阅读说明：本技术 一种应用于电解水的PdCuFeCoNi高熵合金纳米颗粒催化剂的制备方法 (Preparation method of PdCuFeCoNi high-entropy alloy nanoparticle catalyst applied to electrolyzed water ) 是由 王立开 孙迎港 鲁法云 李忠芳 于 2021-10-26 设计创作，主要内容包括：本发明公开了一种电解水催化剂的制备方法,制备高熵合金纳米颗粒负载炭黑XC-72用于催化电解水,属于纳米材料合成领域。合成路线主要包括：在油胺溶剂加入还原金属盐,利用表面活性剂阻止高熵合金纳米颗粒团聚,控制其形成特定形貌；配制洗液清洗合金表面油胺及表面活性剂,获得高分散、粒径均一的高熵合金纳米颗粒；高熵合金颗粒负载炭黑XC-72得到其电解水催化剂,该催化剂在全pH下均表现出优异的析氢和析氧性能,是一种高效的电解水催化剂。本发明方法制备方法简单、安全,所得的高熵合金纳米催化剂是一种理想的电解水催化剂。(The invention discloses a preparation method of an electrolytic water catalyst, which is used for preparing high-entropy alloy nanoparticle loaded carbon black XC-72 for catalyzing electrolytic water and belongs to the field of synthesis of nano materials. The synthetic route mainly comprises: adding reducing metal salt into an oleylamine solvent, and utilizing a surfactant to prevent high-entropy alloy nano particles from agglomerating to control the high-entropy alloy nano particles to form a specific shape; preparing washing liquid to wash the surface oleylamine and the surfactant of the alloy to obtain high-dispersion high-entropy alloy nano particles with uniform particle size; the high-entropy alloy particle loaded carbon black XC-72 is used for obtaining the water electrolysis catalyst, and the catalyst shows excellent hydrogen and oxygen evolution performances under the full pH condition, and is a high-efficiency water electrolysis catalyst. The preparation method is simple and safe, and the obtained high-entropy alloy nano catalyst is an ideal water electrolysis catalyst.)

1. A preparation method of PdCuFeCoNi high-entropy alloy nanoparticle catalyst applied to electrolyzed water is characterized by comprising the following steps: (1) mixing and heating five kinds of reductive metal salts such as Pd, Cu, Fe, Co, Ni and the like in oleylamine, and reacting at a safe and controllable temperature, (2) mixing oleylamine containing a surfactant with the metal salt mixture, and performing ultrasonic dispersion to ensure uniform mixing, (3) protecting and modifying alloy nanoparticles by using the surfactant to prevent the high-entropy alloy nanoparticles from agglomerating, (4) heating and stirring the mixed solution to obtain the high-entropy alloy nanoparticles with high dispersion and uniform particle size, and (5) cleaning the surface oleylamine and the surfactant of the alloy by using a mixed washing solution of alcohol and alkane, and loading the high-entropy alloy particles on a carrier to obtain the electrolytic water catalyst.

2. The process for preparing an alloy according to claim, wherein: in the step (1), palladium salt, copper salt, iron salt, cobalt salt and nickel salt are used in a round-bottom flask, and the metal salt comprises nitrate, acetate, acetylacetone salt, chloride salt and the like, but is not limited to the above.

3. The process for preparing an alloy according to claim, wherein: the surfactant in the step (2) can comprise polyvinylpyrrolidone (PVP), Triton X-114, Cetyl Trimethyl Ammonium Bromide (CTAB), polyethylene glycol and the like, and the surfactant needs to be ultrasonically dispersed in an oleylamine solution for 0.1 to 2 hours.

4. The process for preparing an alloy according to claim, wherein: and (3) mixing oleylamine containing a surfactant with the metal salt mixture, and performing ultrasonic dispersion for 0.5-10 h to ensure that the oleylamine and the metal salt mixture are uniformly mixed.

5. The process for preparing an alloy according to claim, wherein: in the step (4), the mixed solution is heated and stirred at the stirring speed of 200-1000rpm and the temperature of 150-250-^oC, and keeping the temperature for 0.5-8 h.

6. The process for preparing an alloy according to claim, wherein: the washing liquid dispersing agent in the step (5) can be alcohols such as methanol, ethanol and the like, the alkane can be n-hexane, cyclohexane and the like, but the washing liquid dispersing agent is not limited to the alcohols, and the mixing ratio of the mixed washing liquid is 1:10-10: 1.

7. The process for preparing an alloy according to claim, wherein: in the step (5), the mass ratio of the total mass of the alloy to the mass of the carbon carrier is 1-50%, and the carbon material can be carbon black XC-72, graphene and nanotubes, but is not limited to the carbon material.

Technical Field

The invention relates to the technical field of synthesis of alloy nanoparticle catalysts and novel electrochemical energy materials, in particular to synthesis of a high-entropy alloy electrocatalyst and application in water electrolysis.

Background

Hydrogen energy has received wide attention as an efficient and environmentally friendly green energy source. The traditional preparation method of hydrogen is a water electrolysis process, but the common commercial platinum-carbon catalyst has high cost and poor stability, and the development of the catalyst is limited. The existing non-platinum-based noble metals such as palladium (Pd) and ruthenium (Ru), and transition metals such as iron (Fe), cobalt (Co), nickel (Ni) and the like have certain catalytic performance for hydrogen production by water electrolysis, but the performance and the catalytic stability thereof need to be further improved. Therefore, the development of the high-efficiency and low-cost water electrolysis catalyst is of great significance.

An alloy generally means that two or more metals are combined by a certain method and have properties superior to those of a simple metal. The high-entropy alloy at least comprises 5 elements, and the atomic percentage of each element is 5-35%. The alloy nano particles have one-dimensional size in a nano-scale range, show the characteristics of volume effect, surface effect, quantum size effect and the like, and can change the physical and chemical properties of the alloy nano particles; the alloy nano particles show different properties from pure metal nano particles in the aspects of catalysis, electrochemistry, optics and the like, but the nano-scale alloy nano particles are easy to agglomerate and have a certain limiting effect on the catalytic performance of the alloy nano particles.

The conventional process of electrolyzing water involves an electrochemical reaction at the cathode where hydrogen evolution occurs and an electrochemical reaction at the anode where oxygen evolution occurs. However, the cathode electrode reaction kinetics is slow, which becomes a key step in the water electrolysis process, and the design of a high-efficiency bifunctional catalyst is the key to solve the problem.

Disclosure of Invention

The invention mainly provides a preparation method of a high-entropy alloy nanoparticle catalyst prepared from non-platinum metals, which is mainly used for a water electrolysis process.

The invention is realized by the following technical scheme, which specifically comprises the following steps:

s1: weighing palladium acetylacetonate, copper acetylacetonate, iron acetylacetonate, cobalt acetylacetonate and nickel acetylacetonate according to a certain proportion, and mixing five metal salts of Pd, Cu, Fe, Co, Ni and the like in oleylamine.

S2: mixing oleylamine containing surfactant with the metal salt mixture, and performing ultrasonic dispersion for 1h to ensure uniform mixing.

S3: the surfactant protects and modifies the alloy nanoparticles to prevent the high-entropy alloy nanoparticles from agglomerating.

S4: and heating and stirring the mixed solution to obtain the high-entropy alloy nano-particles which are composed of 5 metals and have high dispersion and uniform particle size.

S5: the mixed washing liquid of alcohol and alkane is used for washing oleylamine and a surfactant on the surface of the alloy, and a high-entropy alloy particle load carrier is used for obtaining the high-activity electrolyzed water catalyst.

As a further preferable scheme, the step S1 specifically includes: the metal salt can be palladium salt, copper salt, iron salt, cobalt salt and nickel salt which are taken in a round-bottom flask, and the metal salt comprises nitrate, acetate, acetylacetone salt, chloride salt and the like.

As a further preferable scheme, the step S2 specifically includes: the surfactant may include polyvinylpyrrolidone (PVP), Triton X-114, Cetyl Trimethyl Ammonium Bromide (CTAB), polyethylene glycol, etc., and should be dispersed in oleylamine solution by ultrasonic for 0.1-2 hr.

As a further preferable scheme, the step S3 specifically includes: mixing oleylamine containing surfactant with metal salt mixture, and ultrasonic dispersing for 0.5-10 hr to ensure uniform mixing.

As a further preferable scheme, the step S4 specifically includes: heating and stirring the mixed solution, controlling the stirring speed at 200-1000rpm and the temperature at 150-250 h, and keeping the temperature for 0.5-8 h.

As a further preferable scheme, the step S5 specifically includes: the lotion dispersant can be alcohol such as methanol and ethanol, and the alkane can be n-hexane and cyclohexane. The mixing ratio of the mixed washing liquid is 1:10-10: 1. The mass ratio of the total mass of the alloy to the carbon carrier is 1-50%, and the carbon material can be carbon black XC-72, graphene and nanotubes, but is not limited to the carbon material.

The invention synthesizes the water electrolysis catalyst which can not only catalyze the Hydrogen Evolution Reaction (HER) of the cathode, but also improve the Oxygen Evolution (OER) reaction rate of the anode.

In another aspect, the invention provides a preparation method for preparing a high-entropy alloy nanoparticle catalyst by using a non-platinum-based metal.

In summary, compared with the existing research, the invention has the advantages that: the high-efficiency long-term stable high-entropy alloy nanoparticle electrolytic water catalyst is prepared by combining various transition metal salts and palladium by a simple and easily-obtained preparation method, so that the catalyst cost is low, and the service life of the catalyst is prolonged.

The effects of different surfactants in the alloy forming process are discussed, and the stability of the catalytic performance and the service life of the surfactant are improved.

The high-entropy alloy is dispersed on the porous carbon material carrier, has a more stable structure and a larger specific surface area, and is beneficial to exposing more catalytic active sites.

The high-entropy alloy formed by the five metals has excellent performance superior to that of simple substance metal, and the synergistic effect between the metals and between the alloy and the carbon material is beneficial to improving the reaction rate of water electrolysis.

Drawings

FIG. 1 is a Transmission Electron Microscope (TEM) analysis diagram of the high-entropy alloy PdCuFeCoNi under different magnifications.

FIG. 2 is an X-ray diffraction spectrum of the prepared high-entropy alloy PdCuFeCoNi.

In FIG. 3, (a) is the high entropy alloy PdCuFeCoNi and commercial Pt/C at 0.5M H₂SO₄The hydrogen evolution test curve of 10mV/s carried out in (1). (b) The hydrogen evolution test curve of 10mV/s is carried out on the high entropy alloy PdCuFeCoNi and commercial Pt/C in 0.5M PBS buffer solution. (c) Is a linear hydrogen evolution test curve of 10mV/s of a high entropy alloy PdCuFeCoNi and commercial Pt/C in a 1M KOH solution. (d) Is a high-entropy alloy PdCuFeCoNi and commercial RuO₂10mV/s oxygen evolution test curve in 1M KOH at 1600 rpm.

Detailed Description

The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

Mixing triton and oleylamine, and performing ultrasonic treatment for 30min to obtain a transparent oily mixed solution. Palladium acetylacetonate, copper acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate were weighed into a 50mL round bottom flask. Pouring the above mixture into a round

And (3) cooling the mixed solution to normal temperature, transferring the mixed solution to a 50mL centrifuge tube, adding 30mL of absolute ethyl alcohol, shaking the mixed solution uniformly, centrifuging the mixed solution at the rotating speed of 8000rpm, and continuously centrifuging the black precipitate for 3 times by using the ethyl alcohol. Preparing a mixed solution of ethanol and n-hexane, preferably, the volume ratio is 1: 1. 1: 2 the black precipitate was washed 1 time by centrifugation. And ultrasonically dispersing the obtained black precipitate in n-hexane to obtain a black high-entropy alloy solution PdCuFeCoNi-Triton X-100.

Example 2

Mixing polyvinylpyrrolidone (PVP) and oleylamine, and performing ultrasonic treatment for 30min to obtain a transparent oily mixed solution. Palladium acetylacetonate, copper acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate were weighed into a 50mL round bottom flask. Pouring the mixed solution into a round-bottom flask for super mixing, and carrying out ultrasonic treatment for 1 h. Heating the mixed solution to 200 deg.C^oAnd C, after the temperature is stable, keeping the temperature for 2 hours. And (3) cooling the mixed solution to normal temperature, transferring the mixed solution to a 50mL centrifuge tube, adding 30mL of absolute ethyl alcohol, shaking the mixed solution uniformly, centrifuging the mixed solution at the rotating speed of 8000rpm, and continuously centrifuging the black precipitate for 3 times by using the ethyl alcohol. Preparing a mixed solution of ethanol and n-hexane, preferably, the volume ratio is 1: 1. 1: 2 the black precipitate was washed 1 time by centrifugation. And ultrasonically dispersing the obtained black precipitate in n-hexane to obtain a black high-entropy alloy solution PdCuFeCoNi-PVP.

Example 3

Taking 5mL of black high-entropy alloy catalyst solution, adding carbon black XC-72, ultrasonically stirring the mixed solution for 30min respectively, and repeating twice to obtain the catalyst solution. Preparation of a working electrode: 5mL of the catalyst solution was loaded with 10mg of carbon black XC-72. Coating 7uL of catalyst on the surface of the substrate with an area of 0.07cm²After the surface of the glassy carbon electrode is dried, 2uL of ethanol solution with the mass fraction of 20% of Nafion is dripped on the glassy carbon electrode, and the glassy carbon electrode is naturally dried in the air. The working electrode is placed in the electrolyte for hydrogen evolution or oxygen evolution test, and the sweep rate of the linear voltammogram is generally 10 mV/s.

As shown in FIG. 1, the resulting high entropy alloy is a spherical particle of 5-8nm, and clear lattice fringes can be seen in a high resolution TEM image. Compared with the standard PDF card, the XRD diffraction peak shown in figure 2 has corresponding shift of the corresponding simple substance metal characteristic peak, and is positioned in each standardIn the middle of the card, the alloy phase is illustrated. In the electrochemical performance test of FIG. 3, at 10mA cm^-2The acid hydrogen evolution potential can reach-0.021V under the current density of (1), and is similar to that of commercial Pt/C. Meanwhile, the high-entropy alloy catalyst has certain electrochemical performance in hydrogen evolution reaction under alkaline and neutral conditions, and is close to commercial Pt/C. At the same time, it also has the same commercial RuO under alkaline condition₂Similar electrochemical oxygen evolution performance.

The above examples are representative of the working of the present invention and clearly do not represent the full scope of patent protection. Any similar experimental principles, experimental operations and drug replacement are equivalent alternatives to the present invention and are within the scope of the present invention.