Platinum-carbon catalyst and energy storage equipment

Abstract

The invention provides a platinum-carbon catalyst and energy storage equipment, and relates to the technical field of catalysts. The platinum-carbon catalyst provided by the invention is a carbon-supported catalyst in which the proportion of platinum atoms in the total metal atoms is not less than 90 at.% in the active metal components; the preparation raw materials of the platinum-carbon catalyst comprise a carbon carrier, the platinum-carbon catalyst further comprises platinum nanoparticles loaded on the carbon carrier, and the dispersity D of the platinum-carbon catalyst meets the condition that D is equal to 0.650.9; the specific surface area of the carbon carrier is 600m < 2 > / g 1200m < 2 > / g, in a Raman spectrum of the carbon carrier, the intensity ratio ID / IG of a peak D to a peak G is 1.6-2.2, and the half-peak width of the peak G is 40-65 cm; wherein D = dXRD / dECSA, dXRD refers to an arithmetic mean value after grain sizes are obtained based on diffraction peaks of corresponding crystal faces of (111), (200) and (220) of platinum, and dXRD is 2nm and 3nm; the calculation formula of the dECSA is shown in the specification; in the formula, rho is the density of platinum, ECSA is the electrochemical activity specific surface area of platinum, and the unit is m < 2 > / gPt. The platinum-carbon catalyst provided by the invention has relatively high quality activity.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and more particularly to a platinum-carbon catalyst and energy storage device. Background Technology

[0002] In fuel cells and metal-air batteries, the oxygen reduction reaction (ORR) is a major factor affecting battery performance. Currently, platinum-carbon catalysts are the key core components. The mass activity (MA) of a catalyst refers to the current produced per unit mass of catalyst at a specific voltage (typically 0.9V). It measures the catalyst's efficiency "by weight," measured in A / g (amperes per gram).

[0003] In fuel cells and metal-air batteries, the oxygen reduction reaction (ORR) is a major factor affecting battery performance. Platinum-carbon catalysts are key components in fuel cells and metal-air batteries; however, currently used platinum-carbon catalysts suffer from poor platinum dispersion and are prone to agglomeration and deactivation. There is an urgent need in the field to significantly improve platinum metal utilization and enhance its catalytic activity in order to promote its large-scale commercial application. Summary of the Invention

[0004] In view of this, this application provides a platinum-carbon catalyst and an energy storage device, which aims to solve at least one of the above-mentioned technical problems.

[0005] Firstly, this application discloses a platinum-carbon catalyst, wherein the platinum-carbon catalyst is a carbon-supported catalyst in which the molar ratio of platinum atoms to total metal atoms in the active metal component is not less than 90%; the raw materials for preparing the platinum-carbon catalyst include a carbon support, and the platinum-carbon catalyst further includes platinum nanoparticles supported on the carbon support, wherein the dispersion D of the platinum-carbon catalyst satisfies: D=0.65. 0.9; In the Raman spectrum of the carbon support, the specific surface area of ​​the carbon support is 600 m². 2 / g 1200m 2 The intensity ratio of the D peak to the G peak (ID / IG) is between 1.6 and 2.2, and the full width at half maximum (FWHM) of the G peak is 40 cm. - ¹ to 65 cm - ¹between; Where D=d XRD / d ECSA d XRD d refers to the arithmetic mean of the grain size obtained from the diffraction peaks of the (111), (200), and (220) corresponding crystal planes of platinum. XRD 2nm 3nm; d ECSA The calculation formula is:

[0006] In the formula, ρ is the density of platinum, and ECSA is the electrochemically active specific surface area of ​​platinum.

[0007] In some embodiments, the (111) crystal plane diffraction peak of the platinum is located at a diffraction angle 2θ of 38° to 40°; And / or, the (200) crystal plane diffraction peak of the Pt is located at a diffraction angle 2θ of 45° to 47°; And / or, the (220) crystal plane diffraction peak of the Pt is located at a diffraction angle 2θ of 66° to 68°; And / or, calculate the grain sizes of the (111), (200) and (220) crystal planes of platinum according to the Scherrer formula.

[0008] In some embodiments, the ECSA is 50m 2 / gPt~90m 2 / gPt.

[0009] In some embodiments, the carbon support is porous carbon particles.

[0010] In some embodiments, the specific surface area of ​​the porous carbon particles is 700~1000 m². 2 / g; And / or, the median pore size D50 of the porous carbon particles is 200 nm to 800 nm.

[0011] In some embodiments, D is 0.75 to 0.85.

[0012] In some embodiments, platinum atoms constitute not less than 95 at.% of the total number of metal atoms in the total metal composition. Preferably, the proportion of platinum atoms to the total number of metal atoms in the total metal composition is not less than 98 at.%.

[0013] In some embodiments, the active metal component includes platinum; and one or more of ruthenium, iron, cobalt, nickel, copper, palladium, tin, manganese, chromium, molybdenum, and tungsten.

[0014] In some embodiments, the mass fraction of elemental platinum in the platinum-carbon catalyst is 30 wt% to 60 wt%. And / or, the mass activity of the platinum-carbon catalyst is greater than or equal to 0.2 mA / µgPt.

[0015] A second aspect of this application provides an energy storage device comprising the aforementioned platinum-carbon catalyst.

[0016] The platinum-carbon catalyst provided in this application embodiment is based on a specific carbon support, the content of elemental platinum in the active metal component supported on the carbon support, and the arithmetic mean of the diffraction peaks of the (111), (200), and (220) corresponding crystal planes of the platinum particles (i.e., d). XRD ) is 2nm The dispersion D of the platinum-carbon catalyst is 3 nm, and the dispersion D satisfies: D = 0.65. 0.9, thereby giving the platinum-carbon catalyst in this application a high mass activity (MA). Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The dispersibility-mass activity trends are shown for Examples 1-12 and Comparative Examples 1-9. Figure 2 Transmission electron microscopy image of the platinum-carbon catalyst prepared in Example 1; Figure 3 Transmission electron microscopy (TEM) image of the platinum-carbon catalyst prepared in Comparative Example 4; Figure 4 Transmission electron microscopy (TEM) image of the platinum-carbon catalyst prepared in Comparative Example 8. Detailed Implementation

[0019] The experimental examples described in this application are merely some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] In the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are used merely as illustrative purposes and do not impose numerical requirements or establish an order.

[0022] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0023] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0024] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0025] In fuel cells and metal-air batteries, the oxygen reduction reaction (ORR) is a major factor affecting battery performance. Platinum-carbon catalysts are key components in fuel cells and metal-air batteries, but currently used platinum-carbon catalysts suffer from poor platinum dispersion and are prone to agglomeration and deactivation. There is an urgent need in the field to significantly improve platinum metal utilization, enhance its catalytic activity and stability, in order to promote its large-scale commercial application.

[0026] Therefore, this application provides a platinum-carbon catalyst, which is a carbon-supported catalyst in which the molar ratio of platinum atoms to total metal atoms in the active metal component is not less than 90%. Specifically, the platinum-carbon catalyst contains a carbon support and platinum nanoparticles supported on the carbon support, wherein the dispersion D of the platinum-carbon catalyst satisfies: D = 0.65. 0.9; the specific surface area of ​​the carbon support is 600 m². 2 / g 1200m 2In the Raman spectrum of the carbon support, the intensity ratio of the D peak to the G peak (ID / IG) is between 1.6 and 2.2, and the full width at half maximum (FWHM) of the G peak is 40 cm⁻¹. - ¹ to 65 cm - ¹between; Where D=d XRD / d ECSA d XRD d refers to the arithmetic mean of the dimensions obtained from the diffraction peaks of the (111), (200), and (220) crystal planes of platinum (Pt). XRD 2nm 3nm; d ECSA The calculation formula is:

[0027] In the formula, ρ is the density of platinum, and ECSA is the electrochemically active specific surface area of ​​platinum, in m³. 2 / gPt.

[0028] This application embodiment uses a specific carbon support, the content of elemental platinum in the active metal component supported on the carbon support, and the arithmetic mean (i.e., d) of the diffraction peaks corresponding to the (111), (200), and (220) crystal planes of the platinum particles. XRD ) is 2nm The dispersion D of the platinum-carbon catalyst is 3 nm, and the dispersion D satisfies: D = 0.65. 0.9, thereby giving the platinum-carbon catalyst in this application a high mass activity (MA).

[0029] It should be noted that in related technologies, the main pathway to improve catalyst mass activity (MA) is through reducing the grain size (d) of platinum nanoparticles. XRD To increase the electrochemically active specific surface area (ECSA), it is generally believed that d XRD The smaller the value, the higher the ECSA. This application's research found that in the prepared platinum-carbon catalyst, controlling the molar ratio of platinum atoms to total metal atoms to be no less than 90% and the specific coordination of the carbon support, in d... XRD 2nm 3nm, and D is 0.65 At a value of 0.9, the platinum-carbon catalyst exhibits high mass activity and surprising performance.

[0030] For example, in the XRD pattern of the platinum-carbon catalyst, the (111) crystal plane diffraction peak of Pt is located at a diffraction angle of 2θ between 38° and 40°, which can also be understood as the (111) crystal plane diffraction peak of Pt being located at a diffraction angle of approximately 39°, and its grain size is D. 111The (200) diffraction peak of Pt is located at a diffraction angle of 2θ between 45° and 47°, which can also be interpreted as the (200) diffraction peak of Pt being located at a diffraction angle of approximately 46°, and its grain size is D. 200 The (220) diffraction peak of Pt is located at a diffraction angle of 2θ between 66° and 68°, which can also be interpreted as the (220) diffraction peak of Pt being located at a diffraction angle of approximately 67°, and its grain size is D. 220 Accordingly, d XRD D 111 D 200 and D 220 The arithmetic mean of the values ​​reflects the size of the coherent diffraction region in the crystal, i.e., the crystal domain size. It should be noted that the specific method for obtaining the grain size from XRD diffraction peaks is not a major improvement of this application. For example, the grain size can be calculated using the Scherrer formula.

[0031] Specifically, the Scherrer formula is as follows: ; Where D is the grain size (usually in nm); K is the shape factor (in this invention, the platinum nanoparticles are approximately spherical grains, and the K value is 0.9); λ is the X-ray wavelength; β is the corrected half-width at half-maximum of the diffraction peak (in radians rad); and θ is the Bragg angle (in radians rad), which is half the position of the diffraction peak (half of 2θ).

[0032] For example, d XRD The values ​​are 2nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nm, 2.9nm, 3.0nm, and any two of the above values.

[0033] It should be noted that d ECSA This can be understood as the equivalent sphere diameter of platinum particles calculated based on their electrochemically active specific surface area (ECSA). It assumes that all platinum atoms constitute an ideal, smooth sphere, and that all surface atoms can be contacted and adsorbed by an electrochemical probe (such as H atoms). It reflects the particle size corresponding to the electrochemically accessible active surface.

[0034] Meanwhile, in the Raman spectrum of the carbon support, the intensity ratio of its D peak to G peak (ID / IG) is between 1.6 and 2.2, and the full width at half maximum (FWHM) of its G peak is 40 cm⁻¹. - ¹ to 65 cm -Between ¹. In this application, by using a carbon support with a specific structure, the dispersion state of platinum particles can be precisely controlled through a moderate defect density, enabling them to form and stabilize in a highly active metastable state (optimal D-value window); at the same time, sufficiently large graphite crystallites can be retained to ensure rapid charge transport. This synergistic effect of the microstructure is a key factor in achieving a breakthrough in catalyst mass activity (MA). It should be noted that the ID / IG and G peak full width at half maximum (FWHM) ranges defined in this invention are not microscopically independent, but rather jointly define a unique carbon support.

[0035] It should be noted that in the platinum-carbon catalyst provided in this application, if the proportion of platinum (Pt) atoms to the total number of metal atoms is less than 90 at.%, Pt is prone to forming Pt-M alloys with other active metal atoms (such as Fe, Co, Ni, etc.). The active sites and reaction pathways are different from those of the platinum catalyst, which makes the relationship between the dispersion D and the mass activity (MA) described in this invention no longer applicable.

[0036] In this embodiment, the arithmetic mean (i.e., d) of the diffraction peaks corresponding to the (111), (200), and (220) crystal planes of the platinum particles loaded on the carbon support is obtained by using a specific carbon support. XRD ) is 2nm The dispersion D of the platinum-carbon catalyst is 3 nm, and the dispersion D satisfies: D = 0.65. 0.9, thereby giving the platinum-carbon catalyst in this application a high mass activity (MA).

[0037] It should be emphasized that the inventors' research found that d in platinum-carbon catalysts XRD 2nm A particle size of 3 nm is beneficial for improving the surface utilization rate of platinum-carbon catalysts and represents the golden size range for achieving "better electronic structure" and "better surface geometry." Under this premise, adjusting the dispersion D is necessary to further optimize the surface atom utilization rate. When d in the platinum-carbon catalyst... XRD 2nm When the dispersion is 3 nm and the dispersion density (D) is between 0.65 and 0.9, the relationship between D and MA exhibits a volcano-shaped curve. This is likely because when D is too low, the particles aggregate severely, with multiple primary particles fusing into large aggregates, burying the internal active sites and causing a sharp decrease in ECSA. Aggregation may impair mass transfer, thus damaging SA (specific activity). It is understandable that ECSA, MA, and specific activity (SA) have the following relationship: MA = ECSA * SA. Here, SA refers to the current generated per unit ECSA at a specific voltage (typically 0.9V). It measures the intrinsic catalytic ability of the catalyst surface, measured in Am. - ² (amperes per square meter) or mA cm -² (milliamperes per square centimeter). ECSA loss is the dominant factor; SA may decrease, leading to MA range.

[0038] When D is too high (e.g., D > 0.9, approaching 1), the particles are close to ideal monodispersity, the active sites are fully exposed, and the ECSA is very high. Meanwhile, overly perfect, isolated single-crystal structures may lack intrinsically more active special sites such as high-index crystal planes and step sites, resulting in a relatively high SA (but not optimal, with room for improvement). According to MA = SA (not optimal) × ECSA (high), since the potential of SA has not been fully activated, MA still has some room for improvement, thus resulting in MA still not being ideal.

[0039] When D is at 0.65 At 0.9, there is no severe particle aggregation, most active sites are retained, and ECSA remains high. Increased SA (relative to D>0.9): This state corresponds to a metastable, loose structure or controllable local inhomogeneity, which precisely forms a large number of highly intrinsically active surface sites (such as specific crystal planes, strain structures, etc.), significantly increasing SA. Result: MA = SA (relative to D>0.9) × ECSA (high), thus increasing the MA value.

[0040] It should be emphasized that, as recorded in Chinese patent CN201910571287.1, it is generally believed that d XRD The smaller the value, the higher the ECSA. Then, in d... XRD Under similar conditions, the higher the physical dispersion of the catalyst, the greater the ECSA and the higher the final MA. Therefore, current efforts focus on synthesizing catalysts with ultra-small particle size and no aggregation, and it is assumed that the higher the dispersion (the closer to ideal monodispersion), the better the MA performance. However, this application innovatively discovers that d XRD 2nm In the Raman spectrum of the carbon support at 3 nm, the intensity ratio of the D peak to the G peak (ID / IG) is between 1.6 and 2.2, and the full width at half maximum (FWHM) of the G peak is 40 cm⁻¹. - ¹ to 65 cm - ¹ and the dispersion D of the platinum particles on the carbon support satisfies: D = 0.7 At 0.9, the platinum-carbon catalyst exhibits high mass activity (MA).

[0041] For example, ECSA can be determined by adsorption-desorption method.

[0042] For example, D is a value between 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, and any two of the above values. Preferably, D is between 0.75 and 0.85.

[0043] For example, the specific surface area of ​​the porous carbon particles is 600 m². 2 / g、700m 2 / g、800m 2 / g, 900m 2 / g, 1000m 2 / g、1100m 2 / g、1200m 2 / g and any two of the above values ​​within a certain range. This facilitates the anchoring of platinum particles by porous carbon particles and improves the mass activity (MA) of the catalyst.

[0044] It should be noted that if the specific surface area of ​​porous carbon particles is too low, they cannot effectively anchor platinum particles, which can easily lead to sintering and aggregation. If the specific surface area of ​​porous carbon particles is too high, their abundant micropores will cause a large amount of electrochemically inaccessible "dead platinum" to be formed after the reduction of the platinum precursor. This will lead to a serious underestimation of ECSA, which in turn will cause the calculated value of dECSA to deviate significantly from the physical true value, making it difficult to obtain high-quality active platinum-carbon catalysts.

[0045] In some embodiments, the ECSA of platinum is 50m. 2 / gPt ~90m 2 / gPt (i.e., 50m) 2 / gPt to 90m 2 / gPt). For example, ECSA is 50m. 2 / gPt, 60m 2 / gPt, 70m 2 / gPt, 80m 2 / gPt, 90m 2 / gPt and the range between any two of the above values.

[0046] In some embodiments, the carbon support is porous carbon particles. Further, the median pore size D50 of the porous carbon particles is 200 nm to 800 nm.

[0047] For example, the median pore size D50 of the porous carbon particles is 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, and any two of the above values.

[0048] For example, the Raman spectroscopy test was performed using a 532 nm laser.

[0049] In some embodiments, the molar ratio of platinum atoms to total metal atoms is not less than 95%, more preferably not less than 98%. This is beneficial for obtaining high-quality, active platinum-carbon catalysts.

[0050] In some embodiments, the active metal component includes platinum and other possible metallic elements. Exemplarily, the other metallic elements include, but are not limited to, one or more of ruthenium (Ru), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), palladium (Pd), tin (Sn), manganese (Mn), chromium (Cr), molybdenum (Mo), and tungsten (W).

[0051] In some embodiments, in the platinum-carbon catalyst, the mass fraction of elemental platinum in the catalyst is 30 wt% to 60 wt%. Exemplarily, the mass fraction of elemental platinum in the catalyst is 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or any range between any two of the above values.

[0052] This invention provides a method for preparing the aforementioned platinum-carbon catalyst, the method comprising the following steps: S100 dissolves the platinum precursor in a dispersion medium to form a platinum precursor solution. The concentration of the platinum precursor in the dispersion medium ranges from 0.003 g Pt / mL to 0.005 g Pt / mL.

[0053] For example, platinum precursors include, but are not limited to, at least one of chloroplatinic acid, platinum nitrate, and platinum acetylacetonate.

[0054] For example, the dispersion medium includes at least one of water, ethanol, and ethylene glycol.

[0055] For example, the concentration of the platinum precursor in the dispersion medium is 0.003 g Pt / mL, 0.004 g Pt / mL, 0.005 g Pt / mL, and any two of the above values.

[0056] S200 involves dispersing a carbon support in a platinum precursor solution, thereby loading the platinum precursor onto the carbon support. The specific gravity of the carbon support is 600 m³ / s. 2 / g ~1200m 2 / g, the intensity ratio of its D peak to G peak, ID / IG, is between 1.6 and 2.2, and the full width at half maximum (FWHM) of its G peak is 40 cm. - ¹ to 65 cm - ¹ Between.

[0057] For example, the carbon support can be directly added to the platinum precursor solution prepared in step S100 and stirred to form a slurry. Alternatively, the carbon support can be first dispersed in a partial dispersion medium, and then the dispersion medium containing the carbon support can be mixed with the platinum precursor solution prepared in step S100 and stirred to form a slurry; this is not limited to any particular method.

[0058] For example, a platinum precursor solution is mixed with a carbon support, and the platinum precursor is uniformly loaded onto the carbon support by methods such as impregnation, equal-volume impregnation, or initial wet impregnation.

[0059] S300 reduces the platinum precursor on the carbon support to metallic platinum.

[0060] For example, platinum precursors are reduced to metallic platinum using methods such as chemical reduction, thermal reduction, or polyol reduction.

[0061] In the preparation method provided in this application, a platinum-carbon catalyst with a dispersion D of 0.65 to 0.9 and an XRD grain size of 2 nm to 3 nm can be prepared by using a carbon support with a specific structure and a suitable precursor concentration. It should be noted that this preparation scheme is merely one example of preparing the aforementioned platinum-carbon catalyst and is not limited to the specific conditions described above. Any method capable of achieving the structural characteristics of the catalyst of this invention falls within the protection scope of this invention.

[0062] Specifically, chemical reduction: a reducing agent (such as sodium borohydride, ascorbic acid, formaldehyde, hydroquinone, etc.) is added to a carbon support slurry loaded with platinum precursors under stirring, and the mixture is reacted at a specific temperature (e.g., 0-100℃) for a period of time (e.g., 1-24 hours).

[0063] Specifically, the polyol method involves using a polyol (such as ethylene glycol) as a solvent and reducing agent, and reacting it for a period of time (e.g., 1-6 hours) under heating (e.g., 120-200°C) and stirring.

[0064] Specifically, thermal reduction: heat treatment of a carbon support loaded with platinum precursors in an inert atmosphere (such as nitrogen or argon) or a reducing atmosphere (such as hydrogen) at a certain temperature (e.g., 200-500°C).

[0065] In some embodiments of this application, prior to step S100, the preparation method of the platinum-carbon catalyst further includes: pretreating the carbon support to increase surface functional groups and improve hydrophilicity. Exemplarily, the functional groups include, but are not limited to, carboxyl groups and / or hydroxyl groups. The carbon support is refluxed in a concentrated acid (such as nitric acid or sulfuric acid) or treated with an oxidant (such as hydrogen peroxide), then washed until neutral and dried. It should be noted that pretreating the carbon support is not a major improvement of this application and is not limited thereto.

[0066] In some embodiments of this application, after step S300, the method for preparing the platinum-carbon catalyst further includes: subjecting the product prepared in step S300 to at least one of the following treatments: cooling, centrifugation, washing, drying, and annealing.

[0067] Specifically, the product is washed with deionized water and / or ethanol.

[0068] Specifically, the product is vacuum dried and washed at 60-100℃.

[0069] Specifically, annealing is performed in an inert or reducing atmosphere to improve the crystal structure. For example, annealing at 200°C to 400°C for 1 hour to 4 hours. Care must be taken to avoid causing particle sintering.

[0070] A second aspect of this application also provides an energy storage device comprising the aforementioned platinum-carbon catalyst. Exemplarily, the energy storage device may be a fuel cell or a metal-air battery.

[0071] Example 1 S1, Weigh a certain amount of mesoporous carbon (specific gravity 900m). 2 / g, ID / IG is 2.2, and the full width at half maximum (FWHM) of the G peak is 45cm. -1 Place them in an oven to dry.

[0072] S2, take 3g of the dried mesoporous carbon from step S1, add 600mL of ethylene glycol, and ultrasonically disperse to obtain a uniform slurry. Then add 7.89g of chloroplatinic acid (platinum precursor, containing 3g of platinum) to the slurry and disperse it evenly. The concentration of platinum precursor in the slurry is 0.005gPt / mL.

[0073] S3, add NaOH to adjust the pH of the slurry to 10-12, and at the same time purge nitrogen to remove oxygen.

[0074] S4 was heated to 140℃ to completely reduce platinum ions to platinum metal. After cooling, it was centrifuged, washed, and freeze-dried to obtain a porous carbon-supported platinum-carbon catalyst.

[0075] Example 2 The difference between this example and Example 1 is that in step S2, the concentration of the platinum precursor in the slurry is 0.0043 gPt / mL. The rest is the same as in Example 1.

[0076] Example 3 The difference between this example and Example 1 is that in step S2, the concentration of the platinum precursor in the slurry is 0.00375 g Pt / mL. The rest is the same as in Example 1.

[0077] Example 4 The difference between this and Example 1 is that in step S1, the specific surface area of ​​the mesoporous carbon is 875m. 2 / g, ID / IG is 1.8. The rest is the same as in Example 1.

[0078] Example 5 The difference between this and Example 1 is that in step S1, the specific surface area of ​​the mesoporous carbon is 759m. 2 / g, G peak half-peak width 48cm -1 The rest is the same as in Example 1.

[0079] Example 6 The difference between this and Example 1 is that in step S1, the specific surface area of ​​the mesoporous carbon is 795m. 2 / g, G peak half-peak width 48cm -1 The rest is the same as in Example 1.

[0080] Example 7 The difference between this and Example 1 is that in step S1, the specific surface area of ​​the mesoporous carbon is 1089m. 2 / g, G peak half-peak width 48cm -1 The rest is the same as in Example 1.

[0081] Example 8 The difference between this and Example 1 is that in step S1, the half-peak width of the G peak of the mesoporous carbon is 40 cm. -1 The rest is the same as in Example 1.

[0082] Example 9 The difference between this and Example 1 is that in step S1, the half-peak width of the G peak of the mesoporous carbon is 55 cm. -1 The rest is the same as in Example 1.

[0083] Example 10 The difference between this and Example 1 is that in step S1, the half-peak width of the G peak of the mesoporous carbon is 65 cm. -1 The rest is the same as in Example 1.

[0084] Example 11 The difference between this example and Example 1 is that in step S2, 7.89g of chloroplatinic acid (a platinum precursor containing 3g of platinum) and 1.65g of cobalt nitrate (a cobalt precursor containing 0.33g of cobalt) are added to the slurry and dispersed evenly. The concentration of the platinum precursor in the slurry is 0.005gPt / mL, and the concentration of the cobalt precursor is 0.00055gCo / mL. The rest is the same as in Example 1.

[0085] Example 12 The difference between this example and Example 1 is that in step S2, 7.89g of chloroplatinic acid (a platinum precursor containing 3g of platinum) and 0.78g of cobalt nitrate (a cobalt precursor containing 0.158g of cobalt) are added to the slurry and dispersed evenly. The concentration of the platinum precursor in the slurry is 0.005gPt / mL, and the concentration of the cobalt precursor is 0.000263gCo / mL. The rest is the same as in Example 1.

[0086] Comparative Example 1 The difference between this example and Example 1 is that the mesoporous carbon used in S1 has an ID / IG ratio of 1.5. Everything else is the same as in Example 1.

[0087] Comparative Example 2 The difference between this example and Example 1 is that the ID / IG ratio of the mesoporous carbon used in S1 is 2.3. Everything else is the same as in Example 1.

[0088] Comparative Example 3 The difference between this and Example 1 is that the mesoporous carbon used in S1 has a G peak half-width of 38 cm. -1 The rest is the same as in Example 1.

[0089] Comparative Example 4 The difference between this and Example 1 is that the mesoporous carbon used in S1 has a G peak half-width of 67 cm. -1 The rest is the same as in Example 1.

[0090] Comparative Example 5 The difference between this example and Example 1 is that in step S2, the concentration of the platinum precursor in the slurry is 0.002 g Pt / mL. Everything else is the same as in Example 1.

[0091] Comparative Example 6 The difference between this example and Example 1 is that in step S2, the concentration of the platinum precursor in the slurry is 0.006 g Pt / mL. Everything else is the same as in Example 1.

[0092] Comparative Example 7 The difference between this and Example 1 is that in step S1, the specific surface area of ​​the mesoporous carbon is 1300m. 2 / g. The rest is the same as in Example 1.

[0093] Comparative Example 8 The difference between this and Example 1 is that in step S1, the specific surface area of ​​the mesoporous carbon is 550m. 2 / g, the half-width of peak G is 48cm. - ¹. The rest is the same as in Example 1.

[0094] Comparative Example 9 The difference between this example and Example 1 is that in step S2, 7.89g of chloroplatinic acid (a platinum precursor containing 3g of platinum) and 2.61g of cobalt nitrate (a cobalt precursor) are added to the slurry and dispersed evenly. The concentration of the platinum precursor in the slurry is 0.005gPt / mL, and the concentration of the cobalt precursor is 0.00087gCo / mL. The rest is the same as in Example 1.

[0095] Experimental Test 1. Particle size test: The particle size of the powder was tested using a Malvern MS3000 instrument, based on anhydrous ethanol + water as dispersant, with a refractive index of 2.4 and a light-blocking degree of 10%.

[0096] 2. Specific surface area: The specific surface area and total pore volume of porous carbon were determined using the iPore620 fully automatic specific surface area and pore size analyzer from Lihualianke, employing the nitrogen isothermal adsorption-desorption method.

[0097] 3. Median pore size D50 test method: The pore size distribution of porous carbon is obtained by fitting the nitrogen isothermal adsorption-desorption curve using the NLDFT model. The proportion of pore volume with a pore size of 2 nm or less to the total pore volume is the micropore proportion.

[0098] 4. Raman spectroscopy testing method: A RenishawinVia microconfocal Raman spectrometer was used for testing. The excitation source was a semiconductor laser with a wavelength of 532 nm. The actual power reaching the sample surface was controlled at 1 mW (after calibration). A 50x telephoto objective lens was used for focusing and signal acquisition. Before testing, the instrument was calibrated using a single-crystal silicon wafer (characteristic peak 520.7 cm⁻¹).

[0099] 5. Adsorption performance of the catalyst.

[0100] The test employed a three-electrode system: the working electrode was a glassy carbon electrode with a catalyst supported, the reference electrode was a standard hydrogen electrode, and the counter electrode was a Pt sheet. The test solution was a 0.1 M perchloric acid solution saturated with nitrogen / oxygen. The cyclic voltammetry scan potential range was set from 0.05 V vs. RHE to 1.05 V vs. RHE, with a scan rate of 50 mV / s. 1 The electrochemical specific surface area (ECSA) of platinum was calculated by potentiometrically depositing the area of ​​the hydrogen adsorption / desorption region. The potential range for LSV testing was from 0.05 V vs. RHE to 1.05 V vs. RHE, with a scan rate of 10 mV s⁻¹. 1 The rotating disk electrode rotates at 1600 rpm, and the mass activity (MA) is calculated as follows: Background subtraction: At the same speed and potential (1600 rpm, 0.9 V vs. RHE), the net current density jnet (unit: mA / cm²geo) is obtained by subtracting the current density of the nitrogen atmosphere from the current density of the oxygen atmosphere.

[0101] Calculation of kinetic current based on the Koutecky-Levich (KL) equation: Applying the KL equation to the net current density at each rotational speed at 0.9 V vs. RHE potential:

[0102] Where, j net Net current density; j dThe limiting diffusion current density after background subtraction is given in the diffusion control region (1600 rpm, 0.4 V vs. RHE) at the same rotational speed; j k : Dynamic current density.

[0103] Mass activity (MA) is (I k / Total mass of platinum on the electrode). The unit is usually A / gPt or mA / µgPt.

[0104] The above experimental examples were subjected to relevant tests, and the test results are shown in Table 1.

[0105] Table 1

[0106] In Examples 1 to 12, the prepared platinum-carbon catalysts meet the requirement that the molar ratio of platinum atoms to total metal atoms is not less than 90%, d XRD 2nm The dispersion D of the platinum-carbon catalyst is 0.65 at 3 nm. 0.9, and the specific surface area of ​​the carbon support is 600 m². 2 / g 1200m 2 / g, ID / IG ratio between 1.6 and 2.2, and full width at half maximum (FWHM) of peak G around 40 cm⁻¹ - ¹ to 65cm - ¹ Accordingly, in conjunction with Table 1 and Figure 1 It can be seen that the platinum-carbon catalyst has a higher MA value.

[0107] Figure 2 The image shows a transmission electron microscope (TEM) image of the Pt / C catalyst in Example 1. The dispersion D is 0.758, indicating that the platinum particles are basically single particles with relatively uniform dispersion and only a small amount of aggregation. Figure 3 The image shows a transmission electron microscope (TEM) image of the Pt / C catalyst in Comparative Example 4. The dispersion D is 0.96, indicating that the platinum particles are highly uniformly dispersed on the carbon support surface, with no obvious agglomerates or clusters observed. The particle spacing is moderate, and the distribution density is uniform. Figure 4 The image shows a transmission electron microscope (TEM) image of the Pt / C catalyst in Comparative Example 8. The dispersion D = 0.51, indicating a highly uneven size distribution. Numerous dense aggregates of varying sizes are present, demonstrating significant particle aggregation. As shown in Table 1, the dispersion D is not between 0.65 and 0.9, resulting in a low MA value for the prepared platinum-carbon catalyst.

[0108] By comparing Example 1 with Comparative Examples 2, 4, and 6, it can be found that Comparative Examples 2, 4, and 6 exhibit excellent dispersion, but their MA activity is reduced. This indicates that higher dispersion does not necessarily mean higher MA activity. This may be because overly dispersed particles result in high proton conduction resistance and difficulty in mass transfer of reactants, causing some platinum surfaces to become "electrochemical dead zones," leading to a decrease in actual MA.

[0109] Compared with Comparative Examples 1 to 4 and Comparative Examples 7 to 8, the carbon support in Comparative Examples 1 to 4 or Comparative Example 8 was not ideal. It exhibited problems such as excessively large or small ID / IG ratios, excessively large or small full width at half maximum (FWHM) of the G peak, and excessively large or small specific surface areas, leading to d... XRD Not meeting 2nm requirements 3nm or dispersion D does not meet 0.65 0.9. For example, in Comparative Example 1, the ID / IG ratio is low due to insufficient carrier anchoring, leading to sintering and aggregation of platinum particles. XRD The values ​​are too high. Comparative Example 6 uses a highly disordered support with an excessively broad G-peak (G peak half-width failure), resulting in poor conductivity and some platinum becoming "dead platinum." For example, Comparative Example 8 uses a carbon support with a low specific surface area, which easily leads to unsatisfactory platinum dispersion and a low MA. This is because the support itself has limited mesopores and cannot provide a sufficient and uniform loading platform, making it easy for platinum particles to be over-loaded or unevenly distributed. All of these are detrimental to obtaining a highly active platinum-carbon catalyst.

[0110] The difference between Examples 11, 12, and Comparative Example 9 lies in the molar ratio of platinum atoms to total metal atoms. In Comparative Example 9, the molar ratio of platinum atoms to total metal atoms is too low, leading to the formation of an alloy catalyst between platinum and cobalt, which is not conducive to obtaining a highly active platinum-carbon catalyst.

[0111] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A platinum-carbon catalyst, characterized in that, The platinum-carbon catalyst is a carbon-supported catalyst in which the molar ratio of platinum atoms to total metal atoms in the active metal component is not less than 90%. The raw materials for preparing the platinum-carbon catalyst include a carbon support, and the catalyst further includes platinum nanoparticles supported on the carbon support. The dispersion D of the platinum-carbon catalyst satisfies: D = 0.

65. 0.9; the specific surface area of ​​the carbon support is 600 m². 2 / g 1200m 2 In the Raman spectrum of the carbon support, the intensity ratio of the D peak to the G peak is between 1.6 and 2.2, and the full width at half maximum (FWHM) of the G peak is 40 cm⁻¹. - ¹ to 65 cm - ¹between; Where D=d XRD / d ECSA d XRD d refers to the arithmetic mean of the grain size obtained from the diffraction peaks of the (111), (200), and (220) corresponding crystal planes of platinum. XRD 2nm 3nm; d ECSA The calculation formula is: In the formula, ρ is the density of platinum, and ECSA is the electrochemically active specific surface area of ​​platinum.

2. The platinum-carbon catalyst according to claim 1, characterized in that, The diffraction peak of the (111) crystal plane of the platinum is located at a diffraction angle of 2θ of 38° to 40°. And / or, the (200) crystal plane diffraction peak of the platinum is located at a diffraction angle 2θ of 45° to 47°; And / or, the (220) crystal plane diffraction peak of the platinum is located at a diffraction angle 2θ of 66° to 68°; And / or, calculate the grain sizes of the (111), (200) and (220) crystal planes of platinum according to the Scherrer formula.

3. The platinum-carbon catalyst as described in claim 1 or 2, characterized in that, The ECSA is 50m 2 / gPt~90m 2 / gPt.

4. The platinum-carbon catalyst as described in claim 1, characterized in that, The carbon support is porous carbon particles.

5. The platinum-carbon catalyst as described in claim 4, characterized in that, The specific surface area of ​​the porous carbon particles is 700 m². 2 / g~1000m 2 / g; And / or, the median pore size D50 of the porous carbon particles is 200 nm to 800 nm.

6. The platinum-carbon catalyst according to claim 1, characterized in that, D ranges from 0.75 to 0.

85.

7. The platinum-carbon catalyst according to claim 1, characterized in that, The molar ratio of platinum atoms to total metal atoms is not less than 95%; Preferably, the molar ratio of platinum atoms to total metal atoms is not less than 98%.

8. The platinum-carbon catalyst according to claim 1, characterized in that, The active metal component includes platinum; and one or more of ruthenium, iron, cobalt, nickel, copper, palladium, tin, manganese, chromium, molybdenum, and tungsten.

9. The platinum-carbon catalyst as described in claim 1, characterized in that, The mass fraction of elemental platinum in the platinum-carbon catalyst is 30 wt% to 60 wt%. And / or, the mass activity of the platinum-carbon catalyst is greater than or equal to 0.2 mA / µgPt.

10. An energy storage device, characterized in that, The energy storage device includes the platinum-carbon catalyst according to any one of claims 1 to 9.

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