Platinum carbon catalysts, methods for their preparation and use

Abstract

The application relates to the technical field of electrolytic water, and discloses a platinum-carbon catalyst as well as a preparation method and application thereof. The platinum-carbon catalyst comprises a carbon carrier and metal platinum loaded on the carbon carrier, the carbon carrier is conductive carbon black which is compounded with phosphorus elements and / or boron elements, and in an XRD spectrum, the platinum-carbon catalyst does not have Pt characteristic peaks, or the ratio between the normalized peak intensity of the unit mass platinum of a Pt (111) characteristic peak and the full width at half maximum is not greater than 1.0, and the ratio between the normalized peak intensity of the unit mass platinum of a Pt (200) characteristic peak and the full width at half maximum is not greater than 0.8. The platinum-carbon catalyst has lower overpotential and higher mass specific activity.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis technology, specifically to a platinum-carbon catalyst, its preparation method, and its application. Background Technology

[0002] PEM (Potassium Ether Electrolysis) water electrolysis technology, with its high electrolysis efficiency, safety, reliability, compact structure, and rapid response to renewable energy, is widely recognized as one of the most promising hydrogen production technologies. PEM water electrolysis for hydrogen production has a huge market, and the demand for catalysts will rapidly increase. However, the anode and cathode catalysts used in PEM water electrolysis for hydrogen production are all precious metal catalysts, resulting in high catalyst costs. Platinum-carbon catalysts are the cathode catalysts in PEM water electrolysis technology and are one of the core components of the technology. Manufacturing highly active, low-cost PEM water electrolysis cathode catalysts is a hot topic in scientific research.

[0003] To date, the most effective hydrogen evolution catalyst is the platinum-carbon catalyst. However, the dispersion of platinum metal in currently used commercial platinum-carbon catalysts is not ideal, resulting in high Pt usage and high catalyst costs. Many complex factors influence the activity and stability of platinum-carbon catalysts. Some literature suggests that the activity and stability of platinum-carbon catalysts are related to the particle size, morphology, and structure of platinum, as well as the type, properties, and platinum loading of the support. Existing technologies mainly improve the performance of platinum-carbon catalysts by controlling the particle size, morphology, and structure of platinum, as well as the specific surface area and pore structure of the support. Other literature reports improving the performance of platinum-carbon catalysts by attaching modifying groups to the carbon surface and modifying the carbon support.

[0004] There is an urgent need in this field to significantly improve the dispersion and utilization rate of Pt, thereby enhancing catalyst activity. This is crucial for reducing catalyst costs and accelerating the commercialization of PEM water electrolysis technology. Summary of the Invention

[0005] The objective of this invention is to provide a platinum-carbon catalyst in which Pt exists in the form of atomic clusters, exhibiting high dispersion and strong interaction between the support and Pt. Therefore, its specific activity and overpotential are significantly higher than those of commercial catalysts. A second objective of this invention, based on the first objective, is to provide a platinum-carbon atomic cluster catalyst with a higher platinum loading. A third objective of this invention is to improve the wet impregnation method for manufacturing platinum-carbon catalysts, achieving catalyst preparation with lower energy consumption.

[0006] To achieve the above objectives, the present invention provides a platinum-carbon catalyst comprising a carbon support and platinum metal supported thereon. The carbon support is conductive carbon black composited with phosphorus and / or boron elements. The platinum-carbon catalyst has no Pt characteristic peak in its XRD pattern, or the ratio of the normalized peak intensity per unit mass of platinum for the Pt(111) characteristic peak to the full width at half maximum (FWHM) is not greater than 1.0, and the ratio of the normalized peak intensity per unit mass of platinum for the Pt(200) characteristic peak to the full width at half maximum (FWHM) is not greater than 0.8.

[0007] Preferably, based on the total mass of the platinum-carbon catalyst, the platinum content in the platinum-carbon catalyst is 1-20% by mass, preferably 5-15% by mass.

[0008] Preferably, when the platinum content of the platinum-carbon catalyst is less than 6% by mass, the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (WHM) of the characteristic peak of Pt(111) is not greater than 0.8 and the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (WHM) of the characteristic peak of Pt(200) is not greater than 0.7.

[0009] Preferably, the characteristic peak of Pt 4f 7 / 2 in the XPS spectrum of the platinum-carbon catalyst is located above 71.8 eV.

[0010] Preferably, based on the total mass of the carbon support, the phosphorus content in the carbon support is 0.01-4% by mass, preferably 0.05-2.5% by mass.

[0011] Preferably, based on the total mass of the carbon support, the boron content in the carbon support is 0.01-4% by mass, more preferably 0.05-2.5% by mass.

[0012] Preferably, the carbon support is conductive carbon black composited with phosphorus and boron elements.

[0013] Preferably, the conductive carbon black is one or more of EC-300J, EC-600JD, ECP600JD, VXC72, VXC72R, Blackpearls 2000, PRINTEX XE2-B, PRINTEX L6, and HIBLAXK40B2.

[0014] Preferably, the oxygen mass fraction in the XPS analysis of the conductive carbon black is greater than 4%.

[0015] Preferably, the resistivity of the conductive carbon black is less than 10 Ω·m.

[0016] Preferably, the specific surface area of ​​the conductive carbon black is 200-2000 m². 2 / g.

[0017] A second aspect of this invention provides a method for preparing a platinum-carbon catalyst, the method comprising:

[0018] (1) After contacting conductive carbon black with phosphorus source and / or boron source in aqueous solution, respectively or simultaneously, the water is removed, and the obtained conductive carbon black is subjected to high temperature treatment under an inert atmosphere to obtain carbon support.

[0019] (2) Remove the solvent from the homogeneous mixture containing the carbon support, platinum source and solvent obtained in step (1) to obtain the precursor material;

[0020] (3) In a reducing atmosphere, the precursor material obtained in step (2) is heat-treated to obtain a platinum-carbon catalyst.

[0021] In step (1), the high temperature treatment is 400-900℃ and the constant temperature time is 0.5-10h;

[0022] In step (3), the heat treatment temperature is 80-200℃ and the time is 1-4h.

[0023] Preferably, the phosphorus source is one or more of phosphoric acid, phosphate, pyrophosphate, polyphosphate, hydrogen phosphate, dihydrogen phosphate, phosphite, and hypophosphite. More preferably, the mass ratio of the carbon material to the phosphorus source (based on phosphorus element) is 10000:1 to 10:1.

[0024] Preferably, the boron source is one or more of boric acid and borate; more preferably, the mass ratio of the carbon material to the boron source (based on boron element) is 10000:1 to 10:1.

[0025] Preferably, in step (1), the conductive carbon black is one or more of EC-300J, EC-600JD, ECP600JD, VXC72, VXC72R, Black Pearls 2000, PRINTEX XE2-B, PRINTEX L6, and HIBLAXK 40B2;

[0026] Preferably, the oxygen mass fraction in the XPS analysis of the conductive carbon black is greater than 4%.

[0027] Preferably, the resistivity of the conductive carbon black is less than 10 Ω·m.

[0028] Preferably, the specific surface area of ​​the conductive carbon black is 200-2000 m². 2 / g.

[0029] Preferably, in step (2), the platinum source is one or more of chloroplatinic acid, chloroplatinate, tetraammineplatinum acetate, and platinum acetylacetonate.

[0030] Preferably, in step (2), the solvent is one or more of water, alcohol, or ketone solvents. More preferably, the solvent is water and / or ethanol, and even more preferably a mixture of water and ethanol.

[0031] Preferably, in step (2), the amount of platinum source used is 0.01-0.25g relative to 1g of carbon support, calculated as platinum element.

[0032] Preferably, in step (2), after the homogeneous mixture is allowed to stand, the solvent is removed, and the standing time is more than 10 hours, preferably 15-24 hours.

[0033] Preferably, in step (2), the drying temperature during solvent removal is below 100°C.

[0034] Preferably, in step (3), the heat treatment temperature is 100-180℃ and the reduction time is 2-3h.

[0035] Preferably, in step (3), the reducing atmosphere includes hydrogen, preferably a mixture of hydrogen and an inert gas, more preferably a mixture of hydrogen and nitrogen; preferably, hydrogen accounts for 5-30% of the total gas volume.

[0036] A third aspect of the present invention provides a platinum-carbon catalyst, which is prepared by the preparation method of the present invention described above.

[0037] The fourth aspect of the present invention provides the application of the platinum-carbon catalyst of the present invention in fuel cells or water electrolysis.

[0038] The fifth aspect of the present invention provides a PEM electrolyzer, wherein the cathode of the PEM electrolyzer uses the platinum-carbon catalyst of the present invention described above.

[0039] Compared with the prior art, the present invention has the following beneficial technical effects through the above technical solution.

[0040] I. This invention creates a novel carbon support by combining conductive carbon black with phosphorus and boron. Platinum-carbon catalysts made with this carbon support can significantly improve the specific activity and overpotential of the catalyst.

[0041] Second, the liquid-phase chemical reduction method commonly used in the manufacture of platinum-carbon catalysts generates a large amount of wastewater, while the gas-phase reduction method has a high reduction temperature and high energy consumption. The improved gas-phase reduction method of this invention has a low reduction temperature, low energy consumption, and no wastewater generation.

[0042] Third, the catalyst of the present invention has significantly better performance than commercial catalysts. Even with a platinum loading much lower than that of commercial catalysts, the overpotential, ECSA and other properties of the catalyst of the present invention are still comparable to those of commercial catalysts, and the specific activity is much higher than that of commercial catalysts. Attached Figure Description

[0043] Figure 1 These are the XRD patterns of the platinum-carbon catalysts in Examples 1-2, 5-6 and Comparative Examples 1-2.

[0044] Figure 2 These are XPS spectra of the platinum-carbon catalysts in Examples 1, 5-6, and Comparative Examples 1-2.

[0045] Figure 3 These are the polarization curves of the platinum-carbon catalysts in Examples 1, 5-6, and Comparative Examples 1-2.

[0046] Figure 4 This is a STEM image of the platinum-carbon catalyst from Example 2. Detailed Implementation

[0047] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0048] The first aspect of the present invention provides a platinum-carbon catalyst comprising a carbon support and platinum metal supported thereon, wherein the carbon support is conductive carbon black composited with phosphorus and / or boron elements, and wherein the platinum-carbon catalyst has no Pt characteristic peak in its XRD pattern, or the ratio of the normalized peak intensity per unit mass of platinum of the Pt(111) characteristic peak to the full width at half maximum (FWHM) is not greater than 1.0 and the ratio of the normalized peak intensity per unit mass of platinum of the Pt(200) characteristic peak to the full width at half maximum (FWHM) is not greater than 0.8.

[0049] Specifically, the statement that "no Pt characteristic peaks are present in the XRD pattern, or the ratio of the normalized peak intensity per unit mass of Pt(111) characteristic peak to the full width at half maximum (FWHM) is not greater than 1.0 and the ratio of the normalized peak intensity per unit mass of Pt(200) characteristic peak to FWHM is not greater than 0.8" indicates that platinum in the platinum-carbon catalyst of the present invention exists at least mostly in an amorphous phase, but does not exclude the presence of a small amount of crystalline phase. Thus, the presence of a small amount of crystalline phase does not affect the performance of the platinum-carbon catalyst.

[0050] The ratio of the normalized peak intensity to the full width at half maximum (FWHM) per unit mass of platinum represents the ratio of the normalized peak intensity (NI) to the full width at half maximum (FWHM) and the mass content of platinum in the catalyst, i.e., normalized peak intensity / (full width at half maximum * platinum mass content), hereinafter also referred to as NI / (FWHM * m PtThe calculation method is as follows: (1) Under the working conditions of the powder X-ray diffractometer (tube voltage 40kV, tube current 40mA, Cu target Kα radiation), X-ray diffraction patterns of the catalyst to be tested in the range of 2θ from 20 to 70° are collected. After deducting the background signal and Kα2, the maximum value of the intensity data in the range of 22-28° is 1 and the minimum value of the intensity data in the range of 65-70° is 0. The normalized peak intensities of the Pt(111) characteristic peak and the Pt(200) characteristic peak of the catalyst to be tested are obtained respectively. (2) The X-ray diffraction pattern after normalization is fitted by peak subdivision to obtain the full width at half maximum (in °) of the Pt(111) characteristic peak and the Pt(200) characteristic peak respectively. The above-mentioned Pt(111) characteristic peak and Pt(200) characteristic peak usually refer to the characteristic peaks of 2θ at 39.8±0.2° and 46.2±0.2° respectively. (3) The normalized peak intensities of the Pt(111) characteristic peak and the Pt(200) characteristic peak are divided by the corresponding full width at half maximum (FWHM) and the platinum mass content in the catalyst, respectively, to obtain the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (FWHM) of the Pt(111) characteristic peak and the Pt(200) characteristic peak of the catalyst.

[0051] Aberration-corrected electron microscopy analysis showed that platinum in the platinum-carbon catalyst of the present invention exists mostly in the form of atomic clusters. Specifically, at least 40%, preferably 60-90%, of the metallic platinum particles are irregular lattice fringes.

[0052] In the platinum-carbon catalyst of the present invention, preferably, the characteristic peak of Pt 4f7 / 2 in the XPS spectrum is located above 71.8 eV. The aforementioned XPS spectrum refers to the XPS spectrum corrected to a C1s peak at 284.3 eV. Typically, for example, when platinum is supported on a carbon support without composite elements, the characteristic peak of Pt 4f7 / 2 is located around 71.4 eV. This indicates that the characteristic peak of Pt 4f7 / 2 in the XPS spectrum of the platinum-carbon catalyst of the present invention is shifted to a higher electron volt level by more than 0.4 eV, for example, 0.43-0.9 eV.

[0053] In the platinum-carbon catalyst of the present invention, preferably, based on the total mass of the platinum-carbon catalyst, the platinum content in the platinum-carbon catalyst is 1-20% by mass, more preferably 1-15% by mass, more preferably 4-15% by mass, and even more preferably 5-10% by mass. Furthermore, it is preferable that the platinum-carbon catalyst of the present invention does not contain any other metal elements besides platinum.

[0054] Preferably, when the platinum content of the platinum-carbon catalyst is less than 6% by mass, the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (WHM) of the characteristic peak of Pt(111) is not greater than 0.8 and the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (WHM) of the characteristic peak of Pt(200) is not greater than 0.7.

[0055] In the platinum-carbon catalyst of the present invention, preferably, the phosphorus content in the carbon support is 0.1-4% by mass, more preferably 0.5-2.5% by mass, based on the total mass of the carbon support.

[0056] In the platinum-carbon catalyst of the present invention, preferably, the boron content in the carbon support is 0.1-4% by mass, more preferably 0.5-3% by mass, based on the total mass of the carbon support.

[0057] According to the present invention, preferably, the carbon support comprises conductive carbon black and phosphorus and / or boron elements compounded therein, hereinafter also referred to as phosphorus-modified carbon support, boron-modified carbon support, or phosphorus-boron-modified carbon support. Preferably, the carbon support of the present invention does not contain any composite elements other than boron. Here, "composite elements" in the present invention refers to nitrogen, phosphorus, boron, sulfur, fluorine, chlorine, bromine, and iodine. More preferably, the carbon support is composed of conductive carbon black and phosphorus and / or boron elements compounded therein, as well as oxygen.

[0058] More preferably, the carbon support comprises conductive carbon black and phosphorus and boron elements incorporated therein. By simultaneously incorporating phosphorus and boron elements, the catalytic performance of the platinum-carbon catalyst can be further improved.

[0059] The conductive carbon black that can be used in this invention may be one or more of ordinary conductive blacks, super conductive blacks, or extra conductive blacks, such as Ketjen black, Cabot conductive black (Cabot, Black Pearls, etc.), Orion conductive black (HIBLACK, PRINTEX, etc.), etc. Specifically, it may be one or more of EC-300J, EC-600JD, ECP600JD, VXC72, VXC72R, Black Pearls 2000, PRINTEX XE2-B, PRINTEX L6, and HIBLAXK 40B2.

[0060] This invention does not restrict the method of preparation or source of conductive carbon black. The conductive carbon black may be acetylene black, furnace black, etc.

[0061] Preferably, in the XPS analysis of the conductive carbon black, the oxygen content is greater than 4% by mass, for example, 5-12% by mass.

[0062] Preferably, the resistivity of the conductive carbon black is less than 10 Ω·m, more preferably less than 5 Ω·m, more preferably less than 3 Ω·m, and even more preferably 0.01-1 Ω·m.

[0063] Preferably, the specific surface area of ​​the conductive carbon black is 200-2000 m². 2 / g, preferably 220-1500m 2 / g.

[0064] (1) After contacting conductive carbon black with phosphorus source and / or boron source in aqueous solution, the water is removed and the obtained conductive carbon black is subjected to high temperature treatment under an inert atmosphere to obtain carbon support.

[0065] (2) Remove the solvent from the homogeneous mixture containing the carbon support, platinum source and solvent obtained in step (1) to obtain the precursor material;

[0066] (3) In a reducing atmosphere, the precursor material obtained in step (2) is heat-treated to obtain a platinum-carbon catalyst.

[0067] In step (1), the high-temperature treatment temperature is 400-900℃, and the constant temperature time is 0.5-10h;

[0068] In step (3), the heat treatment temperature is 80-200℃ and the time is 1-4h.

[0069] The preparation method of the second aspect of the present invention can be used to prepare the platinum-carbon catalyst of the first aspect. In step (1), the conductive carbon black is the same as described above, and will not be repeated here.

[0070] According to the present invention, in step (1), the phosphorus source and the boron source are not particularly limited, and soluble phosphoric acid and phosphates, soluble boric acid or borates, etc., can be used. Specifically, the phosphorus source can be one or more of phosphoric acid, phosphates, pyrophosphates, polyphosphates, hydrogen phosphates, dihydrogen phosphates, phosphites, and hypophosphites. More preferably, the mass ratio of the carbon material to the phosphorus source (based on elemental phosphorus) is 10000:1 to 10:1, preferably 100-15:1. The boron source can be one or more of boric acid and borates. Borates can be, for example, sodium borate, potassium borate, etc. More preferably, the mass ratio of the carbon material to the boron source (based on elemental boron) is 10000:1 to 10:1, preferably 100-15:1.

[0071] There are no particular limitations on the method for contacting conductive carbon black with a phosphorus source and / or a boron source in an aqueous solution. When using a single phosphorus source or boron source, the conductive carbon black can be contacted with an aqueous solution containing the phosphorus source or boron source; when using both phosphorus and boron sources, the contact can be performed separately or simultaneously. Specifically, the conductive carbon black can be contacted with an aqueous solution of one of the phosphorus and boron sources before contacting the other, or it can be contacted with an aqueous solution containing both phosphorus and boron sources.

[0072] According to the present invention, in step (1), the temperature of the high-temperature treatment is 400-900℃, preferably 450-700℃, more preferably 450-600℃; the constant temperature time is 0.5-10h, preferably 1-5h, more preferably 1.5-4h.

[0073] The inert atmosphere can be at least one of nitrogen, argon, neon, and helium. The high-temperature treatment can be performed in any apparatus that provides the aforementioned high-temperature treatment conditions, such as a tube furnace.

[0074] According to the present invention, the phosphorus-boron modified conductive carbon black obtained in step (1) can be easily dispersed in an aqueous phase. However, some conductive carbon blacks, such as Ketjen black, are difficult to disperse directly in an aqueous phase.

[0075] According to the present invention, in step (2), the platinum source can be one or more of chloroplatinic acid, chloroplatinate, tetraammineplatinum acetate, and platinum acetylacetonate. Chloroplatinate can be potassium chloroplatinate or sodium chloroplatinate, etc.

[0076] Preferably, the amount of platinum source used is 0.01-0.25g, more preferably 0.04-0.18g, relative to 1g of the carbon support.

[0077] According to the present invention, in step (2), the precursor material is obtained by dissolving the carbon support and platinum source in a solvent to form a homogeneous mixture, and then removing the solvent from the homogeneous mixture. There is no particular limitation on the type of solvent. The solvent can be one or more of water, alcohol solvents, or ketone solvents; the alcohol solvent can be, for example, ethanol, and the ketone solvent can be, for example, acetone. More preferably, the solvent is water, ethanol, or a homogeneous mixture of ethanol and water (the volume ratio of ethanol to water can be, for example, 0.1-10:1, preferably 1-5:1). The present invention also does not particularly limit the amount of solvent used; for example, it can be 3-20 mL relative to 1 g of carbon support.

[0078] This invention involves mixing a carbon support, a platinum source, and a solvent to obtain the aforementioned homogeneous mixture, preferably with stirring. The invention does not impose particular limitations on the stirring rate and time, as long as the homogeneous mixture is formed. Furthermore, to further accelerate the dissolution process by heating, the homogeneous mixture can also be formed.

[0079] As a method for removing the solvent from the homogeneous mixture, evaporation can be used to remove the solvent from the homogeneous mixture. The evaporation temperature and process can adopt existing techniques known to those skilled in the art. According to the present invention, in step (2), the drying temperature for removing the solvent is below 100°C. For example, the solvent can be removed by drying in an oven at 60-95°C for 12-24 hours.

[0080] According to a preferred embodiment of the present invention, in step (2), after the homogeneous mixture is allowed to stand, the solvent is removed. The standing time is more than 10 hours, preferably 12-72 hours, and more preferably 15-24 hours.

[0081] According to the present invention, in step (3), the heat treatment is carried out in a reducing atmosphere. The reducing atmosphere preferably includes hydrogen, more preferably a mixture of hydrogen and an inert gas, wherein the inert atmosphere can be nitrogen and / or argon, specifically a mixture of hydrogen and nitrogen. Preferably, hydrogen accounts for 5-30% by volume of the total gas volume. The heat treatment can be carried out in any apparatus that provides the above-described heat treatment conditions, for example, in a tube furnace.

[0082] According to the present invention, in step (3), the temperature of the heat treatment is 80-200℃, preferably 100-180℃, more preferably 100-160℃, and the reduction time is 1-4h, preferably 2-3h. Furthermore, the heating rate of the heat treatment can be 4-15℃ / min, generally 5℃ / min.

[0083] A third aspect of the present invention provides a platinum-carbon catalyst, which is prepared by the method described in the second aspect of the present invention.

[0084] A third aspect of the present invention provides a platinum-carbon catalyst, which is prepared by the method described in the second aspect of the present invention.

[0085] The fourth aspect of the present invention provides the application of the platinum-carbon catalyst of the present invention in fuel cells or water electrolysis.

[0086] The platinum-carbon catalyst of the present invention is suitable as an anode catalyst in fuel cells, and is not particularly limited to fuel cells. For example, it can be used in hydrogen fuel cells (e.g., proton exchange membrane hydrogen fuel cells), direct alcohol fuel cells (e.g., direct alcohol fuel cells with methanol or ethanol as anode fuel), etc.

[0087] The fifth aspect of the present invention provides a PEM electrolyzer, wherein the cathode of the PEM electrolyzer uses the platinum-carbon catalyst of the present invention described above.

[0088] In this invention, except for "carbon carrier containing composite elements" which can be determined based on the context or its own limitations, all other references to "carbon carrier" refer to carbon carriers that do not contain composite elements; the same applies to subordinate concepts of carbon carrier, such as conductive carbon black.

[0089] In this invention, "carbon black" and "carbon black" are interchangeable technical terms.

[0090] In this invention, "inert gas" refers to a gas that, in the preparation method of this invention, does not cause any perceptible effect on the performance of the carbon support containing phosphorus and / or boron elements.

[0091] The present invention will be described in detail below through embodiments. The instruments and testing methods used in the embodiments and comparative examples of the present invention are as follows:

[0092] Instruments, methods and conditions for XRD analysis: X-ray diffraction analysis (XRD) was performed on a Shimadzu XRD-6000 X-ray diffractometer from Japan. The test conditions included: tube voltage 40 kV, tube current 40 mA, Cu target Kα radiation, and 2θ scan range of 10° to 70°.

[0093] NI / (FWHM*m Pt The calculation method is as follows: (1) Under the working conditions of the powder X-ray diffractometer (tube voltage 40kV, tube current 40mA, Cu target Kα radiation), X-ray diffraction patterns of the catalyst to be tested in the range of 20-70° were collected. After deducting the background signal and Kα2, the maximum value of the intensity data in the range of 22-28° was 1 and the minimum value of the intensity data in the range of 65-70° was 0. The normalized peak intensities of the Pt(111) characteristic peak at 39.8±0.2° and the Pt(200) characteristic peak at 46.2±0.2° were obtained respectively. (2) The X-ray diffraction patterns after normalization were fitted to obtain the full width at half maximum (in °) of the Pt(111) characteristic peak and the Pt(200) characteristic peak respectively. (3) The normalized peak intensities of the Pt(111) and Pt(200) characteristic peaks were divided by the corresponding full width at half maximum (FWHM) and the platinum mass content in the catalyst, respectively, to obtain the NI / (FWHM*m) ratios of the Pt(111) and Pt(200) characteristic peaks of the catalyst. Pt ).

[0094] The X-ray photoelectron spectroscopy (XPS) analyzer was a VG Scientific ESCALab220i-XL model equipped with Avantage V5.926 software. The XPS analysis conditions were as follows: excitation source was monochromatic AlKα X-rays, power was 330 W, and the baseline vacuum was 3 × 10⁻⁶. -9 mbar. In addition, the electron binding energy was corrected using the C1s peak (284.3 eV) of elemental carbon, and the subsequent peaking software was XPSPEAK.

[0095] Instruments, methods, and conditions for elemental analysis: Elemental analyzer (Vario EL Cube), reaction temperature 1150℃, 5mg sample weighed, reduction temperature 850℃, carrier gas helium flow rate 200mL / min, oxygen flow rate 30mL / min, oxygen flow time 70s.

[0096] Instruments, methods, and conditions for testing the platinum mass fraction in platinum-carbon catalysts: Take 30 mg of the prepared Pt / C catalyst, add 30 mL of aqua regia, reflux at 120 °C for 12 h, cool to room temperature, take the supernatant, dilute it, and test the Pt content using ICP-AES.

[0097] The aberration-corrected transmission electron microscope (AC-STEM) is a JEOL ARM200F model.

[0098] Electrochemical performance was tested using Solartron Analytical EnergyLab and Princeton Applied Research (Model 636A). The methods and test conditions were as follows: the catalyst polarization curve (LSV) was measured at 2500 rpm in N2-saturated 0.5 M H2SO4, and the electrochemical active area (ECSA) was measured in N2-saturated 0.5 M H2SO4. For all tests, the catalyst was prepared as a uniformly dispersed slurry and coated onto a 5 mm diameter glassy carbon electrode. The platinum content of the catalyst on the electrode was controlled within the range of 1-4 μg. No iR correction was performed in the calculations.

[0099] The resistivity test was performed using a four-probe resistivity tester, model KDY-1. The method and test conditions were as follows: pressure 3.9±0.03MPa and current 500±0.1mA.

[0100] Instruments, methods, and conditions for testing the platinum mass fraction in platinum-carbon catalysts: Take 30 mg of the prepared Pt / C catalyst, add 30 mL of aqua regia, reflux at 120 °C for 12 h, cool to room temperature, take the supernatant, dilute it, and test the Pt content using ICP-AES.

[0101] Ketjenblack ECP600JD (manufactured by Lion Corporation, Japan) was purchased from Suzhou Yilongsheng Energy Technology Co., Ltd. Using the aforementioned instrumental methods, the results showed a specific surface area of ​​1362 m². 2 / g, pore volume 2.29mL / g, oxygen mass fraction 6.9%, I D / I G The value is 1.25, and the resistivity is 1.31 Ω·m.

[0102] The commercial platinum-carbon catalyst (HISPEC 4000, manufactured by Johnson Matthey) was tested using the aforementioned instrumental method, and the results showed that the mass fraction of platinum was 40.2%.

[0103] Preparation Example 1

[0104] This embodiment illustrates the preparation of the phosphorus-boron modified carbon support of the present invention.

[0105] Add 10 mL of anhydrous ethanol to 1 g of Ketjenblack ECP600JD, then add 20 mL of 0.5 wt% sodium dihydrogen phosphate and 1.1 wt% ammonium borate pentahydrate aqueous solution and impregnate for 24 h; dry in an oven at 100 °C; then place in a tube furnace and heat the tube furnace to 500 °C at a rate of 5 °C / min, and maintain the temperature for 3 h; after natural cooling, obtain the phosphorus-boron modified carbon support, designated as carbon support A.

[0106] Preparation Example 2

[0107] This embodiment illustrates the preparation of the phosphorus-modified carbon support of the present invention.

[0108] The carbon support was prepared according to the method of Preparation Example 1, except that ammonium borate pentahydrate was not added, and a phosphorus-modified carbon support was obtained, designated as carbon support B.

[0109] Preparation Example 3

[0110] This embodiment illustrates the preparation of the boron-modified carbon support of the present invention.

[0111] The carbon support was prepared according to the method of Preparation Example 1, except that sodium dihydrogen phosphate was not added, and a boron-modified carbon support was obtained, which was designated as carbon support C.

[0112] Example 1

[0113] This embodiment illustrates the preparation of the platinum-carbon catalyst of the present invention.

[0114] With a ratio of 0.27 mmol chloroplatinic acid per gram of carbon support, chloroplatinic acid was first dissolved in 5 ml of water. 1 g of carbon support A was then dispersed in the chloroplatinic acid solution until uniformly dispersed. After standing for 16 h, the solution was dried in an oven at 60 °C to obtain the catalyst precursor. The precursor was then ground and placed in a tube furnace, heated to 160 °C, and heat-treated for 2 h in an atmosphere of N2:H2 = 4:1. The temperature was then lowered under the N2 atmosphere to obtain a platinum-carbon catalyst with a loading of 5%.

[0115] Example 2

[0116] This example illustrates the preparation of a platinum-carbon catalyst.

[0117] The platinum-carbon catalyst was prepared according to the method of Example 1, except that 0.57 mmol of chloroplatinic acid was added per gram of carbon support, and the heat treatment temperature was 140°C, to obtain a platinum-carbon catalyst with a loading of 10%.

[0118] Example 3

[0119] This embodiment illustrates the preparation of the platinum-carbon catalyst of the present invention.

[0120] The platinum-carbon catalyst was prepared according to the method of Example 2, except that the heat treatment temperature was 180°C, and a platinum-carbon catalyst with a loading of 10% was obtained.

[0121] Example 4

[0122] This embodiment illustrates the preparation of the platinum-carbon catalyst of the present invention.

[0123] The platinum-carbon catalyst was prepared according to the method of Example 2, except that the heat treatment temperature was 100°C, and a platinum-carbon catalyst with a loading of 10% was obtained.

[0124] Example 5

[0125] This embodiment illustrates the preparation of the platinum-carbon catalyst of the present invention.

[0126] The platinum-carbon catalyst was prepared according to the method of Example 1, except that the carbon support B of Preparation Example 2 was used to prepare a 5% loaded platinum-carbon catalyst.

[0127] Example 6

[0128] This embodiment illustrates the preparation of the platinum-carbon catalyst of the present invention.

[0129] The platinum-carbon catalyst was prepared according to the method of Example 1, except that the carbon support C of Preparation Example 3 was used to prepare a 5% loaded platinum-carbon catalyst.

[0130] Comparative Example 1

[0131] The platinum-carbon catalyst was prepared according to the method in Example 2, except that the support was KetjenblackECP600JD and a 10% loading of platinum-carbon catalyst was prepared.

[0132] Comparative Example 2

[0133] The platinum-carbon catalyst was a commercially available catalyst, brand name HISPEC4000 (platinum mass fraction 40.2%).

[0134] Test Example 1

[0135] The XRD patterns of the platinum-carbon catalysts in Examples 1-2, 5-6 and Comparative Examples 1-2 were determined, as follows: Figure 1 As shown. From Figure 1The NI / (FWHM*m) values ​​of the characteristic peaks of Pt(111) and Pt(200) were calculated from the XRD spectra of each spectrum. Pt The results are shown in Table 1.

[0136] Table 1

[0137]

[0138] As shown in Table 1, the NI / (FWHM*m) characteristic peak of the platinum-carbon catalyst of the present invention is 111. Pt ) NI / (FWHM*m not greater than 1.0 and with characteristic peak of Pt(200) Pt The value of NI / (FWHM*m) for the characteristic peak of Pt(111) is not greater than 0.8. Furthermore, when the platinum content in the platinum-carbon catalyst is less than 6% by mass, the value of NI / (FWHM*m) for the characteristic peak of Pt(111) is not greater than 0.8. Pt ) NI / (FWHM*m not greater than 0.8 and with characteristic peak of Pt(200) Pt (Not greater than 0.7)

[0139] The XRD spectra of Examples 3-4 were measured using the same method described above, and the results were similar to those of Example 2. The NI / (FWHM*m) of the characteristic peaks of Pt(111) and Pt(200) were calculated. Pt All of them satisfy the above relationship.

[0140] Test Example 2

[0141] XPS spectra of Examples 1, 5-6 and Comparative Examples 1-2 were measured, as follows: Figure 2 As shown. From Figure 2 It can be seen that the characteristic peak of Pt4f 7 / 2 in Example 5 is located at 72.0 eV, which is about 0.6 eV shifted to the high electron volt direction relative to Comparative Example 1 and about 1.0 eV shifted to the high electron volt direction relative to Comparative Example 2.

[0142] The XRD spectra of Examples 2-4 were measured using the same method described above, and the characteristic peaks of Pt 4f 7 / 2 were all above 71.8 eV.

[0143] Test Example 3

[0144] The performance of the platinum-carbon catalysts prepared in the above examples and comparative examples was measured, and the results are shown in Table 2. Figure 3 The polarization curves of the platinum-carbon catalysts of Examples 1, 5-6 and Comparative Examples 1-2 are shown.

[0145] Table 2

[0146]

[0147] As can be seen from the results in Table 2, Examples 1-6 using the platinum-carbon catalyst of the present invention have lower overpotential and higher mass-to-carbon activity than the commercial catalyst of Comparative Example 2.

[0148] A comparison of Examples 2, 5-6 with Comparative Example 1 shows that the platinum-carbon catalyst of the present invention, by using the phosphorus and / or boron-modified carbon support of the present invention, can significantly reduce the overpotential while improving the specific activity. Figure 3 It can be seen that the simultaneous composite phosphorus and boron can further improve the catalyst performance, especially at high current densities, such as 50 mA / cm². 2 In the above cases, the catalyst with both phosphorus and boron composites exhibits a lower overpotential, while the overpotential of phosphorus or boron composites alone approaches that of Comparative Example 1. Therefore, composites of phosphorus or boron alone can only improve catalyst performance at low current densities, while composites of both phosphorus and boron can comprehensively enhance catalyst performance, resulting in lower energy consumption during high-current operation in actual electrolyzers.

[0149] The comparison of Examples 2-4 shows that a heat treatment temperature of 100-140℃ can further reduce the overpotential while improving the specific activity.

[0150] Test Example 4

[0151] The platinum-carbon catalyst of Example 2 was observed using STEM to obtain... Figure 4 STEM photos. Through analysis of... Figure 4 Statistical analysis of the STEM images shows that approximately 91% of the platinum particles in this platinum-carbon catalyst have irregular lattice striations.

[0152] The platinum-carbon catalysts of Examples 1, 3-6 were observed using the same method, and all met the requirement of at least 60% of the platinum particles having irregular lattice fringes.

[0153] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A platinum-carbon catalyst, characterized in that, The platinum-carbon catalyst comprises a carbon support and platinum metal supported thereon. The carbon support is conductive carbon black composited with phosphorus and / or boron elements. The platinum-carbon catalyst has no Pt characteristic peak in its XRD pattern, or the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (FWHM) of the Pt(111) characteristic peak is not greater than 1.0 and the ratio of the normalized peak intensity per unit mass of platinum to FWHM of the Pt(200) characteristic peak is not greater than 0.

8. The Pt 4f 7 / 2 characteristic peak of the platinum-carbon catalyst is located above 71.8 eV in its XPS pattern.

2. The platinum-carbon catalyst according to claim 1, wherein, Based on the total mass of the platinum-carbon catalyst, the platinum content in the platinum-carbon catalyst is 1-20% by mass.

3. The platinum-carbon catalyst according to claim 1, wherein, Based on the total mass of the platinum-carbon catalyst, the platinum content in the platinum-carbon catalyst is 5-15% by mass.

4. The platinum-carbon catalyst according to claim 1, wherein, When the platinum content of the platinum-carbon catalyst is less than 6% by mass, the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (WHM) of the characteristic peak of Pt(111) is not greater than 0.8, and the ratio of the normalized peak intensity per unit mass of platinum to the full width at half maximum (WHM) of the characteristic peak of Pt(200) is not greater than 0.

7.

5. The platinum-carbon catalyst according to claim 1, wherein, Based on the total mass of the carbon support, the phosphorus content in the carbon support is 0.01-4% by mass.

6. The platinum-carbon catalyst according to claim 1, wherein, Based on the total mass of the carbon support, the phosphorus content in the carbon support is 0.05-2.5% by mass.

7. The platinum-carbon catalyst according to claim 1, wherein, Based on the total mass of the carbon support, the boron content in the carbon support is 0.01-4% by mass.

8. The platinum-carbon catalyst according to claim 1, wherein, Based on the total mass of the carbon support, the boron content in the carbon support is 0.05-2.5% by mass.

9. The platinum-carbon catalyst according to claim 1, wherein, The carbon support is conductive carbon black composited with phosphorus and boron elements.

10. The platinum-carbon catalyst according to any one of claims 1-9, wherein, The conductive carbon black is one or more of EC-300J, EC-600JD, ECP600JD, VXC72, VXC72R, Black Pearls 2000, PRINTEX XE2-B, PRINTEX L6, and HIBLAXK 40B2.

11. The platinum-carbon catalyst according to any one of claims 1-9, wherein, The oxygen mass fraction in the XPS analysis of the conductive carbon black was greater than 4%.

12. The platinum-carbon catalyst according to any one of claims 1-9, wherein, The resistivity of the conductive carbon black is less than 10 Ω·m.

13. The platinum-carbon catalyst according to any one of claims 1-9, wherein, The specific surface area of ​​the conductive carbon black is 200-2000 m². 2 / g.

14. A method for preparing the platinum-carbon catalyst according to claim 1, characterized in that, include: (1) After contacting conductive carbon black with phosphorus source and / or boron source in aqueous solution, respectively or simultaneously, the water is removed, and the obtained conductive carbon black is subjected to high temperature treatment under an inert atmosphere to obtain carbon support. (2) Remove the solvent from the homogeneous mixture containing the carbon support, platinum source and solvent obtained in step (1) to obtain the precursor material; (3) In a reducing atmosphere, the precursor material obtained in step (2) is heat-treated to obtain a platinum-carbon catalyst; In step (1), the high temperature treatment is 400-900℃ and the constant temperature time is 0.5-10h; In step (3), the heat treatment temperature is 80-200℃ and the time is 1-4h.

15. The preparation method according to claim 14, wherein, The phosphorus source is one or more of phosphoric acid, phosphate, pyrophosphate, polyphosphate, hydrogen phosphate, dihydrogen phosphate, phosphite, and hypophosphite.

16. The preparation method according to claim 14 or 15, wherein, The mass ratio of the conductive carbon black to the phosphorus source (calculated as phosphorus) is 10000:1 to 10:

1.

17. The preparation method according to claim 14, wherein, The boron source is one or more of boric acid and borate.

18. The preparation method according to claim 14 or 17, wherein, The mass ratio of the conductive carbon black to the boron source (calculated as boron) is 10000:1 to 10:

1.

19. The preparation method according to claim 14, wherein, In step (1), the conductive carbon black is one or more of EC-300J, EC-600JD, ECP600JD, VXC72, VXC72R, Black Pearls 2000, PRINTEX XE2-B, PRINTEX L6 and HIBLAXK 40B2.

20. The preparation method according to claim 14 or 19, wherein, The oxygen mass fraction in the XPS analysis of the conductive carbon black was greater than 4%.

21. The preparation method according to claim 14 or 19, wherein, The resistivity of the conductive carbon black is less than 10 Ω·m.

22. The preparation method according to claim 14 or 19, wherein, The specific surface area of ​​the conductive carbon black is 200-2000 m². 2 / g.

23. The preparation method according to claim 14, wherein, In step (2), the platinum source is one or more of chloroplatinic acid, chloroplatinate, tetraammineplatinum acetate, and platinum acetylacetonate.

24. The preparation method according to claim 14 or 23, wherein, In step (2), the solvent is one or more of water, alcohol solvents or ketone solvents.

25. The preparation method according to claim 14 or 23, wherein, The solvent is water and / or ethanol.

26. The preparation method according to claim 14 or 23, wherein, The solvent is a mixture of water and ethanol.

27. The preparation method according to claim 14 or 23, wherein, In step (2), the amount of platinum source used is 0.01-0.25g relative to 1g of carbon support.

28. The preparation method according to claim 14 or 23, wherein, In step (2), the uniform mixture is allowed to stand for more than 10 hours before the solvent is removed.

29. The preparation method according to claim 28, wherein, In step (2), the settling time is 15-24 hours.

30. The preparation method according to claim 14 or 23, wherein, In step (2), the drying temperature during solvent removal is below 100°C.

31. The preparation method according to claim 14, wherein, In step (3), the heat treatment temperature is 100-180℃ and the reduction time is 2-3h.

32. The preparation method according to claim 14, wherein, In step (3), the reducing atmosphere includes hydrogen.

33. The preparation method according to claim 14, wherein, In step (3), the reducing atmosphere is a mixture of hydrogen and inert gas.

34. The preparation method according to claim 14, wherein, In step (3), the reducing atmosphere is a mixture of hydrogen and nitrogen.

35. The method according to any one of claims 32-34, wherein, Hydrogen accounts for 5-30% of the total gas volume.

36. A platinum-carbon catalyst, characterized in that, The catalyst is prepared by the method described in any one of claims 14-35.

37. An application of a platinum-carbon catalyst, characterized in that, The application of the platinum-carbon catalyst according to any one of claims 1-13 and 36 in fuel cells or water electrolysis.

38. A PEM electrolytic cell, characterized in that, The cathode of the PEM electrolyzer uses a platinum-carbon catalyst according to any one of claims 1-13 and 36.

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