Highly conductive ir@tio2 anode catalyst, preparation method and application thereof in proton exchange membrane electrolyzer

Abstract

The application relates to a high-conductivity and high-activity Ir@TiO2 anode catalyst, a preparation method and application thereof in a proton exchange membrane electrolytic cell, and belongs to the technical field of inorganic functional catalyst materials. The iridium source and the titanium source are mixed at room temperature, a reducing agent magnesium diboride is added, the mass ratio of the magnesium diboride and the iridium source is 2:1, the mass ratio of the titanium source and the iridium source is 1-100:1; then the mixture is placed in a high-temperature and high-pressure reaction kettle, and is reacted at 80-200 DEG C for 10 min-4 h, and the high-conductivity, high-activity and easily enlarged Ir@TiO2 anode catalyst is obtained after being reduced to room temperature. The obtained Ir@TiO2 anode catalyst is dispersed in a mixed solution of water and ethanol with a volume ratio of 1:1, is prepared into slurry, is prepared into a membrane electrode through a coating means, and is assembled in a PEM electrolytic cell, and when the iridium load is 0.5 mg / cm 2 , the high activity and stability are still maintained.

Description

Technical Field

[0001] This invention belongs to the field of inorganic functional catalytic materials technology, specifically relating to a highly conductive and highly active Ir@TiO2 anode catalyst, its preparation method, and its application in a proton exchange membrane (PEM) electrolyzer. Background Technology

[0002] In recent years, the consumption of fossil fuels and the emission of greenhouse gases have exacerbated the energy crisis and climate change, and the fossil fuel-based energy system can no longer meet the requirements of sustainable development. Hydrogen, with its high calorific value, high energy density, and environmental friendliness, is an important carrier for alleviating energy problems. Coupled with renewable electricity and water, the production of "green hydrogen" with zero carbon emissions is currently the mainstream of the hydrogen energy industry. Among the water splitting technologies reported so far, proton exchange membrane (PEM) water electrolysis technology has become a focus of attention due to its advantages such as high current density and high product purity. More importantly, its fast response time makes it the most suitable technology for hydrogen production coupled with electricity (ACS Catal. 2022, 12, 6159-6171).

[0003] The main components of a PEM electrolyzer include bipolar plates, a gas diffusion layer, a proton exchange membrane, and anode and cathode catalysts. Due to the highly oxidizing and acidic operating environment of PEM electrolyzers, only a few noble metal-based electrocatalysts (typically IrO2 as the anode catalyst) can maintain reasonable catalytic activity and stability under such conditions. However, the high cost of noble metals makes hydrogen production from PEM electrolyzers very expensive. Therefore, there is an urgent need to develop low-cost anode catalysts for electrolyzers (NanoResearch Energy, 2022, 1: e9120032).

[0004] The design of supported catalysts provides a feasible technical route for achieving the goal of low-cost electrolyzer catalysts. In the acidic oxygen evolution reaction (OER), the supported materials used for supported catalysts have been reported to include carbon-based, titanium-based, and tin-based materials (ACS Catal. 2021, 11, 7, 4107–4116). Although carbon-based materials have good conductivity, they are unstable during acidic OER testing, leading to metal shedding. Titanium-based and tin-based oxides are widely used as supports for acidic OER catalysts due to their good stability. However, their own conductivity is extremely poor, requiring the loading of large amounts of iridium to improve the overall conductivity of the catalyst before it can be used in PEM electrolyzers.

[0005] To date, although numerous IrO2-TiO2 composite catalysts have been reported, their poor conductivity limits their application in PEM electrolyzers. Therefore, commercially available catalysts still primarily utilize scarce, expensive, and high-loading IrO2. Developing anode catalyst materials that balance conductivity and corrosion resistance, while also offering low loading and high performance, is an urgent need under current energy conversion methods. Summary of the Invention

[0006] The present invention aims to reduce the cost of PEM electrolyzers by providing a method for preparing a highly conductive and high-performance Ir@TiO2 anode catalyst and its application in PEM electrolyzers.

[0007] This invention provides a method for preparing a highly conductive and high-performance Ir@TiO2 anode catalyst, which uses various titanium compounds as titanium sources and various iridium compounds as iridium sources. The mass ratio of titanium source to iridium source can be adjusted according to the iridium loading, and the adjustable range is 1~100:1.

[0008] The preparation of the highly conductive and high-performance Ir@TiO2 anode catalyst of this invention involves mixing an iridium source and a titanium source at room temperature, adding magnesium diboride as a reducing agent (mass ratio of magnesium diboride to iridium source is 2:1), and then placing the mixture in a high-temperature and high-pressure reactor. The reaction is carried out at 80–200 °C for 10 min–4 h. After cooling to room temperature, a highly conductive, highly active, and easily scaled-up Ir@TiO2 anode catalyst is obtained. In this anode catalyst, Ir exists as a nano-conductive network structure composed of single atoms and single particles. The obtained Ir@TiO2 anode catalyst is dispersed in a 1:1 volume ratio of water and ethanol to prepare a slurry. The catalyst is then coated onto PEM (polyethylene terephthalate) to form a film electrode, which is then assembled in a PEM electrolyzer with an iridium loading of 0.5 mg / cm³. 2 Even at that time, it still maintains high activity and stability.

[0009] In the above method, the titanium compound is one of tetrabutyl titanate, titanium oxysulfate, titanium trichloride, and titanium isopropoxide.

[0010] In the above method, the iridium compound is one of iridium trichloride, potassium hexachloroiridate, chloroiridium acid, iridium acetylacetone, and tetrairidium dodecylcarbonyl.

[0011] In the above method, the mass ratio of titanium source to iridium source is 1~100:1.

[0012] The Ir@TiO2 anode catalyst obtained by the above method has high conductivity, high activity and high stability in acidic oxygen evolution reaction, and can be prepared at the gram level.

[0013] This invention enables the rapid synthesis of gram-scale, highly conductive, and highly active Ir@TiO2 anode catalysts, representing a successful and universally applicable preparation method.

[0014] Compared with conventional Ir@TiO2 anode catalysts, the anode catalyst obtained by this method has good electrical conductivity.

[0015] Compared to commercial iridium-based catalysts, the catalyst obtained by this method has a significantly lower iridium content.

[0016] The Ir@TiO2 anode catalyst of this invention exhibits high electrocatalytic oxygen evolution activity and stability under acidic conditions: current density reaches 10 mA / cm². 2 At that time, the required overpotential is 280 mV, and it remains stable for more than 100 hours.

[0017] The Ir@TiO2 anode catalyst of this invention exhibits high activity and stability in a PEM electrolyzer: at a voltage of 1.8 V, the current density reaches 2.2 A / cm². 2 At 2 V, the current density reaches 3.6 A / cm. 2 Furthermore, at 1 A / cm 2 At the specified current density, the electrolytic cell can operate stably for 2000 hours. Attached Figure Description

[0018] Figure 1 X-ray diffraction (XRD) pattern of the Ir@TiO2 anode catalyst prepared in Example 1.

[0019] Figure 2 Transmission electron microscopy (TEM) and spherical aberration electron microscopy (STEM) images of the Ir@TiO2 anode catalyst prepared in Example 1 are shown in Figure (a) and Figure (b), respectively.

[0020] Figure 3 The polarization curve (a) and stability test curve (b) of the Ir@TiO2 anode catalyst prepared in Example 1 for the water cracking oxygen release reaction in an acidic electrolyte (0.1 M HClO4) are shown. The voltages have been converted to the voltages corresponding to the standard hydrogen electrode. The above data were obtained by testing with a Shanghai Chenhua CHI660e electrochemical workstation.

[0021] Figure 4 Polarization curves of the Ir@TiO2 anode catalyst prepared in Example 1 in a PEM electrolyzer. The test temperature was controlled at 80 °C, and the current density for stability testing was set to 1 A / cm². 2 . Detailed Implementation

[0022] The present invention will be further described in conjunction with the embodiments and accompanying drawings. However, the scope of protection of the present invention includes, but is not limited to, the following embodiments. Any changes and adjustments made without departing from the spirit and scope of the present invention will also be included within the scope of protection of the present invention. Example 1

[0023] Preparation of Ir@TiO2 anode catalyst: 0.3 g of titanium oxysulfate and 0.15 g of iridium acetylacetone were dissolved in 20 mL of deionized water, with the addition of a special reducing agent, magnesium diboride (mass of which was 0.3 g). After the mixture was homogeneous, it was transferred to a high-temperature and high-pressure reactor. The reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was completed, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the target catalyst (referred to as product 1). The mass of the product was approximately 400 mg.

[0024] The raw materials were increased tenfold, and the same operation as above was performed: 3 g of titanium oxysulfate and 1.5 g of iridium acetylacetonate were dissolved in 200 mL of deionized water, with the addition of a special reducing agent, magnesium diboride (3 g in mass). After the mixture was homogeneous, it was transferred to a high-temperature and high-pressure reactor, and the reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was completed, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the target catalyst (referred to as product 2), with a product mass of approximately 5 g.

[0025] Some structural and property studies were conducted on the materials prepared by the above method (corresponding to product 1).

[0026] Figure 1 The XRD pattern of the obtained Ir@TiO2 anode catalyst is shown. The positions in the spectrum are assigned to the diffraction peaks of anatase TiO2 and Ir (TiO2:PDF#21-1272;Ir:46-1044), indicating that the material is Ir supported on anatase TiO2.

[0027] Figure 2 a is a TEM image of the obtained Ir@TiO2 anode catalyst, showing that Ir can be uniformly supported on the TiO2 substrate in the catalyst; Figure 2 b is a STEM image of the obtained Ir@TiO2 anode catalyst, showing that Ir can be uniformly loaded on the TiO2 substrate in the catalyst. In addition, Ir in the Ir@TiO2 catalyst is presented as a nano-conductive network structure composed of single atoms and single particles.

[0028] The prepared Ir@TiO2 anode catalyst was studied in a three-electrode system with 0.1 M HClO4 electrolyte to investigate its electrocatalytic oxygen evolution performance. Ir@TiO2 was used as the anode (working area 0.071 cm²). 2The platinum wire serves as the counter electrode, and the saturated calomel electrode as the reference electrode. It should be noted that the main cell of the electrochemical workstation is the external power source for the electrocatalytic oxygen evolution process; the potential obtained using the saturated calomel electrode as the reference electrode is converted into a reversible hydrogen electrode potential in the property diagram.

[0029] Figure 3 The polarization curves and stability test results of the obtained Ir@TiO2 anode catalyst under the three-electrode system test conditions show that the catalyst has good oxygen evolution reaction activity and stability, with a current density reaching 10 mA / cm². 2 At that time, the required overpotential is 280 mV, and it can operate stably for more than 100 hours.

[0030] The prepared Ir@TiO2 anode catalyst was used to fabricate a film electrode via ultrasonic spraying for PEMWE activity evaluation. It is noted that the cathode catalyst was Pt / C, the gas diffusion layer was titanium felt, the testing temperature was 80 ℃, and the active area was 5 cm². 2 The iridium loading is 0.5 mg / cm³. 2 .

[0031] Figure 4 The polarization curves of the Ir@TiO2 anode catalyst in a PEM electrolyzer are shown. The test results indicate that the Ir@TiO2 anode catalyst exhibits high activity in the PEM electrolyzer. At 1.8 V, the current density reaches 2.2 A / cm². 2 At 2 V, the current density reaches 3.6 A / cm. 2 Furthermore, at 1 A / cm 2 At the specified current density, the electrolytic cell operates stably for more than 2000 hours. Example 2

[0032] Similar to Example 1, 0.3 g of titanium oxysulfate and 0.06 g of iridium acetylacetone were dissolved in 20 mL of deionized water, with the aid of a special reducing agent, magnesium diboride (0.12 g by mass). After thorough mixing, the mixture was transferred to a high-temperature, high-pressure reactor. The reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was complete, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the Ir@TiO2 anode catalyst. The product mass was approximately 300 mg. The electrocatalytic oxygen evolution performance was studied in 0.1 M HClO4 electrolyte, with a current density reaching 10 mA / cm². 2 At that time, the overpotential is approximately 320 mV. Example 3

[0033] Similar to Example 1, 0.3 g of titanium oxysulfate and 0.24 g of iridium acetylacetone were dissolved in 20 mL of deionized water, with the aid of a special reducing agent, magnesium diboride (0.48 g). After thorough mixing, the mixture was transferred to a high-temperature, high-pressure reactor. The reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was complete, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the Ir@TiO2 anode catalyst. The product mass was approximately 450 mg. The electrocatalytic oxygen evolution performance was studied in 0.1 M HClO4 electrolyte, with a current density reaching 10 mA / cm². 2 At that time, the overpotential is approximately 260 mV. Example 4

[0034] Similar to Example 1, 0.3 g of titanium oxysulfate and 0.003 g of iridium acetylacetone were dissolved in 20 mL of deionized water, with the aid of a special reducing agent, magnesium diboride (0.006 g by mass). After thorough mixing, the mixture was transferred to a high-temperature, high-pressure reactor, and the reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was complete, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the Ir@TiO2 anode catalyst. The product mass was approximately 300 mg. The electrocatalytic oxygen evolution performance was studied in 0.1 M HClO4 electrolyte, with a current density reaching 10 mA / cm². 2 At that time, the overpotential is approximately 420 mV. Example 5

[0035] Similar to Example 1, 0.3 g of titanium oxysulfate and 0.015 g of iridium acetylacetone were dissolved in 20 mL of deionized water, with the aid of a special reducing agent, magnesium diboride (0.03 g by mass). After thorough mixing, the mixture was transferred to a high-temperature, high-pressure reactor, and the reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was complete, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the Ir@TiO2 anode catalyst. The product mass was approximately 310 mg. The electrocatalytic oxygen evolution performance was studied in 0.1 M HClO4 electrolyte, with a current density reaching 10 mA / cm². 2 At that time, the overpotential is approximately 400 mV. Example 6

[0036] Similar to Example 1, 0.3 g of titanium oxysulfate and 0.006 g of iridium acetylacetone were dissolved in 20 mL of deionized water, with the aid of a special reducing agent, magnesium diboride (0.012 g by mass). After thorough mixing, the mixture was transferred to a high-temperature, high-pressure reactor, and the reaction temperature was raised to 80 °C and maintained for 10 min. After the reaction was complete, the supernatant was discarded, and the product was repeatedly washed with deionized water and ethanol to obtain the Ir@TiO2 anode catalyst. The product mass was approximately 305 mg. The electrocatalytic oxygen evolution performance was studied in 0.1 M HClO4 electrolyte, with a current density reaching 10 mA / cm². 2 At that time, the overpotential is approximately 410 mV. Example 7

[0037] Similar to Example 1, replacing titanium oxysulfate with one of titanium dioxide, titanium sulfate, titanium nitride, titanium carbide, or titanium isopropoxide also yields an Ir@TiO2 anode catalyst. The electrocatalytic oxygen evolution performance was studied in a 0.1 M HClO4 electrolyte, achieving a current density of 10 mA / cm². 2 At these times, the overpotentials are 270 mV, 275 mV, 290 mV, 280 mV, and 300 mV, respectively. Example 8

[0038] Similar to Example 1, replacing iridium acetylacetone with one of iridium trichloride, potassium hexachloroiridate, chloroiridic acid, or tetrairidium dodecylcarbonyl can also yield Ir@TiO2 anode catalyst. Electrocatalytic oxygen evolution performance was studied in 0.1 M HClO4 electrolyte, with a current density reaching 10 mA / cm². 2 At these times, the overpotentials are 275 mV, 280 mV, 290 mV, and 300 mV, respectively. Example 9

[0039] Similar to Example 1, Ir@TiO2 anode catalysts were also obtained by gradually increasing the reaction temperature from 80 °C to 200 °C. The Ir@TiO2 anode catalysts obtained at reaction temperatures of 100 °C, 150 °C, 180 °C, and 200 °C were used to study their electrocatalytic oxygen evolution performance in a 0.1 M HClO4 electrolyte, achieving a current density of 10 mA / cm². 2 At these times, the overpotentials were 275 mV, 270 mV, 280 mV, and 265 mV, respectively, which were not significantly different from the overpotential (280 mV) in Example 1. Example 10

[0040] Similar to Example 1, Ir@TiO2 anode catalysts were also obtained by gradually increasing the reaction time from 10 min to 4 h. The Ir@TiO2 anode catalysts obtained at reaction times of 30 min, 60 min, 120 min, 180 min, and 240 min were used to study their electrocatalytic oxygen evolution performance in 0.1 M HClO4 electrolyte. The overpotentials were 285 mV, 280 mV, 275 mV, 278 mV, and 270 mV, respectively, and the performance was similar to that of Example 1 (280 mV).

Claims

1. Use of a high conductive Ir@TiO2 anode catalyst in a proton exchange membrane electrolyzer, characterized in that: The method comprises the following steps: mixing an iridium source and a titanium source at room temperature, adding a reducing agent magnesium diboride, wherein the mass ratio of the titanium source and the iridium source is 1-5:1, and the mass ratio of the magnesium diboride and the iridium source is 2:1; then placing the mixture in a high-temperature and high-pressure reaction kettle, reacting at 80-200 DEG C for 10 min-4 h, and obtaining the high-conductivity Ir@TiO2 anode catalyst by one-step method after the temperature is reduced to room temperature.

2. The use of a high conductive Ir@TiO2 anode catalyst in a proton exchange membrane electrolyzer according to claim 1, characterized in that: In the catalyst synthesis process, the titanium source is one of tetrabutyl titanate, titanyl sulfate, titanium trichloride and titanium isopropoxide.

3. Use of a high conductive Ir@TiO2 anode catalyst in a proton exchange membrane electrolyzer according to claim 1, characterized in that: The iridium source is one of iridium trichloride, potassium hexachloroiridate, chloroiridic acid, acetylacetone iridium and twelve carbonyl iridium.

4. The use of a high conductive Ir@TiO2 anode catalyst in a proton exchange membrane electrolyzer according to claim 1, characterized in that: The Ir@TiO2 anode catalyst is dispersed in a mixed solution of water and ethanol with a volume ratio of 1:1 to prepare a slurry, a membrane electrode is prepared by a coating method, and the membrane electrode is assembled in a proton exchange membrane electrolysis cell.

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