A low-iridium electrolyzed water catalyst, its preparation method and application

Abstract

The present invention provides a method for preparing a low-iridium electrolysis catalyst, comprising the following steps: mixing an iridium source, a carrier material, a precursor alkaline solution, and an additive to obtain a catalyst; the carrier material is an oxide nanomaterial; and the additive is a surfactant. x The nanocomposite material of the coating layer has a simple preparation method and is stable and reliable. The use of a specific carrier material greatly reduces the amount of precious metal Ir in the catalyst. The use of amorphous iridium oxide for the outer layer effectively reduces the coverage of the catalyst active sites, and IrO x Subsequent high-temperature calcination can further convert it into crystalline IrO2. Compared with commercial IrO2, the prepared iridium-based composite nanocatalyst has better catalytic activity and stability under acidic conditions, providing a new option for commercial anode catalysts for hydrogen production by water electrolysis.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to a low-iridium water electrolysis catalyst, a preparation method and application thereof. Background Art

[0002] With the growing demand for low-carbon emissions reduction, green hydrogen production technologies are gaining widespread attention. Hydrogen production through water electrolysis using renewable energy is currently the lowest-carbon process among many hydrogen production technologies. Currently, water electrolysis for hydrogen production is mainly divided into alkaline water electrolysis (AWE), proton exchange membrane (PEM) water electrolysis, and solid oxide (SOE) water electrolysis. Compared to alkaline and SOE technologies, PEM water electrolysis equipment offers flexible control, close contact between components, low resistance, and the ability to produce hydrogen at high current densities. More importantly, PEM electrolyzers have a fast response time, can tolerate power fluctuations from the power supply, and can seamlessly couple with renewable energy. The catalyst is the core component of the electrolyzer and influences the efficiency of the catalytic reaction. Due to the highly acidic environment localized within the proton exchange membrane, the catalyst requires extremely high corrosion resistance.

[0003] Currently, the anode catalysts used in industry are primarily iridium-based. This is because few catalysts can maintain both high stability and high catalytic activity in both strong acidic and oxidizing environments. However, due to the limited reserves and high cost of iridium, the large-scale application of PEM water electrolysis for hydrogen production still faces significant challenges. Therefore, the development of efficient and stable low-Ir catalysts is a current research hotspot.

[0004] There are some reports on the current research based on low Ir catalysts: some foreign companies such as Umicore and Heraeus have developed low Ir-based catalysts with good catalytic performance; in China, the Ir0.6Sn0.4 catalyst (71wt%) prepared by the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences has a performance of 2A·cm-2@1.82V in a full electrolytic cell test. However, there is still a certain gap compared with foreign work, especially in the development of low Ir catalysts, which is still relatively slow and has not yet formed a mature catalyst product. Therefore, for the development of iridium-based OER catalysts, improving the activity of the catalyst and effectively reducing the amount of iridium are of great significance to the realization of large-scale PEM hydrogen production in the future. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing a low-iridium electrolysis catalyst. The silicon oxide composite nanomaterial with an amorphous iridium oxide coating layer prepared by the present invention is used as a catalyst for acidic water electrolysis, which greatly reduces the amount of precious metal Ir used, reduces the catalyst cost, and obtains higher OER catalytic activity and stability.

[0006] The present invention provides a method for preparing a low-iridium water electrolysis catalyst, comprising the following steps:

[0007] The iridium source, the carrier material, the precursor alkaline solution and the additive are mixed and reacted to obtain the product;

[0008] The carrier material is an oxide nanomaterial; the additive is a surfactant.

[0009] Preferably, the oxide nanomaterial is selected from one or more of silicon oxide, tantalum oxide, tungsten oxide, tin oxide or titanium oxide.

[0010] Preferably, the precursor alkaline solution is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide or ammonia water;

[0011] The surfactant includes one or more of CTAB, EDTA, APTES or PVP.

[0012] Preferably, the mass ratio of the iridium source to the additive is 0.01 to 50.

[0013] Preferably, the iridium source is selected from one or more of chloroiridic acid, iridium acetylacetonate, iridium chloride, potassium chloroiridate, sodium chloroiridate and iridium acetate; and the mass ratio of the iridium source to the base is 0.5 to 3.

[0014] Preferably, the reaction temperature is 120-180° C.; and the reaction time is 6-24 h.

[0015] Preferably, after the reaction, the product is centrifuged, washed with deionized water and anhydrous ethanol, and then vacuum dried.

[0016] Preferably, the particle size of the oxide nanomaterial is 50 to 100 nm.

[0017] The present invention provides a low-iridium water electrolysis catalyst, which is prepared by the preparation method described in any one of the above technical solutions.

[0018] The present invention provides a membrane electrode comprising the low-iridium water electrolysis catalyst described in the above technical solution.

[0019] The present invention provides a PEM device, comprising the membrane electrode described in the above technical solution.

[0020] The present invention provides the use of a low-iridium water electrolysis catalyst prepared by the preparation method described in any one of the above technical solutions in an electrolytic water oxygen evolution reaction.

[0021] Compared with the prior art, the present invention provides a method for preparing a low-iridium electrolysis catalyst, comprising the following steps: mixing an iridium source, a carrier material, a precursor alkaline solution, and an additive to obtain a catalyst; the carrier material is an oxide nanomaterial; and the additive is a surfactant. x The nanocomposite material of the coating layer has a simple preparation method and is stable and reliable. The use of a specific carrier material greatly reduces the amount of precious metal Ir in the catalyst. The use of amorphous iridium oxide for the outer layer effectively reduces the coverage of the catalyst active sites, and IrO x Subsequent high-temperature calcination can further convert it into crystalline IrO2. Compared with commercial IrO2, the prepared iridium-based composite nanocatalyst has better catalytic activity and stability under acidic conditions, providing a new option for commercial anode catalysts for hydrogen production by water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM image of the silicon oxide nanomaterial prepared in Example 1 of the present invention;

[0023] Figure 2 This is a TEM image of the iridium oxide composite nanomaterial prepared in Example 1 of the present invention;

[0024] Figure 3 This is the XRD image of the iridium oxide composite nanomaterial prepared in Example 1 of the present invention;

[0025] Figure 4 IrO with different proportions prepared in Example 1 of the present invention x / SiO2(m Ir :m SiO2 =0.1~1.0) polarization curve of electrochemical oxygen evolution of catalyst in sulfuric acid solution;

[0026] Figure 5 IrO with different proportions prepared in Example 1 of the present invention x / SiO2(m Ir :m SiO2 =0.1~1.0) mass activity diagram of the catalyst obtained after electrochemical oxygen evolution test in sulfuric acid solution;

[0027] Figure 6 IrO prepared in Example 1 of the present invention x / Performance diagram of SiO2 nanomaterials used in PEM electrolysis devices;

[0028] Figure 7 This is a TEM image of Example 3 of the present invention;

[0029] Figure 8 IrO prepared in Example 3 of the present inventionx / Performance diagram of TiO2 nanomaterials used in PEM electrolytic devices. DETAILED DESCRIPTION

[0030] The present invention provides a low-iridium water electrolysis catalyst, its preparation method and application. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art and they all fall within the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0031] The present invention provides a method for preparing a low-iridium water electrolysis catalyst, comprising the following steps:

[0032] The iridium source, the carrier material, the precursor alkaline solution and the additive are mixed and reacted to obtain the product;

[0033] The carrier material is an oxide nanomaterial; the additive is a surfactant.

[0034] The present invention provides a method for preparing a low-iridium water electrolysis catalyst. Preferably, a carrier material is prepared first.

[0035] The carrier material of the present invention is an oxide nanomaterial; the oxide nanomaterial is selected from one or more of silicon oxide, tantalum oxide, tungsten oxide, tin oxide or titanium oxide.

[0036] The present invention does not limit the sources of the above oxides, and they can be commercially available or prepared by methods well known to those skilled in the art.

[0037] The particle size of the oxide nanomaterial of the present invention is 50-100 nm.

[0038] In one preferred embodiment of the present invention, the method for preparing silicon oxide is as follows:

[0039] SiO2 material is prepared by mixing ethyl orthosilicate, ammonia water and ethanol.

[0040] In some preferred embodiments of the present invention, the precursor alkaline solution is selected from one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide or ammonia water;

[0041] In some preferred embodiments of the present invention, the surfactant includes one or more of CTAB, EDTA, APTES or PVP.

[0042] In some preferred embodiments of the present invention, the iridium source is selected from one or more of chloroiridic acid, iridium acetylacetonate, iridium chloride, potassium chloroiridate, sodium chloroiridate and iridium acetate; and the mass ratio of the iridium source to the base is 0.5 to 3.

[0043] In some preferred embodiments of the present invention, the mass ratio of the iridium source to the additive is 0.01-50.

[0044] In some preferred embodiments of the present invention, the mass ratio of the iridium source to the carrier material is 1:(1-30).

[0045] The present invention can adopt the method of mixing an iridium source, a carrier material, a precursor alkaline solution and an additive; or the additive can be mixed with the precursor alkaline solution and then mixed with the iridium source and the carrier material, which is not limited in the present invention.

[0046] The reaction temperature of the present invention is preferably 120-180°C, more preferably 130-180°C, and most preferably 140-180°C. The reaction time is preferably 6-24h, more preferably 8-24h, and most preferably 10-24h.

[0047] According to the present invention, after the reaction, the reaction product is further centrifuged, washed with deionized water and anhydrous ethanol, and then vacuum dried.

[0048] The present invention is not limited to the above specific steps and operations, which are well known to those skilled in the art.

[0049] The present invention uses a hydrothermal method to directly load amorphous iridium oxide onto an oxide support to obtain an iridium-based composite nanomaterial. The present invention uses silicon oxide, which is inexpensive, easy to prepare, and resistant to acid corrosion, as the support material, significantly reducing the amount of precious metal iridium used and lowering costs. The mass percentage of metallic iridium in the low-iridium catalyst is less than 15%. Compared with commercially available IrO2, the low-iridium-based composite nanomaterial has higher catalytic activity and mass activity, providing a new option for commercial anode catalysts for hydrogen production by water electrolysis and promising broad market prospects.

[0050] The present invention provides a low-iridium water electrolysis catalyst, which is prepared by the preparation method described in any one of the above technical solutions.

[0051] The size of the amorphous IrOx of the present invention is 2-5 nm.

[0052] The present invention has clearly described the above preparation method, which will not be repeated here.

[0053] The present invention provides the use of a low-iridium water electrolysis catalyst prepared by the preparation method described in any one of the above technical solutions in an electrolytic water oxygen evolution reaction.

[0054] A membrane electrode comprises the catalyst described in the above technical solution.

[0055] A PEM device comprises the membrane electrode described in the above technical solution.

[0056] The present invention also provides a method for oxygen evolution by electrolysis of water, comprising a low-iridium water electrolysis catalyst prepared by the preparation method described in any one of the above technical solutions.

[0057] The present invention provides a method for preparing a low-iridium electrolysis catalyst, comprising the following steps: mixing an iridium source, a carrier material, a precursor alkaline solution, and an additive to obtain a catalyst; the carrier material is an oxide nanomaterial; and the additive is a surfactant. x The nanocomposite material of the coating layer has a simple preparation method and is stable and reliable. The use of a specific carrier material greatly reduces the amount of precious metal Ir in the catalyst. The use of amorphous iridium oxide for the outer layer effectively reduces the coverage of the catalyst active sites, and IrO x Subsequent high-temperature calcination can further convert it into crystalline IrO2. Compared with commercial IrO2, the prepared iridium-based composite nanocatalyst has better catalytic activity and stability under acidic conditions, providing a new option for commercial anode catalysts for hydrogen production by water electrolysis.

[0058] To further illustrate the present invention, a low-iridium water electrolysis catalyst, a preparation method thereof, and applications thereof are described in detail below with reference to examples.

[0059] Example 1

[0060] IrO x Preparation of / SiO2 composite nanomaterials:

[0061] SiO2 material is prepared by mixing tetraethyl orthosilicate, ammonia and ethanol. The prepared SiO2 has a nanosphere morphology with a diameter of about 50 to 100 nm. 20 mg of SiO2 is weighed and added to 10 mL of deionized water, ultrasonically dispersed evenly, and then stirred with chloroiridic acid and a precursor alkaline mixed solution (including a surfactant) to control the mass ratio of metal iridium to silicon oxide. Ir :m SiO2 =1:2, hydrothermal reaction at 180℃ for 24h; then the obtained product was washed, centrifuged and dried to obtain IrO x / SiO2(m Ir :m SiO2 =1:2) composite nanomaterials;

[0062] The SiO2 prepared above can be confirmed to be nanoparticle morphology through SEM photos. Figure 1 .

[0063] The IrO prepared above x The TEM images of the / SiO2 composite nanomaterials show that they are nanoparticles with amorphous IrO coated on the outer layer. x The diameter is about 2 to 5 nm and is evenly distributed. See the TEM image. Figure 2 .

[0064] The IrO prepared above x The crystal structure of the / SiO2 composite nanomaterial can be determined to be an amorphous phase through the XRD spectrum. Figure 3 .

[0065] The IrO prepared above x Acidic OER performance test method of / SiO2 composite nanomaterials:

[0066] Data were collected using a CHI660e electrochemical workstation. Testing was performed using a three-electrode electrolytic cell. 5 mg of the catalyst prepared above was weighed and dispersed in 980 μL of isopropanol. 20 μL of a 5% Nafion solution was added and ultrasonicated for 30 min to form a uniform slurry. 10 μL of the catalyst dispersion was drop-coated on a 5 mm diameter gold electrode, allowed to dry naturally, and used as the working electrode. A silver / silver chloride electrode and a carbon rod were used as the reference electrode and counter electrode, respectively. A 0.5 M sulfuric acid solution was used as the electrolyte.

[0067] Activity testing: Linear sweep voltammetry (LSV) was performed over a voltage range of 0.9–1.6 V vs. RHE at a scan rate of 5 mV / s. The test was repeated several times until the data stabilized, and the last measurement was used. Commercial IrO2 was also tested for OER performance under the same conditions for comparison.

[0068] Experimental results:

[0069] The electrochemical experimental results are shown in Figure 4 、 Figure 5 .

[0070] LSV results show that compared with commercial IrO2, the IrO prepared by the present invention is x / SiO2 composite nanomaterials have higher catalytic activity and mass activity.

[0071] Membrane electrode preparation and testing

[0072] The IrO obtained in Case 1 was implemented x / SiO2 catalyst was used in PEM water electrolysis device for testing, using two electrodes for testing; the cathode used a commercial platinum carbon catalyst for hydrogen evolution reaction, and the anode used IrO x / SiO2 catalyst is used for oxygen evolution reaction. After the above-mentioned cathode and anode catalysts are prepared into membrane electrodes by spray-transfer method, the anode catalyst loading is 0.5mg Ir / cm 2 , assembled into a PEM device. Figure 5 As shown, at 2A / cm 2 At the current density, its potential is 2.02V, indicating that the catalyst is expected to be used as an anode oxygen evolution catalyst for PEM water electrolysis to produce hydrogen.

[0073] In summary, the IrO prepared by the present invention x / SiO2 composite nanomaterials showed good catalytic performance in PEM tests.

[0074] Example 2

[0075] In addition to changing the mass ratio of metal iridium to silicon oxide (m Ir :m SiO2 ), other methods and conditions are the same as in Example 1, and the OER catalytic performance is shown in Figure 4 、 Figure 5 .

[0076] The comparison of different embodiments shows that when the mass ratio of metal iridium to silicon oxide is m Ir :m SiO2 =1:7, the prepared IrO x / SiO2 composite nanomaterials have the highest mass activity, and the Ir loading is only 12.2wt%. While ensuring relatively high catalytic activity, the loading of precious metal Ir is greatly reduced, the catalyst cost is reduced, and it is expected to realize the application of low-iridium OER catalysts in the field of PEM water electrolysis for hydrogen production.

[0077] Example 3

[0078] IrO x Preparation of TiO2 composite nanomaterials:

[0079] 20 mg of TiO2 was added to 10 mL of deionized water and ultrasonically dispersed, and then stirred with chloroiridic acid and precursor alkaline mixed solution (including surfactant) to control the mass ratio of metal iridium to titanium oxide. Ir :m TiO2 =1:1, hydrothermal reaction at 180℃ for 24h; then the obtained product was washed, centrifuged and dried to obtain IrO x / TiO2 composite nanomaterials.

[0080] The IrO prepared above x The TEM images of the / TiO2 composite nanomaterials show that they are nanoparticles with amorphous IrO coated on the outer layer. xThe diameter is about 2 to 5 nm and is evenly distributed. See the TEM image. Figure 7 .

[0081] The IrO obtained in Case 3 was implemented x / TiO2 catalyst was used in PEM water electrolysis device for testing, using two electrodes for testing; the cathode used a commercial platinum carbon catalyst for hydrogen evolution reaction, and the anode used IrO x / TiO2 catalyst is used for oxygen evolution reaction. After the above-mentioned cathode and anode catalysts are prepared into membrane electrodes by spray-transfer method, the anode catalyst loading is 0.5mg Ir / cm 2 , assembled into a PEM device. Figure 8 As shown, at 2A / cm 2 At this current density, its potential is 2.03V.

[0082] Example 4

[0083] 20 mg of SnO2 was added to 10 mL of deionized water and dispersed evenly by ultrasonication. Then, the mixture was stirred with chloroiridic acid and precursor alkaline mixed solution (including surfactant) to control the mass ratio of metal iridium to titanium oxide. Ir :m SnO2 =1:2, hydrothermal reaction at 180℃ for 24h; then the obtained product was washed, centrifuged and dried to obtain IrO x / SnO2 composite nanomaterials.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a low-iridium water electrolysis catalyst, characterized in that: The steps include: SiO2 material was prepared by mixing tetraethyl orthosilicate, ammonia water and ethanol. The prepared SiO2 had a nanosphere morphology with a diameter of 50-100 nm. 20 mg of SiO2 was weighed and added to 10 mL of deionized water, ultrasonically dispersed evenly, and then stirred with iridium chloride, a precursor alkaline mixed solution and a surfactant to control the mass ratio of metal iridium to silicon oxide. Ir :m SiO2 = 1:7,180 o C for 24 h; then the obtained product is washed, centrifuged and dried to obtain the product.

2. A low-iridium water electrolysis catalyst, characterized in that The method according to claim 1 is used to prepare the present invention.

3. A membrane electrode comprising the low-iridium water electrolysis catalyst according to claim 2.

4. A PEM device comprising the membrane electrode according to claim 3.

5. Use of the low-iridium water electrolysis catalyst prepared by the preparation method according to claim 1 in the electrolysis of water and oxygen evolution reaction.

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