Titanium dioxide nanorarray supported ru monatomic material, preparation method thereof and application thereof as basic hydrogen evolution reaction electrocatalyst

Abstract

The application discloses a rutile phase titanium dioxide supported noble metal ruthenium monatomic nanomaterial, a preparation method thereof and application of the nanomaterial as a basic hydrogen evolution reaction catalyst. The rutile phase titanium dioxide nanorod material with an array morphology is synthesized on a carrier through a hydrothermal reaction, and the nanomaterial loaded with monatomic ruthenium is obtained through an impregnation-thermal reduction method. The obtained material can be directly used for an electrode of an electrolytic cell, and diffusion and conductive limitation caused by an added binder are avoided. Compared with a conventional Pt / C catalyst, the rutile phase titanium dioxide with huge reserves and low price and excellent stability is used as a main structure in the application, and the amount of the noble metal ruthenium is greatly reduced through a monatomic loading strategy, and the cost is effectively reduced. Compared with the conventional commercial Pt / C, the material has higher HER activity and stability, and has an industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material chemistry and electrocatalysis, and particularly relates to a titanium dioxide nanometer array loaded Ru monatomic material, a preparation method thereof and application thereof as an alkaline hydrogen evolution reaction electrocatalyst. BACKGROUND

[0002] Hydrogen, as an important chemical industry raw material, itself occupies a very important position in chemical production. At the same time, because hydrogen itself has high energy density (142 MJ / kg) and clean and pollution-free combustion product characteristics, it has received more and more widespread attention in today's increasingly severe energy problems. At present, the main method for producing hydrogen in industry is steam reforming of methane, coal gasification and water electrolysis. The first two methods account for as high as 95% of the scale in the current hydrogen production because of the relatively mature petroleum industry system and the relatively low cost in large-scale industrial production. However, the hydrogen production based on petrochemical industry not only consumes a large amount of petrochemical resources, but also greatly increases industrial carbon emissions. Water electrolysis itself not only relies on cheap and abundant water as raw material, but also has hydrogen and oxygen as reaction products, which is environmentally friendly. At the same time, the water electrolysis process itself can utilize unstable voltage of new energy power such as solar power and wind power, which is not convenient for grid connection, greatly expanding the use environment of new energy power. With the development of the times, people's pursuit of a better natural environment, it is becoming more and more important to improve the proportion of water electrolysis method in hydrogen production.

[0003] Platinum-based catalysts have become the mainstream of water electrolysis cathode catalysts due to their superior performance. However, due to the low reserves and high price of platinum itself, platinum-based catalysts still have obstacles in large-scale industrial application of water electrolysis hydrogen production. Therefore, in order to further reduce the cost, the main research directions are to use low-cost non-noble metals to prepare catalysts, and to minimize the amount of noble metals in the catalyst while ensuring the overall performance of the catalyst by optimizing the synthesis strategy. In the latter approach, loading noble metals on carbon-based materials with good electrical conductivity is the most common material development method, but such a method still requires a relatively high amount of noble metals. Using noble metals to replace non-noble transition metal oxides is also a common catalyst development approach, but the overall reaction inertness of transition metal oxides in hydrogen evolution reaction (HER) makes it difficult for these catalysts to perform as well as carbon-based materials with the same mass density. SUMMARY

[0004] Therefore, the present application aims to solve the technical problem of providing a titanium dioxide nanometer array loaded Ru monatomic material, a preparation method thereof and an application thereof as an alkaline hydrogen evolution reaction electrocatalyst, the material provided by the present application reduces the amount of noble metal ruthenium, and higher electrocatalytic hydrogen production activity and stability are obtained.

[0005] The present application provides a preparation method of a titanium dioxide nanometer array loaded Ru monatomic material, comprising the following steps:

[0006] A) etching the titanium dioxide nanometer array loaded on the carrier in a high-temperature reducing atmosphere to obtain a titanium dioxide nanowire array containing O vacancies;

[0007] B) immersing the titanium dioxide nanowire array containing O vacancies in a ruthenium source solution, and then sequentially performing drying and high-temperature reduction to obtain a titanium dioxide nanometer array loaded Ru monatomic material.

[0008] Preferably, the preparation method of the titanium dioxide nanometer array loaded on the carrier comprises the following steps:

[0009] Mixing a titanium source solution with a strong acid solution, adding a carrier and obtaining the titanium dioxide nanometer array loaded on the carrier through a high-temperature and high-pressure hydrothermal reaction.

[0010] Preferably, the titanium source compound in the titanium source solution is selected from one or more of titanate esters containing a titanate group;

[0011] The concentration of the titanate group in the titanium source solution is 0.05-0.15 mol / L, and further preferably 0.08-0.10 mol / L;

[0012] The strong acid is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid; wherein the concentration of the strong acid in the titanium source solution is preferably 4-8 mol / L, and further preferably 5.5-6.5 mol / L;

[0013] The carrier is selected from one or more of carbon cloth, carbon paper and conductive glass, and is preferably carbon cloth or carbon paper.

[0014] Preferably, the titanium source compound is selected from one or more of tetraethyl titanate, tetrabutyl titanate and isopropyl titanate;

[0015] The carbon cloth and carbon paper are preferably subjected to hydrophilic treatment before use; the hydrophilic treatment preferably comprises immersion in concentrated sulfuric acid and concentrated nitric acid.

[0016] Preferably, the temperature of the hydrothermal reaction is 120-190 DEG C; and the time of the hydrothermal reaction is 8-15 h.

[0017] Preferably, in step A), the etching temperature is 300-800℃; and the etching time is 8-24h.

[0018] The reducing atmosphere is argon-hydrogen mixed gas or carbon monoxide and argon mixed gas; in the argon-hydrogen mixed gas, the volume content of hydrogen is 3-20%, and in the carbon monoxide and argon mixed gas, the volume content of carbon monoxide is 3-20%.

[0019] Preferably, the ruthenium source is selected from one or more of ruthenium chloride, ruthenium acetylacetonate and ruthenium acetate; and the concentration of the ruthenium source in the solution is 0.002-0.010 mol / L.

[0020] Preferably, in step B), the high-temperature reduction temperature is 200-500℃; the high-temperature reduction time is 8-24h; and the high-temperature reduction atmosphere is argon-hydrogen mixed gas or carbon monoxide and argon mixed gas, wherein in the argon-hydrogen mixed gas, the volume content of hydrogen is 3-20%, and in the carbon monoxide and argon mixed gas, the volume content of carbon monoxide is 3-20%.

[0021] The application further provides a titanium dioxide nanometer array loaded Ru monatomic material prepared by the above preparation method, and the mass content of the ruthenium is 0.01-0.50%.

[0022] The application further provides a titanium dioxide nanometer array loaded Ru monatomic material prepared by the above preparation method or the application of the above titanium dioxide nanometer array loaded Ru monatomic material as an alkaline hydrogen evolution reaction electrocatalyst.

[0023] Compared with the prior art, the application provides a preparation method of a titanium dioxide nanometer array loaded Ru monatomic material, which comprises the following steps: A) etching titanium dioxide nanometer arrays loaded on a carrier in a high-temperature reducing atmosphere to obtain titanium dioxide nanometer wire arrays containing O vacancies; B) immersing the titanium dioxide nanometer wire arrays containing O vacancies in a ruthenium source solution, and then sequentially performing drying and high-temperature reduction to obtain the titanium dioxide nanometer array loaded Ru monatomic material. The titanium dioxide nanometer array directly loaded on the carrier is synthesized through a hydrothermal reaction, and a large number of oxygen vacancies are modified on the surface of the material through high-temperature reduction. The noble metal Ru monatomic is further anchored through the O vacancies, and the local environment of the Ru monatomic is precisely controlled. The obtained nanomaterial is loaded on the carrier and can be directly used as an electrode of an electrolytic cell, avoiding the problems of slow diffusion rate and poor conductivity caused by the use of a binder, and simplifying the electrode manufacturing process. Compared with the traditional Pt / C catalyst with high noble metal Pt content, the disadvantages of high price and low reserves greatly limit the large-scale development of the Pt / C catalyst. The application selects titanium dioxide as the main structure because of its abundant reserves, low price and good stability, greatly reduces the amount of noble metal, improves the utilization rate of Ru atoms and reduces the cost. Compared with the commercial Pt / C, the material has higher HER activity and stability, and has high industrial application prospect. The non-noble metal oxide titanium dioxide as the main material not only greatly improves the catalytic performance, but also has excellent stability. After 100h of continuous constant current (10mA / cm 2 ) test, the overpotential of the material hardly changes. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The X-ray diffraction pattern of the titanium dioxide nanometer array loaded ruthenium monatomic material prepared in Example 1 of the application;

[0025] Figure 2 The scanning electron microscope image of the titanium dioxide nanometer array loaded ruthenium monatomic material prepared in Example 1 of the application;

[0026] Figure 3 The local structure analysis of the titanium dioxide nanometer array loaded ruthenium monatomic material prepared in Example 1 of the application;

[0027] Figure 4 The area-normalized linear sweep voltammetry curve of the titanium dioxide nanometer array loaded ruthenium monatomic material prepared in Example 1 of the application and the comparison with the commercial Pt / C. DETAILED DESCRIPTION

[0028] The application provides a preparation method of a titanium dioxide nanometer array loaded Ru monatomic material, which comprises the following steps:

[0029] A) etching the titanium dioxide nanometer array loaded on the carrier in a high-temperature reducing atmosphere to obtain a titanium dioxide nanowire array containing O vacancies;

[0030] B) immersing the titanium dioxide nanowire array containing O vacancies in a ruthenium source solution, and then sequentially drying and high-temperature reducing to obtain a titanium dioxide nanometer array loaded Ru monatomic material.

[0031] The present application first prepares a titanium dioxide nanometer array loaded on a carrier, and the specific method is as follows:

[0032] The titanium source solution is mixed with a strong acid solution, and after adding the carrier, a high-temperature and high-pressure hydrothermal reaction is carried out to obtain a titanium dioxide nanometer array loaded on the carrier.

[0033] The titanium source compound in the titanium source solution is selected from one or more of titanate esters including a titanate group; preferably, the titanium source compound is selected from one or more of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate.

[0034] The concentration of the titanate group in the titanium source solution is 0.05-0.15 mol / L, and further preferably 0.08-0.10 mol / L.

[0035] The strong acid is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid; wherein the concentration of the strong acid in the titanium source solution is preferably 4-8 mol / L, and further preferably 5.5-6.5 mol / L;

[0036] The carrier is selected from one or more of carbon cloth, carbon paper, and conductive glass, and is preferably carbon cloth or carbon paper, and when the carrier is carbon cloth or carbon paper, the material performance is better. The carbon cloth and carbon paper are preferably subjected to hydrophilic treatment before use; the hydrophilic treatment preferably includes immersion in concentrated sulfuric acid and concentrated nitric acid.

[0037] The temperature of the hydrothermal reaction is 120-190℃, and is preferably 120, 130, 140, 150, 160, 170, 180, 190, or any value between 120-190℃; the time of the hydrothermal reaction is 8-15h, and is preferably 8, 9, 10, 11, 12, 13, 14, 15, or any value between 8-15h.

[0038] After the hydrothermal reaction is completed, the product is washed and dried to obtain a titanium dioxide nanometer array loaded on a carrier.

[0039] After obtaining the titanium dioxide nanometer array loaded on the carrier, the titanium dioxide nanometer array loaded on the carrier is etched in a high-temperature reducing atmosphere to obtain a titanium dioxide nanowire array containing O vacancies.

[0040] The etching temperature is 300-800 DEG C, preferably 300, 400, 500, 600, 700, 800, or any value between 300-800 DEG C; the etching time is 8-24h, preferably 8, 10, 12, 14, 16, 18, 20, 22, 24, or any value between 8-24h;

[0041] The reducing atmosphere is argon-hydrogen mixed gas or carbon monoxide and argon mixed gas; in the argon-hydrogen mixed gas, the volume content of hydrogen is 3-20%, preferably 3%, 5%, 10%, 15%, 20%, or any value between 3-20%; in the carbon monoxide and argon mixed gas, the volume content of carbon monoxide is 3-20%, preferably 3%, 5%, 10%, 15%, 20%, or any value between 3-20%.

[0042] The titanium dioxide nanowire array containing O vacancies is immersed in a ruthenium source solution, and then sequentially dried and high-temperature reduced to obtain a titanium dioxide nanowire array loaded Ru monatomic material.

[0043] The ruthenium source is selected from one or more of ruthenium chloride, ruthenium acetylacetone, and ruthenium acetate; the concentration of the ruthenium source in the ruthenium source solution is 0.002-0.010 mol / L, preferably 0.002, 0.004, 0.006, 0.008, 0.010, or any value between 0.002-0.010 mol / L.

[0044] The high-temperature reduction temperature is 200-500 DEG C, preferably 200, 250, 300, 350, 400, 450, 500, or any value between 200-500 DEG C; the high-temperature reduction time is 8-24h, preferably 8, 12, 16, 20, 24, or any value between 8-24h; the high-temperature reduction atmosphere is argon-hydrogen mixed gas or carbon monoxide and argon mixed gas, wherein the volume content of hydrogen in the argon-hydrogen mixed gas is 3-20%, preferably 3%, 5%, 10%, 15%, 20%, or any value between 3-20%; the volume content of carbon monoxide in the carbon monoxide and argon mixed gas is 3-20%, preferably 3%, 5%, 10%, 15%, 20%, or any value between 3-20%.

[0045] The application also provides a titanium dioxide nanowire array loaded Ru monatomic material prepared by the above preparation method, wherein the mass percentage of ruthenium is 0.01%-0.50%, preferably 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, or any value between 0.01%-0.50%.

[0046] The application further provides a titanium dioxide nanometer array loaded Ru monatomic material prepared by the preparation method, or application of the titanium dioxide nanometer array loaded Ru monatomic material in an alkaline hydrogen evolution reaction electrocatalyst.

[0047] Compared with the prior art, the application has the following beneficial effects:

[0048] (1) The application synthesizes titanium dioxide nanometer arrays directly loaded on carbon cloth through a hydrothermal reaction, and a large number of oxygen vacancies are modified on the surface of the material through high-temperature reduction. The noble metal Ru monatomic is further anchored by the O vacancies, and the local environment of the Ru monatomic is precisely controlled.

[0049] (2) The obtained nanomaterial is loaded on the carbon cloth and can be directly used as an electrode of an electrolytic cell, avoiding the problems of slow diffusion rate and poor conductivity caused by the use of a binder, and simplifying the electrode manufacturing process.

[0050] (3) Compared with the high noble metal Pt content of the traditional Pt / C catalyst, the disadvantages of high price and low reserves greatly limit the large-scale development of the Pt / C catalyst. The application selects titanium dioxide, which is abundant in reserves, low in price and good in stability, as the main structure, greatly reduces the amount of noble metal, improves the utilization rate of Ru atoms and reduces the cost. Compared with the commercial Pt / C, the material has higher HER activity and stability, and has high industrial application prospect.

[0051] (4) The material uses non-noble metal oxide titanium dioxide as the main material, which not only greatly improves the catalytic performance, but also has excellent stability. After 100 h of continuous constant current (10 mA / cm 2 ) test, the overpotential of the material almost does not change obviously.

[0052] In order to further understand the application, the titanium dioxide nanometer array loaded Ru monatomic material provided by the application, the preparation method thereof and the application of the material as an alkaline hydrogen evolution reaction electrocatalyst are described below in combination with examples, and the protection scope of the application is not limited by the following examples.

[0053] Example 1

[0054] Preparation of a titanium dioxide nanometer array loaded noble metal Ru monatomic catalyst:

[0055] Mix concentrated hydrochloric acid and deionized water 1:1 to obtain a hydrochloric acid solution, use a pipette to take 0.5 mL of tetrabutyl titanate, and dissolve it in 15 mL of the above hydrochloric acid solution, and stir at room temperature for 1 h. Then add the above solution to a 25 mL polytetrafluoroethylene hydrothermal reactor, and put a piece of 2 cm x 3 cm hydrophilic carbon cloth into it. Put it into a stainless steel reactor shell, tighten the cover, and react in an oven at 150°C for 12 h to obtain a titanium dioxide nanometer array grown on the carbon cloth. The carbon cloth is washed with deionized water and ethanol in turn and dried in a drying oven at 60°C, and finally the obtained sample is placed in a tube furnace, and reduced and etched at 500°C under Ar / H2 reducing atmosphere for 12 h to obtain a titanium dioxide nanometer array with a surface rich in oxygen vacancy defects. Then put the above material into a solution containing 5 mM of ruthenium chloride, and stand for 30 mins. Then wash several times with water, and soak in ethanol for 30 mins to remove the excess adsorbed ruthenium ions on the surface, and dry the washed sample in a drying oven at 60°C for 3 h. Finally, place it in a tube furnace at 400°C under Ar / H2 atmosphere (hydrogen volume content is 3%) for 1 h. The obtained titanium dioxide nanometer array supported ruthenium monatomic catalyst is obtained.

[0056] The content of Ru in the above prepared titanium dioxide nanometer array supported ruthenium monatomic catalyst is 0.1 wt% by electron probe microelement analysis.

[0057] The above prepared titanium dioxide nanometer array supported ruthenium monatomic catalyst is the same as rutile phase titanium dioxide, and its X-ray diffraction spectrum is shown in Figure 1 .

[0058] The scanning electron microscope image of the above prepared titanium dioxide nanometer array supported ruthenium monatomic catalyst is shown in Figure 2 .

[0059] The local structure of ruthenium in the above prepared titanium dioxide nanometer array supported ruthenium monatomic catalyst is shown in Figure 3 . It can be seen from Figure 3 that ruthenium exists in the form of monatomic, and there is no ruthenium-ruthenium bond.

[0060] The performance test method of the above prepared titanium dioxide nanometer array supported ruthenium monatomic catalyst for basic hydrogen evolution reaction is as follows:

[0061] CHI660e electrochemical workstation is used for data collection. A three-electrode electrolytic cell is used for testing, the working electrode is the above prepared carbon cloth loaded with the above material, the reference electrode is a Hg / HgO electrode, the counter electrode is a 1 cm x 1 cm platinum sheet electrode, and the electrolyte is a 1.0M KOH solution.

[0062] Activity test: linear sweep voltammetry curve, scan rate 5 mV / s.

[0063] Stability test: chronoamperometry, set current density 10 mA / cm 2 , test time 100 h, record the voltage curve under constant current density for 100 h.

[0064] Experimental results:

[0065] The electrochemical test results are shown in Figure 4 .

[0066] When the current density is 200 mAcm -2 , the potential required by the titanium dioxide nanometer array loaded ruthenium single atom catalyst is 60 mV less than that of the commercial Pt / C.

[0067] In summary, the activity of the titanium dioxide nanometer array loaded ruthenium single atom catalyst (Ru@TiO2) prepared by the present application is far superior to that of the current commercial Pt / C.

[0068] Examples 2-4

[0069] Only the concentration of the Ru source solution is changed, and the loading of Ru in TiO2 can be controlled, and the rest of the conditions are the same as those in Example 1, and the HER catalytic performance is shown in Table 1.

[0070] As shown by the comparison of different examples, when the concentration of the Ru impregnation solution is 5 mM, the mass activity of the catalyst reaches the optimum, and the catalytic performance will not be obviously increased by further increasing the content of Ru.

[0071] Table 1

[0072] Example Ru source impregnation solution concentration (mM) Ru content (wt%) Overshoot (10 mA / cm 2 )]]> 2 0.5 - 48 mV 3 2 0.04 24 mV 1 5 0.1 20 mV 4 10 0.12 19 mV

[0073] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a titanium dioxide nanorarray supported Ru monatomic material, characterized in that, The method comprises the following steps: A) etching the titanium dioxide nanometer array loaded on the carrier in a high-temperature reducing atmosphere to obtain a titanium dioxide nanowire array containing O vacancies; The reducing atmosphere is argon-hydrogen mixed gas or carbon monoxide and argon mixed gas; in the argon-hydrogen mixed gas, the volume content of hydrogen is 3% to 5%, and in the carbon monoxide and argon mixed gas, the volume content of carbon monoxide is 3% to 5%; B) immersing the titanium dioxide nanowire array containing O vacancies in a ruthenium source solution, and then sequentially performing drying and high-temperature reduction to obtain a titanium dioxide nanometer array loaded Ru monatomic material; the atmosphere for the high-temperature reduction is argon-hydrogen mixed gas or carbon monoxide and argon mixed gas, wherein, in the argon-hydrogen mixed gas, the volume content of hydrogen is 3% to 5%, and in the carbon monoxide and argon mixed gas, the volume content of carbon monoxide is 3% to 5%.

2. The production method according to claim 1, characterized by, The preparation method of the titanium dioxide nanometer array loaded on the carrier comprises the following steps: Mixing a titanium source solution with a strong acid solution, and then adding a carrier to obtain the titanium dioxide nanometer array loaded on the carrier through high-temperature and high-pressure hydrothermal reaction.

3. The production method according to claim 2, characterized by, The titanium source compound in the titanium source solution is selected from one or more of titanate esters containing a titanate group; The concentration of the titanate group in the titanium source solution is 0.05 to 0.15 mol / L; The strong acid is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid; wherein the concentration of the strong acid in the titanium source solution is 4 to 8 mol / L; The carrier is selected from one or more of carbon cloth, carbon paper and conductive glass.

4. The production method according to claim 3, characterized by, The titanium source compound is selected from one or more of tetraethyl titanate, tetrabutyl titanate and isopropyl titanate; The concentration of the titanate group in the titanium source solution is 0.08 to 0.10 mol / L; The concentration of the strong acid in the titanium source solution is 5.5 to 6.5 mol / L; The carrier is selected from carbon cloth or carbon paper; the carbon cloth or carbon paper is subjected to hydrophilic treatment before use; the hydrophilic treatment comprises soaking in concentrated sulfuric acid and concentrated nitric acid.

5. The preparation method according to claim 2, characterized in that, The temperature of the hydrothermal reaction is 120 to 190 ℃; and the time of the hydrothermal reaction is 8 to 15 h.

6. The method of claim 1, wherein, In step A), the temperature of the etching is 300 to 800 ℃; and the time of the etching is 8 to 24 h.

7. The preparation method according to claim 1, characterized in that, The ruthenium source is selected from one or more of ruthenium chloride, ruthenium acetylacetone and ruthenium acetate; and the concentration of the ruthenium source in the ruthenium source solution is 0.002 to 0.010 mol / L.

8. The method of claim 1, wherein, In step B), the temperature of the high-temperature reduction is 200 to 500 ℃; and the time of the high-temperature reduction is 8 to 24 h.

9. A TiO2 nanorarray supported Ru single-atom material prepared by the method of any one of claims 1-8, wherein, The mass content of ruthenium is 0.01% to 0.50%.

10. Application of the titanium dioxide nanometer array loaded Ru monatomic material prepared by the preparation method in any one of claims 1 to 8 or the titanium dioxide nanometer array loaded Ru monatomic material in claim 9 as an alkaline hydrogen evolution reaction electrocatalyst.

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