Titanium dioxide loaded metal composite material and its preparation method and application

Abstract

The present invention discloses a titanium dioxide-loaded metal composite material, its preparation method, and application. The composite material comprises a titanium substrate and a titanium dioxide nanoarray, wherein the titanium dioxide nanoarray is grown on the surface of the titanium substrate; the titanium dioxide nanoarray is composed of titanium dioxide nanorods; and the surface of the titanium dioxide nanorods is loaded with metal rhodium nanoparticles. The present invention utilizes the structure of the three-dimensional titanium dioxide nanoarray to fully expose the rhodium nanoparticles on the external surface, greatly increasing the active surface area, thereby improving the activity of the titanium dioxide-loaded metal composite material as a hydrogen evolution reaction catalyst. In the composite material preparation method of the present invention, ethylene glycol is used as the reaction solvent. The resulting titanium dioxide nanoarray has three-dimensional anisotropy and high stability, providing a large surface area and a more complex electron transport path. The rhodium nanoparticles are then loaded by a wet chemical method, which is beneficial to improving the catalytic activity of the rhodium nanoparticles.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and specifically relates to a titanium dioxide-loaded metal composite material and a preparation method and application thereof. Background Art

[0002] Hydrogen is a clean energy source with the greatest potential to replace fossil fuels. Hydrogen production by water electrolysis is an effective way to produce hydrogen efficiently, with the characteristics of being green and environmentally friendly, flexible in production and high in product purity. In the process of water electrolysis, the selection of highly active cathode hydrogen evolution reaction (HER) catalysts is crucial to improving the efficiency of water electrolysis. At present, catalysts for hydrogen production by water electrolysis are mainly divided into three categories: precious metals, transition metals and non-metals. Precious metal catalysts mainly refer to Pt group metals and their alloys. Precious metal catalysts can effectively reduce the overpotential of the HER reaction and have excellent catalytic performance, but their reserves are extremely low, their cost is high and their electrochemical stability is poor, which limits their large-scale industrial application. Among them, the precious metal rhodium (Rh) has high electrochemical activity and is cheaper than Pt, but its disadvantage is that it is easy to agglomerate and has poor stability. Therefore, how to improve the shortcomings of the precious metal rhodium, which is easy to agglomerate and has poor stability, is an urgent problem to be solved. Summary of the Invention

[0003] To overcome the problems of the prior art, one object of the present invention is to provide a titanium dioxide-loaded metal composite material. A second object of the present invention is to provide a method for preparing the titanium dioxide-loaded metal composite material. A third object of the present invention is to provide applications of the titanium dioxide-loaded metal composite material. A fourth object of the present invention is to provide a membrane electrode.

[0004] This application modulates the electronic structure of the precious metal through a transition metal-based support. The structure of the titanium dioxide three-dimensional nanoarray fully exposes the precious metal rhodium on the external surface, significantly increasing its active surface area. This improves the atomic utilization and stability of the precious metal rhodium, prevents agglomeration, and thus enhances the activity of the hydrogen evolution reaction catalyst. Furthermore, by depositing the rhodium directly onto the substrate during the preparation process, the use of an adhesive is avoided, thereby reducing mass transfer resistance and minimizing delamination.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides a titanium dioxide-loaded metal composite material, comprising a titanium substrate, a titanium dioxide nanoarray grown on the surface of the titanium substrate; the titanium dioxide nanoarray consists of titanium dioxide nanorods; and the surface of the titanium dioxide nanorods is loaded with metal rhodium nanoparticles.

[0007] Preferably, the titanium substrate is titanium foam or titanium sheet.

[0008] More preferably, the shape of the titanium foam or titanium sheet is square or circular. Further preferably, the square length is ≤380 mm, and the square width is ≤380 mm. Further preferably, the diameter of the circle is ≤380 mm.

[0009] More preferably, the thickness of the titanium substrate is 1 to 5 mm.

[0010] Preferably, the diameter of the titanium dioxide nanorods is 10 to 30 nm.

[0011] Preferably, the metal rhodium nanoparticles are spherical nanoparticles. More preferably, the metal rhodium nanoparticles have a particle size of 2-5 nm.

[0012] The second aspect of the present invention provides a method for preparing the titanium dioxide-loaded metal composite material according to the first aspect, comprising the following steps:

[0013] S1, mixing ethylene glycol, hydrochloric acid and a titanium substrate, and performing a solvothermal reaction 1 to prepare a material in which titanium dioxide nanoarrays are grown on the surface of the titanium substrate;

[0014] S2. Mixing the composite material of S1, ethylene glycol, urea and a rhodium source, and performing a solvent thermal reaction 2 to obtain the titanium dioxide-supported metal composite material.

[0015] Preferably, in step S1, the volume ratio of ethylene glycol to hydrochloric acid is (10-20):1.

[0016] More preferably, in step S1, the volume ratio of ethylene glycol to hydrochloric acid is (13-17):1.

[0017] Preferably, in step S1, the reaction temperature of the solvent thermal reaction 1 is 180-220° C., and the reaction time is 16-24 h.

[0018] More preferably, in step S1, the reaction temperature of the solvent thermal reaction 1 is 180-210° C., and the reaction time is 18-22 h.

[0019] Preferably, step S1 further comprises the following steps: after performing the solvent thermal reaction 1, collecting the solid product, washing and drying it to obtain the titanium dioxide-supported metal composite material.

[0020] More preferably, the drying temperature is 50-70° C., and the drying time is 5-7 hours.

[0021] Preferably, in step S2, the molar ratio of the urea to the rhodium atoms in the rhodium source is (30-40):1.

[0022] Preferably, the rhodium source is a soluble rhodium salt.

[0023] More preferably, the rhodium source is rhodium chloride hydrate.

[0024] Preferably, in step S2, the usage ratio of urea to ethylene glycol is (300-400) mmol:1L.

[0025] Preferably, in step S2, the reaction temperature of the solvent thermal reaction 2 is 140-180°C, and the reaction time is 10-14 hours.

[0026] More preferably, in step S2, the reaction temperature of the solvent thermal reaction 2 is 150-170°C, and the reaction time is 11-13 hours.

[0027] The third aspect of the present invention provides use of the titanium dioxide-supported metal composite material described in the first aspect in a hydrogen evolution reaction catalyst.

[0028] A fourth aspect of the present invention provides a membrane electrode, which comprises a proton exchange membrane, a catalyst layer, and a diffusion layer stacked in sequence; the catalyst layer comprises the titanium dioxide-loaded metal composite material described in the first aspect.

[0029] The beneficial effects of the present invention are:

[0030] The present invention provides a titanium dioxide-loaded metal composite material, in which a titanium dioxide nanoarray is grown on a titanium substrate, thereby realizing in-situ construction of a transition metal main body with a three-dimensional structure. The titanium dioxide nanoarray is composed of titanium dioxide nanorods, and the surfaces of the nanorods are loaded with metal rhodium nanoparticles. The structure of the three-dimensional titanium dioxide nanoarray can fully expose the rhodium nanoparticles on the outer surface, greatly increasing the active surface area, thereby improving the activity of the titanium dioxide-loaded metal composite material as a hydrogen evolution reaction catalyst.

[0031] Specifically, compared with the prior art, the present invention has the following advantages:

[0032] 1. The present invention also provides a method for preparing a titanium dioxide-loaded metal composite material. First, a titanium dioxide nanoarray is grown in situ on a titanium substrate. Ethylene glycol is used as a reaction solvent, which is beneficial to improving the stability of the product. The prepared titanium dioxide nanoarray has three-dimensional anisotropy, provides a large surface area and a more complex electron transmission path; then, a wet chemical method is used to load precious metal rhodium nanoparticles. The rhodium nanoparticles are fully exposed on the outer surface of the three-dimensional titanium dioxide nanoarray, thereby greatly increasing its active surface area and improving the catalytic activity of the rhodium nanoparticles.

[0033] 2. The present invention also provides the use of a titanium dioxide-supported metal composite material in a hydrogen evolution reaction catalyst, wherein rhodium has high catalytic activity for the hydrogen evolution reaction and extremely high corrosion resistance to various electrolytes. The structure of the titanium dioxide three-dimensional nanoarray is utilized to fully expose rhodium nanoparticles on the external surface, thereby greatly increasing the active surface area, thereby reducing the overpotential in acidic, neutral, and alkaline electrolytes, and improving the catalytic performance of the hydrogen evolution catalyst. When applied to acidic and alkaline hydrogen evolution reactions, it can exhibit high catalytic activity and stability, and has great application potential in membrane electrode and hydrogen fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a scanning electron microscope image of the Ti / TiO2 material in Example 1;

[0035] Figure 2 This is a scanning electron microscope image of the Ti / TiO2 material in Example 1 from another observation angle;

[0036] Figure 3 This is a transmission electron microscope image of the Ti / TiO2 material in Example 1;

[0037] Figure 4 This is a scanning electron microscope image of the Ti / TiO2 material in Example 2;

[0038] Figure 5 This is a scanning electron microscope image of the Ti / TiO2 material in Comparative Example 1;

[0039] Figure 6 This is a scanning electron microscope image of the Ti / TiO2 material in Comparative Example 1 from another observation angle;

[0040] Figure 7 This is a scanning electron microscope image of the Ti / TiO2 material in Comparative Example 2;

[0041] Figure 8 This is a scanning electron microscope image of the Ti / TiO2 material in Comparative Example 3;

[0042] Figure 9 This is a scanning electron microscope image of the Ti / TiO2 material in Comparative Example 4;

[0043] Figure 10 The physical pictures of different Ti / TiO2 materials in Example 1 and Comparative Examples 1-4 are shown;

[0044] Figure 11 is the XRD pattern of the Ti / TiO2 material in Example 1;

[0045] Figure 12 is a scanning electron microscope image of the Ti / TiO2-Rh composite material in Example 1;

[0046] Figure 13 TEM image of the Ti / TiO2-Rh composite material in Example 1;

[0047] Figure 14 The catalytic performance of the Ti / TiO2-Rh composite materials of Examples 1, 3, and 4 in acidic hydrogen evolution reaction;

[0048] Figure 15 The catalytic performance of the Ti / TiO2-Rh composite materials of Examples 1, 3, and 4 in alkaline hydrogen evolution reaction;

[0049] Figure 16 The catalytic performance of the Ti / TiO2-Rh composite materials of Example 1 and Comparative Examples 2-4 in acidic hydrogen evolution reaction;

[0050] Figure 17 The catalytic performance of the Ti / TiO2-Rh composite materials of Example 1 and Comparative Examples 2-4 in alkaline hydrogen evolution reaction;

[0051] Figure 18 The catalytic performance of the Ti / TiO2-Rh composite materials of Examples 1-2 and Comparative Example 5 in acidic hydrogen evolution reaction;

[0052] Figure 19 The catalytic performance of the Ti / TiO2-Rh composite materials of Examples 1-2 and Comparative Example 5 in alkaline hydrogen evolution reaction. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below through specific examples. Unless otherwise specified, the raw materials used in the following examples can be obtained from conventional commercial sources or prepared and isolated by simple synthesis; unless otherwise specified, the processes used are conventional processes in the art.

[0054] Example 1

[0055] This embodiment provides a titanium dioxide-loaded metal composite material, the preparation method of which is as follows:

[0056] (1) 15 mL of ethylene glycol (EG), 1 mL of hydrochloric acid, and 2 cm × 3 cm titanium foam were sequentially added to a reactor and mixed; the reactor containing the mixture was placed in an oven, heated to 200°C, and maintained for 20 h; after the reaction was completed, the reactor was cooled to room temperature, the solid product was collected and washed, and the sample was placed in an oven at 60°C and maintained for 6 h for drying to obtain a material with titanium dioxide nanoarrays grown on the surface of a titanium substrate, which was recorded as Ti / TiO2 material;

[0057] (2) The composite material was cut into 1 cm × 2 cm pieces, and the composite material, 6 mL of ethylene glycol, 2.04 mmol of urea, and 0.06 mmol of rhodium chloride trihydrate were added to a round-bottom flask in sequence and mixed, and the rhodium salt was dissolved by stirring. The round-bottom flask was placed in an oil bath, and the oil bath was heated from room temperature to 160 ° C and maintained for 12 h to obtain the titanium dioxide-loaded metal composite material, which was recorded as Ti / TiO2-Rh composite material.

[0058] Example 2

[0059] This embodiment provides a titanium dioxide-loaded metal composite material and a preparation method thereof, and the preparation method is similar to that of Example 1. The difference is that the titanium foam is replaced by a titanium sheet.

[0060] Example 3

[0061] This embodiment provides a titanium dioxide-supported metal composite material and a preparation method thereof, and the preparation method is similar to that of Example 1. The difference is that the reaction time in step (2) is replaced from 12 h to 10 h.

[0062] Example 4

[0063] This embodiment provides a titanium dioxide-supported metal composite material and a preparation method thereof, and the preparation method is similar to that of Example 1. The difference is that the reaction time in step (2) is replaced from 12 h to 14 h.

[0064] Comparative Example 1

[0065] The preparation method of this comparative example is similar to that of Example 1, except that 15 mL of ethylene glycol in step (1) is replaced by 12 mL of ethylene glycol and 3 mL of water.

[0066] Comparative Example 2

[0067] The preparation method of this comparative example is similar to that of Example 1, except that 15 mL of ethylene glycol in step (1) is replaced by 7.5 mL of ethylene glycol and 7.5 mL of water.

[0068] Comparative Example 3

[0069] The preparation method of this comparative example is similar to that of Example 1, except that 15 mL of ethylene glycol in step (1) is replaced by 3 mL of ethylene glycol and 12 mL of water.

[0070] Comparative Example 4

[0071] The preparation method of this comparative example is similar to that of Example 1, except that 15 mL of ethylene glycol in step (1) is replaced by 15 mL of water.

[0072] Comparative Example 5

[0073] This comparative example provides a titanium-loaded metal composite material, and its preparation method is as follows:

[0074] A metal Ti sheet was used, and the upper Ti sheet was cut into 1 cm × 2 cm. The Ti sheet, 6 mL of ethylene glycol, 2.04 mmol of urea and 0.06 mmol of rhodium chloride trihydrate were added to a round-bottom flask in sequence and mixed. The rhodium salt was stirred to dissolve the round-bottom flask. The round-bottom flask was placed in an oil bath, and the oil bath was heated from room temperature to 160 ° C and maintained for 12 hours to obtain the titanium dioxide-loaded metal composite material, which was recorded as a Ti-Rh composite material.

[0075] Material characterization

[0076] Figure 1 and Figure 2 is a scanning electron microscope (SEM) image of the Ti / TiO2 material in Example 1; Figure 3 TEM image of the Ti / TiO2 material in Example 1; Figure 4 is a scanning electron microscope image of the Ti / TiO2 material in Example 2; Figure 1-4 It can be seen that the nanorods arrayed by solvothermal method using ethylene glycol and hydrochloric acid are well arranged, have finer sizes and larger specific surface area. Figure 5-9 This is a scanning electron microscope image of the Ti / TiO2 array material in comparative examples 1-4. As the amount of water increases, the size of the arrayed TiO2 gradually becomes wider and uneven, and the TiO2 array layer gradually becomes thicker, resulting in a decrease in electrochemical performance.

[0077] Figure 10 The following are actual pictures of different Ti / TiO2 materials in Example 1 and Comparative Examples 1-4. It can be seen from the pictures that the titanium foam prepared by adding only water is almost broken and cannot be used for subsequent electrochemical testing, while the product of Example 1 using ethylene glycol as the reaction solvent is the most complete.

[0078] Figure 11 is the XRD pattern of the Ti / TiO2 material in Example 1;

[0079] Figure 12 is a scanning electron microscope image of the composite material in Example 1; Figure 13 is a transmission electron microscope image of the composite material in Example 1; Figure 3 and Figure 13 It can be seen that the metal rhodium nanoparticles are loaded on the titanium dioxide nanorods. Figure 12 It can be seen that titanium dioxide nanorods loaded with metal rhodium nanoparticles form a nanoarray.

[0080] Experimental analysis

[0081] The products of Examples 1-4 and Comparative Examples 2-5 were subjected to a hydrogen evolution test method. The specific test method and results are as follows:

[0082] 1. The test method includes the following steps: (1) Preparation of the working electrode: The sample is clamped in a platinum electrode holder, 1cm·1cm is immersed in the electrolyte, and then the electrocatalytic test is performed. (2) Acidic performance test: A three-electrode test method is used, with the platinum electrode holder containing the catalyst TiO2 / Rh as the working electrode, the reference electrode is saturated calomel, the counter electrode is a carbon rod, and the electrolyte is 0.5 mol / L H2SO4 solution. The linear sweep voltammetry (LSV) method is used for the test. The LSV test range is 0.1V to 0.45V, and the scan rate is 5mV / s. (3) Alkaline performance test: A three-electrode test method is used, with the platinum electrode holder containing the catalyst TiO2 / Rh as the working electrode, the reference electrode is saturated calomel, the counter electrode is a carbon rod, and the electrolyte is 1 mol / L KOH solution. The linear sweep voltammetry (LSV) method is used for the test.

[0083] 2. Figure 14 The catalytic performance of the composite materials of Examples 1, 3, and 4 in acidic hydrogen evolution reaction; Figure 15 The catalytic performance of the composite materials of Examples 1, 3 and 4 in alkaline hydrogen evolution reaction is analyzed. Figure 14 and 15 The overpotentials of the composite materials of Examples 1, 3, and 4 at different current densities in the acidic / alkaline hydrogen evolution reaction catalysis can be obtained, and the results are shown in Table 1:

[0084] Table 1

[0085] <![CDATA[Acidic 10 mA·cm -2 > <![CDATA[Acidic 50 mA·cm -2 > <![CDATA[Alkaline 10 mA·cm -2 > <![CDATA[Alkaline 50 mA·cm -2 > Example 1 24 72 37 75 Example 3 48 85 54 179 Example 4 55 89 50 164

[0086] In the acidic LSV test, the product of Example 1 showed a -2 The overpotential is only 24 mV at 50 mA cm -2 The overpotential is only 72mV; in the alkaline LSV test, at 10mA cm -2 The overpotential is only 37mV at 50mAcm -2 The overpotential is only 75 mV. The test results show that the product obtained by reacting for 12 hours in step (2) has a low overpotential and the best electrochemical performance.

[0087] 3. Figure 16 The catalytic performance of the composite materials of Example 1 and Comparative Examples 2-4 in acidic hydrogen evolution reaction; Figure 17 The catalytic performance of the composite materials of Example 1 and Comparative Examples 2-4 in alkaline hydrogen evolution reaction is analyzed. Figure 16 and 17 The overpotentials of the composite materials of Example 1 and Comparative Examples 2-4 at different current densities in the acidic / alkaline hydrogen evolution reaction catalysis can be obtained, and the results are shown in Table 2:

[0088] Table 2

[0089] <![CDATA[Acidic 10 mA·cm -2 > <![CDATA[Acidic 50 mA·cm -2 > <![CDATA[Alkaline 10 mA·cm -2 > <![CDATA[Alkaline 50 mA·cm -2 > Example 1 24 72 37 75 Comparative Example 2 Poor performance Poor performance Poor performance Poor performance Comparative Example 3 51 98 104 none Comparative Example 4 Poor performance Poor performance 121 none

[0090] Note: The corresponding voltage range in the graph with poor performance or no performance cannot be read.

[0091] Through LSV testing, it can be seen that the precious metal rhodium loaded on the full EG and hydrochloric acid arrays exhibit excellent performance under acidic and alkaline conditions, while the precious metal rhodium loaded on TiO2 in other ratio arrays exhibits poor electrochemical performance and cannot be used for electrocatalytic reactions.

[0092] 4. Figure 18 The catalytic performance of the composite materials of Examples 1-2 and Comparative Example 5, and the intermediate product (Ti / TiO2 material) of Examples 1-2 in acidic hydrogen evolution reaction; Figure 19 The catalytic performance of the alkaline hydrogen evolution reaction of the composite materials of Examples 1-2 and Comparative Example 5, and the intermediate products of Examples 1-2; Figure 18 and 19 The overpotentials of the composite materials of Examples 1-2 and Comparative Example 5, as well as the intermediate products of Examples 1-2, at different current densities in the acidic / alkaline hydrogen evolution reaction catalysis are obtained, and the results are shown in Table 3:

[0093] Table 3

[0094]

[0095] The LSV test shows that rhodium has high catalytic activity for the hydrogen evolution reaction and extremely high corrosion resistance to various electrolytes. Comparative Example 1 and Comparative Example 5 show that the structure of the titanium dioxide three-dimensional nanoarray fully exposes the rhodium nanoparticles on the outer surface, greatly increasing the active surface area, reducing the overpotential in acidic and alkaline electrolytes, and improving the catalytic performance of the hydrogen evolution catalyst. It can be applied to acidic and alkaline hydrogen evolution reactions to show high catalytic activity and stability, and has great application potential in membrane electrode and hydrogen fuel cells.

[0096] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A titanium dioxide-loaded metal composite material, characterized in that: The invention comprises a titanium substrate, a titanium dioxide nanoarray is grown on the surface of the titanium substrate; the titanium dioxide nanoarray is composed of titanium dioxide nanorods; and the surface of the titanium dioxide nanorods is loaded with metal rhodium nanoparticles; The preparation method of the titanium dioxide-loaded metal composite material comprises the following steps: S1. Mixing ethylene glycol, hydrochloric acid, and a titanium substrate to perform a solvothermal reaction 1 to obtain a material having a titanium dioxide nanoarray grown on the surface of the titanium substrate; the volume ratio of the ethylene glycol to the hydrochloric acid is (10-20):1; the reaction temperature of the solvothermal reaction 1 is 180-220° C., and the reaction time is 16-24 hours; S2. Mix the product of S1, ethylene glycol, urea and rhodium source, and carry out solvent thermal reaction 2 to obtain the titanium dioxide-supported metal composite material; the reaction temperature of the solvent thermal reaction 2 is 140-180° C., and the reaction time is 10-14 hours.

2. The titanium dioxide-loaded metal composite material according to claim 1, characterized in that The titanium substrate is foamed titanium or a titanium sheet.

3. The method for preparing the titanium dioxide-supported metal composite material according to claim 1 or 2, characterized in that: The steps include: S1. Mixing ethylene glycol, hydrochloric acid, and a titanium substrate to perform a solvothermal reaction 1 to obtain a material having a titanium dioxide nanoarray grown on the surface of the titanium substrate; the volume ratio of the ethylene glycol to the hydrochloric acid is (10-20):1; the reaction temperature of the solvothermal reaction 1 is 180-220° C., and the reaction time is 16-24 hours; S2. Mix the product of S1, ethylene glycol, urea and rhodium source, and carry out solvent thermal reaction 2 to obtain the titanium dioxide-supported metal composite material; the reaction temperature of the solvent thermal reaction 2 is 140-180° C., and the reaction time is 10-14 hours.

4. The method for preparing a titanium dioxide-supported metal composite material according to claim 3, wherein: In step S2, the molar ratio of urea to rhodium atoms in the rhodium source is (30-40):1; And / or, the rhodium source is a soluble rhodium salt.

5. The method for preparing a titanium dioxide-supported metal composite material according to claim 3, wherein: In step S2, the usage ratio of urea to ethylene glycol is (300-400) mmol:1L.

6. Use of the titanium dioxide-supported metal composite material according to claim 1 or 2 in preparing a hydrogen evolution reaction catalyst.

7. A membrane electrode, characterized in that The membrane electrode comprises a proton exchange membrane, a catalyst layer, and a diffusion layer stacked in sequence; the catalyst layer comprises the titanium dioxide-loaded metal composite material according to claim 1 or 2.

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