Preparation method and application of surface titanium oxygen species anchored iridium oxide oxygen evolution electrocatalyst

Abstract

The application discloses a preparation method and application of an oxygen-evolving electrocatalyst of iridium oxide anchored by surface titanium oxygen species. The catalyst is obtained by electro-oxidizing a titanium nitride supported metal iridium cluster pre-catalyst. The surface titanium oxygen species is obtained by electrochemical reconstruction of titanium nitride, and the iridium oxide is obtained by electro-oxidizing a metal iridium cluster. When the catalyst is used for an anode oxygen evolution reaction, the catalyst has excellent catalytic activity and significantly improved stability. Compared with existing catalysts, the catalyst provided by the application is obtained by electro-oxidizing a pre-catalyst. In a PEM electrolytic cell, the titanium nitride carrier in the pre-catalyst plays a role of a pore-forming agent in the electro-oxidation dissolution process, and the catalytic layer is spontaneously thickened, thereby solving the problems of poor uniformity and mechanical stability of a super-thin catalytic layer electrode of a PEM water electrolysis cell, and more easily realizing large-scale industrial application under an ultra-low iridium load.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst technology, and relates to a method for preparing an iridium oxide oxygen evolution electrocatalyst anchored on a surface titanium oxide species. It also relates to its use as an electrocatalyst for the oxygen evolution reaction in the preparation of acidic electrolytes, and its application as a PEM anode in PEM water electrolysis. It also has potential application value in other fields such as energy development and environmental protection. Background Technology

[0002] Hydrogen production via renewable energy electrolysis is currently the lowest carbon emission technology among hydrogen source options, with 60%–80% of its production cost coming from the electrolyzer. The development of a highly efficient, stable, and inexpensive catalyst to reduce electrolysis energy consumption and extend device lifespan remains a challenge. Acidic medium PEM electrolysis technology is an ideal method for efficiently producing high-purity hydrogen, featuring high energy conversion efficiency, high hydrogen production rate, and high hydrogen purity. Furthermore, it exhibits rapid dynamic / static response characteristics under complex operating conditions, meeting the requirements of hydrogen production systems using fluctuating power sources.

[0003] The oxygen evolution catalyst material of PEM anodes directly affects device efficiency and cost. Currently, only high-Ir-loading materials can operate stably in commercial equipment, and the development of low-Ir-loading anode electrodes remains a key constraint on the large-scale deployment of PEM water electrolysis. The development of novel anode materials and corresponding membrane electrodes that can control and stabilize operating conditions will enable the construction of high-performance, long-life PEM water electrolysis hydrogen production equipment, achieving large-scale, low-cost hydrogen production. This is expected to drive cost reduction, efficiency improvement, and industrialization of large-scale PEM hydrogen production. Summary of the Invention

[0004] This invention addresses the aforementioned problems by providing a method for preparing and applying an iridium oxide oxygen evolution electrocatalyst anchored to surface titanium oxide species. This solves the issues of poor anode catalyst stability and difficulty in constructing an anode electrode structure with an ultrathin catalyst layer in existing PEM water electrolysis technology. The catalyst material is economical, exhibits high oxygen evolution activity, and has a simple preparation method, demonstrating significant application potential.

[0005] To achieve the above objectives, the technical solution adopted in this invention is summarized as follows: the catalyst is obtained by electro-oxidation of a titanium nitride-supported iridium cluster pre-catalyst. Specifically, the surface titanium oxide species are obtained through electrochemical reconstruction of titanium nitride, and the iridium oxide is obtained by electro-oxidation of the iridium cluster.

[0006] The specific technical solution adopted is as follows:

[0007] In a first aspect, the present invention provides a method for preparing an iridium oxide oxygen evolution electrocatalyst anchored to surface titanium oxide species, comprising the following steps:

[0008] A. Preparation of precatalyst

[0009] After ultrasonically mixing the titanium nitride, surfactant, and iridium hydrochloric acid solution, the mixture was heated in an oil bath at 120°C while being stirred. After the reaction was completed, the mixture was cooled to room temperature, and the black product was separated by centrifugation, washed multiple times with organic solvent, and dried in a vacuum oven at 60°C. The resulting black powder was the titanium nitride-supported iridium cluster precatalyst.

[0010] B. Precatalyst electro-oxidation

[0011] Using a titanium nitride-supported iridium cluster precatalyst as the anode and a Pt / C catalyst as the cathode, electro-oxidation was carried out in a PEM electrolyzer to obtain an iridium oxide oxygen evolution catalyst anchored to surface titanium oxygen species.

[0012] Preferably, the preferred process conditions for each of the above steps are as follows:

[0013] (1) Step A

[0014] The preparation method of the mixed solution of titanium nitride, surfactant, and iridium salt includes the following steps: (a) accurately weigh titanium nitride and P123 surfactant at a mass ratio of 1:2 and disperse them separately in ethylene glycol, then sonicate until homogeneous; (b) accurately weigh iridium hydrochloric acid and dissolve it in ethylene glycol, then sonicate to obtain a homogeneous solution; (3) mix the solutions from steps (1) and (2) and continue sonicating for half an hour. The molar ratio of titanium nitride to iridium hydrochloric acid is 0.65:0.1–0.4.

[0015] Further optimization is achieved by using titanium nitride with an average size of 20 nm; and selecting iridium hydrochloric acid from chloroiridium acid.

[0016] During the reaction, the mixture was heated in an oil bath at 120°C for 3 hours while being stirred at a speed of 1200 rpm.

[0017] After the reaction was completed, the black product was separated by centrifugation, washed repeatedly with anhydrous ethanol, and finally dried in a vacuum oven at 60°C for 12 hours to obtain a titanium nitride-supported iridium cluster precatalyst.

[0018] (2) Step B

[0019] The pre-catalyst loading was 0.28 mg·cm³. -2 The cathode catalyst is 40 wt% Pt / C, and the Pt spray loading is 0.4 mg. Pt ·cm -2 The electro-oxidation conditions were 1 A·cm⁻¹ in a PEM electrolytic cell. -2 After 24 hours of electro-oxidation, an iridium oxide oxygen evolution catalyst anchored to surface titanium oxygen species was obtained through titanium nitride oxidation dissolution.

[0020] In a second aspect, the present invention provides an iridium oxide oxygen evolution electrocatalyst anchored to surface titanium oxide species, which is prepared by the above method.

[0021] X-ray diffraction patterns show that the catalyst contains two phases: metallic iridium and titanium nitride. Energy dispersive X-ray spectroscopy shows that titanium oxide species are mainly distributed on the surface of iridium oxide. According to high-angle annular dark-field scanning transmission electron microscopy images, iridium oxide exhibits an amorphous morphology, with titanium species anchored on the surface, appearing as atoms with relatively dark contrast.

[0022] The above catalyst was prepared as an anode material for electrocatalysis. The results showed that the thickness of the anode catalyst layer of the membrane electrode increased significantly after electro-oxidation, indicating that the initially prepared ultrathin catalyst layer can spontaneously thicken during electro-oxidation and tend to become more uniform and porous.

[0023] The material of this invention can be applied in proton exchange membrane (PEM) water electrolysis tanks under acidic electrolyte conditions.

[0024] It was prepared as an anode electrode material for a proton exchange membrane (PEM) electrolyzer. Full-cell tests were conducted in an acidic PEM water electrolyzer to simulate an industrial water electrolysis environment. The results showed that this catalyst, as an anode, achieved 1.0 and 2.0 A·cm⁻¹ in the PEM electrolyzer. -2 The required current densities are 1.6 and 1.8 V, respectively, which are 60 and 140 mV lower than those using titanium dioxide as a carrier. Meanwhile, this electrode material can operate efficiently and stably for 200 hours without significant degradation.

[0025] Therefore, in a third aspect, the present invention provides the application of the above-mentioned surface titanium oxide species-anchored iridium oxide oxygen evolution electrocatalyst in the preparation of an acidic electrolytic oxygen evolution electrode.

[0026] In a fourth aspect, the present invention provides an acidic electrochemical oxygen evolution anode electrode, comprising an anode support and a catalyst material supported thereon, wherein the catalyst material is an iridium oxide oxygen evolution electrocatalyst with surface titanium oxide species anchored by any of the methods described above.

[0027] Preferably, the acidic electrolytic oxygen anode electrode is the anode of the PEM electrolytic cell.

[0028] In a fifth aspect, the present invention provides a method for electrolyzing water, using the above-described electrolytic oxygen anode electrode as the PEM electrolysis anode.

[0029] Preferably, the electrolyte is a 0.5M HClO4 solution or deionized water.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] (1) In this invention, a novel surface titanium oxide oxygen evolution electrocatalyst anchored by titanium nitride-supported iridium clusters is prepared by electrochemical oxidation reconstruction. The catalyst exhibits high catalytic activity and significantly enhanced stability in the oxygen evolution reaction.

[0032] (2) The catalyst provided by this invention, as an anode catalyst in a PEM water electrolyzer, can spontaneously transform the initial electrode with an ultrathin catalyst layer into a catalyst layer structure with suitable thickness, uniform structure, and good mechanical stability through the self-thickening effect of the pre-catalyst during the electro-oxidation process. This avoids the problems of uneven catalyst distribution, poor contact, poor local conductivity, and structural instability caused by insufficient thickness of the existing ultrathin catalyst layer. Therefore, it is easier to realize large-scale industrial applications with ultra-low iridium loading.

[0033] (3) The catalyst provided by the present invention is simple to prepare, the raw materials are environmentally friendly, the use of harmful solvents is reduced, the energy consumption of the reaction process is low, the prepared catalyst is uniformly dispersed, it is practical, easy to promote, and easy to realize large-scale industrial preparation and application. Attached Figure Description

[0034] Figure 1 The X-ray diffraction pattern is shown for the titanium nitride-supported iridium cluster precatalyst prepared in Example 1.

[0035] Figure 2 This is a high-angle annular dark-field-scanning transmission electron microscope image of iridium oxide anchored to the surface titanium oxide species prepared in Example 1.

[0036] Figure 3 The energy-dispersive X-ray spectrum of iridium oxide anchored to the surface titanium oxide species prepared in Example 1.

[0037] Figure 4 This is a scanning electron microscope cross-sectional view of the iridium oxide film electrode anode catalyst layer with titanium nitride-supported metallic iridium clusters as a precatalyst in Example 1 and surface titanium oxide species anchored after electro-oxidation.

[0038] Figure 5 The polarization curves of the iridium oxide catalyst with surface titanium oxide species anchored in Example 1 and the catalyst prepared in Comparative Example 2 are compared as anode catalysts for PEM water electrolysis.

[0039] Figure 6 The iridium oxide with surface titanium oxide species anchored as prepared in Example 1 was used as a 1Acm anolyte for PEM water electrolysis. -2 Stability test results. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The “range” disclosed in this document takes the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this way are inclusive and composable; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 100–140 and 500–900 are listed for a specific parameter, it is also expected that ranges of 100–140 and 500–900 are also included. Furthermore, if the minimum range values ​​are listed as 1 and 2, and if the maximum ranges are listed as 3, 4, and 5, then the following ranges are all expected: 1–2, 1–4, 1–5, 2–3, 2–4, and 2–5.

[0042] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between "0~5" have been listed in this document, and "0~5" is simply an abbreviation of these numerical combinations.

[0043] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0044] I. Preparation of Catalyst Materials

[0045] Example 1

[0046] The method for preparing the iridium oxide oxygen evolution electrocatalyst anchored by surface titanium oxide species provided in this embodiment includes the following steps:

[0047] (1) Accurately weigh 40 mg of titanium nitride and 80 mg of P123 surfactant and disperse them in 10 mL of ethylene glycol, then sonicate until homogeneous.

[0048] (2) Accurately weigh 122.1 mg of chloroiridic acid and dissolve it in 10 mL of ethylene glycol. Sonicate the solution to obtain a homogeneous solution.

[0049] (3) Mix the solutions from steps (1) and (2), put them into a 50 ml flask, continue sonicating for half an hour, then heat in an oil bath at 120°C for 3 hours while stirring at 1200 rpm.

[0050] (4) After the reaction was completed, the product was cooled to room temperature, and the black product was separated by centrifugation, washed several times with anhydrous ethanol, and finally dried in a vacuum oven at 60°C for 12 hours to obtain the titanium nitride supported metal iridium cluster precatalyst.

[0051] (5) Electro-oxidation was carried out in a PEM electrolytic cell using a titanium nitride-supported iridium cluster pre-catalyst as the anode, with a coating loading of 0.28 mg·cm³. -2 The cathode catalyst is 40 wt% Pt / C, and the Pt spray loading is 0.4 mg. Pt ·cm -2 It uses a DuPont 212 proton exchange membrane with an electrode area of ​​5 cm². 2 The test temperature was 80℃, and the electro-oxidation condition was 1 A·cm. -2 After 24 hours, an iridium oxide oxygen evolution catalyst anchored to surface titanium oxygen species was obtained through titanium nitride oxidation dissolution.

[0052] Example 2

[0053] Repeat the steps of Example 1, except that in step (2), the mass of chloroiridium acid is 40.7 mg.

[0054] Example 3

[0055] Repeat the steps of Example 1, except that in step (2), the mass of chloroiridium acid is 81.4 mg.

[0056] Example 4

[0057] Repeat the steps of Example 1, except that in step (2), the mass of chloroiridium acid is 162.8 mg.

[0058] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

[0059] Comparative Example 1

[0060] Repeat the steps of Example 1, except that titanium nitride is not added to the preparation of the precursor solution.

[0061] Comparative Example 2

[0062] Repeat the steps of Example 1, except that titanium dioxide is added instead of titanium nitride in the preparation of the precursor solution.

[0063] II. Performance Characterization Test

[0064] Figure 1 The image shows the X-ray diffraction pattern of the titanium nitride-supported iridium cluster precatalyst prepared in Example 1. This electrocatalyst contains two phases: iridium and titanium nitride.

[0065] Figure 2 High-angle annular dark-field-scanning transmission electron microscope image of iridium oxide anchored to the surface titanium oxide species prepared in Example 1. Figure 2 As can be seen, iridium oxide exhibits an amorphous form, with titanium species anchored on the surface, appearing as atoms with relatively dark contrast.

[0066] Figure 3 The energy-dispersive X-ray spectrum of iridium oxide anchored to the surface titanium oxide species prepared in Example 1. Figure 3 It can be seen that titanium oxide species are mainly distributed on the surface of iridium oxide.

[0067] Figure 4 This is a scanning electron microscope (SEM) cross-sectional image of the iridium oxide film electrode anode catalyst layer anchored with the titanium nitride-supported metallic iridium cluster precatalyst and the surface titanium oxide species obtained after electro-oxidation, as shown in Example 1. Figure 4 It is evident that the thickness of the anodic catalyst layer of the membrane electrode increases significantly after electro-oxidation, indicating that the initially prepared ultrathin catalyst layer can spontaneously thicken during the electro-oxidation process, tending to become more uniform and porous.

[0068] III. Electrochemical Performance Testing

[0069] The electrocatalytic performance of iridium oxide anchored to surface titanium oxide species was tested using a PEM electrolyzer system. The catalyst prepared in Example 1 was subjected to PEM electrolyzer polarization curve testing at 1 A·cm⁻¹. -2 The stability of the assembled electrolytic cell was tested under current density.

[0070] Figure 5 The polarization curves of the iridium oxide catalyst with surface titanium oxide species anchored in Example 1 and the catalyst prepared in Comparative Example 2, used as anode catalysts for PEM water electrolysis, are compared. Figure 5 As can be seen, the catalyst prepared in Example 1, when used as an anode, achieved 1.0 and 2.0 A·cm⁻¹ in the PEM electrolyzer. -2 The current densities required were 1.6 and 1.8 V, respectively, which were 60 and 140 mV lower than those in Comparative Example 2.

[0071] Figure 6 The iridium oxide with surface titanium oxide species anchored as prepared in Example 1 was used as a PEM anode catalyst for water electrolysis at 1 A·cm⁻¹. -2 Stability test results. (From...) Figure 6As can be seen, the electrode material prepared in Example 1 can operate efficiently and stably for 200 hours without significant attenuation.

[0072] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for preparing an iridium oxide oxygen evolution electrocatalyst anchored to surface titanium oxide species, characterized in that, Includes the following steps: A. Preparation of precatalyst After ultrasonically mixing the titanium nitride, surfactant, and iridium hydrochloric acid solution, the mixture was heated in an oil bath at 120°C while being stirred. After the reaction was completed, the mixture was cooled to room temperature, and the black product was separated by centrifugation, washed multiple times with organic solvent, and dried in a vacuum oven at 60°C. The resulting black powder was the titanium nitride-supported iridium cluster precatalyst. B. Precatalyst electro-oxidation Using a titanium nitride-supported iridium cluster precatalyst as the anode and a Pt / C catalyst as the cathode, electro-oxidation was carried out in a PEM electrolyzer to obtain an iridium oxide oxygen evolution catalyst anchored to surface titanium oxygen species.

2. The preparation method according to claim 1, characterized in that: in, In step A, the preparation method of the mixed solution of titanium nitride, surfactant and iridium hydrochloric acid includes the following steps: (a) accurately weigh titanium nitride and surfactant according to the mass ratio of 1:2 and disperse them in ethylene glycol, and sonicate them to homogenize; (b) accurately weigh iridium hydrochloric acid and dissolve it in ethylene glycol, and sonicate it to obtain a homogenized solution; (c) mix the solutions in steps (1) and (2) and continue to sonicate for half an hour. During the reaction, the mixture was heated in an oil bath at 120°C for 3 hours while being stirred at a speed of 1200 rpm. After the reaction was completed, the black product was separated by centrifugation, washed repeatedly with anhydrous ethanol, and finally dried in a vacuum oven at 60°C for 12 hours to obtain a titanium nitride-supported iridium cluster precatalyst.

3. The preparation method according to claim 2, characterized in that: in, The surfactant was selected from P123 surfactant, and the titanium nitride had an average size of 20 nm; the iridium hydrochloric acid was selected from chloroiridium acid. In step (c), the molar ratio of titanium nitride to iridium hydrochloric acid is 0.65:0.1 to 0.

4.

4. The preparation method according to claim 1, characterized in that: in, In step B, the pre-catalyst loading is 0.28 mg·cm³. -2 The cathode catalyst is 40 wt% Pt / C, and the Pt spray loading is 0.4 mg. Pt ·cm -2 The electro-oxidation conditions were 1 A·cm⁻¹ in a PEM electrolytic cell. -2 After 24 hours of electro-oxidation, an iridium oxide oxygen evolution catalyst anchored to surface titanium oxygen species was obtained through titanium nitride oxidation dissolution.

5. A surface-anchored iridium oxide oxygen evolution electrocatalyst, characterized in that, It is prepared by the method described in any one of claims 1 to 4.

6. The application of the iridium oxide oxygen evolution electrocatalyst anchored to surface titanium oxide species as described in claim 5 in the preparation of an acidic electrolytic oxygen evolution electrode.

7. An acidic electrolytic oxygen anode electrode, characterized in that, It includes an anode support and a catalyst material supported thereon, wherein the catalyst material is an iridium oxide oxygen evolution electrocatalyst with surface titanium oxide species anchored by the method described in any one of claims 1 to 4.

8. The acidic electrolytic oxygen anode electrode according to claim 7, characterized in that, The acidic electrolytic oxygen anode electrode is the anode of the PEM electrolytic cell.

9. A method for electrolyzing water, characterized in that: The acidic electrolytic oxygen anode electrode as described in claim 7 or 8 is used as the PEM electrolysis anode.

10. The method for electrolyzing water according to claim 9, characterized in that: in, The electrolyte is 0.5M HClO4 solution or deionized water.

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