made annealing treatment.

3. a kind of preparation method of double shells hollow ball-shape nickel cobaltate nano particles according to claim 2, feature exist In, in annealing process, when the annealing rate is respectively 5 DEG C/min, 7 DEG C/min, 10 DEG C/min, can obtain respectively it is solid, Single layer shell and the spherical nickel cobaltate nano particles of double shells form the cobalt acid nickel nanosphere of different structure.