Sulfur-doped nanocarbon cage, preparation method thereof, and fuel cell catalyst

Abstract

The present invention relates to the technical field of novel nanocarbon materials, and discloses a sulfur-doped nanocarbon cage having a microporous structure and a mesoporous structure, wherein the BET specific surface area of ​​the nanocarbon cage is greater than 500 m 2 / g, the ratio of the specific surface area in the micropores to the total specific surface area is less than 30%; the total pore volume of the nanocarbon cage is greater than 1cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage is 80-98%, and the mass percentage of sulfur is 0.1-10% as measured by X-ray photoelectron spectroscopy. The sulfur-doped nanocarbon cage has a high specific surface area and a large amount of mesoporous structure and can be used as a carrier in fuel cell catalysts; the method provided by the present invention can simply and efficiently realize the preparation of sulfur-doped nanocarbon cages. The prepared sulfur-doped nanocarbon cage has a complete structure and low production cost, which is conducive to large-scale application.

Description

Technical Field

[0001] The present invention relates to the technical field of novel nano-carbon materials, and in particular to a sulfur-doped nano-carbon cage, a preparation method thereof, and a fuel cell catalyst. Background Art

[0002] Carbon nanocages are a unique new type of nanographite structure with a unique hollow structure similar to fullerenes and a relatively controllable nanosize. This unique hollow porous nanographite structure can give the material a series of unique physical and chemical properties, and is expected to be used in many fields such as industrial catalysis, electrochemical energy storage, drug carriers, and optical devices.

[0003] Hierarchical porous nanocarbon materials are a new type of porous nanocarbon materials that integrate different pore structures, such as micropores (less than 2nm), mesopores (2-50nm), or macropores (greater than 50nm). Compared with conventional carbon materials with a single pore structure, hierarchical porous carbon materials not only have high porosity characteristics, but also have a unique three-dimensional interconnected pore structure. Therefore, they have significant application advantages in the field of energy storage and conversion. On the one hand, the rich pore structure of hierarchical porous carbon materials can increase their electrochemically active surface area, thereby improving intrinsic activity; on the other hand, the three-dimensional interconnected pores they construct can provide multi-directional, high-throughput ion transport channels, thereby accelerating the kinetics of surface / interface electrochemical reactions.

[0004] While hierarchical pore structures enable precise control of pore structure to a certain extent, the backbones of most hierarchical porous carbon materials are primarily composed of sp2 and sp3 hybridized carbon atoms. This single component composition results in a lack of functionality, hindering further advancements and breakthroughs in their applications in energy storage and conversion, as well as catalysis. Leveraging the structural advantages of three-dimensional interconnected pores and introducing other atoms into the carbon backbone and surface is an effective approach to enhancing their energy storage and conversion, catalytic, and other properties. The introduction of heteroatoms can modulate the surface chemical structure, offsetting the functional limitations of the single carbon backbone component, and thereby enhancing intrinsic activity.

[0005] In current research, the doping of carbon materials is generally achieved by first preparing a carbon material with a certain structure, then mixing the carbon material with a compound containing heteroatoms, drying, calcining, acid-washing and purification, and then drying it again. This process has cumbersome operating steps, high production costs, and is easy to destroy the original structure of the carbon material. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of cumbersome doping steps, high production costs, and easy destruction of the original structure of carbon materials in existing carbon materials, and to provide a sulfur-doped nanocarbon cage and its preparation method and fuel cell catalyst. The method provided by the present invention can simply and efficiently realize the preparation of sulfur-doped nanocarbon cages. The sulfur-doped nanocarbon cages have a high specific surface area and a large number of mesoporous structures, and can be used as a carrier in fuel cell catalysts.

[0007] In order to achieve the above object, the present invention provides a sulfur-doped nanocarbon cage in the first aspect, wherein the nanocarbon cage has a microporous structure and a mesoporous structure, and the BET specific surface area of ​​the nanocarbon cage is greater than 500m 2 / g, the ratio of the specific surface area in the micropores to the total specific surface area is less than 30%; the total pore volume of the nanocarbon cage is greater than 1cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage measured by X-ray photoelectron spectroscopy is 80-98%, and the mass percentage of sulfur is 0.1-10%.

[0008] A second aspect of the present invention provides a method for preparing sulfur-doped nanocarbon cages, the method comprising the following steps:

[0009] (1) Precursor preparation: providing a homogeneous solution containing a nickel source, a polybasic organic carboxylic acid, a sulfur source, and a solvent, and then removing the solvent from the homogeneous solution to obtain a complex precursor material, wherein the sulfur source is selected from a Group IA bisulfate and / or sulfate;

[0010] (2) calcining: calcining the complex precursor material obtained in step (1) at a constant temperature of 450-700° C. under an inert atmosphere to obtain a pyrolysis product;

[0011] (3) Acid washing: providing an aqueous solution containing the pyrolysis product obtained in step (2), and contacting it with an acid for reaction, followed by solid-liquid separation, washing and drying.

[0012] A third aspect of the present invention provides a fuel cell catalyst, comprising a carrier and metal Pt supported on the carrier, wherein the carrier is the nanocarbon cage described in the first aspect or the nanocarbon cage prepared according to the method described in the second aspect.

[0013] Through the above technical solution, the present invention has the following advantages:

[0014] (1) The sulfur-doped nanocarbon cage provided by the present invention has a microporous structure and a mesoporous structure, and the BET specific surface area is greater than 500 m 2 / g, the proportion of micropore specific surface area to total specific surface area is less than 30%; the total pore volume is greater than 1cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage measured by X-ray photoelectron spectroscopy is 80-98%, and the mass percentage of sulfur is 0.1-10%; the sulfur-doped nanocarbon cage provided by the present invention has a high specific surface area and a large amount of mesoporous structure, and can be used as a carrier in fuel cell catalysts; preferably, the sulfur-doped nanocarbon cage provided by the present invention also has a spherical or quasi-spherical morphology and a certain degree of graphitization.

[0015] (2) The preparation method provided by the present invention uses sulfate / bisulfate as a sulfur source and activator, and is combined with a nickel source and a polybasic organic carboxylic acid to prepare a complex precursor material. By controlling the calcination temperature, sulfur-doped nanocarbon cages with a microporous structure and a large number of mesoporous structures are prepared. The method of the present invention can simply and efficiently realize the preparation of sulfur-doped nanocarbon cages. The prepared sulfur-doped nanocarbon cages have a complete structure and low production cost, which is conducive to large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage prepared in Example 1;

[0017] Figure 2 is an X-ray photoelectron spectroscopy (XPS) graph of the sulfur-doped nanocarbon cage prepared in Example 1;

[0018] Figure 3 This is the XPS S2p spectrum of the sulfur-doped nanocarbon cage prepared in Example 1;

[0019] Figure 4 is the nitrogen isothermal adsorption / desorption curve of the sulfur-doped nanocarbon cage prepared in Example 1;

[0020] Figure 5 is the mesopore size and volume distribution curve of the sulfur-doped nanocarbon cage prepared in Example 1;

[0021] Figure 6 is the micropore size and volume distribution curve of the sulfur-doped nanocarbon cage prepared in Example 1;

[0022] Figure 7 This is a high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage prepared in Example 3;

[0023] Figure 8 This is a high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage prepared in Example 4;

[0024] Figure 9 This is a high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage prepared in Example 5;

[0025] Figure 10This is the XPS spectrum of the nano-carbon material prepared in Comparative Example 1;

[0026] Figure 11 is the nitrogen isothermal adsorption / desorption curve of the nano-carbon material prepared in Comparative Example 1;

[0027] Figure 12 This is the pore volume and pore size distribution curve of the nano-carbon material prepared in Comparative Example 1;

[0028] Figure 13 This is the XPS spectrum of the nano-carbon material prepared in Comparative Example 2. DETAILED DESCRIPTION

[0029] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0030] The first aspect of the present invention provides a sulfur-doped nanocarbon cage, wherein the nanocarbon cage has a microporous structure and a mesoporous structure, and the BET specific surface area of ​​the nanocarbon cage is greater than 500 m 2 / g, the ratio of the specific surface area in the micropores to the total specific surface area is less than 30%; the total pore volume of the nanocarbon cage is greater than 1cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage measured by X-ray photoelectron spectroscopy is 80-98%, and the mass percentage of sulfur is 0.1-10%.

[0031] According to some embodiments of the present invention, the nanocarbon cage has a microporous structure and a mesoporous structure, and the BET specific surface area of ​​the nanocarbon cage is greater than 500m 2 / g, the ratio of the specific surface area in the micropores to the total specific surface area is less than 30%, preferably, the BET specific surface area of ​​the nanocarbon cage is 500-1600m 2 / g, and the proportion of the specific surface area in micropores to the total specific surface area is less than 20%.

[0032] According to some embodiments of the present invention, the total pore volume of the nanocarbon cage is greater than 1 cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%, preferably, the total pore volume of the nanocarbon cage is greater than 1.4cm 3 / g, the proportion of micropore volume to total pore volume is less than 10%, more preferably, the total pore volume of the nanocarbon cage is 1.4-3.6cm 3 / g, and the proportion of micropore volume to total pore volume is 2.5-4.5%.

[0033] According to some embodiments of the present invention, preferably, in the pore size distribution curve of the nanocarbon cage, there is a micropore distribution peak at 0.59-0.63 nm, and there are two mesopore distribution peaks at 2.73-4.1 nm and 3.877-15.6 nm.

[0034] In the present invention, the pore structure properties of the sulfur-doped nanocarbon cages were determined using the BET test method. Specifically, a Quantachrome AS-6B analyzer was used for measurement. The BET specific surface area and pore volume of the nanocarbon cages were obtained using the Brunauer-Emmett-Taller (BET) method. The mesopore distribution curve was calculated from the desorption curve using the Barrett-Joyner-Halenda (BJH) method, and the micropore size distribution curve was calculated from the isotherm curve using the Horvath-Kawazoe (HK) method.

[0035] According to some embodiments of the present invention, the mass percentage of carbon on the surface of the nanocarbon cage measured by X-ray photoelectron spectroscopy is 80-98%, and the mass percentage of sulfur is 0.1-10%. Preferably, the mass percentage of carbon on the surface of the nanocarbon cage measured by X-ray photoelectron spectroscopy is 84-95%, and the mass percentage of sulfur is 0.2-5%.

[0036] According to some embodiments of the present invention, the sulfur-doped nanocarbon cages may further contain oxygen, which may be oxygen in various forms formed on the surface of the sulfur-doped nanocarbon cages during the preparation process. Preferably, the mass percentage of oxygen on the surface of the nanocarbon cages, as measured by X-ray photoelectron spectroscopy, is 2-15%, more preferably 4-15%.

[0037] According to some embodiments of the present invention, the sulfur-doped nanocarbon cage may contain doping elements known to those skilled in the art that can be applied to nanocarbon materials. Preferably, the sulfur-doped nanocarbon cage does not contain elements such as nickel, nitrogen, boron, phosphorus, fluorine, chlorine, bromine, and iodine.

[0038] According to some embodiments of the present invention, the content of carbon, sulfur, and oxygen on the surface of the sulfur-doped nanocarbon cage is measured using X-ray photoelectron spectroscopy. X-ray photoelectron spectroscopy analysis is performed on an ESCALab250 X-ray photoelectron spectrometer equipped with Thermo Avantage V5.926 software from Thermo Scientific. The excitation source is monochromatic Al Kα X-ray with an energy of 1486.6 eV and a power of 150 W. The penetration energy used in the narrow scan is 30 eV. The base vacuum during the analysis test is 6.53×10 -9 mbar. Electron binding energies were calibrated using the C1s peak of elemental carbon (284.6 eV). Data processing was performed using ThermoAvantage software, and quantitative analysis was performed using the sensitivity factor method in the analysis module. Prior to testing, the sulfur-doped nanocarbon cages were dried in a helium atmosphere at 150°C and 1 standard atmosphere for 3 hours.

[0039] According to some embodiments of the present invention, preferably, the nanocarbon cage has a spherical or spherical morphology. Preferably, the diameter of the nanocarbon cage is 2-200 nm, preferably 3-50 nm. In the present invention, the surface morphology of the material is characterized by high-resolution transmission electron microscopy (HRTEM), and the model of the high-resolution transmission electron microscope used is JEM-2100 (JEOL Ltd.), and the high-resolution transmission electron microscope test conditions are: accelerating voltage 200 kV. The diameter of the nanocarbon cage can be measured by high-resolution transmission electron microscope images.

[0040] According to some embodiments of the present invention, preferably, in the Raman curve of the nanocarbon cage, I D / I G The range is 0.5-1.5, preferably 0.5-1.1. The nanocarbon cage of the present invention has obvious D peak and G peak, and has a certain degree of graphitization. In the present invention, the Raman test of the nanocarbon cage adopts visible laser Raman measurement method, using 532nm light source to perform Raman characterization on the functional groups of the nanocarbon cage to obtain a characteristic spectrum.

[0041] According to some embodiments of the present invention, preferably, in the X-ray photoelectron spectrum of the nanocarbon cage, the nanocarbon cage has characteristic peaks of sulfur at 161±1eV, 162-166eV and 168±2eV, or has characteristic peaks of sulfur at 162-166eV and 168±2eV.

[0042] According to some embodiments of the present invention, preferably, the mass percentage of sulfur, as determined by a characteristic peak corresponding to 162-166 eV in the X-ray photoelectron spectrum of the nanocarbon cage, is 2-90%, preferably 70-88%, based on the total amount of sulfur on the surface of the nanocarbon cage. In the present invention, the characteristic peak of sulfur in the X-ray photoelectron spectrum of the nanocarbon cage is located at 162-166 eV, indicating that the sulfur in the nanocarbon cage of the present invention is combined with carbon to form a C-S bond, and exists in the form of thiophene sulfur.

[0043] In the present invention, the "sulfur" in the term "sulfur-doped nanocarbon cage" refers to elemental sulfur, and specifically refers to elemental sulfur in various forms formed on the surface of the sulfur-doped nanocarbon cage during the preparation process of the sulfur-doped nanocarbon cage.

[0044] In the present invention, the term "mesopore" is defined as a pore with a pore diameter in the range of 2-50 nm. Pores with a pore diameter less than 2 nm are defined as "micropores".

[0045] A second aspect of the present invention provides a method for preparing sulfur-doped nanocarbon cages, the method comprising the following steps:

[0046] (1) Precursor preparation: providing a homogeneous solution containing a nickel source, a polybasic organic carboxylic acid, a sulfur source, and a solvent, and then removing the solvent from the homogeneous solution to obtain a complex precursor material, wherein the sulfur source is selected from a Group IA bisulfate and / or sulfate;

[0047] (2) calcining: calcining the complex precursor material obtained in step (1) at a constant temperature of 450-700° C. under an inert atmosphere to obtain a pyrolysis product;

[0048] (3) Acid washing: providing an aqueous solution containing the pyrolysis product obtained in step (2), and contacting it with an acid for reaction, followed by solid-liquid separation, washing and drying.

[0049] According to some embodiments of the present invention, the method for preparing sulfur-doped nanocarbon cages uses sulfate / bisulfate as a sulfur source and activator, and simultaneously prepares a complex precursor material with a nickel source and a polybasic organic carboxylic acid. By controlling the calcination temperature, a sulfur-doped nanocarbon cage with a microporous structure and a mesoporous structure is prepared. The BET specific surface area of ​​the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, the proportion of micropore specific surface area to total specific surface area is less than 30%; the total pore volume is greater than 1cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage measured by X-ray photoelectron spectroscopy is 80-98%, and the mass percentage of sulfur is 0.1-10%. The method of the present invention can simply and efficiently achieve the preparation of sulfur-doped nanocarbon cages. The prepared sulfur-doped nanocarbon cages have a complete structure, a high specific surface area, and a large amount of mesoporous structure.

[0050] According to some embodiments of the present invention, the sulfur-doped nanocarbon cage may contain doping elements known to those skilled in the art that can be applied to nanocarbon materials. Preferably, the sulfur-doped nanocarbon cage does not contain elements such as nickel, nitrogen, boron, phosphorus, fluorine, chlorine, bromine, and iodine.

[0051] According to some embodiments of the present invention, in step (1), there is no particular limitation on the method for forming the homogeneous solution. For example, the homogeneous solution may be formed by heating, more preferably by heating and stirring. The present invention also does not particularly limit the heating temperature and stirring rate, as long as the homogeneous solution can be formed.

[0052] According to some embodiments of the present invention, preferably, in step (1), the complex precursor material is a complex precursor material obtained by dissolving a nickel source, a polybasic organic carboxylic acid and a sulfur source in a solvent to form a homogeneous solution, and then removing the solvent in the homogeneous solution. There is no particular limitation on the type of the solvent, and the solvent is based on the ability to form a homogeneous solution. Preferably, the solvent is water and / or ethanol, more preferably water; the present invention does not have any particular limitation on the amount of the solvent, and the solvent is also based on the ability to form a homogeneous solution. The solvent in the homogeneous solution can be removed by direct evaporation, and the temperature and process of evaporation can adopt existing technologies known to those skilled in the art. For example, the solvent in the homogeneous solution can be removed by heating and evaporating to dryness.

[0053] According to some embodiments of the present invention, preferably, in step (1), the nickel source is selected from one or more of organic acid salts, carbonates and basic carbonates containing nickel, preferably carbonates and / or basic carbonates containing nickel, more preferably basic nickel carbonate.

[0054] According to some embodiments of the present invention, preferably, the sulfur source is selected from one or more of potassium sulfate, sodium sulfate, potassium bisulfate and sodium bisulfate, more preferably potassium bisulfate and / or sodium bisulfate, further preferably potassium bisulfate.

[0055] According to some embodiments of the present invention, preferably, the polybasic organic carboxylic acid is selected from one or more of citric acid, maleic acid, trimesic acid, terephthalic acid and malic acid, more preferably citric acid and / or terephthalic acid.

[0056] According to some embodiments of the present invention, preferably, the molar ratio of the nickel source, the polybasic organic carboxylic acid, and the sulfur source, calculated as nickel element, is 1:0.1-10:0.1-2, preferably 1:0.5-3:0.3-2, and more preferably 1:0.7-1.5:0.5-1.2. This preferred embodiment is more conducive to obtaining hierarchical porous nanocarbon cages with a high specific surface area containing both micropores and mesopores.

[0057] According to some embodiments of the present invention, preferably, in step (2), the inert atmosphere is provided by at least one of nitrogen, argon, neon and helium, preferably a nitrogen atmosphere.

[0058] According to some embodiments of the present invention, in step (2), the constant temperature roasting temperature is 450-700° C., preferably, the constant temperature roasting temperature is 500-650° C. In the present invention, if the constant temperature roasting temperature is too low, the nickel element in the nanocarbon material cannot be completely removed, while if the temperature is too high, the structure of the nanocarbon cage will be affected and the yield of the carbon cage will be reduced. Only by controlling the constant temperature roasting temperature within the above-defined range can the preparation of sulfur-doped nanocarbon cages be achieved.

[0059] According to some embodiments of the present invention, preferably, the roasting method includes: heating to a constant temperature section at a rate of 0.5-30°C / min, preferably heating to a constant temperature section at a rate of 1-10°C / min; maintaining a constant temperature in the constant temperature section for 20-600 min, preferably 60-480 min.

[0060] According to some embodiments of the present invention, in step (3), the acid can be any acid commonly used in the art, as long as it can remove the nickel element from the pyrolysis product. Preferably, the acid is an aqueous solution of an inorganic acid and / or an aqueous solution of an organic acid, preferably one or more of an aqueous solution of hydrochloric acid, an aqueous solution of sulfuric acid, an aqueous solution of nitric acid, and an aqueous solution of citric acid, more preferably an aqueous solution of hydrochloric acid. Preferably, the concentration of the aqueous solution of an inorganic acid and / or an aqueous solution of an organic acid is 0.1-10 mol / L; and the pH value of the acid is less than 7. The present invention has no particular requirements for the amount of the acid used, as long as it can remove the nickel element from the pyrolysis product.

[0061] According to some embodiments of the present invention, preferably, in step (3), the temperature for contact reaction of the aqueous solution of the pyrolysis product with the acid is 20-120° C., preferably 60-100° C.; and the time for contact reaction is 0.1-48 h, preferably 4-12 h.

[0062] According to some embodiments of the present invention, the washing is used to remove the acid remaining on the sulfur-doped nanocarbon cages caused by the acid washing process. Therefore, various water washing methods that can wash the sulfur-doped nanocarbon cages to neutrality are applicable to the present invention.

[0063] According to some embodiments of the present invention, drying is used to remove water from the sulfur-doped nanocarbon cages. Drying can be performed at normal pressure or reduced pressure. Drying conditions may include: a temperature of 100-120° C. and a time of 6-10 hours.

[0064] According to some embodiments of the present invention, preferably, the nickel source, polybasic organic carboxylic acid and sulfur source are used in such an amount that the mass percentage of carbon on the surface of the prepared sulfur-doped nanocarbon cage is 80-98%, and the mass percentage of sulfur is 0.1-10%.

[0065] According to some embodiments of the present invention, more preferably, the nickel source, polybasic organic carboxylic acid and sulfur source are used in such an amount that the mass percentage of carbon on the surface of the prepared sulfur-doped nanocarbon cage is 84-95%, and the mass percentage of sulfur is 0.2-5%.

[0066] According to some embodiments of the present invention, the sulfur-doped nanocarbon cages prepared by the method of the present invention may contain doping elements that are known to those skilled in the art and can be applied to nanocarbon materials. Preferably, the sulfur-doped nanocarbon cages do not contain elements such as nickel, nitrogen, boron, phosphorus, fluorine, chlorine, bromine, and iodine.

[0067] A third aspect of the present invention provides a fuel cell catalyst, comprising a carrier and metal Pt supported on the carrier, wherein the carrier is the nanocarbon cage described in the first aspect or the nanocarbon cage prepared according to the method described in the second aspect.

[0068] According to some embodiments of the present invention, the fuel cell catalyst can be prepared using a method for preparing a fuel cell catalyst known in the art, and the present invention is not particularly limited thereto. Preferably, the method for preparing the fuel cell catalyst comprises:

[0069] (a) dispersing the sulfur-doped nanocarbon cages in a solvent, and then adding a platinum compound to the solvent in which the sulfur-doped nanocarbon cages are dispersed to obtain a suspension;

[0070] (b) contacting a reducing agent with the suspension.

[0071] According to some embodiments of the present invention, the solvent can be any solvent known in the art for preparing fuel cell catalysts, preferably at least one of water, ethanol, and ethylene glycol. Preferably, the amount of the solvent used is 50-1500 mL per gram of sulfur-doped nanocarbon cages.

[0072] According to some embodiments of the present invention, the platinum compound can be any platinum compound known in the art for use in preparing fuel cell catalysts, such as at least one of chloroplatinic acid, chloroplatinates, platinum chloride, platinum nitrate, and platinum complexes, preferably chloroplatinic acid. Preferably, the molar ratio of the sulfur-doped nanocarbon cage to the platinum compound, calculated as elemental platinum, is 10-70:1.

[0073] According to some embodiments of the present invention, the reducing agent can be a reducing agent known in the art, for example, at least one of formaldehyde, formic acid, sodium thiosulfate, sodium borohydride and potassium borohydride, preferably formic acid. Preferably, the molar ratio of the reducing agent to the platinum compound calculated as platinum element is 2-10:1

[0074] According to some embodiments of the present invention, preferably, the pH of the suspension is 9-11.

[0075] According to some embodiments of the present invention, preferably, the reducing agent is contacted with the suspension at a temperature of 30-90° C. for a contact time of 0.1-8 hours. Preferably, after contacting the reducing agent with the suspension, the method further comprises filtering the reaction mixture, washing the filter cake obtained by filtration, and drying the filter cake.

[0076] According to some embodiments of the present invention, preferably, based on the total weight of the fuel cell catalyst, the loading amount of Pt in the fuel cell catalyst is 40 wt %.

[0077] The sulfur-doped nanocarbon cage provided by the present invention has a high specific surface area and a large amount of mesoporous structure, and can be used as a carrier in fuel cell catalysts. Since the present invention only involves the improvement of the carrier, there is no special restriction on the other composition and structure of the fuel cell catalyst when the sulfur-doped nanocarbon cage of the present invention is applied to the fuel cell catalyst. When the Pt / C catalyst prepared by the sulfur-doped nanocarbon cage provided by the present invention is applied to the redox reaction, the half-wave potential is 0.860-0.871V and the electrochemical active area (ECSA) is 50.61-100.44m 2 g -1 -Pt, mass specific activity is 0.069-0.089A mg -1 -Pt, area specific activity of 0.083-0.138 mA mg -1 -Pt.

[0078] The present invention will be described in detail below through examples.

[0079] Unless otherwise specified, all reagents used in the present invention are of analytical grade and commercially available.

[0080] The surface morphology of the material was characterized using high-resolution transmission electron microscopy (HRTEM). The microscope used was a JEM-2100 (JEOL Ltd.) at an accelerating voltage of 200 kV. The diameter of the sulfur-doped nanocarbon cages was measured from the HRTEM images.

[0081] The pore structure properties of the material were determined using the BET test method. Specifically, a Quantachrome AS-6B analyzer was used. The specific surface area and pore volume of the material were obtained using the Brunauer-Emmett-Taller (BET) method. The mesopore distribution curve was calculated from the desorption curve using the Barrett-Joyner-Halenda (BJH) method. The micropore size distribution curve was calculated from the isotherm curve using the Horvath-Kawazoe (HK) method.

[0082] The content of various elements on the surface of the materials and the content of various sulfur and oxygen species were determined by X-ray photoelectron spectroscopy (XPS). The X-ray photoelectron spectroscopy analysis was performed on an ESCALab250 X-ray photoelectron spectrometer equipped with Thermo Avantage V5.926 software from Thermo Scientific. The excitation source was monochromatic Al Kα X-ray with an energy of 1486.6 eV and a power of 150 W. The penetration energy used for narrow scanning was 30 eV. The base vacuum during the analysis was 6.53×10 - 9 mbar. Electron binding energies were calibrated using the C1s peak of elemental carbon (284.6 eV). Data processing was performed using Thermo Avantage software, and quantitative analysis was performed using the sensitivity factor method in the analysis module. Prior to testing, the material was dried in a helium atmosphere at 150°C and 1 standard atmosphere for 3 hours.

[0083] The Raman test uses visible laser Raman measurement method and uses a 532nm light source to perform Raman characterization on the functional groups of the nanocarbon cage to obtain a characteristic spectrum.

[0084] The electrochemical performance of the Pt / C catalyst was tested in accordance with GB / T 20042.4-2009 Test method for proton exchange membrane fuel cell electrocatalysts.

[0085] Examples 1-5 are used to illustrate sulfur-doped nanocarbon cages and their preparation methods.

[0086] Example 1

[0087] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), polybasic organic carboxylic acid and sulfur source of 1:0.7:1, 30 g of basic nickel carbonate, 29.4 g of citric acid and 27.8 g of potassium hydrogen sulfate were weighed and added to a beaker containing 50 mL of deionized water, and stirred at 70 ° C to obtain a homogeneous solution, which was further heated and evaporated to dryness to obtain a complex precursor material;

[0088] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 100 mL / min, and the temperature is raised to 650°C at a rate of 2.5°C / min. After holding the temperature for 2 h, heating is stopped and the product is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0089] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 10 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 140 °C for 2 h to obtain sulfur-doped nanocarbon cages.

[0090] The high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage is shown in Figure 2. Figure 1 As shown, from Figure 1 It can be seen that the sulfur-doped nanocarbon cage has a spherical or quasi-spherical morphology, and the diameter of the nanocarbon cage is 20-30 nm.

[0091] The X-ray photoelectron spectroscopy (XPS) of the sulfur-doped nanocarbon cage is shown in Figure 2. Figure 2 As shown, from Figure 2 Clear XPS peaks for C, O, and S are visible, demonstrating effective sulfur doping. Based on the peak areas, the mass percentages of each element on the surface of the sulfur-doped nanocarbon cages can be calculated: carbon (91.81%), oxygen (4.95%), and sulfur (3.24%).

[0092] The XPS S2p spectrum of the sulfur-doped nanocarbon cage is as follows Figure 3 As shown in the figure, it can be seen that there are characteristic peaks of sulfur at 162-166eV and 168±2eV. According to the product peak area after peak separation, it can be calculated that the sulfur content corresponding to the characteristic peak at 162-166eV accounts for 86.44% of the total sulfur content.

[0093] The isothermal adsorption-desorption curves and pore volume and pore size distribution curves of the sulfur-doped nanocarbon cage are shown as follows: Figure 4 、 Figure 5 and Figure 6 As shown in Figure 2, the BET specific surface area of ​​sulfur-doped nanocarbon cages was calculated to be 1539.772 m 2 / g, the specific surface area in micropores is 221.386m 2 / g, accounting for 14.4% of the total specific surface area; the total pore volume of sulfur-doped nanocarbon cages is 3.523 cm 3 / g, micropore volume is 0.1cm 3 / g, accounting for 2.84% of the total pore volume; from the pore volume and pore size distribution curve, it can be seen that the micropore volume and pore size distribution curve has a distribution peak at 0.62nm, and the mesopore volume and pore size distribution curve has two distribution peaks at 3.94nm and 12.3nm, indicating that the sulfur-doped nanocarbon cage is a nanocarbon material with microporous structure and mesoporous structure.

[0094] Raman testing shows that the sulfur-doped nanocarbon cage has obvious D peak and G peak, I D / I G =1.005, indicating that the nanocarbon material has a certain degree of graphitization.

[0095] Example 2

[0096] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), polybasic organic carboxylic acid and sulfur source of 1:1.2:1, 30 g of basic nickel carbonate, 50.37 g of citric acid and 27.8 g of potassium hydrogen sulfate were weighed and added to a beaker containing 50 mL of deionized water, and stirred at 70 ° C to obtain a homogeneous solution, which was further heated and evaporated to dryness to obtain a complex precursor material;

[0097] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 60 mL / min, and the temperature is raised to 600°C at a rate of 2.5°C / min. After holding the temperature for 2 h, heating is stopped and the product is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0098] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 10 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 140 °C for 2 h to obtain sulfur-doped nanocarbon cages.

[0099] High-resolution transmission electron microscopy observation and measurement show that the sulfur-doped nanocarbon cage has a spherical or quasi-spherical morphology, and the diameter of the nanocarbon cage is 5-20 nm.

[0100] X-ray photoelectron spectroscopy (XPS) analysis revealed that the surface carbon content of the sulfur-doped nanocarbon cage was 86.89% by mass, the oxygen content was 10.35% by mass, and the sulfur content was 2.76% by mass. The XPS S2p spectrum of the sulfur-doped nanocarbon cage exhibited characteristic sulfur peaks at 161±2 eV, 162-166 eV, and 168±2 eV. Based on the product of peak areas after peak separation, it was calculated that the sulfur content corresponding to the characteristic peak at 162-166 eV accounted for 79.6% of the total sulfur content.

[0101] The BET specific surface area of ​​the sulfur-doped nanocarbon cage was 1096.314 m 2 / g, the specific surface area in micropores is 186.416m 2 / g, accounting for 17.0% of the total specific surface area; the total pore volume of sulfur-doped nanocarbon cages is 2.761 cm 3 / g, and the micropore volume is 0.087cm 3 / g, accounting for 3.15% of the total pore volume; the micropore volume and pore size distribution curve of the sulfur-doped nanocarbon cage has a distribution peak at 0.63nm, and the mesopore volume and pore size curve has two distribution peaks at 3.7nm and 10nm, indicating that the sulfur-doped nanocarbon cage is a nanocarbon material with microporous structure and mesoporous structure.

[0102] Raman testing shows that the sulfur-doped nanocarbon cage has obvious D peak and G peak, I D / I G =0.823, indicating that the nanocarbon material has a certain degree of graphitization.

[0103] Example 3

[0104] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), polybasic organic carboxylic acid and sulfur source of 1:1.2:0.7, 30 g of basic nickel carbonate, 50.37 g of citric acid and 19.5 g of potassium hydrogen sulfate were weighed and added to a beaker containing 70 mL of deionized water, and stirred at 70°C to obtain a homogeneous solution, which was then heated and evaporated to dryness to obtain a complex precursor material;

[0105] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 100 mL / min, and the temperature is raised to 500°C at a rate of 5°C / min. After maintaining the temperature for 2 h, heating is stopped and the mixture is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0106] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 8 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 120 °C for 2 h to obtain sulfur-doped nanocarbon cages.

[0107] The high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage is shown in Figure 2. Figure 7 As shown, from Figure 7 It can be seen that the sulfur-doped nanocarbon cage has a spherical or quasi-spherical morphology, and the diameter of the nanocarbon cage is 5-15 nm.

[0108] X-ray photoelectron spectroscopy (XPS) analysis revealed that the surface carbon content of the sulfur-doped nanocarbon cage was 90.68% by mass, the oxygen content was 8.74% by mass, and the sulfur content was 0.58% by mass. The XPS S2p spectrum of the sulfur-doped nanocarbon cage exhibited characteristic sulfur peaks at 161±2 eV, 162-166 eV, and 168±2 eV. Based on the product of peak areas after peak separation, it was calculated that the sulfur content corresponding to the characteristic peak at 162-166 eV accounted for 73.68% of the total sulfur content.

[0109] The BET specific surface area of ​​the sulfur-doped nanocarbon cage was 524.312 m 2 / g, and the specific surface area in micropores is 52.68m 2 / g, accounting for 8.4% of the total specific surface area; the total pore volume of sulfur-doped nanocarbon cages is 1.456 cm 3 / g, and the micropore volume is 0.057cm 3 / g, accounting for 3.9% of the total pore volume; the micropore volume and pore size distribution curve of the sulfur-doped nanocarbon cage has a distribution peak at 0.59nm, and the mesopore volume and pore size curve has two distribution peaks at 4.1nm and 15.6nm, indicating that the sulfur-doped nanocarbon cage is a nanocarbon material with microporous structure and mesoporous structure.

[0110] Raman testing shows that the sulfur-doped nanocarbon cage has obvious D peak and G peak, I D / I G =0.748, indicating that the nanocarbon material has a certain degree of graphitization.

[0111] Example 4

[0112] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), polybasic organic carboxylic acid and sulfur source of 1:1.2:0.5, 30 g of basic nickel carbonate, 66.45 g of terephthalic acid and 14 g of potassium hydrogen sulfate were weighed and added to a beaker containing 50 mL of deionized water, and stirred at 70°C to obtain a homogeneous solution, which was then heated and evaporated to dryness to obtain a complex precursor material;

[0113] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 300 mL / min, and the temperature is raised to 500°C at a rate of 5°C / min. After maintaining the temperature for 2 h, heating is stopped and the mixture is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0114] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 8 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 120 °C for 2 h to obtain sulfur-doped nanocarbon cages.

[0115] The high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage is shown in Figure 2. Figure 8 As shown, from Figure 8 It can be seen that the sulfur-doped nanocarbon cage has a spherical or quasi-spherical morphology, and the diameter of the nanocarbon cage is 5-15 nm.

[0116] X-ray photoelectron spectroscopy (XPS) analysis revealed that the surface carbon content of the sulfur-doped nanocarbon cage was 94.07% by mass, the oxygen content was 4.5% by mass, and the sulfur content was 1.43% by mass. The XPS S2p spectrum of the sulfur-doped nanocarbon cage exhibited characteristic sulfur peaks at 161±2 eV, 162-166 eV, and 168±2 eV. Based on the product of peak areas after peak separation, it was calculated that the sulfur content corresponding to the characteristic peak at 162-166 eV accounted for 84.31% of the total sulfur content.

[0117] The BET specific surface area of ​​the sulfur-doped nanocarbon cage was 1286.850 m 2 / g, the specific surface area in micropores is 190.015m 2 / g, accounting for 14.76% of the total specific surface area; the total pore volume of sulfur-doped nanocarbon cages is 2.044 cm 3 / g, micropore volume is 0.088cm 3 / g, accounting for 4.3% of the total pore volume; the micropore volume and pore size distribution curve of the sulfur-doped nanocarbon cage has a distribution peak at 0.62nm, and the mesopore volume and pore size curve has two distribution peaks at 2.73nm and 3.877nm, indicating that the sulfur-doped nanocarbon cage is a nanocarbon material with microporous structure and mesoporous structure.

[0118] Raman testing shows that the sulfur-doped nanocarbon cage has obvious D peak and G peak, I D / I G =0.657, indicating that the nanocarbon material has a certain degree of graphitization.

[0119] Example 5

[0120] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), polybasic organic carboxylic acid and sulfur source of 1:0.7:1, 30 g of basic nickel carbonate, 29.4 g of citric acid and 24 g of sodium bisulfate were weighed and added to a beaker containing 100 mL of deionized water, stirred at 70 ° C to obtain a homogeneous solution, and continued to heat and evaporate to dryness to obtain a complex precursor material;

[0121] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 300 mL / min, and the temperature is raised to 650°C at a rate of 5°C / min. After the temperature is kept constant for 2 h, heating is stopped and the product is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0122] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 8 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 120 °C for 2 h to obtain sulfur-doped nanocarbon cages.

[0123] The high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage is shown in Figure 2. Figure 9 As shown, from Figure 9 It can be seen that the sulfur-doped nanocarbon cage has a spherical or quasi-spherical morphology, and the diameter of the nanocarbon cage is 10 nm.

[0124] X-ray photoelectron spectroscopy (XPS) analysis revealed that the surface carbon content of the sulfur-doped nanocarbon cage was 92.51% by mass, the oxygen content was 5.36% by mass, and the sulfur content was 2.13% by mass. The XPS S2p spectrum of the sulfur-doped nanocarbon cage exhibited characteristic sulfur peaks at 161±2 eV, 162-166 eV, and 168±2 eV. Based on the product of peak areas after peak separation, it was calculated that the sulfur content corresponding to the characteristic peak at 162-166 eV accounted for 79.56% of the total sulfur content.

[0125] The BET specific surface area of ​​the sulfur-doped nanocarbon cage was 678.217 m 2 / g, the specific surface area in micropores is 124.5m 2 / g, accounting for 18.3% of the total specific surface area; the total pore volume of sulfur-doped nanocarbon cages is 1.742 cm 3 / g, and the total pore volume of micropores is 0.073 cm 3 / g, accounting for 4.2% of the total pore volume; the micropore volume and pore size distribution curve of the sulfur-doped nanocarbon cage has a distribution peak at 0.63nm, and the mesopore volume and pore size curve has two distribution peaks at 3.86nm and 12.3nm, indicating that the sulfur-doped nanocarbon cage is a nanocarbon material with microporous structure and mesoporous structure.

[0126] Raman testing shows that the sulfur-doped nanocarbon cage has obvious D peak and G peak, I D / I G =0.925, indicating that the nanocarbon material has a certain degree of graphitization.

[0127] Comparative Example 1

[0128] (1) Preparation of precursor: 30 g of basic nickel carbonate and 30 g of citric acid were weighed and added to a beaker containing 30 mL of deionized water. The mixture was stirred at 70° C. to obtain a homogeneous solution, which was then heated and evaporated to dryness to obtain a complex precursor material.

[0129] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 200 mL / min, and the temperature is raised to 600°C at a rate of 10°C / min. After maintaining the temperature for 2 h, heating is stopped and the mixture is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0130] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 10 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 140 °C for 2 h to obtain the nanocarbon material.

[0131] The X-ray photoelectron spectroscopy (XPS) of the nanocarbon material is shown in FIG. Figure 10 As shown in the figure, it can be seen that there are obvious XPS peaks of Ni, C, and O, which proves that nickel is present in the nano-carbon material and has not been completely removed. The mass percentage of each element on the surface of the nano-carbon material was calculated based on its peak area, among which the mass percentage of nickel is 8.26%, the mass percentage of carbon is 83.11%, and the mass percentage of oxygen is 8.54%.

[0132] The isothermal adsorption-desorption curve and pore volume and pore size distribution curve of the nanocarbon material are shown in Figures 2 and 3. Figure 11 and Figure 12 As shown in the figure, the BET specific surface area of ​​the nanocarbon material was calculated to be 264.968 m 2 / g, the specific surface area in the micropores is 0; the pore volume of the nanocarbon material is 0.677cm 3 / g, the micropore volume is 0; the pore volume and pore size curve of the nano-carbon material has two distribution peaks at 3.86nm and 15nm, indicating that there is no microporous structure in the nano-carbon material.

[0133] Comparative Example 2

[0134] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), polybasic organic carboxylic acid and sulfur source of 1:0.7:1, 30 g of basic nickel carbonate, 29.4 g of citric acid and 27.8 g of potassium hydrogen sulfate were weighed and added to a beaker containing 50 mL of deionized water, and stirred at 70 ° C to obtain a homogeneous solution, which was further heated and evaporated to dryness to obtain a complex precursor material;

[0135] (2) Calcination: The complex precursor material is placed in a porcelain boat, which is then placed in the constant temperature zone of a tube furnace. Nitrogen gas is introduced at a flow rate of 100 mL / min, and the temperature is raised to 400°C at a rate of 2.5°C / min. After maintaining the temperature for 2 h, heating is stopped and the mixture is cooled to room temperature under a nitrogen atmosphere to obtain a pyrolysis product.

[0136] (3) Acid washing: The pyrolysis product was added to a 2.0 M HCl aqueous solution and stirred at 80 °C for 10 h, then filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 140 °C for 2 h to obtain the nanocarbon material.

[0137] The X-ray photoelectron spectroscopy (XPS) of the nanocarbon material is shown in FIG. Figure 13 As shown in the figure, it can be seen that there are obvious XPS peaks of Ni, C, O, and S, which proves that the nickel element is not completely removed in the nano-carbon material. The mass percentage of each element on the surface of the nano-carbon material is calculated based on its peak area, among which the mass percentage of nickel is 2.23%, the mass percentage of carbon is 84.3%, the mass percentage of oxygen is 11.03%, and the mass percentage of sulfur is 2.44%.

[0138] The BET specific surface area of ​​the nanocarbon material was 456.78 m 2 / g, the specific surface area in micropores is 21.32m 2 / g, accounting for 4.67% of the total specific surface area; the total pore volume of the nanocarbon material is 1.432cm 3 / g, the total pore volume of micropores is 0.012cm 3 / g, accounting for 0.8% of the total pore volume; the micropore volume and pore size distribution curve of the nanocarbon material has a distribution peak at 0.63nm, and the mesopore volume and pore size curve has two distribution peaks at 3.78nm and 11.4nm, indicating that the nanocarbon material is a nanocarbon material with microporous structure and mesoporous structure.

[0139] Test Case

[0140] This test example is used to illustrate a fuel cell catalyst and its preparation method.

[0141] Preparation of Pt / C catalyst: 0.6 g of the sulfur-doped nanocarbon cages obtained in Examples 1-5 was respectively dispersed in 200 mL of deionized water, a certain amount of chloroplatinic acid was added, and ultrasonic dispersion was performed to form a suspension, and then an aqueous sodium carbonate solution was added to adjust the pH of the suspension to 10; the above suspension was heated to 80°C, and formic acid was added under stirring to carry out a reduction reaction, wherein the molar ratio of the reducing agent to chloroplatinic acid calculated as platinum element was 5:1, and the reaction was maintained for 8 hours; the mixture after the reaction was filtered, washed until the pH of the solution was neutral, and dried at 100°C to obtain Pt / C catalysts A1-A5 with a Pt loading of 40 weight%.

[0142] Catalytic performance test of Pt / C catalyst: The prepared Pt / C catalysts A1-A5 were applied to the redox reaction (ORR) for catalytic performance test, and the corresponding catalytic performance is shown in Table 1.

[0143] Comparative test example

[0144] Preparation of Pt / C catalyst: 0.6 g of the nanocarbon material obtained in Comparative Examples 1-2 was dispersed in 200 mL of deionized water, a certain amount of chloroplatinic acid was added, and ultrasonic dispersion was performed to form a suspension. Then, an aqueous sodium carbonate solution was added to adjust the pH of the suspension to 10; the above suspension was heated to 80°C, and formic acid was added under stirring to carry out a reduction reaction, wherein the molar ratio of the reducing agent to chloroplatinic acid calculated as platinum element was 5:1, and the reaction was maintained for 8 hours; the mixture after the reaction was filtered, washed until the pH of the solution was neutral, and dried at 100°C to obtain Pt / C catalysts D1-D2 with a Pt loading of 40% by weight.

[0145] According to the method of the test example, the prepared Pt / C catalysts D1-D2 were applied to the redox reaction (ORR) to test the catalytic performance. The corresponding catalytic performance is shown in Table 1.

[0146] Table 1

[0147]

[0148]

[0149] From the above data, it can be seen that the sulfur-doped nanocarbon cages provided by the present invention have a microporous structure and a large number of mesoporous structures, with a large specific surface area and pore volume. When used as a carrier for fuel cell catalysts (Pt / C catalysts), the half-wave potential is 0.860-0.871V and the electrochemical active area (ECSA) is 50.61-100.44m 2 g -1 -Pt, mass specific activity is 0.069-0.089A mg -1 -Pt, area specific activity of 0.083-0.138 mA mg-1 -Pt, good catalytic performance.

[0150] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A proton exchange membrane fuel cell catalyst, comprising a carrier and metal Pt supported on the carrier, wherein the carrier is a sulfur-doped nanocarbon cage, the nanocarbon cage has a microporous structure and a mesoporous structure, and the BET specific surface area of ​​the nanocarbon cage is 1096.314-1600 m 2 / g, the ratio of the specific surface area in the micropores to the total specific surface area is less than 30%; the total pore volume of the nanocarbon cage is greater than 1cm 3 / g, the proportion of micropore volume to total pore volume is less than 15%; X-ray photoelectron spectroscopy measures the mass percentage of carbon on the surface of the nanocarbon cage to be 80-98%, the mass percentage of sulfur to be 2.76-10%, and the mass percentage of oxygen to be 4-15%; In the pore size distribution curve of the nanocarbon cage, there is a micropore distribution peak at 0.59-0.63 nm, and two mesopore distribution peaks at 2.73-4.1 nm and 3.877-15.6 nm; In the X-ray photoelectron spectrum of the nanocarbon cage, the nanocarbon cage has a characteristic spectrum peak of sulfur at 168±2 eV.

2. The fuel cell catalyst according to claim 1, wherein The ratio of the specific surface area in the micropores of the nanocarbon cage to the total specific surface area is less than 20%; the total pore volume of the nanocarbon cage is greater than 1.4 cm 3 / g, the proportion of micropore volume to total pore volume is less than 10%; the mass percentage of carbon on the surface of the nanocarbon cage is 84-95%, and the mass percentage of sulfur is 2.76-5% as measured by X-ray photoelectron spectroscopy.

3. The fuel cell catalyst according to claim 1 or 2, wherein The nanocarbon cage has a spherical or spherical-like morphology.

4. The fuel cell catalyst according to claim 1, wherein The diameter of the nanocarbon cage is 2-200 nm.

5. The fuel cell catalyst according to claim 4, wherein The diameter of the nanocarbon cage is 3-50 nm.

6. The fuel cell catalyst according to claim 1, wherein In the Raman curve of the nanocarbon cage, I D / I G The range is 0.5-1.

5.

7. The fuel cell catalyst according to claim 6, wherein In the Raman curve of the nanocarbon cage, I D / I G The range is 0.5-1.

1.

8. The fuel cell catalyst according to claim 1, wherein Based on the total amount of sulfur on the surface of the nanocarbon cage, the mass percentage of sulfur determined by the characteristic peak corresponding to 162-166 eV in the X-ray photoelectron spectrum of the nanocarbon cage is 2-90%.

9. The fuel cell catalyst according to claim 8, wherein Based on the total amount of sulfur on the surface of the nanocarbon cage, the mass percentage of sulfur determined by the characteristic peak corresponding to 162-166 eV in the X-ray photoelectron spectrum of the nanocarbon cage is 70-88%.

10. The fuel cell catalyst according to claim 1, wherein The preparation method of the sulfur-doped nanocarbon cage comprises the following steps: (1) Precursor preparation: providing a homogeneous solution containing a nickel source, a polybasic organic carboxylic acid, a sulfur source, and a solvent, and then removing the solvent from the homogeneous solution to obtain a complex precursor material, wherein the sulfur source is selected from a Group IA hydrogen sulfate and / or sulfate; (2) Calcination: Under the protection of an inert atmosphere, the complex precursor material obtained in step (1) is calcined at a constant temperature of 450-700° C. to obtain a pyrolysis product; (3) Acid washing: providing an aqueous solution containing the pyrolysis product obtained in step (2), and contacting it with an acid for reaction, followed by solid-liquid separation, washing and drying.

11. The fuel cell catalyst according to claim 10, wherein In step (1), the nickel source is selected from one or more organic acid salts, carbonates and basic carbonates containing nickel.

12. The fuel cell catalyst according to claim 11, wherein In step (1), the nickel source is a carbonate and / or basic carbonate containing nickel.

13. The fuel cell catalyst according to claim 10, wherein The sulfur source is selected from one or more of potassium sulfate, sodium sulfate, potassium hydrogen sulfate and sodium hydrogen sulfate.

14. The fuel cell catalyst according to claim 13, wherein The sulfur source is potassium hydrogen sulfate.

15. The fuel cell catalyst according to claim 10, wherein In step (1), the polybasic organic carboxylic acid is selected from one or more of citric acid, maleic acid, trimesic acid, terephthalic acid and malic acid.

16. The fuel cell catalyst according to claim 10, wherein The molar ratio of the nickel source, the polybasic organic carboxylic acid and the sulfur source calculated on the basis of nickel element is 1:0.1-10:0.1-2.

17. The fuel cell catalyst according to claim 16, wherein The molar ratio of the nickel source, the polybasic organic carboxylic acid and the sulfur source calculated on the basis of nickel element is 1:0.5-3:0.3-2.

18. The fuel cell catalyst according to claim 17, wherein The molar ratio of the nickel source, the polybasic organic carboxylic acid and the sulfur source calculated on the basis of nickel element is 1:0.7-1.5:0.5-1.

2.

19. The fuel cell catalyst according to claim 10, wherein In step (1), the solvent is water and / or ethanol.

20. The fuel cell catalyst according to claim 10, wherein In step (2), the constant temperature roasting temperature is 500-650°C.

21. The fuel cell catalyst according to claim 10, wherein The calcination method comprises: heating to a constant temperature section at a rate of 0.5-30°C / min; and maintaining the constant temperature in the constant temperature section for 20-600 minutes.

22. The fuel cell catalyst according to claim 21, wherein The calcination method comprises: heating to a constant temperature section at a rate of 1-10°C / min; and maintaining the constant temperature in the constant temperature section for 60-480 minutes.

23. The fuel cell catalyst according to claim 10, wherein In step (3), the acid is an inorganic acid aqueous solution and / or an organic acid aqueous solution.

24. The fuel cell catalyst according to claim 23, wherein In step (3), the acid is one or more of a hydrochloric acid aqueous solution, a sulfuric acid aqueous solution, a nitric acid aqueous solution and a citric acid aqueous solution.

25. The fuel cell catalyst according to claim 24, wherein In step (3), the acid is an aqueous hydrochloric acid solution.

26. The fuel cell catalyst according to claim 10, wherein In step (3), the pH value of the acid is less than 7.

27. The fuel cell catalyst according to claim 10, wherein In step (3), the temperature for the contact reaction between the aqueous solution of the pyrolysis product and the acid is 20-120° C., and the contact reaction time is 0.1-48 h.

28. The fuel cell catalyst according to claim 27, wherein In step (3), the temperature for the contact reaction between the aqueous solution of the pyrolysis product and the acid is 60-100° C.; and the contact reaction time is 4-12 hours.

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