High-performance iridium-based oxide electrocatalyst material and simple preparation method thereof

Abstract

This invention discloses a high-performance iridium-based oxide catalyst material and its simple preparation method. For the first time, this invention utilizes a heteroelement doping strategy to control the high valence state of iridium under ambient pressure, thereby optimizing the electrocatalytic water oxidation performance of iridium-based oxides in strongly acidic environments. The experimental operation is simple, and the yield of samples is large, effectively solving the problems of low catalytic activity and poor stability of current iridium-based oxide materials, which is conducive to large-scale industrial production. Compared with commercial iridium dioxide catalysts, the composite iridium-based oxide material synthesized in this invention has the characteristics of high catalytic activity, strong catalytic stability, and high cost-effectiveness.

Description

Technical Field

[0001] This invention belongs to the field of iridium-based catalyst material modification, specifically relating to a high-performance iridium-based oxide electrocatalyst material and its simple preparation method. Background Technology

[0002] Producing "green hydrogen energy" through electrocatalytic water splitting holds promise for achieving global carbon emission reduction targets. However, the most promising green hydrogen production technology currently available, proton exchange membrane electrolysis, still exhibits certain shortcomings, the biggest limitation being the existing electrocatalyst materials for oxygen production. Although iridium-based electrocatalysts have attracted increasing attention due to their good activity and stability in acidic solvents, their low-quality activity and high economic cost hinder their large-scale application. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a high-performance iridium-based oxide electrocatalyst material and a simple preparation method thereof.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a high-performance iridium-based oxide electrocatalyst material includes the following steps:

[0006] (1) Mix barium salt, sodium salt and iridium oxide evenly and grind thoroughly, then press into sheets; preferably, the barium salt is barium acetate, the sodium salt is sodium carbonate and the iridium oxide is iridium dioxide.

[0007] (2) Place the material obtained in step (1) into a gas tube furnace, use pure argon to thoroughly purge the gas tube furnace three times, and finally anneal it at high temperature in pure oxygen; preferably, the high temperature annealing conditions are to keep it at 700-1000℃ for 5-10 hours.

[0008] (3) Repeat the above steps multiple times, and confirm the phase by XRD each time until it is clear that there is no impurity phase and the target product is obtained.

[0009] This invention uses sodium carbonate as the dopant source, which facilitates rapid decomposition and uniform diffusion of the dopant source and eliminates the introduction of other impurity elements, such as sulfur (sodium sulfate) or nitrogen (sodium nitrate). Simultaneously, a pure oxygen atmosphere and ultra-high temperature annealing promote the formation of intrinsically high-valence active sites, thereby optimizing the electrocatalytic water oxidation performance. The principle is that sodium ions have a stable low-valence state (+1) in the iridium-based oxide structure and clearly occupy iridium active sites. According to the principle of electroneutrality, the valence state of iridium at the active sites is significantly increased, thus improving the catalytic activity of the iridium-based oxide material.

[0010] The beneficial effects of this invention are as follows:

[0011] This invention is the first to utilize the strategy of sodium doping with alkaline metal elements to improve the valence state of iridium active sites under normal pressure, thereby regulating the electrocatalytic water oxidation performance of iridium-based oxide materials. The experimental operation is simple and the yield is high, effectively solving the problems of poor electrocatalytic performance and high economic cost of current iridium-based oxide materials. Attached Figure Description

[0012] Figure 1 XRD patterns of the products prepared for comparative examples and embodiments;

[0013] Figure 2 Ir L3 edge X-ray absorption spectra of the products prepared for comparative examples and embodiments;

[0014] Figure 3 Electrocatalytic oxygen production activity diagrams of the products prepared in comparative examples and embodiments;

[0015] Figure 4 Electrocatalytic oxygen production stability graphs of the products prepared for comparative examples and embodiments. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Comparative Example

[0018] A method for preparing barium iridium materials inert to conventional electrocatalytic reactions includes the following steps:

[0019] (1) 1021.7 mg of barium acetate and 672.7 mg of iridium dioxide were ground and mixed evenly, and then compressed into tablets.

[0020] (2) Place the material obtained in step (1) into a gas tube furnace, purge the gas tube furnace three times with pure argon, and finally introduce pure oxygen and anneal at 800°C for 5 hours.

[0021] (3) Repeat the above steps twice, and confirm the phase by XRD each time until it is clear that there is no impurity phase. The product obtained is BaIrO3.

[0022] Example 1

[0023] A method for preparing a core-shell structured graphene material with alkaline water-splitting properties includes the following steps:

[0024] (1) 1021.7 mg barium acetate, 53.0 mg sodium carbonate and 672.7 mg iridium dioxide were ground and mixed evenly, and then compressed into tablets.

[0025] (2) Place the material obtained in step (1) into a gas tube furnace, purge the gas tube furnace three times with pure argon, and finally introduce pure oxygen and anneal at 800°C for 5 hours.

[0026] (3) Repeat the above steps three times, confirming the phase each time by XRD characterization, until it is clear that no impurity phase exists; the product obtained is BaNa. 0.25 Ir 0.75 O 3-δ Where δ represents an oxygen vacancy.

[0027] Example 2

[0028] A method for preparing a core-shell structured graphene material with alkaline water-splitting properties includes the following steps:

[0029] (1) 2043.4 mg barium acetate, 212.0 mg sodium carbonate and 896.9 mg iridium dioxide were ground and mixed evenly, and then compressed into tablets.

[0030] (2) Place the material obtained in step (1) into a gas tube furnace, purge the gas tube furnace three times with pure argon, and finally introduce pure oxygen and anneal at 800°C for 5 hours.

[0031] (3) Repeat the above steps three times, confirming the phase each time by XRD characterization, until it is clear that no impurity phase exists. The product obtained is BaNa. 0.5 Ir 0.5 O 3-δ .

[0032] from Figure 1 It can be seen that the samples prepared in the comparative examples and embodiments have a pure phase structure; from Figure 2 It can be seen that the valence state of the iridium active sites in Examples 1 and 2 increases continuously with increasing doping concentration. The electrocatalytic oxygen production performance of the materials prepared in the comparative examples and examples was tested in a strongly acidic solvent (pH = 0, such as sulfuric acid solution) using the standard three-electrode method. The test results are as follows: Figure 3 and Figure 4 As shown, the embodiments exhibit a lower electrocatalytic oxygen production overpotential compared to the comparative examples, indicating that the present invention optimizes the electrocatalytic water oxidation energy of iridium-based oxide materials by controlling the valence state of active sites through doping, and the iridium-based oxide material with a doping concentration of 50 at% shows the highest performance optimization.

[0033] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance iridium-based oxide catalyst material, characterized in that: Includes the following steps: (1) Thoroughly grind the barium salt, sodium salt and iridium oxide powders and press them into tablets; (2) The material obtained in step (1) is placed in a gas tube furnace, the gas tube furnace is thoroughly purged, and finally annealed at high temperature in a pure oxygen atmosphere. (3) Repeat the above steps multiple times until it is confirmed that there are no impurities and thus the target catalyst is obtained; In step (1), the barium salt is barium acetate; the sodium salt is sodium carbonate; and the iridium-based oxide is commercially available iridium dioxide. In step (2), the high-temperature annealing is carried out at 700-1000℃ for 5-10 hours.

2. The method for preparing the high-performance iridium-based oxide catalyst material according to claim 1, characterized in that: In step (2), the gas used for washing is argon.

3. A high-performance iridium-based oxide catalyst material, characterized in that: It is prepared using the preparation method described in claim 1 or 2.

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