Supported nano iridium catalyst as well as preparation method and application thereof

Abstract

The invention discloses a supported nano iridium catalyst as well as a preparation method and application thereof, and belongs to the technical field of chemical engineering. The preparation method comprises the following steps: mixing propyl alcohol, water and tetrabutyl stannate to obtain a first solution; adding an iridium source into the first solution to obtain a second solution; standing the second solution in air, and drying to obtain a dried product; and calcining the dried product in a muffle furnace to obtain the supported nano iridium catalyst. The invention also discloses the supported nano iridium catalyst prepared by the preparation method and an application of the supported nano iridium catalyst in an anode catalyst for hydrogen production by electrolysis of water. The supported nano iridium catalyst prepared by the invention has low noble metal loading capacity, high activity and chemical stability, and can be used in the field of hydrogen production by electrolysis of water; the catalyst is prepared by adopting a sol-gel method, and the molar ratio of reactants is regulated, so that the utilization rate of iridium can be effectively increased, and the catalyst has higher reaction activity while the use amount of iridium is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic catalysts, and in particular to a supported nano-iridium catalyst, a preparation method and application thereof. Background Art

[0002] The main function of the catalyst for water electrolysis is to reduce the energy barrier of the electrolysis reaction, thereby improving the efficiency and rate of water electrolysis. The catalyst can promote the water electrolysis reaction, reduce the activation energy of the reaction, and make the hydrogen and oxygen production rates of water electrolysis faster, thereby improving the efficiency of water electrolysis and reducing costs.

[0003] Commonly used catalysts for water electrolysis include platinum group metals, iridium, aluminum oxide, zirconium oxide, tungsten oxide, copper oxide, iron oxide, etc. Among them, iridium-based catalysts have become an important anode catalyst choice for PEM water electrolysis hydrogen production due to their excellent electrochemical performance and stability. Currently, the most commonly used OER (oxygen evolution reaction) catalysts are iridium oxide and iridium black, but the iridium utilization rate of traditional iridium-based catalysts is low, and their catalytic layer cannot provide enough active sites in the OER reaction. Therefore, it is necessary to design and prepare an OER catalyst with low iridium content, higher activity, and simple preparation process. Summary of the invention

[0004] The object of the present invention is to provide a supported nano-iridium catalyst, a preparation method and application thereof, so as to at least solve the above technical problems.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, a method for preparing a supported nano-iridium catalyst is provided, comprising the following steps:

[0007] S1, mixing propanol, water and tetrabutyl stannate to obtain a first solution;

[0008] S2, adding an iridium source to the first solution to obtain a second solution;

[0009] S3, allowing the second solution to stand in air and then drying to obtain a dried product;

[0010] S4. The dried product is placed in a muffle furnace and calcined to obtain a supported nano-iridium catalyst.

[0011] The preparation method of the present invention is a sol-gel method, wherein tetrabutyl stannate is first hydrolyzed (C 16 H 36 Sn) to form tin hydroxide (Sn(OH) 4 ), the iridium source is then hydrolyzed to generate iridium hydroxide (Ir(OH) 3), and then the two undergo condensation reaction to generate Sn-O-Ir, forming a porous network structure; and then after drying and calcination, a supported nano-iridium catalyst (IrO 2 SnO 2 The propanol added in the present invention mainly plays a homogenizing role, so that the generated tin hydroxide powder can maintain a uniform particle size and reduce agglomeration.

[0012] Furthermore, in S1, water and propanol are first mixed and then tetrabutyl stannate is added and stirred and mixed. Preferably, the stirring time is 15 to 30 minutes;

[0013] Furthermore, in S1, the molar ratio of water to propanol is 1:8 to 1:12, and the molar ratio of water to tetrabutyl stannate is 50:1 to 100:1.

[0014] Furthermore, in S2, the iridium source is hydrated iridium trichloride (IrCl 3 ·3H 2 O) or hydrated hexachloroiridium(IV) acid (H 2 IrCl 6 ·xH 2 O).

[0015] Furthermore, in S2, the molar ratio of tin to iridium in the second solution is 3:1 to 5:1.

[0016] Furthermore, in S2, the iridium source is added and then stirred for 1.5 to 2 hours, preferably 2 hours.

[0017] Furthermore, in S3, the second solution is allowed to stand in air for 8 to 12 hours and then dried in an oven at 60° C. to 80° C.

[0018] Furthermore, in S4, the calcination temperature of the muffle furnace is 350° C. to 450° C., and the calcination time is 1.5 to 3 hours, preferably 2 hours.

[0019] On the other hand, the invention provides the use of the above-mentioned supported nano-iridium catalyst in an anode catalyst for producing hydrogen by electrolyzing water.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Compared with the mechanical grinding method, the sol-gel method adopted in the present invention has a more complete reaction, and the molar ratio of tin and iridium can be precisely controlled to achieve the preparation of supported catalysts with different iridium contents, and further by controlling the molar ratio of the reactants tin and iridium, the utilization rate of iridium is effectively improved, so that the catalyst has a higher reaction activity while reducing the amount of iridium used.

[0022] 2. Compared with the Adams melting method, the sol-gel method used in the present invention does not produce harmful gases to pollute the environment.

[0023] 3. The preparation method of the present invention is simple and a catalyst with excellent performance can be obtained without a complicated annealing process.

[0024] 4. The catalyst prepared by the sol-gel method of the present invention has good carrier dispersion and can more precisely control the composition of each material. The secondary particle size of the particles generated by the sol-gel method is basically distributed in the submicron range, with a large corresponding specific surface area and a high specific surface area. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the LSV diagram of the polarization curve of the test example of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. The terms "first", "second", etc. in the present invention are used to distinguish different objects, rather than to describe a specific order.

[0027] Example 1

[0028] As a preferred embodiment of the present invention, the preparation method of the supported nano-iridium catalyst of this embodiment is as follows:

[0029] S1. After mixing 149.6 mL of propanol (about 2.001 mol) and 4.2 mL of water (about 0.233 mol), 1.02 g of tetrabutyl stannate (about 0.00294 mol) was added and stirred for 20 min to obtain a first solution;

[0030] S2, adding 0.52 g of hydrated iridium trichloride (about 0.00147 mol) to the first solution according to a molar ratio of tin to iridium (Sn:Ir) of 2:1 and mechanically stirring for 2 h to obtain a second solution;

[0031] S3, leaving the second solution in air for 8 hours and then drying it in an oven at 60° C. to obtain a drying product;

[0032] S4, placing the dried product in a muffle furnace and calcining it at 450°C for 2h to obtain a supported nano-iridium catalyst IrO with a Sn:Ir molar ratio of 2:1 2 SnO 2 .

[0033] Example 2

[0034] As a preferred embodiment of the present invention, the preparation method of the supported nano-iridium catalyst of this embodiment is as follows:

[0035] S1. After mixing 149.6 mL of propanol (about 2.001 mol) and 4.2 mL of water (about 0.233 mol), 1.02 g of tetrabutyl stannate (about 0.00294 mol) was added and stirred for 20 min to obtain a first solution;

[0036] S2, adding 0.35 g of hydrated iridium trichloride (about 0.00098 mol) to the first solution according to a molar ratio of tin to iridium (Sn:Ir) of 3:1 and mechanically stirring for 2 h to obtain a second solution;

[0037] S3, leaving the second solution in air for 8 hours and then drying it in an oven at 60° C. to obtain a drying product;

[0038] S4, placing the dried product in a muffle furnace and calcining it at 450°C for 2h to obtain a supported nano-iridium catalyst IrO with a Sn:Ir molar ratio of 3:1 2 SnO 2 .

[0039] Example 3

[0040] As a preferred embodiment of the present invention, the preparation method of the supported nano-iridium catalyst of this embodiment is as follows:

[0041] S1. After mixing 149.6 mL of propanol (about 2.001 mol) and 4.2 mL of water (about 0.233 mol), 1.02 g of tetrabutyl stannate (about 0.00294 mol) was added and stirred for 20 min to obtain a first solution;

[0042] S2, adding 0.26 g of hydrated iridium trichloride (about 0.000735 mol) to the first solution according to a molar ratio of tin to iridium (Sn:Ir) of 4:1 and mechanically stirring for 2 h to obtain a second solution;

[0043] S3, leaving the second solution in air for 8 hours and then drying it in an oven at 60° C. to obtain a drying product;

[0044] S4, placing the dried product in a muffle furnace and calcining at 450°C for 2h to obtain a supported nano-iridium catalyst IrO with a Sn:Ir molar ratio of 4:1 2 SnO 2 .

[0045] Comparative Example

[0046] The commercial iridium oxide catalyst used in this comparative example is the scientific iridium oxide IrO produced by Ningbo Zhongke Kexin Energy. 2 .

[0047] Test example

[0048] The catalysts of Examples 1 to 3 and the comparative example were tested as follows:

[0049] 2 mg of catalyst, 360 μL of isopropanol, 40 μL of deionized water, and 18 μL of 5 wt% Nafion solution were ultrasonically mixed to form a homogeneous ink. Then, 4 μL of the homogeneous ink was dropped onto the glassy carbon electrode using a pipette. A three-electrode electrolytic cell was used with an electrolyte of 0.5 mol / L H 2 SO 4 The solution was prepared by using an electrochemical workstation at room temperature, and data was collected by linear sweep voltammetry at a scan rate of 10 mV / s between 1.3 and 1.8 V. The polarization curve LSV diagram was obtained after iR correction of the potential, as shown in Figure 1 shown.

[0050] Figure 1 Comparison of different catalysts at 10 mA / cm 2 The corresponding overpotential under the current density is similar to that of the commercial catalyst IrO 2 In comparison, the overpotential of the catalyst of the embodiment of the present invention is significantly reduced, with the lowest being only 220 mV (0.22 V). 2 The overpotential increases rapidly, indicating that the OER activity of the commercial catalyst is relatively low. At the same potential, the current density of the catalyst of the present invention is also significantly higher than that of the commercial catalyst IrO 2 . And, from Figure 1 It can also be seen that at the same current density, the catalyst performance of Example 2 of the present invention is the lowest, indicating that the IrO 2 SnO 2 Supported catalysts performed best.

[0051] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or modifications made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a supported nano-iridium catalyst, characterized in that: The following steps are involved: S1, mixing propanol, water and tetrabutyl stannate to obtain a first solution; S2, adding an iridium source to the first solution to obtain a second solution; S3, allowing the second solution to stand in air and then drying to obtain a dried product; S4. The dried product is placed in a muffle furnace and calcined to obtain a supported nano-iridium catalyst.

2. The method for preparing a supported nano-iridium catalyst according to claim 1, wherein: In S1, water and propanol are first mixed and then tetrabutyl stannate is added and stirred. Preferably, the stirring time is 15 to 30 minutes.

3. The method for preparing a supported nano-iridium catalyst according to claim 1, wherein: In the S1, the molar ratio of water to propanol is 1:8 to 1:12, and the molar ratio of water to tetrabutyl stannate is 50:1 to 100:

1.

4. The method for preparing a supported nano-iridium catalyst according to claim 1, wherein: In S2, the iridium source is hydrated iridium trichloride or hydrated hexachloroiridic (IV) acid.

5. The method for preparing a supported nano-iridium catalyst according to claim 1, wherein: In S2, the molar ratio of tin to iridium in the second solution is 3:1 to 5:

1.

6. The method for preparing a supported nano-iridium catalyst according to claim 1, wherein: In S2, the iridium source is added and then stirred for 1.5 to 2 hours, preferably 2 hours.

7. The method for preparing a supported nano-iridium catalyst according to claim 1, characterized in that: In S3, the second solution is allowed to stand in air for 8 to 12 hours and then dried in an oven at 60 to 80°C.

8. The method for preparing a supported nano-iridium catalyst according to claim 1, characterized in that: In the step S4, the calcination temperature of the muffle furnace is 350° C. to 450° C., and the calcination time is 1.5 to 3 hours, preferably 2 hours.

9. A supported nano-iridium catalyst, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. The use of a supported nano-iridium catalyst according to claim 9, characterized in that: Application in anode catalyst for hydrogen production by water electrolysis.

Images