CN113151856B

CN113151856B - Preparation of high-entropy alloy phosphide nanoparticle catalyst and application of high-entropy alloy phosphide nanoparticle catalyst in hydrogen production by water electrolysis

Info

Publication number: CN113151856B
Application number: CN202110424556.3A
Authority: CN
Inventors: 赵明; 王思懿; 赵亮; 曹景沛; 韦宇檑
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2021-04-20
Filing date: 2021-04-20
Publication date: 2023-03-28
Anticipated expiration: 2041-04-20
Also published as: CN113151856A

Abstract

The invention discloses a preparation method of a high-entropy alloy phosphide nanoparticle catalyst and application thereof in hydrogen production by water electrolysis, wherein four or more than four metal sources are taken firstly and placed in oleylamine together with a phosphorus source, and the molar ratio of the metal source to the phosphorus source is 1:2, adding a buffer reagent, and uniformly stirring the mixture; heating the mixture to 150 ℃ under an inert atmosphere, stirring for reaction, cooling, washing, centrifuging after the reaction is finished, and dissolving by using normal hexane to obtain a high-entropy alloy phosphide nanoparticle solution; and loading the nano particle solution on active carbon in an ultrasonic carbon loading manner, and calcining to obtain the carbon-loaded high-entropy alloy phosphide nano particle catalyst. The preparation method has the advantages of easily available raw materials, low reaction temperature, simple post-treatment and no generation of toxic phosphorus steam and other by-products, and the prepared high-entropy alloy phosphide catalyst has good catalytic performance in a water electrolysis hydrogen production system.

Description

Preparation of high-entropy alloy phosphide nanoparticle catalyst and application of high-entropy alloy phosphide nanoparticle catalyst in hydrogen production by water electrolysis

Technical Field

The invention relates to the technical field of preparation of nano materials and catalysts, in particular to preparation of a high-entropy alloy phosphide nano particle catalyst and application of the high-entropy alloy phosphide nano particle catalyst in hydrogen production by water electrolysis.

Background

The metal phosphide is a gap-filling type compound formed by filling nonmetallic element phosphorus in metal atom crystal lattices, and the compound has the properties of metal and semiconductor at the same time, has physical and chemical properties similar to those of carbide, boride and nitride, and has good heat conductivity and electrical conductivity and thermal stability. The synthesis of transition metal phosphide, especially the control of its morphology and structure at nanoscale, has become a hotspot in the field of material synthesis. The preparation method of metal phosphide can be mainly divided into a hydrothermal method, a solvothermal method, a programmed heating method, a phosphate thermal decomposition method, a metal organic precursor decomposition method and the like. The hydrothermal method and the solvothermal method respectively use water and an organic solvent as reaction media, the raw materials are dissolved in the water/organic solvent under the application of high pressure, and the reaction conditions are mild. Both hydrothermal method and solvothermal method have the advantages of simple operation, low cost, easily-achieved reaction conditions and the like, and the synthesized nano material has good dispersibility and high purity, so that the hydrothermal method and the solvothermal method are commonly used methods for preparing metal nano phosphide.

The high-entropy alloy originally refers to an alloy consisting of five or more elements with equal molar ratios, and the concentration of the element components is not limited by equal proportion any more along with the research. Currently, high entropy alloys are defined in two forms, composition-based and entropy-based: for composition-based definitions, high entropy alloys refer to alloys consisting of five or more elements, each element at a concentration between 5 and 35%; based on the definition of entropy, the mixed configuration entropy of a high-entropy alloy can be described by the following formula:

S＝-R∑x _i ln(x _i )

wherein R is a molar gas constant and xi represents a mole fraction of the elemental constituent. For the alloy with the element component number of more than or equal to 5, the alloy with the mixed configuration entropy S of more than or equal to 1.5R is the high-entropy alloy.

Compared with single-phase alloy, the high-entropy alloy has the following advantages:

A. the entropy of the mixed configuration is high, a stable single-phase solid solution structure is formed, and the catalytic effect is more stable and durable.

B. The metal atoms occupy randomly in the crystal lattice to form crystal lattice distortion, so that the high-entropy alloy has higher hardness.

C. The diffusion effect is slow, which is beneficial to the formation of nano-scale particles.

D. The synergistic effect between elements is stronger, which is beneficial to the improvement of catalytic performance.

The concept of high entropy introduces a new approach to the development of advanced materials with unique properties, and high entropy alloys are also a hotspot in materials science in recent years.

Disclosure of Invention

The invention aims to provide a high-entropy alloy phosphide nanoparticle catalyst and a preparation method thereof, and the high-entropy alloy phosphide nanoparticle catalyst is mild in reaction conditions, simple and feasible, and safe and environment-friendly.

The invention also aims to provide the application of the high-entropy alloy phosphide nanoparticle catalyst prepared by the method in hydrogen production by water electrolysis.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a preparation method of a high-entropy alloy phosphide nanoparticle catalyst comprises the following steps:

(1) Taking four or more than four metal sources in an equimolar ratio, placing the metal sources and the phosphorus source together in oleylamine, wherein the molar ratio of the metal sources to the phosphorus source is 1:2, adding a buffer reagent, and uniformly stirring the mixture;

(2) Heating the mixture to 150 ℃ under an inert atmosphere, stirring and reacting until the mixture becomes a black solution, cooling after the reaction is finished, centrifuging, washing, and dissolving by using normal hexane to obtain a high-entropy alloy phosphide nano-particle solution;

(3) And loading the nano particle solution on active carbon in an ultrasonic carbon loading manner, and calcining to obtain the carbon-loaded high-entropy alloy phosphide nano particle catalyst.

Preferably, the metal source in step (1) is selected from metal palladium, metal platinum, and at least two of three metals of metal cobalt, metal nickel and metal copper; the phosphorus source is triphenylphosphine; the buffer reagent is tetrabutylammonium bromide TBAB and trioctylphosphine oxide TOPO.

More preferably, the metal source in step (1) is acetylacetone metal salt, which is easily available, has high solubility in oil phase, and has high phase compatibility with oleylamine as both reducing agent and solvent.

Preferably, the centrifugation step in step (2) is: the reaction solution was mixed with absolute ethanol and centrifuged.

Preferably, the washing step in step (2) is: the centrifuged solid was washed with absolute ethanol.

Preferably, the calcining temperature in the step (3) is 400 ℃, and the holding time is 2h.

The invention also provides a high-entropy alloy phosphide nano-particle catalyst prepared by the method, and the catalyst is of a nano structure.

The invention also provides application of the high-entropy alloy phosphide nano-particle catalyst in hydrogen production by acidic electrolysis of water.

Compared with the prior art, the invention has the following beneficial effects:

the invention forms high-entropy alloy nanoparticles by a metal source and a phosphorus source through a solvothermal synthesis method, and loads the nanoparticles on active carbon by an ultrasonic carbon loading method. Compared with the existing preparation method, the preparation method provided by the invention requires the reaction temperature of only 150 ℃, which is far lower than the reaction temperature generally higher than 200 ℃ in the existing method, and does not generate toxic phosphorus steam and other byproducts; the raw materials of oleylamine, triphenylphosphine, acetylacetone salt and the like are also easily available and have relatively low cost. The high-entropy alloy phosphide catalyst prepared by the invention has good catalytic performance in an acidic water electrolysis hydrogen production system.

Drawings

FIG. 1 is an energy spectrum of the nanoparticle catalyst prepared in example 2 of the present invention.

FIG. 2 is a transmission electron micrograph of the high-entropy alloy phosphide prepared in example 2 of the invention.

FIG. 3 is a transmission electron microscope image of the nanoparticle catalyst prepared in example 2 of the present invention.

FIG. 4 is a graph of the current density and the reaction overpotential of the catalysis of the acidic electrolysis of water to separate out hydrogen from the nanoparticles prepared in examples 1 and 2 of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments.

Example 1: preparation of high-entropy alloy phosphide nanoparticle catalyst PdCONIPTP

(1) Respectively taking 0.1mmol of palladium acetylacetonate, 0.1mmol of cobalt acetylacetonate, 0.1mmol of nickel acetylacetonate and 0.1mmol of platinum acetylacetonate, adding the obtained mixture into a pressure-resistant bottle, and reacting according to the metal source: phosphorus source =1, 2 mol ratio 0.8mmol triphenylphosphine was added, 1mmol TBAB, 3mmol TOPO was added as buffer reagent, 6mL oleylamine was poured in, and the mixture was stirred well.

(2) After introducing nitrogen into the suspension to replace the air in the pressure-resistant bottle, the bottle cap is screwed on, and the mixture is magnetically stirred in an oil bath kettle at 150 ℃ for four hours until the mixture becomes a black solution. After the reaction is finished, uniformly mixing the solution with absolute ethyl alcohol, centrifuging, washing the obtained solid with absolute ethyl alcohol again, and adding n-hexane for dissolving to obtain the high-entropy alloy phosphide solution. And loading the high-entropy alloy phosphide on XC-72 activated carbon through ultrasonic carbon loading, performing rotary evaporation, transferring to a tubular furnace, calcining at 400 ℃, and preserving heat for 2 hours to obtain a powdery catalyst.

Example 2: preparation of high-entropy alloy phosphide nanoparticle catalyst PdCoNiPtCuP

(1) Respectively taking 0.1mmol of palladium acetylacetonate, 0.1mmol of cobalt acetylacetonate, 0.1mmol of nickel acetylacetonate, 0.1mmol of platinum acetylacetonate and 0.1mmol of copper acetylacetonate, adding the obtained mixture into a pressure-resistant bottle, and adding the obtained product into the pressure-resistant bottle according to the metal source: phosphorus source = 1mmol triphenylphosphine, 1mmol TBAB, 3mmol TOPO as buffer reagent, 6mL oleylamine was poured in and the mixture was stirred well.

(2) After introducing nitrogen into the suspension to replace the air in the pressure-resistant bottle, the bottle cap is screwed on, and the mixture is magnetically stirred for four hours at 150 ℃ in an oil bath pan until the mixture becomes a black solution. After the reaction is finished, uniformly mixing the solution with absolute ethyl alcohol, centrifuging, washing the obtained solid with absolute ethyl alcohol again, and adding n-hexane for dissolving to obtain the high-entropy alloy phosphide solution. And loading the high-entropy alloy phosphide on XC-72 activated carbon through ultrasonic carbon loading, performing rotary evaporation, transferring to a tubular furnace, calcining at 400 ℃, and preserving heat for 2 hours to obtain a powdery catalyst.

FIG. 1 is a spectrum diagram of the nanoparticle catalyst prepared in example 2; as is clear from fig. 1, EDS point analysis of the nanoparticles revealed that six elements, pd, co, ni, pt, cu, and P, were present in the nanoparticles.

FIG. 2 is a transmission electron microscope image of the high-entropy alloy phosphide prepared in the example 2; FIG. 3 is a transmission electron micrograph of the nanoparticle catalyst prepared in this example 2; as can be seen from fig. 2 and 3, the gray areas are carbon-supported, the black spheres are the catalyst prepared, and the catalyst is nano-structured and about 8nm in diameter.

Example 3: application of high-entropy alloy phosphide nanoparticle catalyst in hydrogen production by electrolyzing water

Dissolving a proper amount of catalyst in a mixed solution of absolute ethyl alcohol and deionized water, which is a mixture of the absolute ethyl alcohol and the deionized water, adding a sulfonic acid membrane to prepare catalyst ink, and loading the catalyst ink on a glassy carbon electrode. After that, the performance of the catalyst in acidic HER was tested using a glassy carbon electrode as a working electrode, a graphite electrode as a counter electrode, and a calomel electrode as a reference electrode. The parameters during the test are set as follows:

and after the test is finished, processing the data to obtain a curve graph of current density and reaction overpotential.

The prepared catalyst is subjected to an icp test to analyze the element content, and the load capacity of Pt on the PdCoNiPtCuP glassy carbon electrode is 0.627 mu g and the load capacity of Pd on the PdCoNiPtCuP glassy carbon electrode is 1.047 mu g through calculation; the loading of Pt on the PdCoNiPtP glassy carbon electrode is 0.539 mug, and the loading of Pd is 1.019 mug.

The results of the test for hydrogen production by electrolysis of water under acidic conditions were compared with the conventional commercial 20% Pt/C catalyst (Pt supported on a glassy carbon electrode at 6.000. Mu.g) and 10% Pd/C catalyst (Pd supported on a glassy carbon electrode at 3.000. Mu.g), and the results are shown in FIG. 4. The results were analyzed as follows:

(1) The performance of the prepared samples was on par with 10% Pd/C catalyst, and the performance of PdCoNiPtCuP was even better than that of the control. And the whole curve is smooth, and no side reaction absorption peak appears.

(2) In the prepared sample, the total amount of the noble metal is far less than that of the noble metal in a control group, which shows that the prepared sample has the performance which is equivalent to that of a control commercial catalyst, and simultaneously, the preparation cost is greatly reduced.

Claims

1. A preparation method of a high-entropy alloy phosphide nanoparticle catalyst is characterized by comprising the following steps:

(1) Taking four or more than four metal sources, placing the metal sources and a phosphorus source in oleylamine together, wherein the molar ratio of the metal sources to the phosphorus source is 1:2, adding a buffer reagent, and uniformly stirring the mixture, wherein the metal source is selected from at least two of metal palladium, metal platinum, and metal cobalt, metal nickel and metal copper; the phosphorus source is triphenylphosphine; the buffer reagent is tetrabutylammonium bromide TBAB and trioctylphosphine oxide TOPO;

(2) Heating the mixture to 150 ℃ under an inert atmosphere, stirring and reacting until the mixture becomes a black solution, cooling, washing and centrifuging after the reaction is finished, and dissolving the black solution by using normal hexane to obtain a high-entropy alloy phosphide nano-particle solution;

2. A method for preparing a high entropy alloy phosphide nanoparticle catalyst according to claim 1, wherein the metal source in step (1) is acetylacetone metal salt.

3. A method for preparing a high-entropy alloy phosphide nanoparticle catalyst according to claim 1, wherein the centrifugation step in the step (2) is: the reaction solution was mixed with absolute ethanol and centrifuged.

4. A method for preparing a high-entropy alloy phosphide nanoparticle catalyst according to claim 1, wherein the washing step in the step (2) is: the centrifuged solid was washed with absolute ethanol.

5. A preparation method of a high-entropy alloy phosphide nanoparticle catalyst according to claim 1, wherein the calcination temperature in the step (3) is 400 ℃ and the holding time is 2 hours.

6. The high-entropy alloy phosphide nanoparticle catalyst prepared by the preparation method of any one of claims 1 to 5.

7. The application of the high-entropy alloy phosphide nanoparticle catalyst of claim 6 in hydrogen production by acidic electrolysis of water.