Ti-ruo2 acid oxygen evolution catalyst based on strain modulation strategy and preparation method thereof

Abstract

The application discloses a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy and a preparation method thereof, and belongs to the technical field of hydrogen production catalysts. The preparation method comprises the following steps: S1, mixing TiO2 with an acidic solution to adjust pH and then dispersing to obtain a TiO2 dispersion liquid; S2, adding the TiO2 dispersion liquid to a soluble Ru salt under ice bath conditions to stir to obtain a mixed solution; S3, mixing the mixed solution with an alkaline solution to stir to adjust pH, and then freeze-drying to obtain a precursor; and S4, immediately pyrolyzing the precursor at high temperature, and then quickly taking out to cool to obtain the Ti-RuO2 acidic oxygen evolution catalyst based on the strain modulation strategy. The mass activity of the obtained catalyst at 1.53V is 6 times that of a commercial RuO2, and the stability is 830h under a current density of 10mA cm ‑2 .

Description

TECHNICAL FIELD

[0001] The application 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

[0002] In the water electrolysis hydrogen production technology, the proton exchange membrane water electrolysis hydrogen production has the advantages of fast start-stop speed, high current density and the like and is considered as the most promising hydrogen production technology. The water electrolysis includes a cathode hydrogen evolution reaction (HER) and an anode oxygen evolution reaction (OER). Among them, the oxygen evolution reaction is a four-electron reaction process and has inherent slow reaction kinetics; in the face of an acidic (PH = 2-3) and high oxidation (~ 2.0V) environment, almost all non-noble metals will be corroded. At present, the oxygen evolution reaction catalysts are mainly noble metals such as ruthenium and iridium. Iridium oxide has the optimal stability and has been used as an anode catalyst for the proton exchange membrane water electrolysis, but has poor activity and high price, and RuO2 has high activity but poor stability.

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

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

[0005] Therefore, the application aims to provide a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy and a preparation method thereof, and the prepared catalyst has high stability and the preparation method is simple and the raw materials are easy to obtain.

[0006] In order to achieve the above-mentioned purpose, the application provides the following technical solutions.

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

[0008] S1. mixing TiO2 with an acidic solution to adjust pH and then dispersing to obtain a TiO2 dispersion liquid;

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

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

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

[0012] The application finds that the reason why the ruthenium-based catalyst is unstable is that, under a high oxidation potential, the strong binding energy between Ru-O induces the participation of lattice oxygen, causes the generation of oxygen vacancies, accelerates the dissolution of active Ru and structural collapse. Atomic doping is the most common modulation strategy, but a single modulation strategy has limited modulation ability on the RuO2 catalyst; the application adopts an acid-dissolution counter-doping and rapid quenching process to prepare an s-Ti-RuO2 catalyst with atomic doping and tensile strain, and electrons are transferred from Ti atoms to adjacent Ru sites through bridging oxygen, and the tensile strain can weaken the Ru-O covalence, so that Ru is in a low valence state, and the dissolution of Ru and the participation of lattice oxygen are inhibited.

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

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

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

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

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

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

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

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

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

[0022] As preferred, the pyrolysis temperature in S4 is 250-550℃, and the heating time is 1-3h.

[0023] As preferred, the pyrolysis in S4 uses a tube furnace.

[0024] As preferred, the cooling in S4 can use natural cooling or liquid nitrogen cooling.

[0025] The application provides a Ti-RuO2 acid oxygen evolution catalyst based on a strain modulation strategy, obtained by the preparation method described above.

[0026] At least the following beneficial technical effects are contained:

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

[0028] The application introduces lattice strain by using rapid quenching, which weakens the Ru-O covalence and inhibits the participation of lattice oxygen, thereby improving the stability of RuO2. The catalyst has a stability of 830h under a current density of 10mA cm -2 . BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The X-ray diffraction (XRD) pattern of the catalyst of Example 1 and Comparative Example 2 is shown in the figure;

[0030] Figure 2 The scanning electron microscope (SEM) pattern of the catalyst of Example 1 is shown in the figure;

[0031] Figure 3 The scanning electron microscope (SEM) pattern of the catalyst of Comparative Example 2 is shown in the figure;

[0032] Figure 4 The scanning electron microscope (SEM) pattern of the catalyst of Comparative Example 3 is shown in the figure;

[0033] Figure 5 The transmission electron microscope (TEM) and element distribution pattern of the catalyst of Example 1 are shown in the figure;

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

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

[0036] Figure 8 Plots of the acid oxygen evolution reaction catalytic performance of the catalysts of Example 1 and Comparative Examples 1-3 tested in a three-electrode system using linear voltammetry scans;

[0037] Figure 9 Chronoamperometric curve of the catalyst of Example 1 at 10 mA cm -2 at 10 mA cm DETAILED DESCRIPTION

[0038] Various illustrative embodiments of the present application are described in detail below. This detailed description is not intended to be a limitation on the application, but rather an exemplification of the present application and various aspects thereof. Other embodiments can be utilized and changes can be made without departing from the scope of the application.

[0039] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. In addition, where particular ranges of values are given, it is intended to include every intervening value between the upper and lower limit of that range. If the upper and lower limits of a range are identical, the range is intended to include only that single value. Any smaller range that falls within the broader range is also intended to be included. These smaller ranges are not by way of limitation.

[0040] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference to the extent allowed by law. In the case of conflict between the description herein and the incorporated material, the description herein shall control.

[0041] In the description of the present application, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, those of ordinary skill in the art will recognize that the present application can be practiced without the specific details given herein. In other instances, well-known methods, procedures and materials have not been described in detail so as not to unnecessarily obscure aspects of the present application. Other embodiments of the present application will be apparent to those of ordinary skill in the art from the description and examples given herein. The description and examples are illustrative only and are not intended to limit the scope of the present application.

[0042] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or the like are open-ended and do not exclude additional, unrecited elements or method steps.

[0043] "room temperature" and "ambient temperature" as used herein refer to 25 ± 2 °C, unless otherwise specified.

[0044] The raw materials and instruments used in the following examples of the present application are commercially available unless otherwise specified.

[0045] Preparation of TiO2: 10 mL of isopropanol was added to 5 mL of tetrabutyl titanate solution. After stirring for 12 h, deionized water was added in 5 portions of 100 mL each under ultrasonic conditions. Drying was performed in a 80 °C air-drying oven to obtain white TiO2 powder, which was used in the examples. Alternatively, liquid organic titanium salts including at least one of titanium tetramethanolate, tetranormal butyl titanate, titanium isopropoxide, titanium isooctanolate, or commercially available TiO2 powder can be used.

[0046] Example 1

[0047] (1) 0.1 mmol of TiO2 was dissolved in 100 mL of deionized water and 0.1 mol L -1 HCl solution to adjust the pH to 2, and ultrasonic treatment was performed for 30 min to completely dissolve the TiO2;

[0048] (2) Then, 0.9 mmol of RuCl3 was added to the above solution under ice bath conditions, and stirring was performed for 4 h. After removing the ice bath, 0.3% wt of ammonia water was added to adjust the pH to 6, and stirring was performed for 12 h. After freezing in a freezer for 12 h, freeze-drying was performed to obtain a precursor.

[0049] (3) The tube furnace was ventilated at both ends, and the temperature was increased to 450 °C at a rate of 5 °C / min. The precursor was placed in a porcelain boat and quickly pushed into the heating zone. After heating for 2 h, the precursor was quickly pushed into the cooling zone for natural cooling to obtain a Ti-doped RuO2 catalyst with tensile strain, which was named s-Ti-RuO2.

[0050] Example 2

[0051] (1) 0.5 mmol of TiO2 was dissolved in 100 mL of deionized water and 0.1 mol L -1 H2SO4 solution to adjust the pH to 2.5, and ultrasonic treatment was performed for 30 min to completely dissolve the TiO2;

[0052] (2) Then, 0.5 mmol of ruthenium nitrate was added to the above solution under ice bath conditions, and stirring was performed for 4 h. After removing the ice bath, 0.3% wt of ammonia water was added to adjust the pH to 6, and stirring was performed for 12 h. After freezing in a freezer for 12 h, freeze-drying was performed to obtain a precursor.

[0053] (3) The tube furnace was ventilated at both ends, and the temperature was raised to 250°C at a rate of 5°C / min. The precursor was placed in a porcelain boat and quickly pushed into the heating zone. After heating for 3 h, it was quickly pushed into the cooling zone and cooled using liquid nitrogen to obtain a Ti-doped RuO2catalyst with tensile strain, designated as s-Ti-RuO2.

[0054] Example 3

[0055] (1) 1 mmol of TiO2was dissolved in 100 mL of deionized water and 0.1 mol L -1 HCl solution to adjust the pH to 3, and ultrasonic treatment was performed for 30 min to completely dissolve the TiO2;

[0056] (2) Then 5 mmol of RuCl3was added to the above solution under ice bath conditions, and stirring was performed for 4 h. After removing the ice bath, 0.3%wt of sodium hydroxide was added to adjust the pH to 6, and stirring was performed for 12 h. After being frozen in a freezer for 12 h, the precursor was obtained by freeze-drying.

[0057] (3) The tube furnace was ventilated at both ends, and the temperature was raised to 550°C at a rate of 5°C / min. The precursor was placed in a porcelain boat and quickly pushed into the heating zone. After heating for 1 h, it was quickly pushed into the cooling zone and cooled at room temperature to obtain a Ti-doped RuO2catalyst with tensile strain, designated as s-Ti-RuO2.

[0058] Comparative Example 1

[0059] The preparation method of the present comparative example was the same as that of Example 1, except that TiO2was replaced by TiCl4. The obtained catalyst was designated as s-Ti-RuO2-2.

[0060] Comparative Example 2

[0061] The preparation method of the present comparative example was the same as that of Example 1, except that in step (3), the precursor was placed in a porcelain boat and heated to 450°C at a rate of 5°C / min under ventilation at both ends of the tube furnace, and then held at 450°C for 2 h to obtain a Ti-doped RuO2catalyst, designated as Ti-RuO2.

[0062] In the present comparative example, the precursor was gradually heated to 450°C, rather than being directly placed at a temperature of 450°C.

[0063] Comparative Example 3

[0064] The preparation method of the present comparative example was the same as that of Example 1, except that no TiO2was added in step (1). The obtained catalyst was designated as s-RuO2.

[0065] Experimental Example

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

[0067] 2. 5 mg of the catalysts obtained in Example 1 and Comparative Example were respectively dispersed in 495 μL of water, 495 μL of isopropanol and 10 μL of a Nafion solution, and were used after ultrasonic dispersion. 10 μL was dropped on a 5 mm glassy carbon electrode as a working electrode, reversible hydrogen was used as a reference electrode, and a carbon rod was used as a counter electrode. The electrocatalytic oxygen evolution performance was studied in a 0.5 M H2SO4 solution, and the acid oxygen evolution reaction catalytic performance is shown in Table 1. Figure 8 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 stability detection at 10 mA cm -2 Current density, and the results are shown in Table 2. Figure 9 It can be seen that the catalyst of Example 1 still has good stability after 830 h.

[0069] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method for preparing a Ti-RuO2 acid oxygen evolution catalyst based on a strain modulation strategy, characterized in that, The method comprises the following steps: S1. mixing TiO2 with an acidic solution to adjust pH and then dispersing to obtain a TiO2 dispersion; S2. adding the TiO2 dispersion to a soluble Ru salt under ice bath conditions and stirring to obtain a mixture; S3. mixing the mixture with an alkaline solution, stirring to adjust pH, and then freeze-drying to obtain a precursor; S4. after a tube furnace is heated to a predetermined heating temperature, the precursor is placed in a porcelain boat and rapidly pushed into a heating zone, so that the precursor is immediately subjected to high-temperature pyrolysis at the heating temperature, and then rapidly taken out for cooling to obtain a Ti-RuO2 acidic oxygen evolution catalyst based on a strain modulation strategy.

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

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

4. The method of claim 1, wherein, The pH value in S1 is 2-3.

5. The preparation method according to claim 1, characterized in that, In S1, ultrasonic dispersion is used, the ultrasonic power is 600 W, and the ultrasonic time is 10-40 min.

6. The method of claim 1, wherein, In S2, the molar ratio of TiO2 to the soluble Ru salt in the mixture is (0.1-1):

1.

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

8. The method of claim 1, wherein, The alkaline solution in S3 is ammonia water or sodium hydroxide.

9. The method of claim 1, wherein, The pyrolysis temperature in S4 is 250-550 DEG C, and the heating time is 1-3 h.

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