Carbon / titanium dioxide supported oxygen reduction catalyst as well as preparation method and application thereof

Abstract

The invention discloses a carbon / titanium dioxide supported oxygen reduction catalyst as well as a preparation method and application thereof, the carbon / titanium dioxide supported oxygen reduction catalyst takes a complex formed by carbon and titanium dioxide as a carrier, and noble metal particles are supported on the carrier; the noble metal particles are at least one of Pt particles and Pd particles; and the loading capacity of the noble metal particles on the carrier is 1-10 wt%. According to the invention, the carrier is composed of carbon and titanium dioxide, and the noble metal particles are uniformly anchored on the carrier, so that the prepared carbon / titanium dioxide supported oxygen reduction catalyst has excellent electro-catalytic oxygen reduction activity and stability, and can be used as a cathode catalyst material in electro-catalytic oxygen reduction reaction.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a carbon / titanium dioxide supported oxygen reduction catalyst, its preparation method, and its applications. Background Technology

[0002] Energy is the material foundation for the existence and development of human society. In today's society, facing the increasing depletion of fossil fuels and the resulting crises such as environmental pollution and climate change, my country has incorporated the vigorous development of renewable energy into its national energy strategic development plan. However, the inherent intermittent nature of renewable energy, along with the high energy loss and high costs associated with long-distance power transmission in conventional power grids, greatly limits the large-scale utilization and development of renewable energy.

[0003] Against this backdrop, fuel cells, as devices capable of directly and efficiently converting the chemical energy of fuel into electrical energy, have become one of the most promising technologies in the renewable energy field due to their high energy conversion efficiency and low carbon emissions. In fuel cells, the cathode achieves energy conversion through the oxygen reduction reaction (ORR). Compared to the anode reaction, the cathode ORR involves a multi-step proton-coupled four-electron transfer process, with very slow reaction kinetics, requiring a high overpotential. This severely limits the energy conversion efficiency and power output of fuel cells. Therefore, developing efficient ORR catalysts is a key bottleneck and research hotspot for improving the overall performance of fuel cells.

[0004] Currently, commercially available ORR catalysts are still primarily noble metal-based Pt / C materials. However, their scarcity, high cost, and insufficient stability severely hinder the large-scale commercial application of fuel cell technology. Given these limitations, developing alternative catalysts that combine low cost, high activity, and high stability is a crucial and challenging task. In recent years, transition metal oxide supports (such as TiO2, SnO2, and WO3) have attracted widespread attention as potential alternatives to carbon supports due to their excellent stability. Among them, TiO2 stands out for its outstanding chemical, electrochemical, and thermal stability. However, compared to carbon materials, TiO2 has lower electrical conductivity, which limits the overall performance of TiO2-based electrocatalysts. Therefore, further improvements to the overall performance of TiO2 electrocatalysts are needed. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon / titanium dioxide supported oxygen reduction catalyst, its preparation method and application. This carbon / titanium dioxide supported oxygen reduction catalyst is effectively used as a room temperature oxygen reduction electrochemical cathode, which improves the effective activation of O2 on the catalyst surface, thereby effectively improving the catalytic activity of the catalyst. Moreover, the preparation process is simple, the reaction conditions are mild, and there are no harsh conditions such as high temperature and high pressure.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A carbon / titanium dioxide supported oxygen reduction catalyst, which uses a composite of carbon and titanium dioxide as a support, wherein noble metal particles are loaded on the support.

[0008] The precious metal particles are at least one of Pt particles and Pd particles;

[0009] The loading of the precious metal particles on the carrier is 1wt%~10wt%.

[0010] In one or more embodiments of the present invention, the particle size of the carrier is 400 nm to 500 nm.

[0011] In one or more embodiments of the present invention, the particle size of titanium dioxide in the carrier is 10 nm to 30 nm.

[0012] In one or more embodiments of the present invention, the particle size of the noble metal particles is less than or equal to 10 nm.

[0013] In one or more embodiments of the present invention, the mass percentage of titanium in the carrier is 30wt% to 40wt%.

[0014] Another specific embodiment of the present invention provides the following technical solution:

[0015] A method for preparing a carbon / titanium dioxide supported oxygen reduction catalyst includes the following steps:

[0016] S1. MOF precursors are prepared by reacting titanium source, ligand, regulator and solvent as raw materials;

[0017] S2. Disperse the MOF precursor and noble metal salt in the reaction solvent to react and obtain the initial product;

[0018] S3. The primary product is calcined to obtain a carbon / titanium dioxide supported oxygen reduction catalyst.

[0019] In one or more embodiments of the present invention, the ratio of the titanium source, ligand, modifier and solvent is (0.5 mL~0.6 mL): (450 mg~500 mg): (5 mL~6 mL): (100 mL~150 mL).

[0020] In one or more embodiments of the present invention, the titanium source is selected from one or both of tetrabutyl titanate and isopropyl titanate; and / or,

[0021] The ligand is selected from one or two of 2,2'-bipyridine-5,5'-dicarboxylic acid and 2-aminoterephthalic acid; and / or,

[0022] The regulator is selected from one or both of benzoic acid and glacial acetic acid; and / or,

[0023] The solvent is selected from one or both of DMF and DMA; and / or,

[0024] The noble metal salt is one or more selected from chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, palladium chloride, and palladium nitrate; and / or,

[0025] The reaction solvent is water.

[0026] In one or more embodiments of the present invention, in step S1, the reaction conditions are: temperature 100℃~180℃, time 24 h~72 h; and / or,

[0027] In step S2, the reaction conditions are: temperature 60℃~80℃, time 12 h~36 h; and / or,

[0028] The calcination conditions are: temperature 600℃~800℃, time 1 h~3 h, and calcination atmosphere is argon or a hydrogen-argon mixture.

[0029] Another specific embodiment of the present invention provides the following technical solution:

[0030] The use of a carbon / titanium dioxide supported oxygen reduction catalyst for electrocatalytic oxygen reduction reactions;

[0031] The carbon / titanium dioxide supported oxygen reduction catalyst is the aforementioned carbon / titanium dioxide supported oxygen reduction catalyst.

[0032] Compared with the prior art, the present invention has the following superior effects:

[0033] 1. The preparation method of the present invention adopts a simple solvothermal synthesis method, using 2,2'-bipyridine-5,5'-dicarboxylic acid or 2-aminoterephthalic acid as ligands to prepare titanium-based MOF precursors. A post-modification synthesis strategy is adopted to anchor noble metals Pt or Pd on the MOF precursors. The resulting carbon / titanium dioxide supported oxygen reduction catalyst has excellent electrocatalytic oxygen reduction activity and stability, and can be used as a cathode catalyst material in electrocatalytic oxygen reduction reactions.

[0034] 2. The carrier selected in this invention is a composite of acid-resistant metal oxide titanium dioxide and carbon, on which noble metal Pt or Pd nanoparticles are anchored. As a cathode catalytic material, it can maintain structural stability and not be corroded in acidic or alkaline media to carry out electrochemical oxygen reduction reaction.

[0035] 3. The preparation method of the present invention is simple, has few synthesis steps, mild reaction conditions, and low cost, which is conducive to large-scale production and application. It can be extended to the synthesis of other noble metal nanoparticle-metal oxide catalysts and has good universality. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is the XRD pattern of the catalyst in Example 2 of the present invention;

[0038] Figure 2 This is a transmission electron microscope image of the catalyst in Example 5 of the present invention;

[0039] Figure 3 High-resolution transmission electron microscopy image and elemental distribution map of the catalyst in Example 5 of this invention;

[0040] Figure 4 The Pt-TiO3 in Examples 2, 5, and 8 2-x Comparison of oxygen reduction polarization test curves of @C catalyst and commercial catalyst Pt / C. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0042] One specific embodiment of the present invention provides a carbon / titanium dioxide supported oxygen reduction catalyst, which uses a composite formed by carbon and titanium dioxide as a support, and noble metal particles are loaded on the support; the noble metal particles are at least one of Pt particles and Pd particles; the loading amount of noble metal particles on the support is 1wt%~10wt%.

[0043] Specifically, in electrocatalytic oxygen reduction reactions, the electrode is typically placed in an acidic or alkaline medium. This invention uses a carbon-titanium dioxide composite as a support. Carbon materials possess high electrical conductivity, while titanium dioxide exhibits chemical, electrochemical, and thermal stability. Combining these two materials imparts structural and performance stability to the catalyst, reducing the likelihood of corrosion. Simultaneously, the noble metals Pt and Pd possess high catalytic activity. Loading noble metal particles onto a support with a high specific surface area not only ensures catalyst stability but also significantly enhances its catalytic activity.

[0044] The loading amount of precious metal particles on the carrier is preferably 3wt% to 10wt%, specifically 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%.

[0045] Furthermore, the particle size of the carrier is 400 nm to 500 nm.

[0046] Specifically, by controlling the particle size and morphology of the support, the support can have a large specific surface area to load noble metal particles. At the same time, the support within the above particle size range can also ensure that the catalyst has high structural stability.

[0047] Furthermore, the particle size of titanium dioxide in the carrier is 10 nm to 30 nm.

[0048] Specifically, titanium dioxide within the aforementioned particle size range has a large specific surface area and abundant active sites, which can effectively enhance the catalytic activity of the catalyst.

[0049] Furthermore, the precious metal particles have a diameter of less than or equal to 10 nm, with an average diameter of approximately 3 nm.

[0050] Specifically, small-diameter noble metal particles have a larger specific surface area, which is beneficial for exposing surface active sites and improving the catalytic activity of the catalyst.

[0051] Furthermore, the mass percentage of titanium in the carrier is 30wt%~40wt%.

[0052] Specifically, the mass percentage of titanium can be 30wt%, 32wt%, 35wt%, 37wt%, 39wt%, or 40wt%. By adjusting the mass percentage of carbon and titanium dioxide in the support, the catalyst can be made to have excellent stability while ensuring its conductivity.

[0053] Another specific embodiment of the present invention provides a method for preparing a carbon / titanium dioxide supported oxygen reduction catalyst, comprising steps 1 to 3.

[0054] Step 1: MOF precursors are prepared by reacting titanium source, ligand, regulator and solvent as raw materials.

[0055] Specifically, the titanium source is selected from one or both of tetrabutyl titanate and isopropyl titanate; the ligand is selected from one or both of 2,2'-bipyridine-5,5'-dicarboxylic acid and 2-aminoterephthalic acid; the regulator is selected from one or both of benzoic acid and glacial acetic acid; and the solvent is selected from one or both of DMF and DMA. The ratio of titanium source, ligand, regulator, and solvent is (0.5 mL~0.6 mL):(450 mg~500 mg):(5 mL~6 mL):(100 mL~150 mL). The reaction conditions are a temperature of 100 ℃~180 ℃ and a time of 24 h~72 h.

[0056] The above raw materials are selected to synthesize titanium-based MOF (metal-organic framework) precursors. The high specific surface area of ​​the titanium-based MOF precursor helps to expose more catalytic active sites in step 3. At the same time, the bipyridine or amino groups contained in the titanium-based MOF precursor framework help to anchor noble metal ions through coordination in step 2.

[0057] Step 2: Disperse the MOF precursor and noble metal salt in the reaction solvent to react and obtain the initial product.

[0058] Specifically, the noble metal salt is one or more of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, palladium chloride, and palladium nitrate, and the reaction solvent is water. The reaction conditions are a temperature of 60℃~80℃ and a time of 12 h~36 h.

[0059] The reaction is carried out in a reaction solvent, which allows the MOF precursor to fix noble metal ions through coordination bonds, so that the noble metal ions are more uniformly anchored in the MOF precursor.

[0060] Step 3: Calcine the primary product to obtain a carbon / titanium dioxide supported oxygen reduction catalyst.

[0061] Specifically, the calcination conditions are a temperature of 600℃~800℃, a time of 1 h~3 h, and a calcination atmosphere of argon or a hydrogen-argon mixture. The hydrogen-argon mixture can be selected from either a 5% hydrogen-argon mixture (5% hydrogen and 95% argon) or a 10% hydrogen-argon mixture (10% hydrogen and 90% argon).

[0062] This invention synthesizes a Ti-MOF precursor through step 1. The Ti-MOF precursor is a flower-shaped sphere composed of two-dimensional thin sheets. The calcined material can well inherit the original morphology of the Ti-MOF precursor, which is beneficial for the catalyst to expose more catalytic active sites.

[0063] Furthermore, compared to the traditional method of first calcining the MOF precursor to prepare the support and then loading noble metal particles, this invention employs a process of first modifying noble metal ions and then calcining. Its advantages lie in the fact that noble metal ions can be uniformly anchored within the MOF precursor framework beforehand through coordination with specific functional groups in the Ti-MOF framework. Subsequently, under controlled calcination conditions, the organic components in the Ti-MOF precursor undergo pyrolysis, while the titanium oxide clusters are converted in situ into titanium dioxide (TiO2), and the anchored noble metal ions are reduced to form noble metal nanoparticles. This process promotes the formation of a tight structure between the in-situ reduced noble metal particles (Pt, Pd) and the in-situ generated TiO2, which can hinder the Oswald ripening and shedding of noble metals, improve the structural stability of the catalyst, and the thin layer of carbon components generated in situ during calcination can also increase the overall conductivity of the catalyst.

[0064] The present invention will be further described in detail below with reference to specific embodiments.

[0065] Example 1

[0066] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment is as follows:

[0067] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0068] Then, 500 mg of MOF precursor was ultrasonically dispersed in 25 mL of deionized water to obtain a MOF precursor dispersion. 100 μL of chloroplatinic acid aqueous solution (8 wt%) was added dropwise to the MOF precursor dispersion, and the mixture was stirred until homogeneous. The mixture was then heated at 60 °C for 24 h, allowed to cool naturally to room temperature, and the precipitate was collected by centrifugation. The precipitate was washed several times with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C to obtain a MOF precursor with a Pt loading of 3%.

[0069] The Pt-supported MOF precursor was calcined at 600 °C in a 10% hydrogen-argon mixed atmosphere for 3 h to obtain Pt-TiO. 2-x @C catalyst.

[0070] Example 2

[0071] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 1 only in that: the Pt-supported MOF precursor is calcined at 700°C in a 10% hydrogen-argon mixed atmosphere for 3 h to obtain Pt-TiO2. 2-x @C catalyst.

[0072] Example 3

[0073] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 1 only in that: the Pt-supported MOF precursor is calcined at 800°C in a 10% hydrogen-argon mixed atmosphere for 3 h to obtain Pt-TiO2. 2-x @C catalyst.

[0074] Example 4

[0075] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment is as follows:

[0076] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0077] Then, 500 mg of MOF precursor was ultrasonically dispersed in 25 mL of deionized water to obtain a MOF precursor dispersion. 250 μL of chloroplatinic acid aqueous solution (8 wt%) was added dropwise to the MOF precursor dispersion, and the mixture was stirred until homogeneous. The mixture was then heated at 60 °C for 24 h, allowed to cool naturally to room temperature, and the precipitate was collected by centrifugation. The precipitate was washed several times with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C to obtain a MOF precursor with a Pt loading of 5%.

[0078] The Pt-supported MOF precursor was calcined at 600 °C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain Pt-TiO. 2-x @C catalyst.

[0079] Example 5

[0080] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 4 only in that: the Pt-supported MOF precursor is calcined at 700°C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain Pt-TiO2. 2-x @C catalyst.

[0081] Example 6

[0082] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 4 only in that: the Pt-supported MOF precursor is calcined at 800°C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain Pt-TiO2. 2-x @C catalyst.

[0083] Example 7

[0084] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment is as follows:

[0085] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0086] Then, 500 mg of MOF precursor was ultrasonically dispersed in 25 mL of deionized water to obtain a MOF precursor dispersion. 500 μL of chloroplatinic acid aqueous solution (8 wt%) was added dropwise to the MOF precursor dispersion, and the mixture was stirred until homogeneous. The mixture was then heated at 60 °C for 24 h, allowed to cool naturally to room temperature, and the precipitate was collected by centrifugation. The precipitate was washed several times with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C to obtain a MOF precursor with a Pt loading of 10%.

[0087] The Pt-supported MOF precursor was calcined at 600 °C in a 10% hydrogen-argon mixed atmosphere for 1 h to obtain Pt-TiO. 2-x @C catalyst.

[0088] Example 8

[0089] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 7 only in that: the Pt-supported MOF precursor is calcined at 700°C in a 10% hydrogen-argon mixed atmosphere for 1 h to obtain Pt-TiO2. 2-x @C catalyst.

[0090] Example 9

[0091] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 7 only in that: the Pt-supported MOF precursor is calcined at 800°C in a 10% hydrogen-argon mixed atmosphere for 1 h to obtain Pt-TiO2. 2-x @C catalyst.

[0092] Example 10

[0093] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 1 only in that: the Pt-supported MOF precursor is calcined at 700°C in an argon atmosphere for 3 h to obtain Pt-TiO. 2-x @C catalyst.

[0094] Example 11

[0095] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 4 only in that: the Pt-supported MOF precursor is calcined at 700°C in an argon atmosphere for 2 h to obtain Pt-TiO. 2-x @C catalyst.

[0096] Example 12

[0097] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 7 only in that: the Pt-supported MOF precursor is calcined at 700°C in an argon atmosphere for 1 h to obtain Pt-TiO. 2-x @C catalyst.

[0098] Example 13

[0099] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment is as follows:

[0100] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0101] Then, 500 mg of MOF precursor was ultrasonically dispersed in 25 mL of deionized water to obtain a MOF precursor dispersion. 100 μL of palladium chloride aqueous solution (8 wt%) was added dropwise to the MOF precursor dispersion, and the mixture was stirred until homogeneous. The mixture was then heated at 60 °C for 24 h, allowed to cool naturally to room temperature, and the precipitate was collected by centrifugation. The precipitate was washed several times with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C to obtain a MOF precursor with a Pd loading of 3%.

[0102] The Pd-supported MOF precursor was calcined at 700 °C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain Pd-TiO. 2-x @C catalyst.

[0103] Example 14

[0104] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment is as follows:

[0105] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0106] Then, 500 mg of MOF precursor was ultrasonically dispersed in 25 mL of deionized water to obtain a MOF precursor dispersion. 250 μL of palladium chloride aqueous solution (8 wt%) was added dropwise to the MOF precursor dispersion, and the mixture was stirred until homogeneous. The mixture was then heated at 60 °C for 24 h, allowed to cool naturally to room temperature, and the precipitate was collected by centrifugation. The precipitate was washed several times with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C to obtain a MOF precursor with a Pd loading of 5%.

[0107] The Pd-supported MOF precursor was calcined at 700 °C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain Pd-TiO. 2-x @C catalyst.

[0108] Example 15

[0109] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment is as follows:

[0110] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0111] Then, 500 mg of MOF precursor was ultrasonically dispersed in 25 mL of deionized water to obtain a MOF precursor dispersion. 500 μL of palladium chloride aqueous solution (8 wt%) was added dropwise to the MOF precursor dispersion, and the mixture was stirred until homogeneous. The mixture was then heated at 60 °C for 24 h, allowed to cool naturally to room temperature, and the precipitate was collected by centrifugation. The precipitate was washed several times with deionized water and anhydrous ethanol, and then dried under vacuum at 80 °C to obtain a MOF precursor with a Pd loading of 10%.

[0112] The Pd-supported MOF precursor was calcined at 700 °C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain Pd-TiO. 2-x @C catalyst.

[0113] Example 16

[0114] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 13 only in that: the Pd-supported MOF precursor is calcined at 700°C in an argon atmosphere for 2 h to obtain Pd-TiO. 2-x @C catalyst.

[0115] Example 17

[0116] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 14 only in that: the Pd-supported MOF precursor is calcined at 700°C in an argon atmosphere for 2 h to obtain Pd-TiO. 2-x @C catalyst.

[0117] Example 18

[0118] The preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst in this embodiment differs from that in Example 15 only in that: the Pd-supported MOF precursor is calcined at 700°C in an argon atmosphere for 2 h to obtain Pd-TiO. 2-x @C catalyst.

[0119] Comparative Example 1

[0120] The catalyst in this comparative example was prepared as follows:

[0121] 3 g of commercially available nano titanium dioxide (brand: Myriel, purity: 99.8%, 25 nm) was calcined at 700℃ in a mixed atmosphere of 10% hydrogen and argon for 2 h to obtain a titanium dioxide sample containing oxygen defects.

[0122] Then, 50 mg of the above titanium dioxide sample was ultrasonically dispersed in 25 mL of deionized water under argon protection to obtain a titanium dioxide dispersion. 10 μL of platinum nitrate aqueous solution (Pt, 18.02%) was added dropwise to the dispersion, and the mixture was stirred at room temperature for 30 minutes. Then, 10 mg / mL of NaBH4 aqueous solution was added dropwise. -1 5 mL of the solution was centrifuged to collect the precipitate, which was then washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 80 °C to obtain Pt-TiO₂ with a Pt loading of 5%. 2-x catalyst.

[0123] Comparative Example 2

[0124] The catalyst in this comparative example was prepared as follows:

[0125] 3 g of commercially available nano titanium dioxide (brand: Myriel, purity: 99.8%, 25 nm) was calcined at 700℃ in a mixed atmosphere of 10% hydrogen and argon for 2 h to obtain a titanium dioxide sample containing oxygen defects.

[0126] Then, 50 mg of the above titanium dioxide sample was ultrasonically dispersed in 25 mL of deionized water under argon protection to obtain a titanium dioxide dispersion. 20 μL of platinum nitrate aqueous solution (Pt, 18.02%) was added dropwise to the dispersion, and the mixture was stirred at room temperature for 30 minutes. Then, NaBH4 aqueous solution (10 mg·mL⁻¹) was added dropwise. -1 5 mL of the precipitate was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 80 °C to obtain Pt-TiO₂ with a Pt loading of 10%. 2-x catalyst.

[0127] Comparative Example 3

[0128] The catalyst in this comparative example was prepared as follows:

[0129] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0130] The MOF precursor was calcined at 700 °C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain TiO2. 2-x / C vector.

[0131] Then 50 mg of the above TiO 2-x / C carrier was ultrasonically dispersed in 25 mL of deionized water under argon protection to obtain a homogeneous dispersion. 10 μL of platinum nitrate aqueous solution (Pt, 18.02%) was added dropwise to the dispersion, and the mixture was stirred at room temperature for 30 minutes. Then, NaBH4 aqueous solution (10 mg·mL⁻¹) was added dropwise. -1 5 mL of the solution was centrifuged to collect the precipitate, which was then washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 80 °C to obtain Pt-TiO₂ with a Pt loading of 5%. 2-x / C catalyst.

[0132] Comparative Example 4

[0133] The catalyst in this comparative example was prepared as follows:

[0134] 0.5 mL of tetrabutyl titanate and 500 mg of 2,2'-bipyridine-5,5'-dicarboxylic acid were dissolved in 150 mL of N,N-dimethylformamide. The mixture was sonicated at room temperature for ten minutes, and then 5 mL of glacial acetic acid was added and stirred until homogeneous to obtain a MOF precursor solution. The MOF precursor solution was placed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 150 °C for 72 h. After naturally cooling to room temperature, the solid was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 100 °C to obtain the MOF precursor.

[0135] The MOF precursor was calcined at 700 °C in a 10% hydrogen-argon mixed atmosphere for 2 h to obtain TiO2. 2-x / C vector.

[0136] Then 50 mg of the above TiO 2-x / C carrier was ultrasonically dispersed in 25 mL of deionized water under argon protection to obtain a homogeneous dispersion. 20 μL of platinum nitrate aqueous solution (Pt, 18.02%) was added dropwise to the dispersion, and the mixture was stirred at room temperature for 30 minutes. Then, NaBH4 aqueous solution (10 mg·mL⁻¹) was added dropwise. -1 5 mL of the precipitate was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and dried under vacuum at 80 °C to obtain Pt-TiO₂ with a Pt loading of 10%. 2-x / C catalyst.

[0137] Figure 1 The figure shows the XRD curve of the catalyst sample obtained in Example 2. It displays the diffraction characteristic peaks of rutile and anatase TiO2 phases. The XRD peak positions of the catalyst are consistent with those of the standard cards for rutile and anatase TiO2 phases. Since Pt is in the form of fine nanoparticles, no diffraction peaks were observed, indicating that the introduction of Pt has no effect on the TiO2 crystal structure, and the catalyst as a whole remains in the TiO2 crystalline phase.

[0138] Figure 2 and Figure 3 The Pt-TiO3 with a Pt loading of 5% in Example 5 is described. 2-x TEM image and elemental mapping (elemental distribution map) of the C catalyst (calcination temperature 700℃), from... Figure 2 It can be seen that Pt forms nanoparticles smaller than 10 nm, while TiO2 nanoparticles have a diameter of around 20 nm; simultaneously, the elemental mapping diagrams show that in Pt-TiO2... 2-x @C catalyst: coexistence and uniform distribution of elements Pt, Ti, O and C.

[0139] The catalysts prepared in each example were compared with a commercially available Pt / C catalyst (Johnson Matthey, USA, Pt loading 20%) for room temperature oxygen reduction activity testing using a three-electrode system. Anode: graphite rod electrode; Reference electrode: Ag / AgCl (0.1M HClO4); Cathode: a 5 mm diameter glassy carbon electrode coated with a thin catalyst film, catalyst loading: 0.2 mg·cm³. -2 Electrolyte: 0.1 M HClO4, results are shown in Table 1 and Figure 4 As shown.

[0140] Table 1 Performance Test Results

[0141]

[0142] As shown in Table 1, this invention uses a carbon and titanium dioxide composite as a support, and by loading a small amount of noble metal, it can effectively improve the activity of the catalyst. Specifically, Example 5 prepared a Pt-TiO₂ catalyst with a Pt loading of 5%. 2-x The @C catalyst exhibits the best performance, with a wave initiation potential of 1.04 V and a half-wave potential of 0.87 V, while also demonstrating excellent stability.

[0143] In Comparative Examples 1 and 2, only titanium dioxide was used as a support for loading noble metal particles, and the resulting catalysts showed weaker performance than those in the examples. In Comparative Examples 3 and 4, catalysts were prepared by first calcining to obtain the support and then loading the noble metal particles. As shown in Table 1, the catalysts in Comparative Examples 3 and 4 showed weaker performance than those in the examples. This demonstrates that the present invention, using carbon and titanium dioxide as supports for loading noble metal particles, can effectively improve the activity of the catalyst. Furthermore, the method of modifying with noble metal ions before calcination is more conducive to forming a tighter structure between the noble metal particles and titanium dioxide, improving the structural stability and activity of the catalyst.

[0144] Furthermore, during calcination, the catalyst obtained by calcining with a mixture of hydrogen and argon exhibits better catalytic performance compared to calcination with pure argon. Analysis suggests this may be because calcination in the hydrogen-argon mixture allows the formation of titanium dioxide with oxygen vacancies, which is more conducive to stabilizing the precious metal particles and simultaneously improving the overall conductivity of the catalyst.

[0145] Figure 4 The Pt-TiO3 in Examples 2, 5, and 8 2-x Oxygen reduction polarization test curves of @C catalyst and commercial catalyst Pt / C, by Figure 4 As can be seen, the catalyst with a 5% Pt loading exhibits the best performance, outperforming the commercially available Pt / C catalyst. With increasing noble metal particle loading, the catalytic activity of the carbon / titanium dioxide supported oxygen reduction catalyst in this invention shows a phenomenon of first increasing and then decreasing, with the 5% Pt loading catalyst showing the best performance.

[0146] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0147] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A carbon / titanium dioxide supported oxygen reduction catalyst, characterized in that, It uses a composite of carbon and titanium dioxide as a carrier, on which precious metal particles are loaded. The precious metal particles are at least one of Pt particles and Pd particles; The loading of the precious metal particles on the carrier is 1wt%~10wt%.

2. The carbon / titanium dioxide supported oxygen reduction catalyst according to claim 1, characterized in that, The particle size of the carrier is 400 nm to 500 nm.

3. The carbon / titanium dioxide supported oxygen reduction catalyst according to claim 1, characterized in that, The titanium dioxide in the carrier has a particle size of 10 nm to 30 nm.

4. The carbon / titanium dioxide supported oxygen reduction catalyst according to claim 1, characterized in that, The particle size of the noble metal particles is less than or equal to 10 nm.

5. The carbon / titanium dioxide supported oxygen reduction catalyst according to claim 1, characterized in that, In the carrier, the mass percentage of titanium is 30wt%~40wt%.

6. A method for preparing a carbon / titanium dioxide supported oxygen reduction catalyst, characterized in that, The steps include: S1. MOF precursors are prepared by reacting titanium source, ligand, regulator and solvent as raw materials; S2. Disperse the MOF precursor and noble metal salt in the reaction solvent to react and obtain the initial product; S3. The primary product is calcined to obtain a carbon / titanium dioxide supported oxygen reduction catalyst.

7. The method for preparing the carbon / titanium dioxide supported oxygen reduction catalyst according to claim 6, characterized in that, The ratio of the titanium source, ligand, modifier and solvent is (0.5 mL~0.6 mL): (450 mg~500 mg): (5 mL~6 mL): (100 mL~150 mL).

8. The method for preparing the carbon / titanium dioxide supported oxygen reduction catalyst according to claim 6, characterized in that, The titanium source is selected from one or both of tetrabutyl titanate and isopropyl titanate; and / or, The ligand is selected from one or two of 2,2'-bipyridine-5,5'-dicarboxylic acid and 2-aminoterephthalic acid; and / or, The regulator is selected from one or both of benzoic acid and glacial acetic acid; and / or, The solvent is selected from one or both of DMF and DMA; and / or, The noble metal salt is one or more selected from chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, palladium chloride, and palladium nitrate; and / or, The reaction solvent is water.

9. The method for preparing the carbon / titanium dioxide supported oxygen reduction catalyst according to claim 6, characterized in that, In step S1, the reaction conditions are: temperature 100℃~180℃, time 24 h~72 h; and / or, In step S2, the reaction conditions are: temperature 60℃~80℃, time 12 h~36 h; and / or, The calcination conditions are: temperature 600℃~800℃, time 1 h~3 h, and calcination atmosphere is argon or a hydrogen-argon mixture.

10. The use of a carbon / titanium dioxide supported oxygen reduction catalyst, characterized in that, Used in electrocatalytic oxygen reduction reactions; The carbon / titanium dioxide supported oxygen reduction catalyst is the carbon / titanium dioxide supported oxygen reduction catalyst according to any one of claims 1 to 5 or the carbon / titanium dioxide supported oxygen reduction catalyst prepared by the preparation method of the carbon / titanium dioxide supported oxygen reduction catalyst according to any one of claims 6 to 9.

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