Carbon-layer semi-confined stable metal heterojunction catalyst and preparation method thereof

Abstract

The application provides a composite material containing metal composite nanoparticles, which comprises metal composite nanoparticles, a heteroatom-doped carbon layer and a carrier; the surface of the carrier is composited with the heteroatom-doped carbon layer; and the metal composite nanoparticles are loaded on the surface of the carrier and embedded in the heteroatom-doped carbon layer. The carbon layer semi-limited domain stable metal heterostructure composite material designed by the application has metal heterojunction nanoparticles with a diameter of 2-20 nm and a 2-8 layer semi-limited domain graphene structure carbon layer; the semi-limited domain structure of the carbon layer can realize high stability of the metal nanoparticles, and the exposed metal active sites are beneficial to the adsorption of reaction molecules, thereby ensuring efficient reaction. The catalyst prepared by the application meets the requirements of high activity and stability of industrial catalysts, has excellent universality, low cost and is easy to realize mass production, and can be popularized in industrial production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nano and sub-nano catalyst preparation, and relates to a composite material containing metal composite nanoparticles and a preparation method and application thereof, in particular to a carbon layer semi-confined stable metal heterojunction catalyst and a preparation method thereof. BACKGROUND

[0002] In recent years, in-situ analysis has revealed the degradation mechanism of electrocatalysts, and specific structures are considered to be effective in resisting degradation. However, it is a great challenge to simultaneously achieve high activity and stability in one nanostructure, because the structure-property relationship affecting activity and stability is different.

[0003] The formation of a carbon layer on the surface of the catalyst can effectively prevent the electrochemical oxidation and physical agglomeration of the catalyst surface. Dong Young Chung et al. reported in 2015 that constructing a dopamine coating layer on the surface of PtFe nanoparticles can improve the high-temperature stability of the particles, which is conducive to the formation of fct-PtFe intermetallic nanoparticles [J. Am. Chem. Soc. 2015, 137, 15478-15485]. Mohanraju Karuppannan et al. loaded uniform carbon-coated PtCo alloy nanoparticles on carbon nanofibers by forming a Pt-aniline complex in 2019, which exhibited extremely high activity and stability [Energy Environ. Sci., 2019, 12, 2820-2829]. However, the carbon layer that physically protects the nanoparticles will block the adsorption sites on the surface of the metal particles, which will affect the activity and stability of the electrocatalyst. Therefore, the pores in the carbon coating layer and the permeability to reactants and electrolytes need to be considered. In electrocatalytic reactions such as oxygen reduction reaction, carbon dioxide reduction reaction, etc., the adsorption of reaction molecules (O2, CO2) on the active sites is required, so it is a great challenge to achieve a balance between high stability and activity. It is very important to introduce functional structural units in catalyst design to achieve electrochemical stability while maintaining high activity.

[0004] Therefore, how to design a more suitable catalyst that can achieve electrochemical stability while maintaining high activity has become one of the focuses of many researchers in the industry. SUMMARY

[0005] Therefore, the present application aims to provide a composite material containing metal composite nanoparticles and a preparation method and application thereof, in particular, a carbon layer semi-limited stable metal heterojunction catalyst.

[0006] The present application provides a composite material containing metal composite nanoparticles, which comprises metal composite nanoparticles, a heteroatom-doped carbon layer and a carrier.

[0007] The carrier surface is composited with a heteroatom-doped carbon layer.

[0008] The metal composite nanoparticles are loaded on the carrier surface and embedded in the heteroatom-doped carbon layer.

[0009] Preferably, the metal composite nanoparticles comprise first metal nanoparticles and a second metal oxide layer coated on the first metal nanoparticles.

[0010] The mass ratio of the first metal nanoparticles to the second metal oxide is (3-5):1.

[0011] The metal composite nanoparticles have a core-shell structure.

[0012] The particle size of the metal composite nanoparticles is 2-20 nm.

[0013] The first metal nanoparticles and the second metal oxide form a heterojunction.

[0014] Preferably, the first metal comprises one or more of a metal element, a binary alloy, a ternary alloy and an intermetallic compound.

[0015] The metal element comprises one or more of Pt, Pd, Ru and Au.

[0016] The binary alloy comprises one or more of PtCo, PtFe, PtCu, PtMn, PtNi, PtRu, PdFe, PdNi, PdCu and PdPt.

[0017] The ternary alloy comprises one or more of PtCoNi, PtCoFe, PtNiFe, PtFeMn, PtNiMn, PtCoMn, PtCoCu, PtNiCu, PtFeCu, PtMnCu, PtCuW, PtRuFe, PtRuNi, PtRuMn, PtRuCo, PtRuCu, PdCoCu, PdCuNi, PdCuCo, PdCuFe and PdCuMn.

[0018] The second metal is at least one of the first metal.

[0019] Preferably, the metal composite nanoparticle comprises a metal heterojunction nanoparticle.

[0020] The composite material containing the metal composite nanoparticle is a catalyst containing the metal composite nanoparticle.

[0021] The metal composite nanoparticle is semi-coated by a heteroatom-doped carbon layer.

[0022] The thickness of the heteroatom-doped carbon layer is 0.5-3 nm.

[0023] The mass ratio of the heteroatom-doped carbon layer to the carrier is 1:(2-5).

[0024] Preferably, the heteroatom comprises a non-metal atom or a metal atom.

[0025] The non-metal comprises one or more of N, S, B, P, F and I.

[0026] The metal comprises one or more of Co, Fe, Cu and Ni.

[0027] The carbon layer is formed by stacking atomic-thickness carbon layers.

[0028] The number of layers of the atomic-thickness carbon layer is 2-8 layers.

[0029] Preferably, the metal composite nanoparticle is semi-confined and stabilized in the heteroatom-doped carbon layer.

[0030] The carrier comprises a carbon carrier or a doped carbon carrier.

[0031] The carbon carrier comprises one or more of XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotube, carbon nanosphere, carbon nanosheet, cerium oxide, titanium oxide and silicon oxide.

[0032] The doping element of the doped carbon carrier comprises one or more of N, S, B, P, F and I.

[0033] The mass ratio of the metal composite nanoparticle to the carrier is 1:(2-5).

[0034] In the composite material, the proportion of metal atoms in the total mass of the composite material is 5wt%-20wt%.

[0035] The present application provides a preparation method of a composite material containing a metal composite nanoparticle, comprising the following steps:

[0036] 1) loading the first metal nanoparticles on a carrier to obtain a carrier loaded with metal nanoparticles;

[0037] 2) mixing the carrier loaded with metal nanoparticles obtained in the above step, a carbon source containing heteroatoms, a second metal source solution and a solvent, and then performing a polymerization reaction, and then drying to obtain a precursor;

[0038] 3) pyrolyzing the precursor obtained in the above step in a protective atmosphere to obtain a full-confined metal nanoparticle composite coated with a carbon layer, and then performing a low-oxygen heat treatment under a low-oxygen atmosphere to obtain a composite material containing metal composite nanoparticles.

[0039] Preferably, the carrier includes a carbon carrier or a doped carbon carrier;

[0040] The carbon carrier includes one or more of XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotubes, carbon nanospheres, carbon nanosheets, cerium oxide, titanium oxide and silicon oxide;

[0041] The doped carbon carrier is obtained by mixing a doping source and a carbon carrier and then pyrolyzing at a high temperature under a protective atmosphere, or by mixing a template and an organic small-molecule carbon source containing heteroatoms, and then performing polymerization and sintering;

[0042] The doping source includes one or more of sulfur powder, boric acid, phosphoric acid, disodium hydrogen phosphate, melamine and dihydrodiamine;

[0043] The mass ratio of the doping source to the carbon carrier is (2-5):1;

[0044] The temperature of the high-temperature pyrolysis is 850-1000℃;

[0045] The temperature rising rate of the high-temperature pyrolysis is 1-10℃ / min;

[0046] The organic small-molecule carbon source containing heteroatoms includes one or more of aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine and thiophene.

[0047] Preferably, the method for loading the first metal nanoparticles includes one or more of an ethylene glycol reduction method, a NaBH4 reduction method, an oleylamine reduction method and an ascorbic acid reduction method;

[0048] The carbon source containing heteroatoms includes one or more of aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, thiophene and a metal organic framework;

[0049] The step 2) further includes an initiator, or the polymerization reaction is performed by adjusting the pH value;

[0050] The temperature of the pyrolysis is 350-1000℃;

[0051] The time of the pyrolysis is 1-5h;

[0052] The oxygen concentration of the low-oxygen atmosphere is 0.01%-0.05%;

[0053] The temperature of the low-oxygen heat treatment is 750-1150℃;

[0054] The time of the low-oxygen heat treatment is 5-20 minutes.

[0055] The application further provides application of the composite material containing the metal composite nanoparticles in a catalyst field.

[0056] The application provides a composite material containing metal composite nanoparticles, which comprises metal composite nanoparticles, a heteroatom-doped carbon layer and a carrier; the surface of the carrier is combined with the heteroatom-doped carbon layer; and the metal composite nanoparticles are loaded on the surface of the carrier and embedded in the heteroatom-doped carbon layer. Compared with the prior art, the application designs a composite material containing metal composite nanoparticles with a specific structure and composition, which is a metal heterostructure composite material with semi-limited carbon layer stability, has metal heterojunction nanoparticles with a diameter of 2-10nm and a semi-limited carbon layer with 2-8 layers of graphite-like structure, and the semi-limited structure of the carbon layer can realize high stability of the metal nanoparticles, and the exposed metal active sites are beneficial to adsorption of reaction molecules, thereby ensuring efficient reaction.

[0057] The application provides a heteroatom-doped carbon layer semi-limited stable metal nanoparticle catalyst, the carbon layer is 2-8 layers of graphitized graphene sheet, the size of the stable metal composite nanoparticle is 2-10 nm, and the heteroatom (N, P, S and B) doped carbon layer can increase the interaction between the metal nanoparticle and the carrier, thereby effectively stabilizing the metal heterojunction nanoparticle and avoiding sintering and agglomeration of the metal particle. The sintering problem of the supported metal heterojunction particle catalyst occurs in the catalytic reaction process, which is a big problem in industrial catalysis. The sintering of the metal heterojunction nanoparticle can lead to deactivation of the catalyst, thereby increasing the cost. Therefore, coating the supported metal nanoparticle catalyst can effectively improve the stability, prolong the service life of the catalyst, and thereby reduce the cost of industrial catalysis. However, when the metal particle is completely wrapped, the reaction molecules need to pass through the coating layer to contact the catalytically active sites on the surface of the metal heterojunction particle, which will delay the catalytic reaction rate and reduce the catalytic activity of the metal nanoparticle. The carbon layer formed by the application does not block the exposure of the active sites of the metal heterojunction nanoparticle, which is beneficial to the contact between the metal heterojunction nanoparticle catalyst and the reactive molecules. The stabilizing effect of the carbon layer is beneficial to the stability of the metal heterojunction nanoparticle at high temperature, and is beneficial to the controllable preparation of the metal intergranular nanoparticle assisted by high temperature.

[0058] The application also provides a preparation method of the composite material. The metal nanoparticle is semi-limited by the carbon layer through oxygen-assisted pyrolysis, and the heterojunction nanoparticle is formed on the surface of the metal nanoparticle. The oxygen-assisted pyrolysis synthesized heteroatom-doped carbon layer semi-limited stable metal heterojunction nanoparticle catalyst prepared by the application meets the requirements of high activity and stability of the industrial catalyst, and the preparation method has excellent universality, wide application in preparation of high-stability and high-activity catalyst, low cost and easy to realize mass production, and can be popularized in industrial production.

[0059] The preparation method of the heteroatom-doped carbon layer semi-limited stable metal nanoparticle catalyst provided by the application uses commercial carbon and small molecule polymerized carbon as the carrier, can be applied to various industrial catalytic conditions, can realize quantitative production, and is easy to commercialize. The method can prepare various single-metal, double-metal and triple-metal nanoparticle catalysts, and can control the composition and ingredients of the metal nanoparticle. The prepared metal heterojunction nanoparticle has uniform particle size distribution, and can realize the preparation of highly uniform and controllable metal nanoparticle catalyst.

[0060] The experimental results show that the PtCo and CoO heterojunction nanoparticles semi-confined in the N-doped carbon layer are prepared, wherein the nanoparticles are loaded on the N-S co-doped carbon nanotubes, and are recorded as SC-PtCo@CoOx / N,S-CNTs. 2 The catalyst has excellent activity and stability in the acid oxygen reduction reaction, and after being applied to the cathode of a proton exchange membrane fuel cell, exhibits a maximum power density of 1.3 W / cm BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 It is a scanning electron microscope (SEM) image of the nitrogen and sulfur co-doped hollow carbon nanotubes in Example 1 of the present application;

[0062] Figure 2 It is a transmission electron microscope (STEM) image of SC-PtCo@CoOx / N,S-CNTs in Example 1 of the present application;

[0063] Figure 3 It is a high-resolution electron microscope (HRTEM) image of the carbon layer semi-confined stable platinum-cobalt alloy nanoparticles SC-PtCo / N,S-CNTs in Example 1 of the present application;

[0064] Figure 4 It is a linear sweep voltammetry (LSV) curve of SC-PtCo / N,S-CNTs obtained in Example 1 of the present application in 0.1M HClO4 solution saturated with O2 at 1600 rpm;

[0065] Figure 5 It is a polarization curve and power density of SC-PtCo / N,S-CNTs prepared in Example 1 of the present application as a cathode of a H2-O2 fuel cell. DETAILED DESCRIPTION

[0066] In order to further understand the present application, the preferred embodiments of the present application are described below in combination with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, and are not a limitation on the claims of the present application.

[0067] All raw materials of the present application are not particularly limited in source, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0068] The raw materials used in the present application are not particularly limited in purity, and the present application is preferably analytical pure or conventional purity in the field of catalyst preparation.

[0069] All the materials in the present application, their trade names and abbreviations are all the conventional trade names and abbreviations in the field, each of which is clear and explicit in the field of its relevant use, and those skilled in the art can purchase or prepare by conventional methods according to the trade name, abbreviation and corresponding use.

[0070] All the processes in the present application, their abbreviations are all the conventional abbreviations in the field, each of which is clear and explicit in the field of its relevant use, and those skilled in the art can understand its conventional process steps according to the abbreviation.

[0071] In the present disclosure, the term "heteroatom-doped carbon layer" refers to a substitution of part of C atoms in the carbon layer with non-metal atoms such as N, S, B and P, forming a carbon layer with defects.

[0072] In the present disclosure, the term "semi-confined stable" refers to that half of the metal heterojunction nanoparticles are coated by the carbon layer and stabilized on the carbon layer, and half of the active sites are highly exposed, while achieving high stability and high activity.

[0073] The present application provides a composite material containing metal composite nanoparticles, which comprises metal composite nanoparticles, a heteroatom-doped carbon layer and a carrier.

[0074] The carrier surface is composited with a heteroatom-doped carbon layer.

[0075] The metal composite nanoparticles are loaded on the surface of the carrier and embedded in the heteroatom-doped carbon layer.

[0076] In the present application, the metal composite nanoparticles preferably comprise first metal nanoparticles and a second metal oxide layer coated on the first metal nanoparticles.

[0077] In the present application, the mass ratio of the first metal nanoparticles to the second metal oxide is preferably (3-5):1, more preferably (3.4-4.6):1, and more preferably (3.8-4.2):1.

[0078] In the present application, the metal composite nanoparticles preferably have a core-shell structure.

[0079] In the present application, the particle size of the metal composite nanoparticles is preferably 2-20 nm, more preferably 6-16 nm, and more preferably 10-12 nm.

[0080] In the present application, the first metal nanoparticles and the second metal oxide preferably form a heterojunction. The heterojunction in the present application is not a heterojunction in a semiconductor material, but a heterojunction or heterostructure between nanomaterials.

[0081] In the present application, the first metal preferably comprises one or more of a metal element, a binary alloy, a ternary alloy and an intermetallic compound, and more preferably is a metal element, a binary alloy, a ternary alloy or an intermetallic compound.

[0082] In the present application, the metal element preferably comprises one or more of Pt, Pd, Ru and Au, and more preferably is Pt, Pd, Ru or Au.

[0083] In the present application, the binary alloy preferably comprises one or more of PtCo, PtFe, PtCu, PtMn, PtNi, PtRu, PdFe, PdNi, PdCu and PdPt, and more preferably is PtCo, PtFe, PtCu, PtMn, PtNi, PtRu, PdFe, PdNi, PdCu or PdPt.

[0084] In the present application, the ternary alloy preferably comprises one or more of PtCoNi, PtCoFe, PtNiFe, PtFeMn, PtNiMn, PtCoMn, PtCoCu, PtNiCu, PtFeCu, PtMnCu, PtCuW, PtRuFe, PtRuNi, PtRuMn, PtRuCo, PtRuCu, PdCoCu, PdCuNi, PdCuCo, PdCuFe and PdCuMn, and more preferably is PtCoNi, PtCoFe, PtNiFe, PtFeMn, PtNiMn, PtCoMn, PtCoCu, PtNiCu, PtFeCu, PtMnCu, PtCuW, PtRuFe, PtRuNi, PtRuMn, PtRuCo, PtRuCu, PdCoCu, PdCuNi, PdCuCo, PdCuFe or PdCuMn.

[0085] In the present application, the second metal is preferably at least one of the first metal.

[0086] In the present application, the metal composite nanoparticle preferably comprises a metal heterojunction nanoparticle.

[0087] In the present application, the composite material containing the metal composite nanoparticle preferably is a catalyst containing the metal composite nanoparticle.

[0088] In the present application, the metal composite nanoparticle is preferably semi-coated by a heteroatom-doped carbon layer.

[0089] In the present application, the thickness of the heteroatom-doped carbon layer is preferably 0.5-3 nm, more preferably 1-2.5 nm, and more preferably 1.5-2 nm.

[0090] In the present application, the mass ratio of the heteroatom-doped carbon layer to the carrier is preferably 1:(2-5), more preferably 1:(2.5-4.5), and more preferably 1:(3-4).

[0091] In the present application, the heteroatom preferably includes a non-metal atom or a metal atom.

[0092] In the present application, the non-metal preferably includes one or more of N, S, B, P, F and I, and more preferably N, P, S or B.

[0093] In the present application, the metal preferably includes one or more of Co, Fe, Cu and Ni, and more preferably Co, Fe, Cu or Ni.

[0094] In the present application, the carbon layer is preferably formed by stacking atomic-level carbon layers. Specifically, the atomic-level carbon layer can be a graphene layer or a graphenelike layer, and the doping in the carbon layer can be ring doping or grafting doping.

[0095] In the present application, the number of atomic-level carbon layers is preferably 2-8, more preferably 3-7, and more preferably 4-6.

[0096] In the present application, the metal composite nanoparticles are preferably semi-confined and stabilized in the heteroatom-doped carbon layer.

[0097] In the present application, the carrier preferably includes a carbon carrier or a doped carbon carrier.

[0098] In the present application, the carbon carrier preferably includes one or more of XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotube, carbon nanosphere, carbon nanosheet, cerium oxide, titanium oxide and silicon oxide, and more preferably XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotube, carbon nanosphere, carbon nanosheet, cerium oxide, titanium oxide or silicon oxide.

[0099] In the present application, the doping element of the doped carbon carrier preferably includes one or more of N, S, B, P, F and I, and more preferably N, S, B, P, F or I, or a N and S double-doped carbon layer, a N and B double-doped carbon layer, a N, S and I triple-doped carbon layer.

[0100] In the present application, the mass ratio of the metal composite nanoparticles to the carrier is preferably 1:(2-5), more preferably 1:(2.5-4.5), and more preferably 1:(3-4).

[0101] In the present application, in the composite material, the proportion of metal atoms in the total mass of the composite material is preferably 5wt%-20wt%, more preferably 8wt%-17wt%, and more preferably 11wt%-14wt%.

[0102] The application is a complete and detailed technical solution, which can better improve the electrochemical stability and catalytic activity of the composite material.

[0103] The application provides a heteroatom-doped carbon layer semi-confined stable metal heterojunction nanoparticle catalyst, which comprises a heteroatom-doped carbon layer and a metal heterojunction nanoparticle, wherein the metal heterojunction nanoparticle is semi-confined by the heteroatom-doped carbon layer.

[0104] Specifically, the heteroatom-doped carbon layer is a 2-8-layer graphene-like layer doped by a nonmetal, and the semi-confined stable metal heterojunction nanoparticle is a heterojunction of a metal or an alloy and a corresponding metal oxide, and has a diameter of 2-20 nm.

[0105] Specifically, the heteroatom is a nonmetal element such as N, P, S or B.

[0106] Specifically, the metal heterojunction nanoparticle is a single-metal nanoparticle such as a Pt, Pd, Ru or Au nanoparticle, a double-metal or triple-metal alloy such as a PtCo, PtFe, PtCu, PtNi, PdCu, PdPt, PtCoNi or PtCuW nanoparticle, and an intermetallic compound nanoparticle, and a heterojunction of the nanoparticle and a corresponding metal oxide nanoparticle is formed. The microstructure of the heterojunction is that the metal nanoparticle is a core, and the corresponding metal oxide is wrapped on the surface of the metal nanoparticle to form a core-shell nanostructure.

[0107] Further,

[0108] The catalyst provided by the application mainly comprises a carbon layer and a metal heterojunction nanoparticle, wherein the metal heterojunction nanoparticle is semi-confined in the carbon layer, the semi-confined carbon layer is a 1-10-layer graphene-like layer doped by atoms such as N, S, P or B, and the size (average diameter) of the semi-confined metal heterojunction nanoparticle is 2-10 nm. The metal nanoparticle is a single-metal nanoparticle such as a Pt, Pd, Ru or Au nanoparticle, a double-metal or triple-metal alloy such as a PtCo, PtFe, PtCu, PtNi, PdCu, PdPt, PtCoNi or PtCuW nanoparticle, and an intermetallic compound nanoparticle.

[0109] In some embodiments, the graphene-like carbon layer preferably has 2-8 layers, and more preferably has 2-5 layers.

[0110] In some embodiments, the size of the semi-confined metal nanoparticle is preferably 2-20 nm, and more preferably 2-10 nm.

[0111] Specifically, the heteroatom in the heteroatom-doped carbon layer is a non-metal atom, including but not limited to N, S, B, P, F, I, etc., and the heteroatom doping is divided into two, three or more atom modifications, such as N and S double-doped carbon layer, N and B double-doped carbon layer, N, S, I triple-doped carbon layer, etc.

[0112] The application provides a preparation method of a composite material containing metal composite nanoparticles, comprising the following steps:

[0113] 1) loading first metal nanoparticles on a carrier to obtain a carrier loaded with metal nanoparticles;

[0114] 2) mixing the carrier loaded with metal nanoparticles obtained in the above step, a carbon source solution containing heteroatoms, a second metal source solution and a solvent, and then performing a polymerization reaction, and then drying to obtain a precursor;

[0115] 3) performing pyrolysis on the precursor obtained in the above step under a protective atmosphere to obtain a full-confined metal nanoparticle composite material coated with a carbon layer, and then performing low-oxygen heat treatment by increasing the temperature under a low-oxygen atmosphere to obtain a composite material containing metal composite nanoparticles.

[0116] First, the first metal nanoparticles are loaded on a carrier to obtain a carrier loaded with metal nanoparticles.

[0117] In the application, the carrier preferably includes a carbon carrier or a doped carbon carrier.

[0118] In the application, the carbon carrier preferably includes one or more of XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotubes, carbon nanospheres, carbon nanosheets, cerium oxide, titanium oxide and silicon oxide, and more preferably XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotubes, carbon nanospheres, carbon nanosheets, cerium oxide, titanium oxide or silicon oxide.

[0119] In the application, the doped carbon carrier is preferably obtained by mixing a doping source and a carbon carrier, and then performing high-temperature pyrolysis under a protective atmosphere, or by mixing a template and an organic small-molecule carbon source containing heteroatoms, and then performing polymerization and sintering.

[0120] In the application, the doping source preferably includes one or more of sulfur powder, boric acid, phosphoric acid, disodium hydrogen phosphate, melamine and dihydrodiamine, and more preferably sulfur powder, boric acid, phosphoric acid, disodium hydrogen phosphate, melamine or dihydrodiamine.

[0121] In the application, the mass ratio of the doping source to the carbon carrier is preferably (2-5):1, more preferably (2.5-4.5):1, and more preferably (3-4):1.

[0122] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0123] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0124] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0125] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0126] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0127] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0128] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0129] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0130] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0131] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0132] In the present application, the temperature of the high-temperature pyrolysis is preferably 850-1000℃, more preferably 880-970℃, and more preferably 910-940℃.

[0133] In the present application, the oxygen concentration of the low-oxygen atmosphere is preferably 0.01% to 0.05%, more preferably 0.015% to 0.045%, more preferably 0.02% to 0.04%, and more preferably 0.025% to 0.035%.

[0134] In the present application, the temperature of the low-oxygen heat treatment is preferably 750 to 1150°C, more preferably 800 to 1100°C, more preferably 850 to 1050°C, and more preferably 900 to 1000°C.

[0135] In the present application, the time of the low-oxygen heat treatment is preferably 5 to 20 minutes, more preferably 8 to 17 minutes, and more preferably 11 to 14 minutes.

[0136] The present application is a complete and detailed overall technical solution that better improves the electrochemical stability and catalytic activity of the composite material. The preparation method of the composite material containing metal composite nanoparticles can be the following steps:

[0137] A preparation method of a carbon-layer semi-confined stable metal heterojunction nanoparticle catalyst includes the following steps:

[0138] 1) providing a heteroatom-doped carbon as a carrier;

[0139] 2) loading metal nanoparticles on the heteroatom-doped carbon carrier;

[0140] 3) performing carbon layer coating on the metal nanoparticle-loaded carbon carrier obtained in step 2) again;

[0141] 4) performing pyrolysis on the twice-coated metal nanoparticle catalyst obtained in step 3) to obtain a carbon-layer fully-confined stable metal nanoparticle catalyst;

[0142] 5) performing short-time low-concentration oxygen treatment at a high temperature on the carbon-layer fully-confined stable metal nanoparticle catalyst obtained in step 4) to obtain a carbon-layer semi-confined structure, and oxygen reacts with the metal nanoparticles at a high temperature to form metal oxides loaded on the surface of the metal nanoparticles to form a heterojunction.

[0143] Specifically, the heteroatom-doped carbon carrier in step 1) can include, but is not limited to, commercial carbon carriers such as XC-72, BP2000, graphite carbon, and Ketjen black, or carbon nanotubes, carbon nanospheres, carbon nanosheets, cerium oxide, titanium oxide, and silicon oxide.

[0144] Specifically, the method of heteroatom doping is to physically mix with sulfur powder, boric acid, phosphoric acid, disodium hydrogen phosphate, melamine, dihydrodiamine, etc. at w / w = 5 / 1-2 / 1. Under the protection of inert gases such as N2, Ar, He, etc., pyrolysis at 850-1000°C for two hours, with a heating rate of 1-10°C / min.

[0145] Specifically, the carbon carrier doped with heteroatoms in step 1) can include but is not limited to self-polymerization of small organic molecules containing heteroatoms with 200 nm silica spheres as templates, and the small molecules include but are not limited to aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, thiophene, etc. The small molecule self-polymerization method can be ammonium persulfate, metal ions (Fe 3+ , Ni 2+ ) initiated self-polymerization, or by adjusting the pH of the solution to promote the occurrence of polymerization reaction.

[0146] Specifically, the method of loading metal nanoparticles in step 2) includes but is not limited to ethylene glycol reduction method, NaBH4 reduction method, oleylamine reduction method, ascorbic acid reduction method, etc.

[0147] Specifically, the secondary coating of the carbon layer involved in step 3) can include but is not limited to small molecules such as aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, thiophene, etc. and metal organic framework coating.

[0148] Specifically, the temperature of the carbon layer in step 4) is 350-1000°C.

[0149] Specifically, the temperature of the oxygen treatment in step 5) is 750-1150°C, the oxygen concentration is 0.01-0.05%, the inert gas is N2, Ar, He, etc., and the oxygen treatment time is 5-20 minutes.

[0150] Further:

[0151] The method for preparing a carbon layer semi-confined stable metal heterojunction nanoparticle catalyst provided by the present disclosure comprises the following steps:

[0152] 1) Provide commercial carbon such as XC-72, BP2000, etc. as a carrier, then physically mix the commercial carbon with S powder, dicyandiamide, melamine, sodium dihydrogen phosphate, etc., and then pyrolyze at high temperature to obtain a carbon carrier doped with heteroatoms. Or choose self-polymerized carbon as a carrier.

[0153] Specifically, the organic small molecule can be dopamine, pyrrole, pyridine, aniline, formaldehyde, thiophene, etc.

[0154] 2) The carbon carrier obtained in step 1) is dispersed in a solution of ethylene glycol, a metal ion precursor is added, and after ultrasonic mixing, high-temperature reduction is performed to obtain metal nanoparticles uniformly loaded on the carbon carrier.

[0155] Specifically, the metal ion precursor can be chloroplatinic acid, chloroauric acid, sodium chloropalladate, etc., and the temperature for alcohol reduction is 80-160°C.

[0156] 3) The carbon carrier material with uniform metal particle loading obtained in step 2) is dispersed in a water or ethanol solution, and small molecule polymerization is performed on its surface to obtain carbon layer-wrapped metal nanoparticles.

[0157] 4) The carbon layer-wrapped metal nanoparticles obtained in step 3) are subjected to pyrolysis treatment, the carbon layer is carbonized at a lower temperature first, and then short-time low-concentration oxygen treatment is performed at a higher temperature, the carbon layer on the surface of the metal particles is etched away at the same time to form a metal particle and oxide heterojunction structure, and a carbon layer semi-confined metal heterojunction nanoparticle catalyst is obtained.

[0158] In some embodiments of the present disclosure, the carbon pyrolysis temperature in step 1) is 800-1000°C, and the pyrolysis treatment is performed in an inert atmosphere of N2, Ar, He, etc.

[0159] In some embodiments of the present disclosure, the mass of the metal ion precursor in step 2) relative to the mass of the carbon carrier is 10-60%; and 100 mg of the carbon carrier is dispersed in 200-500 ml of ethylene glycol to ensure uniform distribution of the carrier.

[0160] In some embodiments of the present disclosure, the polymerized small molecules in step 3) can be dopamine, pyrrole, pyridine, aniline, formaldehyde, thiophene, etc.

[0161] In some embodiments of the present disclosure, the carbon layer carbonization temperature in step 4) is 650-800°C, the oxygen treatment temperature is 950-1150°C, the oxygen concentration is 0.01-0.05%, the inert gas is N2, Ar, He, etc., and the oxygen treatment time is 5-20 minutes.

[0162] Further:

[0163] The present disclosure provides a preparation method of a heteroatom-doped carbon layer semi-confined stable metal heterojunction nanoparticle catalyst, which is a specific example of a preparation method and includes the following steps:

[0164] 1) Provide a heteroatom-doped carbon as a carrier;

[0165] 2) A certain amount of the carrier of step 1) is dispersed in an ethylene glycol solution, a metal ion precursor solution is added for high-temperature reduction, centrifuged after a period of time, washed with ethanol to remove the surface ethylene glycol, and vacuum dried to obtain metal nanoparticles loaded on the carbon carrier;

[0166] 3) The metal nanoparticle-loaded carbon material obtained in step 2) is again dispersed in an ethanol solution, ultrasonically dispersed uniformly, an initiator for polymerization is first added, then a polymerization monomer is added for polymerization, and the carbon carrier-loaded metal nanoparticles are coated. After centrifugation, washing with ethanol and vacuum drying.

[0167] 4) The carbon layer-coated metal nanoparticles obtained in step 3) are first carbonized at a lower temperature to carbonize the carbon layer, then treated with low-concentration oxygen at a higher temperature for a short time, and the carbon layer on the surface of the metal particles is etched away to obtain a carbon layer semi-confined metal nanoparticle catalyst.

[0168] In some embodiments, the heteroatom-doped carbon carrier in step 1) of the above preparation method can include, but is not limited to, commercial carbon carriers such as XC-72, BP2000, graphite carbon, and Ketjen black, which are physically uniformly mixed with sulfur powder, boric acid, phosphoric acid, disodium hydrogen phosphate, melamine, dihydrodiamine, etc. at w / w = 5 / 1-2 / 1. Pyrolysis is carried out at 850-1000°C for two hours under the protection of inert gases such as N2, Ar, and He, with a heating rate of 1-10°C / min.

[0169] In other embodiments, the heteroatom-doped carbon carrier in step 1) can include, but is not limited to, small molecules containing heteroatoms self-polymerized with 200 nm silica spheres as templates, and the small molecules can include, but are not limited to, aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, thiophene, etc. The small molecule self-polymerization method can be ammonium persulfate (initiator), metal ions (Fe 3+ , Ni 2+ ) (initiator), etc. to initiate self-polymerization, or the polymerization reaction can be promoted by adjusting the pH of the solution.

[0170] In some embodiments, the amount of carbon carrier used in step 2) of the above preparation method can be 100-500 mg, dispersed in 0.2-1 L of ethylene glycol solution. The metal ion precursor solution can be an ethanol / water / ethylene glycol solution of one of 100-500 mg / ml chloroplatinic acid, chloropalladic acid, chloroauric acid, etc., with an ethanol mass fraction of 95-99.9%, an ethylene glycol mass fraction > 99%, and the water used is deionized water with a neutral pH.

[0171] In some embodiments, the carbon layer coating involved in step 3) of the above preparation method can include, but is not limited to, self-polymerization of small molecules containing heteroatoms with 200 nm silica spheres as templates, and the small molecules include, but are not limited to, aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, thiophene, etc. The self-polymerization of small molecules can be initiated by ammonium persulfate (initiator), metal ions (Fe 3+ , Ni 2+ ) (initiator), etc. or by adjusting the pH of the solution to promote the occurrence of polymerization reaction. One or two 0.05-1M CoCl2, FeCl3, PtCl4, MnCl2, etc. ethanol / water / ethylene glycol solutions can be added during the self-polymerization of small molecules to realize the preparation of bimetallic or trimetallic nanoparticle catalysts.

[0172] In some embodiments, the temperature of the low-temperature carbonization of the carbon layer in step 4) of the above preparation method is 650-800℃, the temperature of the oxygen treatment is 950-1150℃, the oxygen concentration is 0.01-0.05%, the inert gas is N2, Ar, He, etc., and the oxygen treatment time is 5-20 minutes.

[0173] In the heteroatom-doped carbon layer semi-confined metal nanoparticle catalyst obtained by the above preparation method, the content of metal atoms accounts for 5-20wt% of the total catalyst, the average diameter of the semi-confined metal nanoparticles ranges from 2 to 10nm, and the ultra-thin carbon layer is 2-8 layers of graphene with a thickness ranging from 0.5 to 3nm.

[0174] The heteroatom-doped carbon layer semi-confined stable metal heterojunction nanoparticle catalyst and the preparation method provided by the application use carbon material as the carrier, which can be a commercial carbon carrier modified with heteroatoms N, S, P, B, etc. or a carbon carrier self-polymerized from small molecules containing heteroatoms. Then, metal nanoparticles such as Pt, Pd, Au, etc. are loaded on the surface of the carbon carrier. After carbon layer coating, low-temperature carbonization, and high-temperature low-oxygen treatment, the carbon layer semi-confined metal nanoparticle catalyst is obtained.

[0175] The application obtains a carbon-layer semi-confined stable metal heterojunction nanoparticle catalyst (composite material) by performing secondary carbon coating and high-temperature oxygen treatment on metal heterojunction nanoparticles loaded on a carbon carrier. The metal nanoparticles prepared by the application can be single-metal, double-metal or triple-metal nanoparticles, and have wide application value in catalytic reactions. The stability of the catalyst is the most important in catalytic research, and the formation of the carbon layer can effectively stabilize the metal nanoparticles, prevent dissociation, particle migration and agglomeration. However, the carbon layer wrapping can block the exposure of the active sites of the metal nanoparticle catalyst, resulting in a decrease in the reaction activity. Therefore, the formation of the carbon layer semi-confined can realize high catalytic activity and stability of the metal nanoparticle catalyst at the same time. Meanwhile, due to the influence of the metal-carrier interaction on the catalytic reaction performance, the heteroatom-doped carbon layer constructed by the preparation method can provide multiple choices, and provide a train of thought for the preparation of high-stability and high-activity catalysts in industry.

[0176] The application provides an application of the composite material containing the metal composite nanoparticles in the field of catalysts.

[0177] The above content of the application provides a carbon-layer semi-confined stable metal heterojunction catalyst and a preparation method thereof. The composite material containing the metal composite nanoparticles with a specific structure and composition designed by the application is a carbon-layer semi-confined stable metal heterostructure composite material, has metal heterojunction nanoparticles with a diameter of 2-10 nm and 2-8 layers of semi-confined graphene-like structure carbon layers, and the semi-confined structure of the carbon layer can realize high stability of the metal nanoparticles, and the exposed metal active sites are beneficial to the adsorption of reaction molecules, and ensure efficient reaction.

[0178] The application provides a heteroatom-doped carbon layer semi-limited stable metal nanoparticle catalyst, the carbon layer is a graphitized 2-8 layer graphene sheet, the size of the stable metal nanoparticle is 2-10 nm, and the heteroatom (N, P, S and B) doped carbon layer can increase the interaction between the metal nanoparticle and the carrier, thereby effectively stabilizing the metal heterojunction nanoparticle and avoiding sintering and agglomeration of the metal particle. The sintering of the metal heterojunction nanoparticle can cause deactivation of the catalyst, thereby increasing the cost. Therefore, coating the supported metal nanoparticle catalyst can effectively improve the stability, prolong the service life of the catalyst, and thereby reduce the cost of industrial catalysis. However, when the metal particle is completely wrapped, the reaction molecules need to pass through the coating layer to contact the catalytically active sites on the surface of the metal heterojunction particle, which can delay the catalytic reaction rate and reduce the catalytic activity of the metal nanoparticle. The carbon layer formed by the application does not block the exposure of the active sites of the metal heterojunction nanoparticle, and is beneficial to the contact between the metal heterojunction nanoparticle catalyst and the reactive molecules. The stabilizing effect of the carbon layer is beneficial to the stability of the metal heterojunction nanoparticle at high temperature, and is beneficial to the controllable preparation of the metal intergranular nanoparticle assisted by high temperature. The carbon layer doped with heteroatoms can regulate the microenvironment of the metal nanoparticle, stabilize the metal nanoparticle, and improve the activity of the particle.

[0179] The application also provides a preparation method of the composite material. The metal nanoparticle is semi-limited by the carbon layer through oxygen-assisted pyrolysis, and the surface of the metal nanoparticle forms a heterojunction nanoparticle. The oxygen-assisted pyrolysis synthesized heteroatom-doped carbon layer semi-limited stable metal heterojunction nanoparticle catalyst prepared by the application can meet the requirements of high activity and stability of the industrial catalyst, and the preparation method has excellent universality, wide application in preparation of high-stability and high-activity catalyst, low cost and easy to realize mass production, and can be popularized in industrial production.

[0180] The preparation method of the heteroatom-doped carbon layer semi-limited stable metal nanoparticle catalyst provided by the application uses commercial carbon and small molecule polymerized carbon as the carrier, can be suitable for various industrial catalytic conditions, can realize quantitative production, and is easy to commercialize. The method can prepare various single-metal, double-metal and triple-metal nanoparticle catalysts, and can regulate the composition and ingredients of the metal nanoparticle. The prepared metal heterojunction nanoparticle has uniform particle size distribution, and can realize the preparation of highly uniform and controllable metal nanoparticle catalysts.

[0181] The experimental results show that the PtCo and CoO heterojunction nanoparticles semi-confined in the N-doped carbon layer are prepared, wherein the nanoparticles are loaded on the N-S co-doped carbon nanotubes, and are denoted as SC-PtCo@CoOx / N,S-CNTs. The catalyst has excellent activity and stability in an acid oxygen reduction reaction, and after being applied to a cathode of a proton exchange membrane fuel cell, exhibits a maximum power density of 1.3 W / cm 2 .

[0182] In order to further illustrate the present application, the composite material containing metal composite nanoparticles and the preparation method and application thereof provided by the present application are described in detail below in combination with examples, but it should be understood that these examples are implemented on the premise of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, which are only for further illustrating the features and advantages of the present application, and are not a limitation on the claims of the present application, and the protection scope of the present application is not limited to the following examples.

[0183] Example 1

[0184] 1) 200 mg Mg(OH)2nanorods are uniformly dispersed into 300 ml ethanol, 2 ml 0.6M ammonium persulfate solution is added, and stirring is performed at 600 rpm. Then, 1 g 2,6-diaminopyridine is added, and stirring is performed at room temperature for 10 h. Centrifugation is performed at 11000 rpm, vacuum drying is performed after centrifugation, and sintering is performed at 1000℃ for 1 h. The powder obtained after sintering is dispersed into 100 ml 1M HCl, stirring is performed at room temperature for 10 h, centrifugation is performed, and washing is performed with water until the supernatant is neutral, to obtain hollow nitrogen and sulfur doped carbon nanotubes (N,S-CNTs).

[0185] 2) 100 mg N,S-CNTs are dispersed into 150 ml ethylene glycol solution, 300 μl 100 mg / ml H2PtCl6*xH2O ethylene glycol dispersion is added, stirring is performed at 160℃ for 10 h, centrifugation is performed, washing is performed with ethanol for three times, and vacuum drying is performed, to obtain platinum nanoparticle loaded nitrogen and sulfur doped carbon nanotubes (Pt NPs / N,S-CNTs).

[0186] 3) 40 mg Pt NPs / N,S-CNTs are dispersed into 60 ml ethanol solution, 200 μl 0.6M ammonium persulfate solution and 0.5 ml 50 mg / ml CoCl2*6H2O solution are added, and stirring is performed at room temperature at 600 rpm. Then, 200 mg 2,6-diaminopyridine is added, stirring is performed at room temperature for 10 h, and vacuum drying is performed after centrifugation.

[0187] 4) The powder obtained after vacuum drying was pyrolyzed at 750 °C for 2 h under argon protection, with a heating rate of 5 °C / min. Then the temperature was increased to 1000 °C, the gas was switched to 0.05% 02 / Ar, and the temperature was decreased for 10 min to obtain carbon layer semi-confined stable platinum cobalt nanoparticles surface covered by cobalt oxide half (SC-PtCo@CoOx / N,S-CNTs). Then the carbon layer semi-confined stable platinum cobalt nanoparticles (SC-PtCo / N,S-CNTs) were obtained by acid washing with 0.1 M HC1.

[0188] The content of the obtained Pt and Co atoms respectively accounts for 5wt% and 6wt% of the whole catalyst, the average diameter of the PtCo alloy nanoparticles is 4-5 nm, and the thickness of the semi-confined carbon layer is 2 nm, which is 4-6 layers of graphene. The SC-PtCo / N,S-CNTs can efficiently electrocatalyze the oxygen reduction reaction, and the activity is higher than that of commercial Pt / C and confined platinum cobalt alloy nanoparticles (C-PtCo / N,S-CNTs). As the cathode of a H2-O2 fuel cell, the power density reaches 1.3 W / cm2under 1 bar pressure. 2 .

[0189] Referring to Figure 1 , Figure 1 is a scanning electron microscope (SEM) image of the nitrogen and sulfur co-doped hollow carbon nanotubes in Example 1 of the present application.

[0190] From Figure 1 it can be seen that it is a hollow tubular structure with an average diameter of 80 nm.

[0191] Referring to Figure 2 , Figure 2 is a transmission electron microscope (STEM) image of SC-PtCo@CoOx / N,S-CNTs in Example 1 of the present application.

[0192] From Figure 2 it can be seen that there is a layer of cobalt oxide on the surface of the platinum cobalt alloy nanoparticles, and the particle size is uniform.

[0193] Referring to Figure 3 , Figure 3 is a high-resolution electron microscope (HRTEM) image of the carbon layer semi-confined stable platinum cobalt alloy nanoparticles SC-PtCo / N,S-CNTs in Example 1 of the present application.

[0194] From Figure 3 it can be seen that the 5 nm platinum cobalt alloy nanoparticles are semi-confined by 5 layers of graphene carbon layer.

[0195] Referring to Figure 4 , Figure 4Linear sweep voltammetry (LSV) curves of SC-PtCo / N,S-CNTs obtained in Example 1 in 0.1 M HCIO4solution saturated with O2at 1600 rpm.

[0196] By Figure 4 It can be seen that SC-PtCo / N,S-CNTs has more excellent oxygen reduction reaction activity than C-PtCo / N,S-CNTs and 20% Pt / C.

[0197] Referring to Figure 5 , Figure 5 Polarization curves and power density of SC-PtCo / N,S-CNTs prepared in Example 1 as the cathode of H2-O2fuel cell. The loading amount of Pt metal is 0.05 mg Pt / cm 2 . The power density of SC-PtCo / N,S-CNTs reaches 1.3 W / cm 2 .

[0198] Example 2

[0199] 1) 200 mg Mg(OH)2nanorods were uniformly dispersed in 300 ml ethanol, 2 ml 0.6 M ammonium persulfate solution was added, and stirred at 600 rpm. Then 1 g 2,6-diaminopyridine was added, and stirred at room temperature for 10 h. Centrifugation was performed at 11000 rpm, and after vacuum drying, sintering was performed at 1000°C for 1 h. The powder obtained after sintering was dispersed in 100 ml 1 M HC1, stirred at room temperature for 10 h, and then centrifuged. After washing with water until the supernatant was neutral, hollow nitrogen and sulfur doped carbon nanotubes (N,S-CNTs) were obtained.

[0200] 2) 100 mg N,S-CNTs were dispersed in 150 ml ethylene glycol solution, 300 μl 100 mg / ml H2PtCl6*xH2O ethylene glycol dispersion was added, and after stirring at 160°C for 10 h, centrifugation was performed, and ethanol was washed three times, and vacuum drying was performed to obtain platinum nanoparticle loaded nitrogen doped carbon nanotubes (Pt NPs / N,S-CNTs).

[0201] 3) 40 mg Pt NPs / N,S-CNTs were dispersed in 60 ml ethanol solution, 200 μl 0.6 M ammonium persulfate solution and 0.2 ml 50 mg / ml CoCl2*6H2O solution were added, and stirred at room temperature at 600 rpm. Then 200 mg 2,6-diaminopyridine was added, and stirred at room temperature for 10 h, and after centrifugation, vacuum drying was performed.

[0202] 4) The powder obtained after vacuum drying was first pyrolyzed at 750 °C for 2 h under argon protection, with a heating rate of 5 °C / min. Then the temperature was raised to 1000 °C, the gas was switched to 0.05% 02 / Ar, and cooled for 10 min to obtain carbon layer semi-confined stable platinum cobalt nanoparticles with the surface half-covered by cobalt oxide (SC-Pt3Co@CoOx / N,S-CNTs). Then the carbon layer semi-confined stable platinum cobalt nanoparticles (SC-Pt3Co / N,S-CNTs) were obtained by acid washing with 0.1 M HC1.

[0203] The content of the obtained Pt and Co atoms accounted for 5 wt% and 6 wt% of the whole catalyst, respectively. The average diameter of the PtCo alloy nanoparticles was 4-5 nm, and the thickness of the semi-confined carbon layer was 2 nm, which was 4-6 layers of graphene.

[0204] Example 3

[0205] 1) 200 mg BP2000 was uniformly mixed with 1 g melamine by physical grinding, and sintered at 1000 °C under Ar protection for 2 h to obtain nitrogen-doped carbon nanospheres (N-C).

[0206] 2) 100 mg N-C was dispersed in 150 ml ethylene glycol solution, 300 μΐ of 100 mg / ml H2PtCl6*xH2O ethylene glycol dispersion was added, and after stirring at 160 °C for 10 h, centrifugation was performed with ethanol washing three times, and vacuum drying was performed to obtain platinum nanoparticle-loaded nitrogen-doped carbon nanospheres (Pt NPs / N-C).

[0207] 3) 40 mg Pt NPs / N-C was dispersed in 60 ml ethanol solution, 200 μΐ of 0.6 M ammonium persulfate solution, 0.2 ml of 50 mg / ml CoCl2*6H2O solution, and 0.3 ml of 50 mg / ml NiCl2*6H2O solution were added, and stirring was performed at room temperature at 600 rpm. Then 100 μΐ of aniline solution was added, and stirring was performed at room temperature for 10 h, and after centrifugation, vacuum drying was performed.

[0208] 4) The powder obtained after vacuum drying was first pyrolyzed at 750 °C for 2 h under argon protection, with a heating rate of 5 °C / min. Then the temperature was raised to 1000 °C, the gas was switched to 0.05% 02 / Ar, and cooled for 10 min to obtain carbon layer semi-confined stable platinum cobalt nanoparticles with the surface half-covered by cobalt oxide (SC-Pt3Co@CoOx / N,S-CNTs). Then the carbon layer semi-confined stable platinum cobalt nanoparticles (SC-Pt3Co / N,S-CNTs) were obtained by acid washing with 0.1 M HC1.

[0209] The content of Pt, Co, Ni atoms obtained is 5wt%, 2wt%, 3wt% of the whole catalyst respectively, the average diameter of PtCoNi alloy nanoparticles is 4-5nm, and the thickness of the semi-confined carbon layer is 2nm, which is 4-6 layers of graphene.

[0210] Example 4

[0211] 1) 200mg XC-72 was mixed with 1g melamine and 200mg sulfur powder, uniformly mixed by grinding, and sintered at 1000℃ under Ar protection for 2h to obtain nitrogen and sulfur co-doped carbon (N,S-C).

[0212] 2) 100mg N,S-C was dispersed in 150ml ethylene glycol solution, 300μl of 100mg / ml H2PtCl6*xH2O ethylene glycol dispersion was added, and after stirring at 160℃ for 10h, it was centrifuged and washed with ethanol three times, and vacuum dried to obtain platinum nanoparticle loaded nitrogen-doped carbon (Pt NPs / N,S-C).

[0213] 3) 40mg Pt NPs / N,S-C was dispersed in 60ml ethanol solution, 200μl of 0.6M ammonium persulfate solution and 0.2ml of 50mg / ml NiCl2*6H2O solution were added, and stirred at room temperature at 600rpm. Then 200mg of 2,6-diaminopyridine was added, and stirred at room temperature for 10h, and vacuum dried after centrifugation.

[0214] 4) The powder obtained after vacuum drying was first pyrolyzed at 750℃ under argon protection for 2h, with a heating rate of 5℃ / min. Then the temperature was raised to 1000℃, the gas was switched to 0.05% O2 / Ar, and cooled for 10min to obtain carbon layer semi-confined stable platinum cobalt nanoparticle surface half-covered by nickel oxide (SC-PtNi@NiOx / N,S-C). Then 0.1M HCl acid washing was used to obtain carbon layer semi-confined stable platinum nickel nanoparticles (SC-PtNi / N,S-C).

[0215] The content of Pt, Ni atoms obtained is 5wt%, 6wt% of the whole catalyst respectively, the average diameter of PtNi alloy nanoparticles is 4-5nm, and the thickness of the semi-confined carbon layer is 2nm, which is 4-6 layers of graphene.

[0216] The carbon layer semi-limited stable metal heterojunction catalyst and the preparation method thereof are described in detail above, the principles and implementation manners of the present application are described by using specific examples, the above example is only used for helping to understand the method and the core idea of the present application, including the best mode, and also enables any person skilled in the art to practice the present application, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The scope of the patent protection of the present application is limited by the claims, and can include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the language expression of the claims, or if they include equivalent structural elements that are not substantially different from the language expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a composite material containing metal composite nanoparticles, characterized in that, Includes the following steps: 1) Load the first metal nanoparticles onto the support to obtain a support loaded with metal nanoparticles; 2) The carrier loaded with metal nanoparticles obtained in the above steps, the carbon source solution containing heteroatoms, the second metal source solution and the solvent are mixed and subjected to polymerization reaction. After drying, the precursor is obtained. 3) Under a protective atmosphere, the precursor obtained in the above steps is pyrolyzed to obtain a carbon-coated fully confined metal nanoparticle composite material. Then, under a low oxygen atmosphere, the temperature is raised to perform low oxygen heat treatment to obtain a composite material containing metal composite nanoparticles. The composite material containing metal composite nanoparticles includes metal composite nanoparticles, a heteroatom-doped carbon layer, and a carrier. The metal composite nanoparticles are semi-confined and stable in a heteroatom-doped carbon layer. The term "semi-confined stability" refers to the fact that half of the metal nanoparticles are coated with a carbon layer and stabilized on the carbon layer, while the other half of the active sites are highly exposed. The oxygen concentration in the low-oxygen atmosphere is 0.01%~0.05%; The temperature of the low-oxygen heat treatment is 750~1150℃; The low-oxygen heat treatment time is 5 to 20 minutes.

2. The preparation method according to claim 1, characterized in that, The carrier surface is coated with a carbon layer doped with heteroatoms; The metal composite nanoparticles are loaded on the surface of a carrier and embedded in a heteroatom-doped carbon layer.

3. The preparation method according to claim 2, characterized in that, The metal composite nanoparticles include a first metal nanoparticle and a second metal oxide layer coated on the first metal nanoparticle. The mass ratio of the first metal nanoparticle to the second metal oxide is (3~5):1; The metal composite nanoparticles have a core-shell structure; The particle size of the metal composite nanoparticles is 2~20 nm; The first metal nanoparticles form a heterojunction with the second metal oxide.

4. The preparation method according to claim 2, characterized in that, The first metal includes one or more of the following: elemental metal, binary alloy, ternary alloy, and intermetallic compound; The metallic element includes one or more of Pt, Pd, Ru, and Au; The binary alloy includes one or more of PtCo, PtFe, PtCu, PtMn, PtNi, PtRu, PdFe, PdNi, PdCu, and PdPt; The ternary alloy includes one or more of PtCoNi, PtCoFe, PtNiFe, PtFeMn, PtNiMn, PtCoMn, PtCoCu, PtNiCu, PtFeCu, PtMnCu, PtCuW, PtRuFe, PtRuNi, PtRuMn, PtRuCo, PtRuCu, PdCoCu, PdCuNi, PdCuCo, PdCuFe, and PdCuMn; The second metal is at least one of the first metals.

5. The preparation method according to claim 2, characterized in that, The metal composite nanoparticles include metal heterojunction nanoparticles. The composite material containing metal composite nanoparticles is a catalyst containing metal composite nanoparticles. The metal composite nanoparticles are partially coated with a carbon layer doped with heteroatoms. The thickness of the heteroatom-doped carbon layer is 0.5~3 nm; The mass ratio of the heteroatom-doped carbon layer to the support is 1:(2~5).

6. The preparation method according to claim 2, characterized in that, The heteroatoms include non-metallic atoms or metallic atoms; The nonmetals include one or more of N, S, B, P, F and I; The metal includes one or more of Co, Fe, Cu and Ni; The carbon layer is formed by stacking carbon layers with atomic-level thickness; The number of atomic-level carbon layers is 2 to 8.

7. The preparation method according to claim 2, characterized in that, The carrier includes a carbon carrier or a doped carbon carrier; The carbon support includes one or more of XC-72, BP2000, graphite carbon, Ketjen black, carbon nanotubes, carbon nanospheres, and carbon nanosheets; The doping element of the doped carbon support includes one or more of N, S, B, P, F and I. The mass ratio of the metal composite nanoparticles to the carrier is 1:(2~5). In the composite material, the proportion of metal atoms to the total mass of the composite material is 5wt% to 20wt%.

8. The preparation method according to claim 1, characterized in that, The carrier includes a carbon carrier or a doped carbon carrier; The doped carbon support is obtained by mixing a dopant source and a carbon support and then pyrolyzing them at high temperature under a protective atmosphere, or by mixing a template and a heteroatom-containing organic small molecule carbon source and then polymerizing and sintering them. The doping source includes one or more of sulfur powder, boric acid, phosphoric acid, disodium hydrogen phosphate, melamine, and dihydrodiamine; The mass ratio of the dopant source to the carbon support is (2~5):1; The temperature of the high-temperature pyrolysis is 850~1000℃; The heating rate of the high-temperature pyrolysis is 1~10℃ / min; The heteroatom-containing organic small molecule carbon source includes one or more of aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, and thiophene.

9. The preparation method according to claim 1, characterized in that, The method for loading the first metal nanoparticles includes one or more of the following: ethylene glycol reduction, NaBH4 reduction, oleylamine reduction, and ascorbic acid reduction. The heteroatom-containing carbon source includes one or more of aniline, pyrrole, pyridine, 2,6-diaminopyridine, dopamine, thiophene, and metal-organic frameworks; Step 2) also includes an initiator, or the polymerization reaction is carried out by adjusting the pH value; The pyrolysis temperature is 350~1000℃; The pyrolysis time is 1 to 5 hours.

10. The application of the composite material containing metal composite nanoparticles prepared by the preparation method according to any one of claims 1 to 9 in the field of catalysts.

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