阅读说明：本技术 二维材料担载单原子掺杂Au24M双金属团簇电催化剂 (Two-dimensional material supported single-atom doped Au24M bimetallic cluster electrocatalyst ) 是由 王立开 张申智 李忠芳 于 2020-06-09 设计创作，主要内容包括：本发明在于制备一种二维材料担载单原子掺杂Au24M(Pt,Au,Pd)双金属团簇电催化剂,该催化剂优势在于：本发明用于燃料电池阴极催化剂,该催化剂为单分散的Au25、Au24Pt、Au24Pd以团簇形式负载于多孔二维材料,合成高效稳定的担载型单原子调控的双金属团簇催化剂；探索单原子调控双金属团簇中掺杂原子种类、掺杂数目、掺杂位点等对其氧还原性能的影响,明确其催化性能的差异,运用计算化学的手段,结合它们的具体结构,阐明催化机理,揭示团簇内金属间协同作用对催化效果影响的规律,建立起单原子掺杂-团簇结构-电催化性能三者之间的关联。该催化剂具有高效的电催化性能,为燃料电池提供了一种新的阴极催化材料,具有良好的应用前景。(The invention aims to prepare a two-dimensional material supported single-atom doped Au24M (Pt, Au, Pd) bimetallic cluster electrocatalyst, which has the advantages that: the catalyst is a monodisperse Au25, Au24Pt and Au24Pd cluster-type supported porous two-dimensional material, and is used for synthesizing a high-efficiency and stable supported type monatomic regulated bimetallic cluster catalyst; the influence of the doping atom type, the doping number, the doping sites and the like in the monatomic regulation bimetallic cluster on the oxygen reduction performance of the bimetallic cluster is explored, the difference of the catalytic performance of the bimetallic cluster is determined, the catalytic mechanism is clarified by using a computational chemistry means and combining the specific structures of the bimetallic cluster, the rule of the influence of the synergy among the metals in the cluster on the catalytic effect is revealed, and the relationship among the monatomic doping, the cluster structure and the electrocatalytic performance is established. The catalyst has high-efficiency electrocatalysis performance, provides a new cathode catalysis material for fuel cells, and has good application prospect.)

1. A method for preparing a two-dimensional material supported monatomic doped Au24M (Pt, Au, Pd) bimetallic cluster electrocatalyst, characterized by: the invention adopts the carbon nano-sheet with proper aperture and structure as the catalyst carrier, and the accurate control is realized at the atomic level, thereby realizing the accurate construction of the supported type single-atom regulation and control bimetallic cluster composite material with high size monodispersity, definite composition and structure and a large number of exposed active sites.

2. Analyzing the difference of the catalytic activity of the bimetallic cluster through the influence of the single atom doping on the catalytic performance of the bimetallic cluster; the specific structure of the catalyst is combined, the synergistic effect among heterogeneous atoms in the cluster and the interaction between the bimetallic cluster and the carrier are revealed, and the catalytic activity of the bimetallic cluster is intensively regulated and controlled by controlling the components and the structure of the bimetallic cluster.

3. The specific preparation process route of the catalyst comprises the following steps:

(1) preparing the monatomic doped gold nanocluster: adding chloroauric acid into tetrahydrofuran solution, adding tetraoctyl ammonium bromide as phase transfer agent, adding platinum salt or palladium salt, and stirring quickly.

4. After reacting for a period of time, adding phenethyl mercaptan, fully reacting metal salt ions in the solution with mercaptan in a matched manner, adding a reducing agent, and continuously reacting for a certain time to obtain Au₂₅(SR)₁₈、Au₂₄Pt(SR) ₁₈、Au₂₄Pd(SR) ₁₈。

(2) preparation of two-dimensional nano material: mixing and stirring zinc salt and a terephthalic acid ligand in N, N-dimethylformamide until the mixture is clear, aging in an oven for a certain time, adding a surfactant into an aged product, uniformly mixing and heating, adding an organic base after 2 hours, stopping heating after reacting for a period of time, washing with N, N-dimethylformamide, centrifuging, drying and carbonizing to obtain the nitrogen-doped two-dimensional porous carbon nanosheet.

6. (3) taking Au₂₅(SR)₁₈、Au₂₄Pt(SR) ₁₈、Au₂₄Pd(SR) ₁₈Respectively dissolving the two-dimensional double-metal cluster into organic solution, dispersing the organic solution into a two-dimensional material by an ultrasonic dispersion and mechanical stirring alternative mixing method, and repeating for 3 times to obtain a supported double-metal cluster product.

(4) the supported bimetallic cluster removal surface protection ligand: the removing method adopts arc plasma jet in a plasma pyrolysis technology, instantaneously pyrolyzes ligands on the surfaces of clusters in an inert atmosphere, and obtains the gold cluster nano catalyst by the monatomic doped bimetallic cluster.

And 8, (5) applying the prepared gold cluster nano-catalysts to oxygen reduction catalysis to obtain the fuel cell cathode high-efficiency catalyst.

9. The two-dimensional material supported monatomic doped Au of claim 1₂₄The preparation method of the M (Pt, Au, Pd) bimetallic cluster electrocatalyst is characterized in that: the molar weight ratio of the chloroauric acid/tetraoctylammonium bromide adopted in the step (1) is 1/1-1/3, the chloroauric acid/tetraoctylammonium bromide is added into a tetrahydrofuran solution and stirred, the stirring speed is 800-1500 rpm, the molar weight ratio of the chloroauric acid/mercaptan ligand is 1: 5-1: 10, the mercaptan ligand can be selected from phenethyl mercaptan, n-hexyl mercaptan, dodecyl mercaptan, thiophenol and the like, and the molar ratio of chloroauric acid to reducing agent is 1: 10-1: 20.

10. the two-dimensional material supported monatomic doped Au of claim 1₂₄The preparation method of the M (Pt, Au, Pd) bimetallic cluster electrocatalyst is characterized in that: the two-dimensional nano material adopted in the step (2) comprises materials such as a two-dimensional porous carbon nano sheet, MXene, CeO2 and black phosphorus; selecting a proper carbon source and a proper pore-forming agent, and preparing a two-dimensional carbon nanosheet with a proper pore size and a proper structure by adopting a soft template method and a hard template method; the surfactant in the preparation of the two-dimensional porous carbon nanosheet can be selected from CTAB, Triton X-114, Triton X-100 and the like.

11. The two-dimensional material supported monatomic doped Au of claim 1₂₄The preparation method of the M (Pt, Au, Pd) bimetallic cluster electrocatalyst is characterized in that: step (3) mixing Au₂₄Dissolving M (Pt, Au, Pd) clusters in organic solvents such as toluene, tetrahydrofuran, dichloromethane and the like respectively; the mixing operation can adopt a dipping method, an ultrasonic oscillation method and an in-situ synthesis method to load the bimetallic cluster on the porous carbon nanosheet.

12. The two-dimensional material supported monatomic doped Au of claim 1₂₄The preparation method of the M (Pt, Au, Pd) bimetallic cluster electrocatalyst is characterized in that: removing the surface protection ligand from the supported bimetallic cluster in the step (4): the removal method mainly adopts three methods: (i) a mild chemical stripping method adopts a proper amount of NaBH4 for treatment to remove the ligand; (ii) oxidizing the end group of the mercaptan ligand on the surface of the cluster by ozone with a certain concentration, reducing the affinity between the ligand and the gold core, and removing the ligand; (iii) and (3) instantly pyrolyzing the ligand on the surface of the cluster in an inert atmosphere by adopting electric arc plasma jet in a plasma pyrolysis technology, and obtaining the gold cluster nano catalyst by using the monatomic-doped bimetallic cluster.

13. The two-dimensional material supported monatomic doped Au of claim 1₂₄The preparation method of the M (Pt, Au, Pd) bimetallic cluster electrocatalyst is characterized in that: the uniform loading amount of the catalyst in the step (5) is 101 mu g/cm²Ensuring that the catalyst achieves the strongest catalytic activity.

Technical Field

The invention relates to the technical field of electrocatalysis of fuel cells, in particular to a two-dimensional material supported monatomic doped Au₂₄The preparation of M (Pt, Au, Pd) bimetallic cluster electrocatalyst and the application of the catalyst in the cathode oxygen reduction reaction of fuel cells.

Background

The Proton Exchange Membrane Fuel Cell (PEMFC) is a device capable of directly converting chemical energy stored in fuel and oxidant into electric energy, has the characteristics of low required working temperature, quick start, high specific power, simple structure and the like, and has huge application prospect. PEMFCs are composed of a cathode, an anode, and a proton exchange membrane, the anode generates a hydrogen fuel oxidation reaction (HOR), and the cathode generates an Oxygen Reduction Reaction (ORR). Since the cathode Oxygen Reduction Reaction (ORR) involves the transfer of multiple electrons and the formation of intermediates during discharge, compared to the anode reaction, is the rate-determining step in the electrocatalytic reaction of fuel cells, the search for an efficient and stable cathode oxygen reduction catalyst is an important means for improving the performance of fuel cells.

The common oxygen reduction catalyst is a commercial platinum-carbon catalyst, but the catalyst has high cost and poor catalytic stability and is easy to poison, so that the catalytic efficiency is low, the effective catalytic active area is reduced, and the large-scale commercial application of the proton exchange membrane fuel cell is restricted. The traditional supported platinum and alloy catalyst thereof have large particle size dispersion and low stability, and only a few metal active components play a catalytic role in the catalytic reaction process, so that the metal utilization efficiency is far lower than an ideal level, and the catalyst cost is increased due to the large-dosage use, thereby limiting the commercial application of the catalyst. The bimetallic cluster regulated and controlled by the single atom has high size monodispersity, definite composition and structure and a large number of exposed active sites, the electronic structure of the whole cluster can be greatly changed and the catalytic performance of the whole cluster can be obviously changed by changing only one atom of the cluster, and the bimetallic cluster is a catalytic material with high economic benefit and practical application value.

The cluster is used for the electrocatalyst, so that the catalytic efficiency of the oxygen reduction reaction is greatly improved, and the cost of the material can be reduced. The use of gold clusters alone, however, often encounters two problems in catalytic reactions. Firstly, the ligands on the surface of the metal clusters may hinder mass transfer and electron transfer, thereby seriously impairing their electrical activity. Secondly, the durability of the metal clusters is greatly limited due to their extremely small size and high surface energy. Therefore, the invention selects a proper substrate to carry the ultra-small doped bimetallic nanocluster, so that the ultra-small doped bimetallic nanocluster is uniformly distributed on the carrier in the form of single atoms, and the single atom catalysis with each metal atom as an active site in the catalysis process is realized; not only improves the catalytic activity and reduces the catalyst cost, but also is beneficial to analyzing the catalytic reaction mechanism to further improve the performance, is vital to improving the performance of the fuel cell, and further promotes the commercial application of the proton exchange membrane fuel cell.

The invention relates to a two-dimensional material supported single-atom doped Au₂₄Preparation of M (Pt, Au, Pd) bimetallic cluster electrocatalyst, and at present, no monatomic doped Au can be supported by a two-dimensional material₂₄Patents for the M (Pt, Au, Pd) bimetallic cluster electrocatalyst scheme are reported.

Disclosure of Invention

In order to solve the two problems, the invention provides a two-dimensional material loaded single-atom doped Au₂₄Examples of the preparation of M (Pt, Au, Pd) bimetallic cluster electrocatalysts.

The invention is characterized in that: the invention adopts the carbon nano-sheet with proper aperture and structure as the catalyst carrier, and the accurate control is realized at the atomic level, thereby realizing the accurate construction of the supported type single-atom regulation and control bimetallic cluster composite material with high size monodispersity, definite composition and structure and a large number of exposed active sites. The difference of catalytic activity is analyzed through the influence of single atom doping on the catalytic performance of the bimetallic cluster; the specific structure of the catalyst is combined, the synergistic effect among heterogeneous atoms in the cluster and the interaction between the bimetallic cluster and the carrier are revealed, and the catalytic activity of the bimetallic cluster is intensively regulated and controlled by controlling the components and the structure of the bimetallic cluster. The invention is realized by the following technical scheme, which specifically comprises the following steps:

(1) preparing the monatomic doped gold nanocluster: adding chloroauric acid into tetrahydrofuran solution, adding tetraoctyl ammonium bromide as phase transfer agent, adding platinum salt or palladium salt, and stirring quickly. And adding mercaptan after reacting for a period of time, fully reacting metal salt ions in the solution with the mercaptan in a matched manner, adding a reducing agent, and reacting for a certain time to obtain the nanogold cluster.

(2) Preparing a two-dimensional nano material: mixing and stirring zinc salt and a terephthalic acid ligand in N, N-dimethylformamide until the mixture is clear, aging in an oven for a certain time, adding a surfactant into an aged product, uniformly mixing and heating, adding an organic base after 2 hours, stopping heating after reacting for a period of time, washing with N, N-dimethylformamide, centrifuging, drying and carbonizing to obtain the nitrogen-doped two-dimensional porous carbon nanosheet.

(3) Taking Au₂₅(SR)₁₈Dissolving the mixture into an organic solution, dispersing the mixture into a two-dimensional material by a method of alternately mixing ultrasonic dispersion and mechanical stirring, and repeating for 3 times to obtain a supported bimetallic cluster product.

(4) Removing the surface protection ligand by the supported bimetallic cluster: the removing method adopts arc plasma jet in the fast pyrolysis technology, instantaneously pyrolyzes the ligand on the surface of the cluster in inert atmosphere, and obtains the gold cluster nano catalyst by the monatomic doped bimetallic cluster.

(5) The prepared gold cluster nano-catalysts are applied to oxygen reduction catalysis to obtain the high-efficiency catalyst of the cathode of the fuel cell.

The molar weight ratio of chloroauric acid/tetraoctylammonium bromide adopted in the step (1) is 1/1-1/3, the reaction medium solvent is toluene, tetrahydrofuran, dichloromethane and other solvents, the molar weight ratio of chloroauric acid/mercaptan ligand is 1: 5-1: 10, the molar weight ratio of chloroauric acid to reducing agent is 1: 10-1: 20, the mercaptan ligand can be selected from phenethyl mercaptan, n-hexyl mercaptan, dodecyl mercaptan, thiophenol, etc.

Selecting a proper carbon source and a proper pore-forming agent from the two-dimensional nano material adopted in the step (2), and preparing a two-dimensional carbon nano sheet with a proper pore diameter and structure by adopting a soft template method and a hard template method; the surfactant in the preparation of the two-dimensional porous carbon nanosheet can be selected from CTAB, Triton X-114, Triton X-100 and the like.

Step (3) mixing Au₂₄Dissolving M (Pt, Au, Pd) clusters in organic solvents such as toluene, tetrahydrofuran, dichloromethane and the like respectively; the mixing operation can adopt a dipping method, an ultrasonic oscillation method and an in-situ synthesis method to load the bimetallic cluster on the porous carbon nanosheet; the mass ratio of the metal cluster to the two-dimensional carbon nano sheet is 0.05-0.3.

Removing the surface protection ligand from the supported bimetallic cluster in the step (4): the removal method mainly adopts three methods: (i) a mild chemical stripping method adopts a proper amount of NaBH4 for treatment to remove the ligand; (ii) oxidizing the end group of the mercaptan ligand on the surface of the cluster by ozone with a certain concentration, reducing the affinity between the ligand and the gold core, and removing the ligand; (iii) and (3) instantly pyrolyzing the ligand on the surface of the cluster in an inert atmosphere by adopting electric arc plasma jet in a plasma pyrolysis technology, and obtaining the gold cluster nano catalyst by using the monatomic-doped bimetallic cluster.

The uniform loading amount of the catalyst in the step (5) is 101 mu g/cm²Ensuring that the catalyst achieves the strongest catalytic activity.

In summary, compared with the prior researches, the invention has the advantages that:

the high-efficiency stable supported type monatomic controlled bimetallic cluster catalyst is synthesized, so that metal is uniformly distributed on a carrier in a monatomic form, the stability of the bimetallic cluster structure is kept, the monatomic catalysis with each metal atom as an active site in the catalytic reaction process is realized, and the catalytic efficiency is improved.

According to the project, carbon nano sheets with proper pore diameter and structure are used as catalyst carriers, under the condition of ensuring that a metal cluster core is single-dispersed, a ligand of a monatomic-regulated bimetallic cluster is removed, the contact and interaction between the metal cluster core and the carriers are realized, the rule of influence of the synergy between metals in the cluster on the catalytic effect is revealed, and the correlation between the structure, the property and the performance is established.

By loading heteroatom-doped carbon nanosheets, the stability and activity of the catalyst are greatly improved₂₅、Au₂₄Pt、Au₂₄The carbon material doped with hetero atoms around the Pd particles can prevent the Pd particles from migrating and agglomerating, thereby greatly improving the stability of the catalyst.

Drawings

FIG. 1 is a diagram of example 1 for preparing a two-dimensional material supporting monatomic doped Au₂₄Pt, Transmission Electron Microscopy (TEM) of the bimetallic cluster.

FIG. 2 shows two-dimensional porous carbon nanosheet supported hybrid prepared in examples 1, 2 and 3Au₂₄Linear scan curves of M (Pt, Au, Pd) bimetallic clusters in oxygen saturated 0.1M KOH solution.

FIG. 3 shows that the two-dimensional porous carbon nanosheets prepared in examples 1, 2 and 3 carry hetero Au₂₄M (Pt, Au, Pd) bimetallic cluster at 0.5MH₂SO₄The hydrogen evolution performance in solution was compared.

Fig. 4 is a summary of the electrocatalytic performance of the two-dimensional porous carbon nanosheet supported hetero Au24M (Pt, Au, Pd) bimetallic cluster samples prepared in examples 1, 2 and 3 in the fuel cell cathode oxygen reduction reaction.

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

(1) 68mg of chloroauric acid and 159mg of tetraoctyl ammonium chloride are weighed, added to 8mL of tetrahydrofuran solution, and stirred rapidly for 1 hour, so that the solution becomes orange red. Adding 175uL of phenethyl mercaptan into the solution, changing the color of the solution from orange red to light yellow, weighing 96mg of sodium borohydride after 15min, dissolving the sodium borohydride into 3mL of cold distilled water, quickly adding the solution into a flask, removing the water phase after reacting for about 8 hours, drying the organic phase, washing with methanol for 5 times to obtain Au₂₅(SR)₁₈Molecule

(2) Mixing zinc acetate, terephthalic acid and N, N-dimethylformamide, stirring until the mixture is clear, then placing the mixture into an oven for aging for 72 hours, adding cetyl trimethyl ammonium bromide into the aged product, uniformly mixing, heating, adding triethylamine after 2 hours, stopping heating after 10 minutes, washing the product with N, N-dimethylformamide, centrifuging and drying. And calcining the dried product to obtain the nitrogen-doped carbon nanosheet.

(3) Taking Au₂₅(SR)₁₈Dissolving into dichloromethane solution, adding nitrogen-doped carbon nanosheets, stirring for 1 hour, performing ultrasound for 30min, repeating for 3 times, and drying the obtained product. Carrying out fast pyrolysis on the loaded product to remove the protective ligand on the surface of the cluster, thus obtaining the two-dimensional porous carbon nanosheet supported hybridAu₂₅And (4) bimetal clusters.

Example 2

(1) 68mg of chloroauric acid, 26mg of chloroplatinic acid and 159mg of tetraoctyl ammonium chloride are weighed, added to 8mL of tetrahydrofuran solution and stirred rapidly for 1 hour, and the solution becomes orange red. Adding 175uL of phenethyl mercaptan into the solution, changing the color of the solution from orange red to light yellow, weighing 96mg of sodium borohydride after 15min, dissolving the sodium borohydride into 3mL of cold distilled water, quickly adding the solution into a flask, removing the water phase after reacting for about 8 hours, drying the organic phase, washing with methanol for 5 times to obtain Au₂₄Pt(SR) ₁₈。

(2) Mixing zinc acetate, terephthalic acid and N, N-dimethylformamide, stirring until the mixture is clear, then placing the mixture into an oven for aging for 72 hours, adding cetyl trimethyl ammonium bromide into the aged product, uniformly mixing, heating, adding triethylamine after 2 hours, stopping heating after 10 minutes, washing the product with N, N-dimethylformamide, centrifuging and drying. And calcining the dried product to obtain the nitrogen-doped carbon nanosheet.

(3) Taking Au₂₄Dissolving Pt in a dichloromethane solution, adding nitrogen-doped carbon nanosheets, stirring for 1 hour, then performing ultrasonic treatment for 30min, repeating for 3 times, and drying the obtained product. Carrying out fast pyrolysis on the loaded product to remove the protective ligand on the surface of the cluster, thus obtaining the two-dimensional porous carbon nanosheet loaded mixed Au₂₄Pt bimetallic cluster.

Example 3

(1) 68mg of chloroauric acid, 28mg of sodium chloropalladate and 159mg of tetraoctylammonium chloride are weighed, added to 8mL of tetrahydrofuran solution and stirred rapidly for 1 hour, and the solution becomes orange red. Adding 175uL of phenethyl mercaptan into the solution, changing the color of the solution from orange red to light yellow, weighing 96mg of sodium borohydride after 15min, dissolving the sodium borohydride into 3mL of cold distilled water, quickly adding the solution into a flask, removing the water phase after reacting for about 8 hours, drying the organic phase, washing with methanol for 5 times to obtain Au₂₄Pd(SR) ₁₈A molecule.

(2) Mixing zinc acetate, terephthalic acid and N, N-dimethylformamide, stirring until the mixture is clear, then placing the mixture into an oven for aging for 72 hours, adding cetyl trimethyl ammonium bromide into the aged product, uniformly mixing, heating, adding triethylamine after 2 hours, stopping heating after 10 minutes, washing the product with N, N-dimethylformamide, centrifuging and drying. And calcining the dried product to obtain the nitrogen-doped carbon nanosheet.

(3) Taking Au₂₄Dissolving Pd in dichloromethane solution, adding nitrogen-doped carbon nanosheets, stirring for 1 hour, then performing ultrasonic treatment for 30min, repeating for 3 times, and drying the obtained product. Carrying out fast pyrolysis on the loaded product to remove the protective ligand on the surface of the cluster, thus obtaining the two-dimensional porous carbon nanosheet loaded mixed Au₂₄And Pd bimetallic clusters.

Example 4

Electrochemical testing characterization was performed in a test cell with a three-electrode system on a CHI 660C electrochemical workstation manufactured by chenhua corporation, supra. Wherein, the carbon rod is a counter electrode, the Ag/AgCl electrode is a reference electrode, and the glassy carbon electrode loaded with the catalyst is a working electrode. Weighing 2.5 mg of catalyst into 1.0 mL of ethanol solution, dropwise adding 10 mu L of Nafion to prepare a standard solution, and carrying out ultrasonic treatment on the mixed solution for 30 minutes to obtain a catalyst suspension with the concentration of 2.5 mg/mL. Uniformly coating 10 mu L of catalyst suspension on a glassy carbon electrode and naturally drying in the air to obtain the catalyst loading of 200 mu g/cm². Placing the working electrode in 0.1M KOH solution saturated with oxygen for oxygen reduction performance; two-dimensional porous carbon nanosheet supported mixed Au prepared simultaneously₂₄M (Pt, Au, Pd) bimetallic cluster at 0.5MH₂SO₄And (4) carrying out hydrogen evolution performance test comparison in the solution.

The above embodiments are preferred embodiments of the present invention, but the scope of the present invention is not limited thereto, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.