Sulfur-doped titanium nitride carrier supported iridium catalyst as well as preparation method and application thereof

Abstract

The invention discloses a sulfur-doped titanium nitride carrier-loaded iridium catalyst and a preparation method and application thereof.S atoms are introduced into TiN lattices, an S-doped TiN (S-TiN) composite carrier is constructed, high-dispersion Ir nano-particles (Ir / S-TiN) are loaded, the strong electron donor characteristic of the S element is utilized, electron distribution on the surface of the carrier is remarkably regulated and controlled, an electron-rich interface environment is formed, and the sulfur-doped titanium nitride carrier-loaded iridium catalyst is obtained. Thus, oxidation corrosion of the TiN carrier in the oxygen evolution reaction process is delayed, the dosage of precious metal is effectively reduced, the surface catalytic activity center utilization rate is increased, and the prepared S-TiN carrier loaded Ir catalyst shows good catalytic activity and catalytic stability in three-electrode equipment. The problems of active site stripping and structure collapse of the traditional TiN carrier loaded Ir-based catalyst under the working conditions of high potential and strong oxidation in the prior art are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a sulfur-doped titanium nitride supported iridium catalyst, its preparation method, and its application. Background Technology

[0002] Social and technological advancements have accelerated the development of proton exchange membrane electrolysis (PEMWE) technology, making it a key technology for renewable energy conversion and storage. Its practical application hinges on its extremely high energy efficiency. However, the slow kinetics of the oxygen evolution reaction (OER), involving four electron transfers, limit the overall rate of water splitting. Currently, OER still heavily relies on iridium (Ir)-based catalysts, and the scarcity and high price of the precious metal Ir have become one of the bottlenecks restricting the large-scale application of PEMWE.

[0003] Dispersing the noble metal Ir on a suitable support material can meet the requirements of sufficient catalyst layer thickness, uniform composition, and structural integrity, while reducing the overall Ir content without sacrificing the conductivity of the electrode plane and the mechanical stability of the structure. Currently, widely used corrosion-resistant transition metal oxides, such as oxides containing titanium, niobium, and tungsten, have much lower conductivity than noble metal oxides when used as support materials. Therefore, high loadings of Ir and its oxides are usually required to ensure sufficient interfacial contact and electron transfer between the catalyst layer and porous transport layers (PTLs).

[0004] Transition metal nitrides have potential advantages as electrocatalyst support materials, among which titanium nitride (TiN) has attracted increasing attention due to its metal-like conductivity. However, under OER conditions, these metal nitrides gradually oxidize, leading to unpredictable catalyst remodeling, which severely affects the expression of catalyst activity and the maintenance of stability. For example, Chen et al. successfully loaded a monolayer of IrO on the TiN surface using physical vapor deposition. x Although the activity of this catalyst in the three-electrode configuration is much higher than that of commercial IrO2 catalysts, at 10 mA cm⁻¹... -2 The overpotential remained as high as 293 mV, and the stability degradation over 290 h was still unsatisfactory. Yang's team prepared an Ir / TiN catalyst with TiN supported on It nanoparticles via ethylene glycol reflux. Similarly, its overpotential of 277 mV was far superior to that of commercial IrO2 and commercial IrO2 / TiO2. However, after 100 h of stability testing, the catalyst underwent strong support corrosion and dissolution, with approximately 88% of the Ti species dissolving into the electrolyte. The catalyst structure underwent uncontrollable degradation and destruction.

[0005] Although the above catalyst materials using TiN as a support to support Ir or IrOx reduce the amount of noble metal Ir to some extent and improve catalytic activity, the oxidation and corrosion of TiN support under strong acid and high potential conditions usually leads to the aggregation and amorphization of Ir species, which seriously affects the structural stability of the catalyst. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of the invention, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including, TiN was mixed with NaBH4 and then subjected to calcination, liquid nitrogen quenching, washing and drying in sequence to obtain TiN with amorphous surface. Amorphous TiN on the surface was mixed with thiourea and then heat-treated to obtain an S-doped TiN support. S-doped TiN support and surfactant were dispersed in ethylene glycol solution to obtain suspension I. Ir precursor was then added and mixed evenly to obtain suspension II. The suspension was refluxed to obtain suspension III. After centrifugation, washing and drying, the sulfur-doped titanium nitride supported iridium catalyst was obtained.

[0010] In a preferred embodiment of the preparation method described in this invention, TiN is mixed with NaBH4, wherein the mass ratio of TiN to NaBH4 is 0.1 to 5:1.

[0011] In a preferred embodiment of the preparation method described in this invention, the steps of calcination, liquid nitrogen quenching, washing, and drying are performed sequentially, wherein the calcination temperature is 300~600℃ and the time is 0.5~4 h. In a preferred embodiment of the preparation method described in this invention, the surface-amorphized TiN is mixed with thiourea and then subjected to heat treatment, wherein the mass ratio of surface-amorphized TiN to thiourea is 0.2~4:1.

[0012] In a preferred embodiment of the preparation method described in this invention, the heat treatment temperature is 300~800℃ and the time is 0.5~8 h.

[0013] As a preferred embodiment of the preparation method described in this invention, wherein: after dispersing the S-doped TiN support and surfactant in an ethylene glycol solution to obtain suspension I, an Ir precursor is added, wherein the surfactant includes one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and polyvinylpyrrolidone, and the mass-to-volume ratio of the S-doped TiN support to the ethylene glycol solution is 1 mg: 1.3 mL to 100 mL.

[0014] In a preferred embodiment of the preparation method described in this invention, the molar ratio of the surfactant to the Ir precursor is 3~200:1, the mass ratio of the Ir precursor to the S-doped TiN support is 0.2~1:1, and the Ir precursor includes one or more of chloroiridium acid, iridium chloride, iridium acetylacetonate, iridium acetate, potassium chloroiridium, sodium chloroiridium, iridium oxide, strontium iridiumate, barium iridiumate, lithium iridiumate, potassium iridiumate, and praseodymium iridiumate.

[0015] As a preferred embodiment of the preparation method described in this invention, the reflux process is used to obtain suspension III, wherein the reflux temperature is 120~180℃ and the time is 1~6 h.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a sulfur-doped titanium nitride supported iridium catalyst.

[0017] As a preferred embodiment of the sulfur-doped titanium nitride supported iridium catalyst of the present invention, the catalyst comprises an S-doped TiN support and Ir clusters, wherein the atomic ratio of Ti to Ir in the catalyst is 1:0.1~0.6.

[0018] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of a sulfur-doped titanium nitride supported iridium catalyst in proton exchange membrane water electrolysis.

[0019] Beneficial effects of this invention: This invention introduces sulfur atoms into the TiN lattice to construct an S-doped TiN (S-TiN) composite support and loads highly dispersed Ir nanoparticles (Ir / S-TiN). Utilizing the strong electron-donating properties of sulfur, the electron distribution on the support surface is significantly modulated, forming an electron-rich interface environment. This delays the oxidative corrosion of the TiN support during the oxygen evolution reaction, effectively reducing the amount of precious metals used and improving the utilization rate of surface catalytic active sites. The prepared S-TiN-supported Ir catalyst exhibits excellent catalytic activity and stability in a three-electrode setup, effectively solving the technical problems of active site stripping and structural collapse in traditional TiN-supported Ir-based catalysts under high-potential, strong-oxidation conditions. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The X-ray diffraction pattern is shown for the Ir catalyst supported on the S-TiN support prepared in Example 1 of this invention.

[0022] Figure 2 This is a comparison diagram of the activity of the S-TiN-supported Ir catalyst prepared in Example 1 of the present invention and the TiN-supported Ir catalyst prepared in Comparative Examples 1 and 2 in a three-electrode system.

[0023] Figure 3 This is a comparison of the potentiostatic stability of the S-TiN-supported Ir catalyst prepared in Example 1 of this invention and the TiN-supported Ir catalyst prepared in Comparative Example 1 in a three-electrode system.

[0024] Figure 4 The image shows the galvanostatic stability of the S-TiN-supported Ir catalyst prepared in Example 1 of this invention in a three-electrode system. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] The method for testing the activity of the sulfur-doped titanium nitride-supported iridium catalyst in a three-electrode system in this invention is as follows: 5 mg of Ir / S-TiN catalyst was taken and 50 μL of Nafion solution and 450 μL of ethanol solution were added. The mixture was ultrasonically dispersed for about 0.5-1 h to form a uniform catalyst ink. 3.5 μL of the above ink solution was pipetted and dropped onto the surface of a glassy carbon electrode with a diameter of about 0.5 mm. After air drying, the electrode was subjected to electrochemical testing in a three-electrode system, wherein the reference electrode was Hg / Hg2SO4, and the counter electrode was a carbon rod or platinum wire.

[0029] Example 1 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 0.5:1, calcined at 400℃ for 1h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain TiN with amorphous surface. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 1:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 500℃ for 3 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and ultrasonically disperse for 1 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 2 mL; add chloroiridium acid and stir for 2 h to mix evenly to obtain suspension II, and reflux at 160 °C for 3 h to obtain suspension III, wherein the mass ratio of chloroiridium acid to S-doped TiN support is 0.3:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridium acid is 4:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst, denoted as Ir / S-TiN.

[0030] XRD tests were performed on the S-doped TiN support prepared in Example 1 and the commercial TiN support. The results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the incorporation of S does not change the crystal structure of TiN.

[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that steps (1) and (2) were omitted, and commercial TiN was directly used as a support to prepare the catalyst. The remaining preparation methods are the same as in Example 1, specifically: Commercial TiN support and hexadecyltrimethylammonium bromide were added to an ethylene glycol solution and ultrasonically dispersed for 1 h to obtain suspension I, wherein the mass-to-volume ratio of TiN support to ethylene glycol solution was 1 mg: 2 mL. Iridic acid was added and stirred for 2 h to obtain suspension II. Suspension III was obtained by reflux at 160 °C for 3 h, wherein the mass ratio of iridium chloro-iridium acid to TiN support was 0.3:1, and the molar ratio of hexadecyltrimethylammonium bromide to iridium chloro-iridium acid was 4:1. After centrifugation, washing, and drying, the sulfur-doped titanium nitride-supported iridium catalyst of this comparative example was obtained, denoted as Ir / TiN.

[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that step (2) is omitted and the TiN with amorphized surface from step (1) is used directly as a support to prepare the catalyst. The rest of the preparation methods are the same as in Example 1. The catalyst of this comparative example is denoted as Ir / (defective)TiN.

[0033] The activity of the sulfur-doped titanium nitride supported iridium catalysts prepared in Example 1 and Comparative Examples 1-2 in a three-electrode system was tested, and the results are as follows: Figure 2 As shown.

[0034] Figure 2 The three-electrode system assembled with this catalyst showed that, at a catalyst loading of 0.5 mg / cm³, -2 Under these conditions, it reaches 10 mA cm -2 The required current density is only 258 mV, indicating that this catalyst has high metal utilization and good catalytic activity. In contrast, the catalyst obtained in Comparative Example 1, when applied to a three-electrode system with a catalyst loading of 0.5 mg cm⁻¹, exhibits high efficiency. -2 Under these conditions, it reaches 10 mA cm -2 The overpotential at the current density was 273 mV, while that in Comparative Example 2 reached 288 mV. Compared to Example 1, the activity of both was significantly reduced.

[0035] The sulfur-doped titanium nitride supported iridium catalysts prepared in Example 1 and Comparative Example 1 were applied to a three-electrode system to test their stability. The results are as follows: Figure 3 As shown.

[0036] Figure 3 The three-electrode system assembled with the catalyst of Example 1 is shown to operate at a catalyst loading of 1 mg / cm³. -2Under these conditions, constant voltage stability tests were conducted at 1.6 V. After 24 h, the catalyst still exhibited a high current retention rate, indicating good catalytic stability. In contrast, the three-electrode system assembled with the catalyst prepared in Comparative Example 1, with a catalyst loading of 1 mg cm⁻¹, showed good stability. -2 Under these conditions, a constant potential stability test was conducted at a voltage of 1.6 V. After 24 h, the current retention rate of the catalyst decreased significantly.

[0037] The stability of the sulfur-doped titanium nitride-supported iridium catalyst prepared in Example 1 was tested in a three-electrode system, and the results are as follows: Figure 4 As shown.

[0038] Figure 4 The three-electrode system assembled with this catalyst showed that, at a catalyst loading of 2 mg / cm³, -2 Under these conditions, at 10 mAcm -2 A constant current test was conducted at the current density, and after 800 h, the performance degradation of the catalyst was <15 mV, indicating that the catalyst exhibits good catalytic stability.

[0039] Example 2 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 0.25:1, calcined at 500℃ for 1h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain TiN with amorphous surface. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 0.5:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 600℃ for 3 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and ultrasonically disperse for 1 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 1.3 mL; add chloroiridic acid and stir for 2 h to mix evenly to obtain suspension II, and reflux at 160℃ for 3 h to obtain suspension III, wherein the mass ratio of chloroiridic acid to S-doped TiN support is 0.4:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridic acid is 5:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst.

[0040] The activity of the catalyst prepared in Example 2 was tested in a three-electrode system, and the overpotential was approximately 263 mV, which is similar to that in Example 1.

[0041] Example 3 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 1:1, calcined at 400℃ for 3h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain TiN with amorphous surface. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 0.25:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 400℃ for 3 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and ultrasonically disperse for 1 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 2 mL; add chloroiridium acid and stir for 3 h to mix evenly to obtain suspension II, and reflux at 180℃ for 3 h to obtain suspension III, wherein the mass ratio of chloroiridium acid to S-doped TiN support is 0.3:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridium acid is 4:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst.

[0042] The activity of the catalyst prepared in Example 3 was tested in a three-electrode system, and the overpotential was approximately 260 mV, which is similar to that in Example 1.

[0043] Example 4 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 0.5:1, calcined at 500℃ for 5h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain surface amorphous TiN. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 2:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 500℃ for 6 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and sonicate for 2 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 1.3 mL; add chloroiridium acid and stir for 3 h to mix evenly to obtain suspension II, and reflux at 140 °C for 3 h to obtain suspension III, wherein the mass ratio of chloroiridium acid to S-doped TiN support is 0.5:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridium acid is 4:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst.

[0044] The activity of the catalyst prepared in Example 4 was tested in a three-electrode system, and the overpotential was approximately 268 mV, which is similar to that in Example 1.

[0045] Example 5 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 0.5:1, calcined at 400℃ for 1h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain TiN with amorphous surface. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 1:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 500℃ for 3 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and ultrasonically disperse for 2 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 1.5 mL; add chloroiridium acid and stir for 3 h to mix evenly to obtain suspension II, and reflux at 160℃ for 3 h to obtain suspension III, wherein the mass ratio of chloroiridium acid to S-doped TiN support is 0.5:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridium acid is 4:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst.

[0046] The activity of the catalyst prepared in Example 5 was tested in a three-electrode system, and the overpotential was approximately 268 mV, which is similar to that in Example 1.

[0047] Example 6 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 0.5:1, calcined at 400℃ for 1h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain TiN with amorphous surface. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 0.25:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 600℃ for 2 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and sonicate for 2 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 1.3 mL; add chloroiridic acid and stir for 2 h to mix evenly to obtain suspension II, and reflux at 150 °C for 3 h to obtain suspension III, wherein the mass ratio of chloroiridic acid to S-doped TiN support is 0.3:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridic acid is 7:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst.

[0048] The activity of the catalyst prepared in Example 6 was tested in a three-electrode system, and the overpotential was approximately 261 mV, which is similar to that in Example 1.

[0049] Example 7 This embodiment provides a method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, specifically as follows: (1) TiN and NaBH4 were mixed at a mass ratio of 0.8:1, calcined at 500℃ for 2h, cooled to room temperature, quenched with liquid nitrogen, washed with water and ethanol 3 times each, and dried at 55℃ for 12h to obtain surface amorphous TiN. (2) After mixing surface-amorphized TiN and thiourea at a mass ratio of 1:1, the mixture was heated in a N2 atmosphere at a speed of 5℃ / min. -1 The S-doped TiN support was obtained by heat treatment at 500℃ for 3 h. (3) Add S-doped TiN support and hexadecyltrimethylammonium bromide to ethylene glycol solution and ultrasonically disperse for 1.5 h to obtain suspension I, wherein the mass-volume ratio of S-doped TiN support to ethylene glycol solution is 1 mg: 4 mL; add chloroiridium acid and stir for 3 h to mix evenly to obtain suspension II, and reflux at 170 °C for 3 h to obtain suspension III, wherein the mass ratio of chloroiridium acid to S-doped TiN support is 0.4:1 and the molar ratio of hexadecyltrimethylammonium bromide to chloroiridium acid is 5:1. Centrifuge, wash and dry to obtain sulfur-doped titanium nitride supported iridium catalyst.

[0050] The activity of the catalyst prepared in Example 7 was tested in a three-electrode system, and the overpotential was approximately 265 mV, which is similar to that in Example 1.

[0051] Comparative Example 3 The difference between this comparative example and Example 1 is that only the mass ratio of TiN to NaBH4 in step (1) is adjusted to 6:1, while the rest of the preparation methods are the same as in Example 1, so as to obtain the sulfur-doped titanium nitride supported iridium catalyst of this comparative example.

[0052] The results showed that Comparative Example 3 was difficult and cumbersome to wash the TiN support.

[0053] Comparative Example 4 The difference between this comparative example and Example 1 is that only the mass ratio of surface-amorphized TiN to thiourea in step (2) is adjusted to 5:1. The rest of the preparation methods are the same as in Example 1, and the sulfur-doped titanium nitride supported iridium catalyst of this comparative example is obtained.

[0054] The results showed that S element was almost difficult to incorporate into the TiN support in the catalyst of Comparative Example 4, and the performance of the prepared catalyst was about 274 mV, which was similar to that of pure Ir / TiN.

[0055] Comparative Example 5 The difference between this comparative example and Example 1 is that only the mass ratio of chloroiridium acid to S-doped TiN support in step (3) is adjusted to 2:1. The rest of the preparation methods are the same as in Example 1, and the sulfur-doped titanium nitride support-supported iridium catalyst of this comparative example is obtained.

[0056] Comparative Example 6 The difference between this comparative example and Example 1 is that only the mass ratio of chloroiridium acid to S-doped TiN support in step (3) is adjusted to 0.1:1. The rest of the preparation methods are the same as in Example 1, and the sulfur-doped titanium nitride support-supported iridium catalyst of this comparative example is obtained.

[0057] The catalysts prepared in Comparative Examples 5 and 6 were tested for overpotential in a three-electrode system. It was found that when the Ir precursor ratio was 2:1 (more Ir), the catalyst performance decreased, possibly due to Ir aggregation during reflux, with a performance of approximately 270 mV. The performance was even worse when the Ir precursor ratio was 0.1:1 (less Ir), due to insufficient Ir content on the catalyst surface and a smaller number of active sites, with a performance of approximately 280 mV.

[0058] Comparative Example 7 The difference between this comparative example and Example 1 is that only the temperature of the heat treatment in step (2) is adjusted to 200℃ and 900℃ respectively. The rest of the preparation methods are the same as in Example 1, and the sulfur-doped titanium nitride supported iridium catalyst of this comparative example is obtained.

[0059] The results showed that thiourea could not be completely decomposed at 200℃. At this temperature, the TiN support was still oxidized and dissolved during the oxygen evolution reaction (OER), leading to structural collapse and poor catalyst stability. At 900℃, the temperature was too high, resulting in more energy consumption and higher cost. Therefore, the catalyst prepared in the temperature range of 300℃ to 800℃ had better catalytic activity and stability.

[0060] In summary, this invention addresses the key bottleneck problem of traditional TiN-supported Ir-based catalysts in PEMWE anodes—the easy oxidation and dissolution of TiN supports under high-potential and strong oxidation conditions, leading to the stripping of active sites and structural collapse of the catalyst, which in turn causes a decline in electrochemical activity and long-term stability. To address this issue, this invention proposes a technical solution based on S-doping to regulate the electronic structure of the support.

[0061] The present invention provides a method for preparing an S-TiN-supported Ir proton exchange membrane anode catalyst for water electrolysis. This method achieves sulfur doping of the TiN support and the preparation of the S-TiN-supported Ir catalyst through a simple calcination and ethylene glycol reflux process. This synthesis method is simple and convenient, does not generate large amounts of toxic or harmful gases during the reaction, and uses readily available and inexpensive sulfur-containing raw materials and TiN support. The entire reaction process is short, safe, low-energy, and environmentally friendly. Compared to traditional TiN-supported Ir catalysts prepared using the same ethylene glycol reflux method, its overpotential is reduced by approximately 15 mV. In the constant potential stability test, the current retention rate of the Ir / S-TiN catalyst is much higher than that of Ir / TiN, indicating that the incorporation of sulfur effectively improves the properties of the TiN support. It not only inhibits the structural collapse caused by the oxidation and dissolution of the TiN support during the oxygen evolution reaction (OER), but also enhances the interaction between the Ir nanoparticles and the support. Thus, under low Ir loading conditions, a synergistic improvement in catalyst activity and stability is achieved, making this catalyst extremely promising for applications.

[0062] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing an iridium catalyst supported on a sulfur-doped titanium nitride support, characterized in that: include, TiN was mixed with NaBH4 and then subjected to calcination, liquid nitrogen quenching, washing and drying in sequence to obtain TiN with amorphous surface. Amorphous TiN on the surface was mixed with thiourea and then heat-treated to obtain an S-doped TiN support. S-doped TiN support and surfactant were dispersed in ethylene glycol solution to obtain suspension I. Ir precursor was then added and mixed evenly to obtain suspension II. The suspension was refluxed to obtain suspension III. After centrifugation, washing and drying, the sulfur-doped titanium nitride supported iridium catalyst was obtained.

2. The preparation method according to claim 1, characterized in that: The process involves mixing TiN with NaBH4, wherein the mass ratio of TiN to NaBH4 is 0.1 to 5:

1.

3. The preparation method according to claim 1, characterized in that: The process involves calcination, liquid nitrogen quenching, washing, and drying, with the calcination temperature being 300~600℃ and the time being 0.5~4 h.

4. The preparation method according to claim 1, characterized in that: The process involves mixing surface-amorphized TiN with thiourea and then subjecting the mixture to heat treatment, wherein the mass ratio of surface-amorphized TiN to thiourea is 0.2~4:

1.

5. The preparation method according to claim 4, characterized in that: The heat treatment is performed at a temperature of 300~800℃ for a time of 0.5~8 h.

6. The preparation method according to claim 1, characterized in that: The process involves dispersing the S-doped TiN support and surfactant in an ethylene glycol solution to obtain suspension I, followed by the addition of the Ir precursor. The surfactant includes one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, and polyvinylpyrrolidone. The mass-to-volume ratio of the S-doped TiN support to the ethylene glycol solution is 1 mg: 1.3 mL to 100 mL.

7. The preparation method according to claim 6, characterized in that: The molar ratio of the surfactant to the Ir precursor is 3~200:1, and the mass ratio of the Ir precursor to the S-doped TiN support is 0.2~1:

1. The Ir precursor includes one or more of the following: iridium chloroiridate, iridium chloride, iridium acetylacetonate, iridium acetate, potassium iridium chloroiridate, sodium iridium chloroiridate, iridium oxide, strontium iridate, barium iridate, lithium iridate, potassium iridate, and praseodymium iridate.

8. The preparation method according to claim 1, characterized in that: The suspension III is obtained by reflux, wherein the reflux temperature is 120~180℃ and the time is 1~6 h.

9. The sulfur-doped titanium nitride supported iridium catalyst prepared by any one of the preparation methods described in claims 1 to 8, characterized in that: The catalyst comprises an S-doped TiN support and Ir clusters, wherein the atomic ratio of Ti to Ir in the catalyst is 1:0.1~0.

6.

10. The application of the sulfur-doped titanium nitride supported iridium catalyst as described in claim 9 in proton exchange membrane water electrolysis.

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