阅读说明：本技术 钯掺杂镍钴尖晶石及其制备方法 (Palladium-doped nickel-cobalt spinel and preparation method thereof ) 是由 魏明锐 田三浩 刘毅辉 于 2021-08-12 设计创作，主要内容包括：本发明公开一种钯掺杂镍钴尖晶石及其制备方法,属于纳米复合材料制备技术领域。该钯掺杂镍钴尖晶石的制备方法,包括以下步骤：S1、将PdCl-(2)溶液、硝酸镍、硝酸钴、尿素和乙醇溶液混合得到第一混合溶液；S2、向所述第一混合溶液中添加聚乙二醇得到第二混合溶液；S3、将所述第二混合溶液在120-150℃下反应得到钯掺杂镍钴尖晶石前驱体；S4、将所述钯掺杂镍钴尖晶石前驱体在350～450℃下煅烧得到钯掺杂镍钴尖晶石。本发明还包括上述制备方法制备得到的钯掺杂镍钴尖晶石。该钯掺杂镍钴尖晶石具有较好的电容性能。(The invention discloses palladium-doped nickel-cobalt spinel and a preparation method thereof, belonging to the technical field of nano composite material preparation. The preparation method of the palladium-doped nickel-cobalt spinel comprises the following steps: s1, mixing PdCl 2 Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution; s2, adding polyethylene glycol into the first mixed solution to obtain a second mixed solution; s3, reacting the second mixed solution at the temperature of 120-150 ℃ to obtain a palladium-doped nickel-cobalt spinel precursor; s4, calcining the palladium-doped nickel cobalt spinel precursor at 350-450 ℃ to obtain palladium-doped nickel cobaltSpinel. The invention also discloses palladium-doped nickel-cobalt spinel prepared by the preparation method. The palladium-doped nickel-cobalt spinel has better capacitance performance.)

1. A preparation method of palladium-doped nickel-cobalt spinel is characterized by comprising the following steps:

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution;

s2, adding polyethylene glycol into the first mixed solution to obtain a second mixed solution;

s3, reacting the second mixed solution at the temperature of 120-150 ℃ to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 350-450 ℃ to obtain the palladium-doped nickel-cobalt spinel.

2. The method of claim 1, wherein the PdCl is PdCl in step S1₂The solution was prepared by the following steps: mixing metal Pd with hydrochloric acid solution, introducing air while stirring, and heating at the temperature of 100-120 ℃.

3. The method of claim 1, wherein the PdCl is PdCl in step S1₂PdCl in solution₂The ratio of the amount of the nickel nitrate, the cobalt nitrate and the urea is 1 (7-10) to 20-25 to 60-70.

4. The method of claim 1, wherein the reaction time is 8-10 hours in step S3.

5. The method for preparing palladium-doped nickel cobalt spinel as claimed in claim 1, wherein in step S2, the polyethylene glycol is one or more of polyethylene glycol 200, polyethylene glycol 400 and polyethylene glycol 600.

6. The method of claim 1, wherein the calcination is performed for 3-4 hours in step S4.

7. The method of claim 1, wherein the ethanol solution has a concentration of 50-60% by volume in step S1.

8. The method for preparing palladium-doped nickel cobalt spinel according to claim 1, wherein in step S2, the polyethylene glycol is added according to the material ratio of the polyethylene glycol to the urea (8-10) ml, (15-25) mmol.

9. The method of preparing palladium-doped nickel cobalt spinel as claimed in claim 1, wherein in step S1, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate.

10. A palladium-doped nickel cobalt spinel prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of nano composite material preparation, in particular to palladium-doped nickel-cobalt spinel and a preparation method thereof.

Background

Environmental pollution hazards caused by improper recovery and disposal of waste three-way catalysts are attracting more and more attention. Therefore, the method reasonably and effectively recovers the noble metal palladium in the waste three-way catalyst, not only can realize the cyclic utilization of the noble metal palladium and has great economic benefit, but also can better protect the environment and meet the concept of sustainable development.

The super capacitor is a novel component for storing energy by converting electric energy and chemical energy on an electrode and electrolyte interface based on electrode materials such as carbon materials and transition metal oxides. The super capacitor has the characteristics of high power density, high charging and discharging speed, long cycle life, environmental friendliness and the like, and is widely applied to the fields of electric power, automobiles, rail transit, military aerospace, intelligent electronics and the like. However, the commercial application of the super capacitor is restricted by the lower energy density of the super capacitor, so that the preparation of the electrode material with good capacitor performance is particularly important.

Disclosure of Invention

According to the invention, the precious metal palladium in the waste three-way catalyst is recovered and is used as the raw material to synthesize the palladium-doped nickel-cobalt spinel used as the electrode material of the super capacitor, so that the pollution of the waste three-way catalyst to the environment is reduced, the precious metal palladium can be recycled, and the prepared electrode material of the super capacitor has better performance.

The invention aims to overcome the technical defects, provides palladium-doped nickel-cobalt spinel and a preparation method thereof, and solves the technical problem of poor capacitance performance of electrode materials in the prior art.

In order to achieve the technical purpose, the technical scheme of the invention provides a preparation method of palladium-doped nickel cobalt spinel, which comprises the following steps:

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution;

s2, adding polyethylene glycol into the first mixed solution to obtain a second mixed solution;

s3, reacting the second mixed solution at the temperature of 120-150 ℃ to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 350-450 ℃ to obtain the palladium-doped nickel-cobalt spinel.

Further, in step S1, the PdCl is PdCl₂The solution was prepared by the following steps: mixing metal Pd with hydrochloric acid solution, introducing air while stirring, and heating at the temperature of 100-120 ℃.

Further, in step S1, the PdCl is PdCl₂PdCl in solution₂The ratio of the amount of the nickel nitrate, the cobalt nitrate and the urea is 1 (7-10) to 20-25 to 60-70.

Further, in step S3, the reaction time is 8 to 10 hours.

Further, in step S2, the polyethylene glycol is one or more of polyethylene glycol 200, polyethylene glycol 400 and polyethylene glycol 600.

Further, in step S4, the calcination time is 3 to 4 hours.

Further, in step S1, the ethanol solution has a volume concentration of 50-60%.

Further, in step S2, the polyethylene glycol is added in a material ratio (8-10) ml (15-25) mmol of the polyethylene glycol to the urea.

Further, in step S1, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate.

In addition, the invention also provides palladium-doped nickel-cobalt spinel prepared by the preparation method.

Compared with the prior art, the invention has the beneficial effects that: PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution, adding polyethylene glycol to react at the temperature of 120-150 ℃ to obtain a palladium-doped nickel-cobalt spinel precursor, and decomposing the urea to generate OH in the hydrothermal reaction process^-The ions form an alkaline environment which is favorable for the generation of palladium-doped nickel-cobalt spinel precipitate, polyethylene glycol is added to assist the formation of a palladium-doped nickel-cobalt spinel microscopic nano structure, and then the palladium-doped nickel-cobalt spinel is obtained by calcining at 350-450 ℃, so that the obtained palladium-doped nickel-cobalt spinel has better capacitance performance.

Drawings

FIG. 1 is an XRD pattern of a palladium doped nickel cobalt spinel prepared according to example 1 of the present invention;

FIG. 2 is a plot of cyclic voltammetry at a sweep rate of 10mv/s for palladium-doped nickel cobalt spinel made in example 1 of the present invention;

FIG. 3 is a constant current charge-discharge plot of palladium doped nickel cobalt spinel prepared in example 1 of the present invention at a current density of 2A/g;

FIG. 4 is a scanning electron micrograph of palladium-doped nickel cobalt spinel prepared according to example 1 of the present invention;

FIG. 5 is a plot of cyclic voltammetry for palladium doped nickel cobalt spinel prepared in example 2 of the present invention at a sweep rate of 10 mv/s;

FIG. 6 is a constant current charge-discharge plot of palladium doped nickel cobalt spinel prepared in example 2 of the present invention at a current density of 2A/g;

FIG. 7 is a scanning electron micrograph of palladium-doped nickel cobalt spinel prepared according to example 2 of the present invention.

Detailed Description

The specific embodiment provides a preparation method of palladium-doped nickel-cobalt spinel, which comprises the following steps:

s0, mixing the metal Pd with the hydrochloric acid solution, introducing air under stirring, and heating at the temperature of 100-120 ℃ for oxidation reaction to obtain PdCl₂A solution;

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution; wherein the PdCl is a compound of formula (I)₂PdCl in solution₂The mass ratio of the nickel nitrate, the cobalt nitrate and the urea is 1 (7-10) to (20-25) to (60-70); the volume concentration of the ethanol solution is 50-60%, and the material ratio of the ethanol solution to the urea is (60-100) ml, (15-25) mmol; further, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate;

s2, adding polyethylene glycol into the first mixed solution according to the material ratio (8-10) ml of (15-25) mmol of the polyethylene glycol and the urea to obtain a second mixed solution; wherein the polyethylene glycol is one or more of polyethylene glycol 200, polyethylene glycol 400 and polyethylene glycol 600;

s3, reacting the second mixed solution at the temperature of 120-150 ℃ for 8-10 hours to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 350-450 ℃ for 3-4 hours to obtain the palladium-doped nickel-cobalt spinel.

The specific embodiment further comprises the palladium-doped nickel cobalt spinel prepared by the preparation method.

Further, the metallic Pd in the present embodiment is prepared by the following steps:

(1) disassembling the waste three-way catalyst, taking out a catalyst carrier in the waste three-way catalyst, and crushing the catalyst carrier to obtain powder;

(2) placing the powder obtained in the step (1) in a muffle furnace for roasting;

(3) washing the powder obtained in the step (2), immersing the powder in a betaine-butanediol solvent, soaking for 10-12 hours, filtering, and washing filter residues for 5-6 times by using deionized water;

(4) soaking the filter residue obtained in the step (3) in a prepared [ Hbet ] [ NTf2] ionic liquid, and leaching for 5-6 hours at the temperature of 90-100 ℃ to obtain a leaching solution;

(5) taking a glassy carbon electrode as a working electrode, a carbon rod as a counter electrode, an Ag/AgCl electrode as a reference electrode, and taking the leaching solution obtained in the step (4) as an electrolyte to carry out an electrodeposition reaction;

(6) and washing the Pd particles obtained by the electrodeposition method for 6 times, drying to obtain the Pd particles, and washing the Pd particles by using anhydrous ethanol and deionized water alternately for 3-4 times respectively.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The metallic Pd in the following examples was prepared by the following steps:

disassembling the waste three-way catalyst, taking out a catalyst carrier in the waste three-way catalyst, and crushing the catalyst carrier to obtain powder;

placing the powder in a muffle furnace for roasting at the temperature of 400 ℃ for 5 hours, washing the roasted powder, immersing the washed powder in a eutectic solvent prepared from betaine and butanediol, soaking for 10 hours, filtering, and washing filter residues for 5 times by using deionized water;

soaking the obtained filter residue in prepared [ Hbet ] [ NTf2] ionic liquid, and leaching for 6 hours at the temperature of 90 ℃ to obtain a leaching solution;

taking a glassy carbon electrode as a working electrode, a carbon rod as a counter electrode, an Ag/AgCl electrode as a reference electrode, and an leaching solution as an electrolyte, and carrying out an electrodeposition reaction under the condition that a potential window is-1V, and the scanning rate is 10 mV/s;

and (3) separating Pd particles in the electrolyte by using a centrifugal machine at the rotating speed of 6000rpm, washing for 6 times by using deionized water, and drying to obtain Pd particles (namely metal Pd).

Example 1

This example provides a palladium-doped nickel cobalt spinel, which is prepared by the following steps:

s0, mixing the metal Pd with the hydrochloric acid solution, introducing air while stirring, and heating at 100 ℃ for oxidation reaction to obtain PdCl₂A solution;

s1, mixing PdCl₂Mixing the solution, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea and an ethanol solution for 30min to obtain a first mixed solution; wherein the PdCl is a compound of formula (I)₂PdCl in solution₂The mass ratio of the nickel nitrate to the cobalt nitrate to the urea is 1:9:20: 60; the volume concentration of the ethanol solution is 50%, and the material ratio of the ethanol solution to the urea is 80ml:18 mmol;

s2, adding polyethylene glycol 200 into the first mixed solution according to the material ratio of the polyethylene glycol to the urea of 10ml:18mmol to obtain a second mixed solution;

s3, reacting the second mixed solution at 120 ℃ for 8 hours to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 400 ℃ for 3 hours, and grinding to obtain the palladium-doped nickel-cobalt spinel nano-particles.

FIG. 1 is an XRD pattern of a palladium doped nickel cobalt spinel obtained in this example, which illustrates the success of this example in obtaining a palladium doped nickel cobalt spinel; fig. 2 is a cyclic voltammetry curve of the palladium-doped nickel-cobalt spinel synthesized in this example at a sweep rate of 10mv/s, which has an obvious redox peak, and illustrates that the prepared palladium-doped nickel-cobalt spinel is a pseudocapacitive energy storage mode. Fig. 3 is a constant current charge-discharge diagram of the palladium-doped nickel-cobalt spinel synthesized in this embodiment at a current density of 2A/g, where the palladium-doped nickel-cobalt spinel electrode has an obvious voltage stagnation platform in both the charge and discharge processes, showing the pseudocapacitance of the palladium-doped nickel-cobalt spinel material, and the charge-discharge process is as long as two hundred seconds, which indicates that the palladium-doped nickel-cobalt spinel has a good capacitance performance. Fig. 4 is a scanning electron microscope image of the palladium-doped nickel-cobalt spinel synthesized in this embodiment, which shows that the palladium-doped nickel-cobalt spinel has an obvious nanorod structure, the diameter of the nanorod is 30-50 nm, the length of the nanorod is 150-300 nm, and meanwhile, the distribution of the nanorods is uniform without obvious agglomeration.

Example 2

The embodiment provides a preparation method of palladium-doped nickel-cobalt spinel, which comprises the following steps:

s0, mixing the metal Pd with the hydrochloric acid solution, introducing air while stirring, and heating at 120 ℃ to obtain PdCl₂A solution;

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution; wherein the PdCl is a compound of formula (I)₂PdCl in solution₂The mass ratio of the nickel nitrate to the cobalt nitrate to the urea is 1:7:25: 65; the volume concentration of the ethanol solution is 60 percent; further, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate;

s2, adding polyethylene glycol into the first mixed solution according to the material ratio of the polyethylene glycol to the urea being 8ml:15mmol to obtain a second mixed solution; wherein the polyethylene glycol is polyethylene glycol 400;

s3, reacting the second mixed solution at 150 ℃ for 9 hours to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 350 ℃ for 4 hours to obtain the palladium-doped nickel-cobalt spinel.

Fig. 5 is a cyclic voltammogram of the palladium-doped nickel-cobalt spinel prepared in this example at a sweep rate of 10mv/s, which shows that the curve has an obvious redox peak, and the prepared palladium-doped nickel-cobalt spinel is used as a pseudocapacitive energy storage mode. Fig. 6 is a constant current charge-discharge diagram of the palladium-doped nickel-cobalt spinel prepared in the embodiment at a current density of 2A/g, wherein the palladium-doped nickel-cobalt spinel electrode has an obvious voltage stagnation platform in both the charge and discharge processes, which shows the pseudocapacitance of the palladium-doped nickel-cobalt spinel, and the charge-discharge process is as long as two hundred seconds, which indicates that the capacitance performance of the palladium-doped nickel-cobalt spinel is better. Fig. 7 is a scanning electron microscope image of the palladium-doped nickel-cobalt spinel prepared in the embodiment, which shows that the palladium-doped nickel-cobalt spinel has an obvious nanorod structure, the diameter of the nanorod is about 30nm, the length of the nanorod is 200-500 nm, and meanwhile, the distribution of the nanorod and the particles is uniform, and no obvious agglomeration phenomenon occurs.

Example 3

The embodiment provides a preparation method of palladium-doped nickel-cobalt spinel, which comprises the following steps:

s0, mixing the metal Pd with the hydrochloric acid solution, introducing air while stirring, and heating at 110 ℃ to obtain PdCl₂A solution;

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution; wherein the PdCl is a compound of formula (I)₂PdCl in solution₂The mass ratio of the nickel nitrate to the cobalt nitrate to the urea is 1:10:25: 70; the volume concentration of the ethanol solution is 55%; further, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate;

s2, adding polyethylene glycol into the first mixed solution according to the material ratio of the polyethylene glycol to the urea of 10ml:25mmol to obtain a second mixed solution; wherein the polyethylene glycol is polyethylene glycol 600;

s3, reacting the second mixed solution at 130 ℃ for 10 hours to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 400 ℃ for 3.5 hours to obtain the palladium-doped nickel-cobalt spinel.

Example 4

The embodiment provides a preparation method of palladium-doped nickel-cobalt spinel, which comprises the following steps:

s0, mixing the metal Pd with the hydrochloric acid solution, introducing air while stirring, and heating at 120 ℃ to obtain PdCl₂A solution;

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution; wherein the PdCl is a compound of formula (I)₂PdCl in solution₂The mass ratio of the nickel nitrate, the cobalt nitrate and the urea is 1:7:22: 70; the volume concentration of the ethanol solution is 60 percent; further, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate;

s2, adding polyethylene glycol into the first mixed solution according to the material ratio of the polyethylene glycol to the urea of 10ml:19mmol to obtain a second mixed solution; wherein the polyethylene glycol is polyethylene glycol 200;

s3, reacting the second mixed solution at 140 ℃ for 8 hours to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 400 ℃ for 4 hours to obtain the palladium-doped nickel-cobalt spinel.

Example 5

The embodiment provides a preparation method of palladium-doped nickel-cobalt spinel, which comprises the following steps:

s0, mixing the metal Pd with the hydrochloric acid solution, introducing air while stirring, and heating at 110 ℃ to obtain PdCl₂A solution;

s1, mixing PdCl₂Mixing the solution, nickel nitrate, cobalt nitrate, urea and ethanol solution to obtain a first mixed solution; wherein the PdCl is a compound of formula (I)₂PdCl in solution₂Nitric acid, nitric acidThe mass ratio of the nickel, the cobalt nitrate and the urea is 1:9:23: 68; the volume concentration of the ethanol solution is 58%; further, the nickel nitrate is nickel nitrate hexahydrate, and the cobalt nitrate is cobalt nitrate hexahydrate;

s2, adding polyethylene glycol into the first mixed solution according to the material ratio of the polyethylene glycol to the urea of 9ml:23mmol to obtain a second mixed solution; wherein the polyethylene glycol is polyethylene glycol 200;

s3, reacting the second mixed solution at 150 ℃ for 10 hours to obtain a palladium-doped nickel-cobalt spinel precursor;

and S4, calcining the palladium-doped nickel-cobalt spinel precursor at 450 ℃ for 3.5 hours to obtain the palladium-doped nickel-cobalt spinel.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.