Ti-RuO2 acidic oxygen evolution catalyst based on strain modulation strategy and preparation method thereof

Abstract

The invention discloses a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy and a preparation method of the Ti-RuO2 acidic oxygen evolution catalyst, and belongs to the technical field of hydrogen production catalysts. The preparation method comprises the following steps: S1, mixing TiO2 with an acidic solution, adjusting the pH value, and dispersing to obtain a TiO2 dispersion liquid; s2, adding soluble Ru salt into the TiO2 dispersion liquid under an ice bath condition, and stirring to obtain a mixed solution; s3, mixing and stirring the mixed solution and an alkaline solution to adjust the pH value, and then freeze-drying to obtain a precursor; and S4, immediately performing high-temperature pyrolysis on the precursor, and then quickly taking out and cooling to obtain the Ti-RuO2 acidic oxygen evolution catalyst based on the strain modulation strategy. The mass activity of the obtained catalyst at 1.53 V is 6 times that of commercial RuO2, and meanwhile, the catalyst has the stability of 830 h at the current density of 10 mA cm <-2 >.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production catalysts, and particularly relates to a Ti-RuO₂ acidic oxygen evolution catalyst based on a strain modulation strategy and a preparation method thereof. Background Art

[0002] In the technology of hydrogen production by electrolyzing water, proton exchange membrane electrolysis for hydrogen production is considered to be the most promising hydrogen production technology due to its advantages such as fast start-stop speed and high current density. Electrolyzing water includes a hydrogen evolution reaction (HER) at the cathode and an oxygen evolution reaction (OER) at the anode. Among them, the oxygen evolution reaction is a four-electron reaction process with inherently slow reaction kinetics; facing an acidic (pH = 2 - 3) and highly oxidative (~2.0 V) environment, almost all non-precious metals will corrode. Currently, the oxygen evolution reaction catalysts are mainly noble metals such as ruthenium and iridium. Iridium oxide has the best stability and has been used as the anode catalyst for proton exchange membrane electrolysis of water, but it has poor activity and high price. RuO₂ has high activity but poor stability.

[0003] Patent CN110820005A discloses a preparation method of a highly efficient and stable ruthenium dioxide-based acidic oxygen evolution electrocatalyst, which is prepared by an impregnation method using RuCl₃ as a ruthenium source coated on a carrier and through one-step heat treatment. Its overpotential at a current density of 10 mA cm -2 is 260 mV, and the stability is only 111 h; Patent CN118558340A discloses a fluorine-doped ruthenium dioxide catalyst, a preparation method thereof and an application in proton exchange membrane electrolysis of water. The fluorine-doped ruthenium dioxide is used, and the overpotential at 10 mA cm -2 is 206 mV, and the stability is 500 h; CN118308751A discloses a ruthenium-based acidic oxygen evolution catalyst, a preparation method thereof and uses. It prepares manganese and cerium-doped ruthenium dioxide, and the overpotential at 10 mA cm -2 is 218 mV, and the stability is only 60 h.

[0004] Most of the above-mentioned catalysts adopt a single regulation strategy and have obvious deficiencies in improving the stability of the catalyst. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a Ti-RuO₂ acidic oxygen evolution catalyst based on a strain modulation strategy and a preparation method thereof. The catalyst prepared by the present invention has high stability and a simple preparation method, and the raw materials are easy to obtain.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy, comprising the following steps:

[0008] S1. Mix TiO2 with an acidic solution, adjust the pH, and then disperse to obtain a TiO2 dispersion;

[0009] S2. Add a soluble Ru salt to the TiO2 dispersion under ice bath conditions and stir to obtain a mixed solution;

[0010] S3. Mix the mixed solution with an alkaline solution, stir to adjust the pH, and then freeze-dry to obtain a precursor;

[0011] S4. Immediately pyrolyze the precursor at high temperature, and then quickly take it out and cool it to obtain a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy.

[0012] The present invention discovers that the reason for the instability of ruthenium-based catalysts is that at high oxidation potentials, the strong binding energy between Ru-O induces the participation of lattice oxygen, resulting in the generation of oxygen vacancies, accelerating the dissolution of active Ru and the disintegration of the structure. Atomic doping is the most common regulation strategy, but the regulation ability of a single regulation strategy for RuO2 catalysts is limited; the present invention uses an acid dissolution and reverse doping process and rapid quenching to prepare an s-Ti-RuO2 catalyst with atomic doping and tensile strain. Electrons transfer from Ti atoms to adjacent Ru sites through bridging oxygen. The tensile strain can weaken the Ru-O covalency, making Ru in a low valence state, inhibiting the dissolution of Ru and the participation of lattice oxygen.

[0013] Preferably, in S1, the concentration of TiO2 in the TiO2 dispersion is 0.1-1 mmol.

[0014] Preferably, in S1, the acidic solution is one of HCl solution, H2SO4 solution, HNO3 solution, or HF solution.

[0015] Preferably, in S1, the pH value is 2-3.

[0016] Preferably, in S1, the dispersion is carried out by ultrasonic dispersion, the ultrasonic power is 600 W, and the ultrasonic time is 10-40 min.

[0017] Preferably, in S2, the molar ratio of TiO2 to the soluble Ru salt in the mixed solution is (0.1-1):1.

[0018] Preferably, the soluble Ru salt is ruthenium trichloride or ruthenium nitrate.

[0019] Preferably, in S2, the stirring time is 4 h.

[0020] Preferably, the pH in S3 is 6; the alkaline solution is ammonia water or sodium hydroxide.

[0021] Preferably, the stirring time in S3 is 12 h.

[0022] Preferably, the pyrolysis temperature in S4 is 250 - 550 °C, and the heating time is 1 - 3 h.

[0023] Preferably, the pyrolysis in S4 is carried out in a tubular furnace.

[0024] Preferably, the cooling in S4 can be natural cooling or liquid nitrogen cooling.

[0025] The present invention provides a Ti - RuO₂ acidic oxygen evolution catalyst based on a strain modulation strategy, which is obtained by the above - mentioned preparation method.

[0026] It has at least the following beneficial technical effects:

[0027] The present invention realizes the atomic - level doping of Ti in RuO₂ by an acid dissolution method. On the one hand, it improves the acid and corrosion resistance of the catalyst under acidic conditions. On the other hand, it adjusts the electronic structure of RuO₂ to optimize the adsorption strength of oxygen - containing intermediates and improve the catalytic activity. At a current density of 10 mA cm -2 it has an overpotential of 245 mV. The turnover frequency of s - Ti - RuO₂ is 8.8 times that of commercial RuO₂, and the mass activity at 1.53 V is 6 times that of commercial RuO₂.

[0028] The present invention introduces lattice strain by rapid quenching, weakens the Ru - O covalent bond, inhibits the participation of lattice oxygen, and improves the stability of RuO₂. At a current density of 10 mA cm -2 it has a stability of 830 h. Description of the Drawings

[0029] Figure 1 It is the X - ray diffraction (XRD) pattern of the catalysts of Example 1 and Comparative Example 2;

[0030] Figure 2 It is the scanning electron microscope (SEM) image of the catalyst of Example 1;

[0031] Figure 3 It is the scanning electron microscope (SEM) image of the catalyst of Comparative Example 2;

[0032] Figure 4 It is the scanning electron microscope (SEM) image of the catalyst of Comparative Example 3;

[0033] Figure 5 It is the transmission electron microscope (TEM) and element distribution map of the catalyst of Example 1;

[0034] Figure 6 Aberration-corrected transmission electron microscopy (AC-TEM) and 110-plane intensity map of the catalyst for Example 1;

[0035] Figure 7 X-ray photoelectron spectroscopy (XPS) graphs of the catalysts for Example 1 and Comparative Example 2;

[0036] Figure 8 Catalytic performance graphs of the catalysts for Example 1 and Comparative Examples 1-3 in the three-electrode system tested by linear voltammetry for the oxygen evolution reaction in acidic media;

[0037] Figure 9 For the catalyst of Example 1 at 10 mA cm -2 Chronopotentiometry curve at the current density. Detailed implementation manners

[0038] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0039] It should be understood that the terms used in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0041] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are only exemplary.

[0042] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0043] In the present invention, unless otherwise specified, "room temperature" and "normal temperature" are both calculated as 25 ± 2°C.

[0044] Unless otherwise specified, the raw materials or instruments used in the following examples of the present invention are all obtained commercially.

[0045] Preparation of TiO2: Add 10 mL of isopropanol to 5 mL of tetrabutyl titanate solution, stir for 12 h, and then add deionized water in 5 portions, 100 mL each, under ultrasonic conditions. Place it in a blast drying oven at 80°C to dry and obtain white TiO2 powder for use in the examples; at the same time, at least one of liquid organic titanium salts including titanium tetramethanolate, tetra-n-butyl titanate, titanium isopropoxide, and titanium isooctylate or commercially available TiO2 powder can be used.

[0046] Example 1

[0047] (1) Dissolve 0.1 mmol of TiO2 in 100 mL of deionized water and 0.1 mol / L -1 HCl solution to adjust the pH to 2, and ultrasonicate for 30 min to completely dissolve it;

[0048] (2) Then add 0.9 mmol of RuCl3 to the above solution under ice bath conditions, stir for 4 h, then remove the ice bath, add 0.3% wt ammonia water to adjust the pH to 6, and stir for 12 h. Place it in a freezer for 12 h and then freeze-dry to obtain the precursor.

[0049] (3) Ventilate both ends of the tubular furnace, heat up to 450°C at a rate of 5°C / min, place the precursor in a porcelain boat and quickly push it into the heating zone. After heating for 2 h, quickly push it to the cooling zone to cool naturally to obtain a Ti-doped RuO2 catalyst with tensile strain, named s-Ti-RuO2.

[0050] Example 2

[0051] (1) Dissolve 0.5 mmol of TiO2 in 100 mL of deionized water and 0.1 mol / L -1 H2SO4 solution to adjust the pH to 2.5, and ultrasonicate for 30 min to completely dissolve it;

[0052] (2) Then add 0.5 mmol of ruthenium nitrate to the above solution under ice bath conditions, stir for 4 h, then remove the ice bath, add 0.3% wt ammonia water to adjust the pH to 6, and stir for 12 h. Place it in a freezer for 12 h and then freeze-dry to obtain the precursor.

[0053] (3) Ventilate both ends of the tubular furnace, heat it to 250 °C at a rate of 5 °C / min, place the precursor in a porcelain boat and quickly push it into the heating zone. After heating for 3 h, quickly push it to the cooling zone and cool it with liquid nitrogen to obtain a Ti-doped RuO2 catalyst with tensile strain, named s-Ti-RuO2.

[0054] Example 3

[0055] (1) Dissolve 1 mmol of TiO2 in 100 mL of deionized water and 0.1 mol / L -1 HCl solution and adjust the pH to 3. Ultrasonic for 30 min to completely dissolve it;

[0056] (2) Then add 5 mmol of RuCl3 to the above solution under ice bath conditions. After stirring for 4 h, remove the ice bath, add 0.3% wt sodium hydroxide to adjust the pH to 6, and stir for 12 h. Place it in a freezer for 12 h and then freeze-dry to obtain the precursor.

[0057] (3) Ventilate both ends of the tubular furnace, heat it to 550 °C at a rate of 5 °C / min, place the precursor in a porcelain boat and quickly push it into the heating zone. After heating for 1 h, quickly push it to the cooling zone and cool it naturally at room temperature to obtain a Ti-doped RuO2 catalyst with tensile strain, named s-Ti-RuO2.

[0058] Comparative Example 1

[0059] The preparation method of this comparative example is the same as that of Example 1, except that TiO2 is replaced by TiCl4, and the obtained catalyst is named s-Ti-RuO2-2.

[0060] Comparative Example 2

[0061] The preparation method of this comparative example is the same as that of Example 1, except that in step (3), the precursor is placed in a porcelain boat, and under the condition of ventilating both ends of the tubular furnace, it is heated to 450 °C at a rate of 5 °C / min and kept warm for 2 h to obtain a Ti-doped RuO2 catalyst, named Ti-RuO2;

[0062] In this comparative example, the precursor is gradually heated to 450 °C instead of directly placing it at 450 °C.

[0063] Comparative Example 3

[0064] The preparation method of this comparative example is the same as that of Example 1, except that TiO2 is not added in step (1), and the obtained catalyst is named s-RuO2.

[0065] Experimental Example

[0066] 1. Through Figures 1-7It can be seen that the method prepares an s-Ti-RuO2 catalyst with atomic doping and tensile strain, and Ti is uniformly distributed in the material. Compared with Ti-RuO2, in the strain-introduced s-Ti-RuO2, the Ru 3d shifts towards the lower binding energy direction, and the Ti 2p shifts towards the higher binding energy direction, indicating that electrons are transferred from Ti to the Ru site through bridging oxygen (Ru gains electrons and the valence decreases). The presence of stress regulates the formation of low-valent Ru, inhibits the dissolution of high-valent Ru in the acidic OER process of s-Ti-RuO2, and improves the durability of OER.

[0067] 2. Respectively, 5 mg of the catalysts obtained in Example 1 and the comparative example were dispersed in 495 μL of water, 495 μL of isopropanol, and 10 μL of Nafion solution, and were ultrasonically dispersed for standby. 10 μL was taken and drop-coated on a 5 mm glassy carbon electrode as the working electrode, a reversible hydrogen electrode was used as the reference electrode, and a carbon rod was used as the counter electrode. The electrocatalytic oxygen evolution performance was studied in a 0.5 M H2SO4 solution. The catalytic performance of the acidic oxygen evolution reaction is shown in Figure 8 , and it can be seen that the catalytic performance of Example 1 is significantly higher than that of the comparative example.

[0068] 3. The electrode prepared from the catalyst of Example 1 was subjected to a stability test at a current density of 10 mA cm -2 , as shown in Figure 9 ; it can be seen that the catalyst of Example 1 still has good stability after 830 h.

[0069] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy, characterized in that, It includes the following steps: S1. Mix TiO2 with an acidic solution, adjust the pH, and then disperse to obtain a TiO2 dispersion; S2. Add a soluble Ru salt to the TiO2 dispersion under ice bath conditions and stir to obtain a mixed solution; S3. Mix the mixed solution with an alkaline solution, stir to adjust the pH, and then freeze-dry to obtain a precursor; S4. Immediately pyrolyze the precursor at a high temperature, and then quickly take it out and cool it to obtain a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy.

2. The preparation method according to claim 1, characterized in that, In S1, the concentration of TiO2 in the TiO2 dispersion is 0.1-1 mmol.

3. The preparation method according to claim 1, characterized in that, In S1, the acidic solution is one of HCl solution, H2SO4 solution, HNO3 solution or HF solution.

4. The preparation method according to claim 1, characterized in that, In S1, the pH value is 2-3.

5. The preparation method according to claim 1, wherein In S1, the dispersion is carried out by ultrasonic dispersion, the ultrasonic power is 600 W, and the ultrasonic time is 10-40 min.

6. The preparation method according to claim 1, characterized in that, In S2, the molar ratio of TiO2 to the soluble Ru salt in the mixed solution is (0.1-1):

1.

7. The preparation method according to claim 1, characterized in that, In S3, the pH value is 6.

8. The preparation method according to claim 1, characterized in that, In S3, the alkaline solution is ammonia water or sodium hydroxide.

9. The preparation method according to claim 1, characterized in that, In S4, the pyrolysis temperature is 250-550 °C, and the heating time is 1-3 h.

10. A Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy, characterized in that, Obtained by the preparation method according to any one of claims 1-9.

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