A carbon-wrapped oxide coating on titanium material surface and its preparation method and application

Abstract

The present invention relates to the technical field of metal surface coating preparation, and specifically to a carbon-wrapped oxide coating on the surface of a titanium material, and a preparation method and application thereof, comprising the following steps: dissolving an organic carboxylic acid ligand in a solvent, adding a defect-rich titanium material for adsorption; adding a metal ligand to the system for reaction, and performing annealing, carbonization and oxidation treatment after the reaction to obtain a titanium material with a carbon-wrapped oxide coating. The present invention is based on a coordination nucleation method, using a metal organic framework material as a carbon source and defect sites on the titanium surface as nucleation centers to in-situ grow a coating material precursor. Through annealing, carbonization and oxidation treatment, a tightly bonded carbon-wrapped oxide coating material is obtained, and the coating has high plating properties, high uniformity, high bonding strength, high conductivity and high corrosion resistance. The preparation scheme has low cost and high synthesis efficiency, and the carbon-wrapped oxide coating can be used for surface protection of titanium-based bipolar plates and diffusion layer components in proton exchange membrane water electrolysis and hydrogen fuel cell equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface coating preparation, and in particular to a carbon-wrapped oxide coating on the surface of a titanium material, a preparation method thereof, and an application thereof. Background Art

[0002] In hydrogen-water conversion systems, water electrolysis and hydrogen fuel cell technologies are considered important development directions for green, low-carbon hydrogen production and utilization. Bipolar plates and diffusion layers are key components in proton exchange membrane water electrolysis (PEMWE) and hydrogen fuel cell (PEMFC) equipment. PEMWE and PEMFC equipment operate under relatively harsh conditions, typically characterized by high acidity, humidity, and temperature. Therefore, high electrical conductivity and corrosion resistance are required of bipolar plate and diffusion layer materials. Titanium is an ideal material for bipolar plates and diffusion layers due to its high corrosion resistance, excellent mechanical strength, high power-to-volume ratio, and high specific energy density. However, titanium oxidizes during use, forming a low-conductivity passivation film, which results in high interfacial contact resistance and increased ohmic losses. A common and effective approach is to apply highly conductive and corrosion-resistant coatings, such as pure metals, nitrides, or carbides, on the titanium surface. Carbon materials are widely used as protective coatings for metal bipolar plates and diffusion layers due to their low cost and excellent electrical conductivity and corrosion resistance.

[0003] Currently, the mainstream coating deposition technologies include physical vapor deposition (PVD) and chemical vapor deposition (CVD). However, due to the poor lattice and thermal expansion coefficient matching between carbon materials and metals, the bonding strength between carbon materials and the base metal is often low, leading to coating detachment over time. Traditional deposition techniques address this bonding strength issue primarily through two methods: one is the use of heterogeneous epitaxial growth techniques, which utilizes lattice matching to reduce lattice distortion and defects caused by lattice constant mismatch, thereby improving material matching and enhancing adhesion. The other is the use of thermal expansion coefficient matching between different materials to reduce overall thermal expansion differences in the coating, thereby alleviating stress and deformation and ensuring structural stability. These traditional deposition techniques often require the stepwise matching of different materials to form a multi-component, multi-layered coating structure. However, differences in lattice structure and thermal expansion coefficient between the different materials still exist, inevitably increasing coating thickness and the number of process steps. Efficient and convenient technologies for the preparation of strong bonding coatings have long been a pressing need in the field of protective coatings for PEMWE and PEMFC equipment components. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a carbon-wrapped oxide coating on the surface of a titanium material, a preparation method and application thereof. The present invention obtains a carbon-wrapped oxide coating with high uniformity, high bonding strength, corrosion resistance and high conductivity on the surface of the titanium material. The obtained carbon-wrapped oxide coating is used for the titanium-based bipolar plates and diffusion layer surfaces of PEMWE and PEMFC equipment, which can effectively prevent titanium metal corrosion while improving the durability of the coating. The preparation method is simple and convenient.

[0005] The mechanism of the coating preparation of the present invention is as follows Figure 1 As shown, metal-organic framework materials are used as carbon sources. Based on the high matching of similar materials, the highly reactive defect sites on the surface of titanium materials are utilized as nucleation centers in the organic titanium metal framework, which rapidly react with organic carboxylic acid ligands to generate strongly bound Ti-O ionic bonds, and then the organic metal framework material is grown in situ, and then a carbon-wrapped oxide coating material is formed by annealing.

[0006] The present invention is achieved through the following solutions.

[0007] The first object of the present invention is to provide a method for preparing a carbon-coated oxide coating on the surface of a titanium material, comprising the following steps:

[0008] The titanium material is treated with an inorganic acid solution to obtain a defect-rich titanium material.

[0009] The organic carboxylic acid ligand, anhydrous methanol and N,N-dimethylformamide are uniformly mixed, and added into the defect-rich titanium material for adsorption, so that the organic carboxylic acid ligand forms a Ti-O ionic bond with the defect sites in the titanium material.

[0010] Then, the metal ligand titanium isopropoxide is added to the system and reacted at 80°C to 150°C. During the reaction, titanium isopropoxide and the organic carboxylic acid ligand in situ grow a metal organic framework material on the surface of the titanium material to form a titanium material loaded with a metal organic framework material coating.

[0011] The titanium material loaded with the metal organic framework material coating is subjected to annealing, carbonization and oxidation treatment to obtain a carbon-wrapped oxide coating on the surface of the titanium material.

[0012] In a preferred embodiment of the present invention, the organic carboxylic acid ligand is one of terephthalic acid, 2-aminoterephthalic acid, 2,5-dihydroxyterephthalic acid and 3,3',5,5'-tetracarboxydiphenylmethane.

[0013] In a preferred embodiment of the present invention, the molar ratio of the organic carboxylic acid ligand, anhydrous methanol and N,N-dimethylformamide is 1:10-20:20-40.

[0014] In a preferred embodiment of the present invention, the molar ratio of titanium isopropoxide to the organic carboxylic acid ligand is 0.5 to 1:1.

[0015] In a preferred embodiment of the present invention, the reaction time is 10 h to 100 h.

[0016] In a preferred embodiment of the present invention, the annealing, carbonization and oxidation treatments are performed in a muffle furnace in an air atmosphere at a temperature of 200° C. to 800° C. for a holding time of 10 min to 120 min.

[0017] In a preferred embodiment of the present invention, the titanium material is immersed in an inorganic acid solution and then rinsed with water to obtain a defect-rich titanium material; the temperature is 70° C. to 100° C., and the immersion time is 1 min to 30 min.

[0018] In a preferred embodiment of the present invention, the inorganic acid solution is selected from one of 0.5 wt % hydrochloric acid, 5 wt % sulfuric acid, 85 wt % phosphoric acid, 5 wt % hydrofluoric acid and 5 wt % to 20 wt % oxalic acid.

[0019] In a preferred embodiment of the present invention, the titanium material includes titanium foil, plate and products.

[0020] The second object of the present invention is to provide a carbon-coated oxide coating on the surface of a titanium material prepared by the above preparation method.

[0021] The third object of the present invention is to provide the application of the carbon-wrapped oxide coating on the surface of the titanium material in the protection of proton exchange membrane water electrolysis and hydrogen fuel cell equipment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention first uses an inorganic acid to treat a titanium material to obtain a defect-rich titanium material; then, the defect-rich titanium material is immersed in a solution containing an organic carboxylic acid ligand, so that the defect-rich titanium material adsorbs the organic carboxylic acid ligand, and the organic carboxylic acid ligand forms a Ti-O ion bond with a defect site in the titanium material. The solvent is made of anhydrous methanol and N,N-dimethylformamide, the anhydrous methanol can stabilize the organic carboxylic acid ligand and can regulate the balance between subsequent nucleation and growth of a metal organic framework; the N,N-dimethylformamide is subsequently decomposed into dimethylamine after heating, which can deprotonate the organic carboxylic acid ligand, promote ligand dissolution, and further form coordination with the metal defect site; then, a metal ligand titanium isopropoxide is added to the system, and at 80°C to 150°C, the titanium isopropoxide and the organic carboxylic acid ligand in situ grow a metal organic framework material on the surface of the titanium material; the titanium material loaded with the metal organic framework material coating is annealed, carbonized, and oxidized to obtain a carbon-coated oxide coating on the surface of the titanium material. The coating prepared by the above method is tightly bonded to the titanium base material in the form of Ti-O covalent bonds, avoiding the shedding and cracking of the coating caused by the mismatch between the carbon layer and the base metal material, improving the bonding strength between the carbon layer and the base metal material, and the coating preparation method is simple, convenient and easy to implement.

[0024] The carbon coating and metal oxide prepared by the invention enable the coating to have both high conductivity and high corrosion resistance.

[0025] The coating prepared by the method of the present invention has the advantages of high coating efficiency, high uniformity and high bonding strength, and is also low in cost, simple to operate and highly repeatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the preparation principle of the carbon-coated titanium oxide coating on the surface of the titanium material of the present invention.

[0027] Figure 2 This is a scanning electron microscope (SEM) image of the surface of the carbon-wrapped titanium oxide coating material in Example 1.

[0028] Figure 3 This is a scanning electron microscope (SEM) image of the thickness cross section of the carbon-wrapped titanium oxide coating material in Example 1.

[0029] Figure 4 This is the full X-ray photoelectron spectroscopy XPS spectrum of the carbon-coated titanium oxide coating material in Example 1 and the narrow scan illustrations of C, Ti, and O elements.

[0030] Figure 5In the figure, a is a physical picture of the carbon-wrapped titanium oxide coating material after the adhesion cross-cut test in Example 1, and b is a tape peeling picture; c is a physical picture of the carbon-wrapped titanium oxide coating material after the adhesion cross-cut test in Comparative Example 1, and d is a tape peeling picture; e is a physical picture of the carbon-wrapped titanium oxide coating material after the adhesion cross-cut test in Comparative Example 2, and f is a tape peeling picture.

[0031] Figure 6 This is a polarization curve test diagram of the carbon-wrapped titanium oxide coating material in the anode working environment simulated in the PEMWE device in Example 1.

[0032] Figure 7 This is a graph of the surface contact resistance of the carbon-coated titanium oxide coating material after a 24h-2V constant potential polarization test in Example 1.

[0033] Figure 8 This is a polarization curve test diagram of the carbon-wrapped titanium oxide coating material in the anode working environment simulated in the PEMFC device in Example 1.

[0034] Figure 9 This is a graph of the surface contact resistance of the carbon-coated titanium oxide coating material after a 24h-0.8V constant potential polarization test in Example 1. DETAILED DESCRIPTION

[0035] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention is further described below with reference to specific examples and accompanying drawings. However, the examples are not intended to limit the present invention. The experimental methods and detection methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0036] The present invention provides a method for preparing a carbon-coated oxide coating on the surface of a titanium material, comprising the following steps:

[0037] (1) The titanium material is treated with an inorganic acid to obtain a defect-rich titanium material.

[0038] It should be noted that when the titanium material is immersed in an inorganic acid solution, titanium generates metal cations under acidic conditions, which causes highly reactive defect sites on the surface of the titanium material.

[0039] (2) The organic carboxylic acid ligand, anhydrous methanol and N,N-dimethylformamide are mixed evenly, and the defect-rich titanium material is added for adsorption, so that the organic carboxylic acid ligand forms a Ti-O ionic bond with the defect sites in the titanium material.

[0040] It should be noted that anhydrous methanol and N, N-dimethylformamide act as solvents. The reason for choosing this solvent is that anhydrous methanol can stabilize the organic carboxylic acid ligands and regulate the balance between nucleation and growth of the metal organic framework. N, N-dimethylformamide decomposes into dimethylamine after heating, which can deprotonate the organic carboxylic acid ligands, promote the dissolution of the ligands, and further bind to the Ti at the metal defect site. 3+ Form coordination.

[0041] Organic carboxylic acid ligands are precursors for the generation of metal-organic framework materials. They are first coordinated with defect sites in titanium materials to form Ti-O ionic bonds, thereby improving the bonding strength between the subsequently generated coating and the titanium material substrate.

[0042] In a preferred embodiment of the present invention, the organic carboxylic acid ligand may be one of terephthalic acid, 2-aminoterephthalic acid, 2,5-dihydroxyterephthalic acid and 3,3',5,5'-tetracarboxydiphenylmethane.

[0043] (3) Then, the metal ligand titanium isopropoxide is added to the system and reacted at 80°C to 150°C. During the reaction, titanium isopropoxide and organic carboxylic acid ligands grow in situ on the surface of the titanium material, and the titanium metal ion center and the bridging organic ligand are interconnected through self-assembly to form an organic-inorganic hybrid metal-organic framework material, thereby obtaining a titanium material loaded with a metal-organic framework coating.

[0044] It should be noted that titanium isopropoxide is selected as the metal ligand because: titanium isopropoxide is soluble in organic solvents, is resistant to acid and oxidation at room temperature, has stable chemical properties, and as a metal ion source, it continuously coordinates and polymerizes with the precursor carboxylic acid through self-assembly in the solution to form a metal-organic framework material coating.

[0045] (4) The titanium material loaded with the metal organic framework coating is subjected to annealing, carbonization and oxidation treatment to obtain a carbon-coated oxide coating on the surface of the titanium material.

[0046] It should be noted that the carbon-encapsulated oxide coating here refers to the reaction between the titanium ions at the center of the metal ions and oxygen to form titanium oxide. The organic ligands in the metal-organic framework material are carbonized at high temperature, encapsulating the titanium oxide in a carbon layer to form a coating material, which is then loaded onto the titanium substrate. This coating has high conductivity and high corrosion resistance, and is tightly bonded to the titanium substrate via Ti-O covalent bonds. This avoids coating shedding and cracking caused by the mismatch between the carbon layer and the base metal material, and improves the bonding strength between the carbon layer and the base metal material.

[0047] In a preferred embodiment of the present invention, the annealing, carbonization and oxidation are carried out in a muffle furnace in an air atmosphere at a temperature of 200° C. to 800° C. for a holding time of 10 min to 120 min.

[0048] The present invention will be specifically described below through the following examples.

[0049] Example 1

[0050] A method for obtaining a carbon-coated titanium oxide-coated titanium sheet by loading a metal organic framework MIL-125-NH2 as a precursor, comprising the following steps:

[0051] (1) Anhydrous oxalic acid was added to pure water and stirred to dissolve to form a 10 wt% oxalic acid solution. After heating to 80° C., the titanium plate was immersed in the oxalic acid solution for 10 min. The titanium plate was then taken out and rinsed with ultrapure water to obtain a defect-rich titanium plate.

[0052] (2) A mixed solution of 2-aminoterephthalic acid (NH2-BDC), anhydrous methanol (MeOH), and 40 mL of N,N-dimethylformamide (DMF) was prepared at a molar ratio of 1:15:30 and stirred at room temperature until the NH2-BDC was fully dissolved. The defect-rich titanium sheet from step (1) was then added to the mixed solution and adsorbed with stirring for 24 h.

[0053] (3) Adding a metal ligand titanium isopropoxide (Ti(OCH(CH3)2)4) in an amount equimolar to NH2-BDC to the mixed solution and titanium plate in step (2), heating to 120°C and reflux for 24 hours, cooling to room temperature, taking out the titanium plate, rinsing with deionized water, and then drying in an oven at 80°C to obtain a titanium plate coated with a metal organic framework MIL-125-NH2 material.

[0054] (4) The titanium plate coated with the metal organic framework MIL-125-NH2 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at 5°C / min and maintained for 30 minutes. After cooling to room temperature, a titanium plate with a carbon-coated titanium oxide coating material is obtained.

[0055] Comparative Example 1

[0056] A method for obtaining a carbon-coated titanium oxide-coated titanium sheet by electrostatic adsorption using a metal organic framework MIL-125-NH2 as a precursor, wherein the specific steps are as follows:

[0057] (1) Use acetone, ethanol and water to rinse the titanium plate in sequence to clean the surface, remove oil and dust.

[0058] (2) 2-aminoterephthalic acid (NH2-BDC), anhydrous methanol (MeOH), and 40 mL of N,N-dimethylformamide (DMF) were mixed in a molar ratio of 1:15:30 to form a mixed solution, and stirred at room temperature until the NH2-BDC was fully dissolved. Then, the titanium plate from step (1) was added to the mixed solution and stirred for electrostatic adsorption for 24 hours.

[0059] (3) Adding a metal ligand titanium isopropoxide (Ti(OCH(CH3)2)4) in an amount equimolar to NH2-BDC to the mixed solution and titanium plate in step (2), heating to 120°C and reflux for 24 hours, cooling to room temperature, taking out the titanium plate, rinsing with deionized water, and then drying in an oven at 80°C to obtain a titanium plate coated with a metal organic framework MIL-125-NH2 material.

[0060] (4) The titanium plate coated with the metal organic framework MIL-125-NH2 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at 5°C / min and maintained for 30 minutes. After cooling to room temperature, a titanium plate with a carbon-coated titanium oxide coating material is obtained.

[0061] Comparative Example 2

[0062] A method for obtaining a carbon-coated titanium oxide coated titanium sheet by directly sputtering carbon and titanium oxide materials through physical vapor deposition magnetron sputtering technology, wherein the specific steps are as follows:

[0063] (1) Use acetone, ethanol and water to rinse the titanium plate in sequence to clean the surface, remove oil and dust.

[0064] (2) The titanium plate was placed in a magnetron sputtering chamber, carbon was used as the sputtering target, Ar was used as the working gas, the gas flow rate was set to 30 sccm, the chamber temperature was set to 150°C, the sputtering pressure was set to 1 Pa, the power was set to 400 W, the bias voltage was set to 60 V, and the sputtering time was set to 300 s. A titanium plate with a carbon coating material was obtained.

[0065] (3) The carbon-coated titanium plate obtained in step (2) is placed in a magnetron sputtering chamber, and carbon and titanium oxide are used as sputtering targets for simultaneous sputtering. Ar is used as the working gas, the gas flow rate is set to 30 sccm, the chamber temperature is 150°C, the sputtering pressure is 1 Pa, the carbon target power is 400 W, the titanium oxide target power is 200 W, the bias voltage is 60 V, and the sputtering time is 300 s to obtain a titanium plate of carbon composite titanium oxide coating material.

[0066] (4) The titanium plate of the carbon-composite titanium oxide coating material obtained in step (3) is placed in a magnetron sputtering chamber, and carbon is used as a sputtering target for sputtering. Ar is used as the working gas, the gas flow rate is set to 30 sccm, the chamber temperature is 150°C, the sputtering pressure is 1 Pa, the carbon target power is 400 W, the bias voltage is 60 V, and the sputtering time is 300 s to obtain a titanium plate of the carbon-wrapped titanium oxide coating material.

[0067] The titanium plate of the carbon-coated titanium oxide coating material obtained in step (4) of Example 1 was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and the obtained Figure 2 、 Figure 3 and Figure 4 .from Figure 2 It can be seen that the obtained carbon-wrapped titanium oxide coating material is uniform and dense on the surface of the titanium plate. Figure 3 The thickness of the coating is about 200 nm. Figure 4 It can be seen that the coating element composition obviously contains Ti, C, and O elements. Ti comes from the substrate and titanium oxide, C comes from the carbon layer formed by carbonization of the MOF material, and O comes from titanium oxide particles formed by the oxidation reaction between MOF and oxygen in the air and the metal Ti ions in the MOF material.

[0068] The titanium sheet of the carbon-coated titanium oxide coating obtained in Example 1 was subjected to a cross-cut test, also known as a "tape test," to measure the adhesion strength of the coating. Figure 5 In step a, use a sharp tool to cross-hatch the coated titanium material, then firmly stick the special 3M tape on the test area and then tear it off. Compare the cross-hatch test area with the ISO 2409:1992 adhesion standard. Figure 5 As can be seen in middle b, after the tape was removed, the cut edge was almost smooth, with no cells falling off. The results show that the prepared carbon-encapsulated titanium oxide coating has good adhesion and meets the ISO Class 0 standard.

[0069] The titanium plate of carbon-coated titanium oxide coating obtained in Comparative Example 1 was subjected to a cross-cut test. Figure 5 In Figure c, use a sharp tool to cross-hatch the coated titanium material, then firmly stick the special 3M tape on the test area and then tear it off. Compare the cross-hatch test area with the ISO 2409:1992 adhesion standard. Figure 5 As shown in Figure d, after the tape was removed, the coating fell off in large fragments along the cut edges, and some grids fell off completely, with the affected area exceeding 65%. These results indicate that the prepared carbon-coated titanium oxide coating has extremely poor adhesion, falling within the ISO Class 5 standard.

[0070] The titanium plate of carbon-coated titanium oxide coating obtained in Comparative Example 2 was subjected to a cross-cut test. Figure 5In the middle, use a sharp tool to cross-hatch the coated titanium material, then firmly stick the special 3M tape on the test area and then tear it off. Compare the cross-hatch test area with the ISO 2409:1992 adhesion standard. Figure 5 As can be seen in Figure f, there is slight peeling after the tape is removed, and the affected cut area is greater than 5% but less than 15%. The results show that the prepared carbon-encapsulated titanium oxide coating has poor adhesion and belongs to the ISO Class 2 standard.

[0071] At 80°C and with a continuous flow of 20 sccm H2, a corrosive acid solution (0.5 M H2SO4 and 5 ppm F - ) was used as the electrolyte to simulate the working environment of the anode bipolar plate and the diffusion layer in the proton exchange membrane water electrolysis (PEMWE) device. A three-electrode system (Ag / AgCl as the reference electrode and platinum as the counter electrode) was used to perform a potentiodynamic polarization (Tafel) test (polarization voltage was -0.6 to 2 V) on the titanium plate of the carbon-wrapped titanium oxide coating material obtained in step (4) of Example 1, and the results were obtained. Figure 6 .from Figure 6 It can be seen that the self-corrosion potential of pure titanium plate is -0.33V, and the corrosion current density under the self-corrosion potential is 9.88μA·cm 2 The self-corrosion potential of the titanium plate coated with carbon-coated titanium oxide is -0.22 V, and the corrosion current density at the self-corrosion potential is 0.75 μA·cm 2 The carbon-coated titanium oxide coating has better corrosion resistance. Under the same simulation conditions, the titanium plate with carbon-coated titanium oxide coating was subjected to 24h constant potential polarization (IT) (constant voltage is 2V) to simulate the life test. The titanium plate after constant potential polarization was subjected to surface contact resistance (ICR) test and the results were as follows: Figure 7 .from Figure 7 It can be seen that under 1.5MPa, the surface contact resistance of pure titanium plate is 14.02mΩ·cm 2 After coating with carbon-wrapped titanium oxide coating, the surface contact resistance is significantly reduced to 5.91mΩ·cm 2 After 24 hours of constant potential polarization, the surface contact resistance of the material is 6.10 mΩ·cm 2 , with almost no change, still meeting the U.S. Department of Energy (DOE) 2020 requirement for bipolar plate surface contact resistance <10mΩ·cm 2 The technical indicators show that the prepared carbon-wrapped titanium oxide coating has better electrical conductivity and meets the service requirements of the anode bipolar plate and diffusion layer in the proton exchange membrane water electrolysis (PEMWE) equipment.

[0072] At 80°C and with a continuous flow of 20 sccm H2, a corrosive acid solution (0.5 mM H2SO4 and 5 ppm F - ) was used as the electrolyte to simulate the working environment of the anode bipolar plate and the diffusion layer in the hydrogen fuel cell (PEMFC) device. A three-electrode system (Ag / AgCl as the reference electrode and platinum as the counter electrode) was used to perform a potentiodynamic polarization (Tafel) test (polarization voltage was -0.5 to 1.6 V) on the titanium plate of the carbon-wrapped titanium oxide coating material obtained in step (4) of Example 1. The results were as follows: Figure 8 .from Figure 8 It can be seen that the self-corrosion potential of pure titanium plate is -0.33V, and the corrosion current density under the self-corrosion potential is 9.88μA·cm 2 The self-corrosion potential of the titanium plate coated with carbon-coated titanium oxide is -0.11 V, and the corrosion current density at the self-corrosion potential is 0.08 μA·cm 2 The carbon-coated titanium oxide coating has better corrosion resistance. Under the same simulation conditions, the titanium sheet with carbon-coated titanium oxide coating was subjected to 24h constant potential polarization (IT) (constant voltage of 0.8V) to simulate the life test. The titanium sheet after constant potential polarization was subjected to surface contact resistance (ICR) test, and the results were as follows: Figure 9 .from Figure 9 It can be seen that under 1.5MPa, the surface contact resistance of pure titanium plate is 14.02mΩ·cm 2 After coating with carbon-wrapped titanium oxide coating, the surface contact resistance is significantly reduced to 5.91mΩ·cm 2 After 24 hours of constant potential polarization, the surface contact resistance of the material is 5.96 mΩ·cm 2 The surface contact resistance after constant potential polarization is still lower than the surface contact resistance of DOE bipolar plate by 10mΩ·cm. 2 The technical indicators show that the carbon-wrapped titanium oxide coating also has better electrical conductivity, which meets the service requirements of the anode bipolar plate and diffusion layer in hydrogen fuel cell (PEMFC) equipment.

[0073] Example 2

[0074] A method for obtaining a carbon-coated titanium oxide-coated titanium sheet by loading a metal organic framework MIL-125-NH2 as a precursor, comprising the following steps:

[0075] (1) Anhydrous oxalic acid was added to pure water and stirred to dissolve to form a 10 wt% oxalic acid solution. After heating to 80° C., the titanium plate was immersed in the oxalic acid solution for 10 min. The titanium plate was then taken out and rinsed with ultrapure water to obtain a defect-rich titanium plate.

[0076] (2) A mixed solution of 2-aminoterephthalic acid (NH2-BDC), anhydrous methanol (MeOH), and 40 mL of N,N-dimethylformamide (DMF) was prepared at a molar ratio of 1:15:30 and stirred at room temperature until the NH2-BDC was fully dissolved. The defect-rich titanium sheet from step (1) was then added to the mixed solution and adsorbed with stirring for 24 h.

[0077] (3) The metal ligand titanium isopropoxide (Ti(OCH(CH3)2)4) is further added to the mixed solution and titanium plate in step (2), the molar ratio of titanium isopropoxide to NH2-BDC is 0.5:1, and the mixture is heated to 120°C and refluxed for 24 hours. After cooling to room temperature, the titanium plate is taken out, rinsed with deionized water, and then dried in an oven at 80°C to obtain a titanium plate coated with a metal organic framework MIL-125-NH2 material.

[0078] (4) The titanium plate coated with the metal organic framework MIL-125-NH2 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at 5°C / min and maintained for 30 minutes. After cooling to room temperature, a titanium plate with a carbon-coated titanium oxide coating material is obtained.

[0079] Example 3

[0080] A method for obtaining a carbon-coated titanium oxide-coated titanium sheet by loading a metal organic framework MIL-125-NH2 as a precursor, comprising the following steps:

[0081] (1) Anhydrous oxalic acid was added to pure water and stirred to dissolve to form a 10 wt% oxalic acid solution. After heating to 80° C., the titanium plate was immersed in the oxalic acid solution for 10 min. The titanium plate was then taken out and rinsed with ultrapure water to obtain a defect-rich titanium plate.

[0082] (2) A mixed solution of 2-aminoterephthalic acid (NH2-BDC), anhydrous methanol (MeOH), and 40 mL of N,N-dimethylformamide (DMF) was prepared at a molar ratio of 1:15:30 and stirred at room temperature until the NH2-BDC was fully dissolved. The defect-rich titanium sheet from step (1) was then added to the mixed solution and adsorbed with stirring for 24 h.

[0083] (3) Adding a metal ligand titanium isopropoxide (Ti(OCH(CH3)2)4) in an amount equimolar to NH2-BDC to the mixed solution and titanium plate in step (2), heating to 80°C and reflux for 24 hours, cooling to room temperature, taking out the titanium plate, rinsing with deionized water, and then drying in an 80°C oven to obtain a titanium plate coated with a metal organic framework MIL-125-NH2 material.

[0084] (4) The titanium plate coated with the metal organic framework MIL-125-NH2 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at 5°C / min and maintained for 30 minutes. After cooling to room temperature, a titanium plate with a carbon-coated titanium oxide coating material is obtained.

[0085] Example 4

[0086] A method for obtaining a carbon-coated titanium oxide-coated titanium sheet by loading a metal organic framework MIL-125-NH2 as a precursor, comprising the following steps:

[0087] (1) Anhydrous oxalic acid was added to pure water and stirred to dissolve to form a 10 wt% oxalic acid solution. After heating to 80° C., the titanium plate was immersed in the oxalic acid solution for 10 min. The titanium plate was then taken out and rinsed with ultrapure water to obtain a defect-rich titanium plate.

[0088] (2) A mixed solution of 2-aminoterephthalic acid (NH2-BDC), anhydrous methanol (MeOH), and 40 mL of N,N-dimethylformamide (DMF) was prepared at a molar ratio of 1:15:30 and stirred at room temperature until the NH2-BDC was fully dissolved. The defect-rich titanium sheet from step (1) was then added to the mixed solution and adsorbed with stirring for 24 h.

[0089] (3) Adding a metal ligand titanium isopropoxide (Ti(OCH(CH3)2)4) in an amount equimolar to NH2-BDC to the mixed solution and titanium plate in step (2), heating to 100°C and reflux for 24 hours, cooling to room temperature, taking out the titanium plate, rinsing with deionized water, and then drying in an oven at 80°C to obtain a titanium plate coated with a metal organic framework MIL-125-NH2 material.

[0090] (4) The titanium plate coated with the metal organic framework MIL-125-NH2 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at 5°C / min and maintained for 30 minutes. After cooling to room temperature, a titanium plate with a carbon-coated titanium oxide coating material is obtained.

[0091] Example 5

[0092] A method for obtaining carbon-wrapped titanium oxide-coated titanium fiber felt by loading a metal organic framework MIL-125 as a precursor, comprising the following steps:

[0093] (1) Add 10 g of anhydrous oxalic acid to 100 ml of water and stir to dissolve to form a 10 wt% oxalic acid solution. After heating to 80 ° C, soak a titanium fiber felt with a length of 20 mm × a width of 10 mm × a thickness of 1 mm in the oxalic acid solution for 10 minutes. After taking it out, rinse it with ultrapure water to obtain defect-rich titanium fiber felt.

[0094] (2) Add 2.5 g of terephthalic acid (BDC) to a beaker containing a mixed solution of 10 mL of anhydrous methanol (MeOH) and 40 mL of N,N-dimethylformamide (DMF) and stir at room temperature until the BDC is fully dissolved. Then, add the defect-rich titanium fiber felt from step (1) to the mixed solution and stir and adsorb for 24 h.

[0095] (3) 2.5 mL of the metal ligand titanium isopropoxide was further added to the mixed solution and titanium fiber felt in step (2), and the mixture was heated to 120° C. and refluxed for 24 h. After cooling to room temperature, the titanium fiber felt was taken out, rinsed with deionized water, and then dried in an oven at 80° C. to obtain a titanium fiber felt coated with a metal organic framework MIL-125 material.

[0096] (4) The titanium fiber felt coated with the metal organic framework MIL-125 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at a rate of 5°C / min and maintained for 30 minutes. After cooling to room temperature, the titanium fiber felt coated with carbon-wrapped titanium oxide is obtained.

[0097] Example 6

[0098] A method for obtaining a carbon-coated titanium rod by loading a metal organic framework MIL-167 as a precursor, comprising the following steps:

[0099] (1) 10 g of anhydrous oxalic acid was added to 100 ml of water and stirred to dissolve to form a 10 wt% oxalic acid solution. After heating to 80 ° C, a titanium rod with a diameter of 10 mm and a length of 20 mm was immersed in the oxalic acid solution for 10 minutes. After being taken out, it was rinsed with ultrapure water to obtain a defect-rich titanium rod.

[0100] (2) Add 2.65 g of 2,5-dihydroxyterephthalic acid (DHTA) to a beaker containing a mixed solution of 10 mL of anhydrous methanol (MeOH) and 40 mL of N,N-dimethylformamide (DMF) and stir at room temperature until the DHTA is fully dissolved. Then, add the defect-rich titanium rod from step (1) to the mixed solution and stir and adsorb for 24 h.

[0101] (3) 2.65 mL of the metal ligand titanium isopropoxide was further added to the mixed solution and titanium rod in step (2), and the mixture was heated to 150° C. and refluxed for 48 h. After cooling to room temperature, the titanium rod was taken out, rinsed with deionized water, and then dried in an oven at 80° C. to obtain a titanium rod coated with a metal organic framework MIL-167 material.

[0102] (4) The titanium rod coated with the metal organic framework MIL-167 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600°C at 5°C / min and maintained for 30 minutes. After cooling to room temperature, a titanium rod with a carbon-coated titanium oxide coating material is obtained.

[0103] Example 7

[0104] A method for obtaining a carbon-coated titanium oxide-coated titanium sheet by loading a metal organic framework MIL-177 as a precursor, comprising the following steps:

[0105] (1) 10 g of anhydrous oxalic acid was added to 100 ml of water and stirred to dissolve to form a 10 wt% oxalic acid solution. After heating to 80°C, a titanium plate with a length of 10 mm, a width of 10 mm, and a thickness of 1 mm was immersed in the oxalic acid solution for 10 min. After being taken out, it was rinsed with ultrapure water to obtain a defect-rich titanium plate.

[0106] (2) Add 2.5 g of 3,3',5,5'-tetracarboxydiphenylmethane (PCN-12) to a beaker containing a mixed solution of 10 mL of anhydrous methanol (MeOH) and 40 mL of N,N-dimethylformamide (DMF) and stir at room temperature until the PCN-12 is fully dissolved. Then, add the defect-rich titanium plate from step (1) to the mixed solution and stir and adsorb for 24 h.

[0107] (3) 2.5 mL of the metal ligand titanium isopropoxide was further added to the mixed solution and titanium plate in step (2), and the mixture was heated to 150° C. and refluxed for 72 h. After cooling to room temperature, the titanium plate was taken out, rinsed with deionized water, and then dried in an oven at 80° C. to obtain a titanium plate coated with a metal organic framework MIL-177 material.

[0108] (4) The titanium plate coated with the metal organic framework MIL-177 material described in step (3) is subjected to annealing, carbonization and oxidation treatment in a muffle furnace, and the temperature is increased to 600° C. at a rate of 5° C. / min and maintained for 30 min. After cooling to room temperature, a titanium plate of carbon-coated titanium oxide coating material is obtained.

[0109] The properties of the materials prepared in Examples 2 to 7 are similar to those in Example 1 and will not be described in detail.

[0110] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, such changes and modifications are intended to be included.

Claims

1. A method for preparing a carbon-coated oxide coating on the surface of a titanium material, characterized in that: The following steps are involved: Treating the titanium material with an inorganic acid solution to obtain a defect-rich titanium material; The organic carboxylic acid ligand, anhydrous methanol and N,N-dimethylformamide are mixed evenly, and the mixture is added to the defect-rich titanium material for adsorption, so that the organic carboxylic acid ligand forms a Ti-O ionic bond with the defect sites in the titanium material; Then, a metal ligand titanium isopropoxide is added to the system and reacted at 80°C to 150°C. During the reaction, the titanium isopropoxide and the organic carboxylic acid ligand in situ grow a metal organic framework material on the surface of the titanium material to form a titanium material loaded with a metal organic framework coating; The titanium material loaded with the metal organic framework coating is subjected to annealing, carbonization and oxidation treatment to obtain a carbon-coated oxide coating on the surface of the titanium material; Annealing, carbonization and oxidation treatment are carried out in a muffle furnace in an air atmosphere at a temperature of 200°C to 800°C and a holding time of 10 minutes to 120 minutes.

2. The preparation method according to claim 1, characterized in that The organic carboxylic acid ligand is one of terephthalic acid, 2-aminoterephthalic acid, 2,5-dihydroxyterephthalic acid and 3,3',5,5'-tetracarboxydiphenylmethane.

3. The preparation method according to claim 1, characterized in that The molar ratio of the organic carboxylic acid ligand, anhydrous methanol and N,N-dimethylformamide is 1:10-20:20-40.

4. The preparation method according to claim 1, characterized in that The molar ratio of the metal ligand titanium isopropoxide to the organic carboxylic acid ligand is 0.5-1:

1.

5. The preparation method according to claim 1, characterized in that The reaction time is 10h~100h.

6. The preparation method according to claim 1, characterized in that The titanium material is immersed in an inorganic acid solution and then rinsed with water to obtain a defect-rich titanium material; the temperature is 70° C. to 100° C., and the immersion time is 1 minute to 30 minutes.

7. The preparation method according to claim 1, characterized in that The inorganic acid solution is selected from one of hydrochloric acid with a concentration of 0.5wt%, sulfuric acid with a concentration of 5wt%, phosphoric acid with a concentration of 85wt%, and hydrofluoric acid with a concentration of 5wt%.

8. A carbon-coated oxide coating on the surface of a titanium material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the carbon-coated oxide coating on the surface of the titanium material according to claim 8 in the protection of proton exchange membrane water electrolysis or hydrogen fuel cell equipment.

Images