Iron impurity adsorption resistant electrode, preparation method and equipment

Abstract

The invention discloses an anti-iron impurity adsorption electrode, a preparation method and equipment, and the electrode comprises a substrate which is at least subjected to cleaning and HCl soaking pretreatment; the electropositive coating is obtained by coating the surface of the substrate with electropositive catalytic slurry, the dry weight loading capacity is 1-3 mg / cm < 2 >, and the electropositive catalytic slurry is prepared from the following raw materials in parts by weight: 0.2-0.7 part of ruthenium oxide powder; 0.2 to 0.7 part of a cationic polymer; and 0.1 part of a surfactant. By optimizing the electrode structure, iron ions can be actively repelled, adsorption and deposition of the iron ions are prevented from the source, and the energy efficiency, stability and economical efficiency of an alkaline water electrolysis hydrogen production system are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alkaline electrolysis hydrogen electrode materials, and particularly relates to an iron impurity adsorption-resistant electrode, a preparation method and equipment. BACKGROUND

[0002] In the field of electrochemical energy conversion, alkaline water electrolysis hydrogen production technology is one of the main technical routes for large-scale green hydrogen production at present due to its mature technology, relatively low cost and easy scale-up. In this process, the hydrogen evolution reaction occurring on the cathode is the key step to determine the energy efficiency and hydrogen production rate of the entire system. A typical alkaline electrolysis tank usually uses a high-concentration potassium hydroxide aqueous solution (such as 25-30wt% KOH) as the electrolyte, and the operating temperature is between 70-90°C. In this harsh environment of strong alkali and high temperature, the structural materials of the electrolysis tank (especially low-carbon steel parts) will inevitably be slowly corroded, resulting in the continuous presence of iron ion impurities (mainly Fe(OH)4 - In addition, if the industrial water purity control is not strict or the raw alkali itself contains iron impurities, this problem will be aggravated. These dissolved iron ions will migrate to the cathode surface under the action of an electric field. In the high reducing environment of the cathode, they are easily reduced to metallic iron or iron hydroxide and deposited on the catalytically active sites of the cathode. This deposition behavior will cause a series of problems, such as active site shielding, increased mass transfer resistance, increased overpotential, and decreased stability.

[0003] Currently, the conventional methods for alleviating the influence of iron ions in industry mainly include: frequent purification and filtration of the electrolyte, use of high-purity and expensive reagents, or setting up ion exchange resin pretreatment facilities before the electrolysis tank inlet. These methods have certain effects, but they are all "passive defense" strategies, and have the disadvantages of high operating cost, complex system, and inability to fundamentally prevent the deposition of iron ions on the cathode surface.

[0004] Therefore, in view of the above technical problems, it is necessary to provide an iron impurity adsorption-resistant electrode, a preparation method and equipment. SUMMARY

[0005] The purpose of the present application is to provide an iron impurity adsorption-resistant electrode, a preparation method and equipment.

[0006] In order to achieve the above-mentioned purpose, the technical scheme provided by an embodiment of the present application is as follows:

[0007] The iron impurity adsorption-resistant electrode comprises

[0008] The substrate is at least cleaned and HCl soaked for pretreatment;

[0009] The positive electrocoating is obtained by coating a positive electrocatalytic slurry on the surface of the substrate, and the dry loading amount is 1-3 mg / cm 2 The raw materials of the positive electrocatalytic slurry include, in parts by weight: 0.2-0.7 parts of ruthenium oxide powder; 0.2-0.7 parts of cationic polymer; and 0.1 part of surfactant.

[0010] In one or more embodiments of the present application, the cationic polymer is selected from polydiallyldimethylammonium chloride.

[0011] In one or more embodiments of the present application, the surfactant is selected from polyoxyethylene ethers. Preferably, Triton X-100 or Tween-20.

[0012] In one or more embodiments of the present application, the substrate is an electrode structure having high electrical conductivity, high specific surface area and corrosion resistance in a strong alkaline environment, and the electrode structure is selected from a nickel foam electrode and a nickel mesh electrode.

[0013] In one or more embodiments of the present application, the method for preparing the anti-iron impurity adsorption electrode comprises:

[0014] Preparation of the substrate and pretreatment thereof;

[0015] Preparation of the positive electrocatalytic slurry, coating on the surface of the substrate to form a coating and solidification.

[0016] In one or more embodiments of the present application, the pretreatment comprises a cleaning process, specifically: sequentially immersing the substrate in acetone, anhydrous ethanol and deionized water, and each ultrasonic cleaning for 15-30 minutes.

[0017] In one or more embodiments of the present application, the pretreatment further comprises acid soaking, specifically: soaking in an HCl solution for 3-10 minutes. Preferably, the concentration of the HCl solution is 1-5 M. Preferably, the concentration of the HCl solution is 3 M.

[0018] In one or more embodiments of the present application, the preparation of the positive electrocatalytic slurry comprises: weighing the ruthenium oxide powder, the cationic polymer, and an appropriate amount of deionized water and the surfactant, mixing, and ball milling for 6-12 hours to form a uniform slurry with appropriate viscosity.

[0019] In one or more embodiments of the present application, the solidification is: irradiation under ultraviolet light with an intensity of 50-100 mW / cm 2 for 5-10 minutes.

[0020] In one or more embodiments of the present application, the electrolytic hydrogen production device comprises an electrolysis chamber and an anti-iron impurity adsorption electrode arranged in the electrolysis chamber.

[0021] Compared with the prior art, the anti-iron impurity adsorption electrode, the preparation method and the device can "actively repel" iron ions, prevent the adsorption and deposition of the iron ions from the source, and improve the energy efficiency, stability and economy of the alkaline electrolytic water hydrogen production system, which helps to promote the cost reduction and efficiency increase of the green hydrogen industry in industrialization, and has urgent needs and great significance. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The electron microscope image of the anti-iron ion adsorption electrode in an embodiment of the present application;

[0024] Figure 2 The surface contrast image of the anti-iron ion adsorption electrode in an embodiment of the present application after long-time operation, wherein the left image is the electrode of Example 1 and the right image is the Raney nickel electrode. DETAILED DESCRIPTION

[0025] In order to make the person skilled in the art better understand the technical solutions in the present disclosure, the technical solutions in the present disclosure will be described clearly and completely in the following by combining the disclosed embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present disclosure, not all. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor should be within the protection scope of the present disclosure.

[0026] In the following embodiment schemes of the present application, the weight standard of each "part" in the composition ratio of the raw materials is the same reference, such as "milligram", "gram", "kilogram" and the like in the same technical scheme.

[0027] In the anti-iron impurity adsorption electrode of the present application, the following components are mainly included:

[0028] The base material is a material with high conductivity, high specific surface area and corrosion resistance in a strong alkali environment, such as foamed nickel, nickel mesh, nickel plate, etc.:

[0029] 1) Substrate pretreatment: The substrate was sequentially immersed in acetone, absolute ethanol and deionized water, each ultrasonic cleaning for 15-30 minutes, to completely remove the surface oil and organic matter. Immersed in 3M HCl for 3-10 min to remove the surface oxide layer and increase the surface roughness, thereby improving the adhesion of the subsequent catalytic layer. Rinse repeatedly with deionized water to neutral, then dry in a vacuum drying oven at 80°C for 2 hours, ready for use.

[0030] 2) Preparation of positive catalytic slurry:

[0031] Take 0.2-0.7 parts of ruthenium oxide powder; take 0.2-0.7 parts of cationic polymer, such as polydiallyldimethylammonium chloride. Mix the above powder with 10 parts of deionized water, 0.1 part of surfactant, and ball mill for 6-12 hours to form a uniform slurry with suitable viscosity.

[0032] 3) Coating: The slurry was uniformly coated on the surface of the pretreated substrate by spraying or scraping. The coating amount was controlled so that the loading amount of the catalytic layer was 1-3 mg / cm 2 .

[0033] 4) UV curing: The coated substrate was immediately placed in a UV light curing box and irradiated under UV light with an intensity of 50-100 mW / cm 2 for 5-10 minutes. UV irradiation can make the polymer crosslink and solidify quickly, and firmly combine with the catalyst particles and the substrate, forming a porous and stable catalytic layer.

[0034] Example 1

[0035] The anti-iron impurity adsorption electrode in this embodiment includes

[0036] 1) Substrate pretreatment: The nickel mesh was sequentially immersed in acetone, absolute ethanol and deionized water, each ultrasonic cleaning for 15 minutes, to completely remove the surface oil and organic matter. Immersed in 3M HCl for 5 min to remove the surface oxide layer and increase the surface roughness, thereby improving the adhesion of the subsequent catalytic layer. Rinse repeatedly with deionized water to neutral, then dry in a vacuum drying oven at 80°C for 2 hours, ready for use.

[0037] 2) Preparation of positive catalytic slurry:

[0038] Take 0.5g of ruthenium oxide powder, 0.3g of cationic polymer polydiallyldimethylammonium chloride. Mix the above powder with 10g of deionized water, 0.1g of surfactant Tween-20, and ball mill for 10 hours to form a uniform slurry with suitable viscosity.

[0039] 3) Coating: The slurry was uniformly coated on the surface of the pretreated substrate by spraying or scraping. The coating amount was controlled so that the loading amount of the catalytic layer was 2 mg / cm2 .

[0040] 4) UV curing: the coated substrate is immediately placed in a UV curing box and irradiated for 10 minutes under UV light with an intensity of 80 mW / cm 2 The UV irradiation can make the polymer quickly cross-link and solidify, and firmly combine with the catalyst particles and the substrate, forming a porous and stable catalytic layer.

[0041] The prepared electrode is as Figure 1 The prepared electrode is used as a cathode for long-term stacking test, and the iron adsorption before and after operation is compared with that of a commonly used Raney nickel electrode. The mass of the electrode of the present embodiment and the Raney nickel electrode before and after operation is weighed, and the iron content is tested by XRF. The results are shown in Table 1. Compared with the Raney nickel electrode, the mass change of the electrode of the present embodiment is smaller, and the surface iron content is lower. Figure 2 The surface morphology of the electrode of the present embodiment and the Raney nickel electrode after operation is shown in Table 1. It can be seen that there is almost no iron impurity adsorbed on the surface of the electrode of the present embodiment, while there is a layer of iron precipitate on the surface of the Raney nickel electrode. The EDS test results are shown in Table 2. It can be seen that the iron content on the surface of the electrode of the present embodiment is very low, while the iron content on the surface of the Raney nickel electrode is as high as 38.5%. In summary, it can be shown that the electrode of the present embodiment can realize anti-iron impurity adsorption when used as a cathode in an alkaline electrolytic cell for a long time.

[0042] Table 1: Comparison of data after long-term operation

[0043]

[0044] Table 2: EDS comparison after long-term operation

[0045]

[0046] Example 2

[0047] The difference between the present embodiment and Example 1 is that 0.2 g of ruthenium oxide powder is weighed; 0.2 g of cationic polymer polydiallyldimethylammonium chloride is weighed. The above-mentioned powder is mixed with 10 g of deionized water and 0.1 g of surfactant Tween-20, and ball-milled for 10 hours to form a uniform and suitable viscosity slurry.

[0048] Table 3: Comparison of data after long-term operation

[0049]

[0050] Table 4: EDS comparison after long-term operation

[0051]

[0052] Example 3

[0053] The difference between this example and Example 1 is that 0.7 g of ruthenium oxide powder is weighed; 0.7 g of cationic polymer polydiallyldimethylammonium chloride is weighed. The above powder is mixed with 10 g of deionized water, 0.1 g of surfactant Tween-20, and ball-milled for 10 hours to form a uniform and suitable viscosity slurry.

[0054] Table 5 Data comparison after long-term operation

[0055]

[0056] Table 6 EDS comparison after long-term operation

[0057]

[0058] Example 4

[0059] The difference between this example and Example 1 is that the solidification is: irradiated under ultraviolet light with an intensity of 50 mW / cm 2 for 5 minutes.

[0060] Table 7 Data comparison after long-term operation

[0061]

[0062] Table 8 EDS comparison after long-term operation

[0063]

[0064] The electrode of this example as a cathode has no obvious cracks and damage after more than 1000 h of long-term operation.

[0065] Example 5

[0066] The difference between this example and Example 1 is that the solidification is: irradiated under ultraviolet light with an intensity of 80 mW / cm 2 for 8 minutes.

[0067] Table 9 Data comparison after long-term operation

[0068]

[0069] Table 10 EDS comparison after long-term operation

[0070]

[0071] The electrode of this example as a cathode has no obvious cracks and damage after 1000 h of long-term operation.

[0072] Comparative Example 1

[0073] The difference between this example and Example 1 is that the cationic polymer is replaced by a phosphonate salt.

[0074] Table 11 Data comparison after long time running

[0075]

[0076] Table 10 EDS comparison after long time running

[0077]

[0078] It is apparent that the present disclosure is not limited to the details of the foregoing exemplary embodiments, and thus modifications and variations can be made in light of the above teachings or can be acquired from practice of the present disclosure. Further, it should be noted that any reasoning or underlying assumptions introduced herein are utilized primarily for the purpose of providing an example understanding of the present disclosure and are not intended to be limiting. Consequently, it is submitted that any and all modifications coming within the meaning and range of equivalency of the appended claims are intended to be embraced therein. No feature described herein should be deemed critical or essential to the practice of the claims unless specifically so identified.

[0079] Further, it should be appreciated that although the specification is described in terms of embodiments, not every embodiment contains only a single independent technical solution, and the specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. An electrode resistant to iron impurity adsorption, characterized in that, include The substrate is pretreated by at least cleaning and HCl immersion. The positively charged coating is obtained by coating a substrate surface with a positively charged catalytic slurry, with a dry weight loading of 1-3 mg / cm³. 2 The raw materials for the positively charged catalytic slurry include, by weight, 0.2-0.7 parts of ruthenium oxide powder; 0.2-0.7 parts of cationic polymer; 0.1 parts surfactant.

2. The anti-iron impurity adsorption electrode according to claim 1, characterized in that, The cationic polymer is selected from: polydiallyldimethylammonium chloride.

3. The anti-iron impurity adsorption electrode according to claim 1, characterized in that, The surfactant is a polyoxyethylene ether.

4. The anti-iron impurity adsorption electrode according to claim 1, characterized in that, The substrate is an electrode structure with high conductivity, high specific surface area and corrosion resistance in a strong alkaline environment. The electrode structure is selected from nickel foam electrode and nickel mesh electrode.

5. The method for preparing the anti-iron impurity adsorption electrode according to any one of claims 1-4, characterized in that, include: Prepare the substrate and perform pretreatment; Prepare a positively charged catalytic slurry, coat it onto the substrate surface to form a coating, and then cure it.

6. The method for preparing the anti-iron impurity adsorption electrode according to claim 5, characterized in that, The pretreatment includes a cleaning process, specifically: immersing the substrate sequentially in acetone, anhydrous ethanol, and deionized water, and ultrasonically cleaning each for 15-30 minutes.

7. The method for preparing the anti-iron impurity adsorption electrode according to claim 6, characterized in that, The pretreatment also includes acid soaking, specifically: soaking in HCl solution for 3-10 minutes.

8. The method for preparing the anti-iron impurity adsorption electrode according to claim 5, characterized in that, The preparation of the positively charged catalytic slurry includes: weighing ruthenium oxide powder, cationic polymer, and appropriate amount of deionized water and surfactant, mixing them, and ball milling for 6-12 hours to form a uniform slurry with suitable viscosity.

9. The method for preparing the anti-iron impurity adsorption electrode according to claim 5, characterized in that, The curing process involves applying a solution at a strength of 50-100 mW / cm. 2 Irradiate under ultraviolet light for 5-10 minutes.

10. An electrolytic hydrogen production apparatus, comprising an electrolysis chamber and an anti-iron impurity adsorption electrode according to any one of claims 1-4 disposed in the electrolysis chamber.

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