Electrolyte modification method for improving performance of alkaline electrolysis water electrode material and application of electrolyte modification method

Abstract

The invention relates to the technical field of nano materials and electrochemistry, in particular to an electrolyte modification method for improving the performance of an alkaline electrolysis water electrode material and application of the electrolyte modification method. An electrolyte modification method for improving the performance of an alkaline electrolysis water electrode material comprises the following steps: S1, weighing a certain amount of water-soluble sulfide, and dissolving the water-soluble sulfide in an alkaline electrolyte; and S2, activating the electrode in the sulfur-containing alkaline electrolyte to obtain the modified alkaline electrolyte. Compared with a traditional method for designing a new electrode material to improve the water electrolysis performance, a small amount of soluble sulfide additive is directly introduced into the electrolyte, so that the catalytic overpotential of the electrode material is effectively reduced, the reaction stability is improved, and efficient operation of an alkaline water electrolysis hydrogen production system is achieved.

Description

Technical Field

[0001] The present invention relates to the field of nanomaterials and electrochemical technology, and in particular to an electrolyte modification method for improving the performance of alkaline water electrolysis electrode materials and an application thereof. The method can be widely used in the field of water electrolysis hydrogen production. Background Art

[0002] As a typical clean energy, hydrogen energy has high energy density and its products are environmentally friendly, and is attracting widespread attention from the international community. Hydrogen production by water electrolysis has become a key technology for building a future carbon-neutral society. Alkaline water electrolysis is one of the most mature technologies for hydrogen production by water electrolysis. Its hydrogen production efficiency depends largely on the electrode materials used. Therefore, current technologies usually start from the development of high-efficiency electrode materials, adjusting the chemical composition of the materials or designing nanostructures to improve electrode performance. However, the manufacture of electrode materials with specific chemical compositions and nanostructures often requires expensive raw materials or complex synthesis processes, which is not conducive to the commercial application of the designed electrode materials. Electrolyte additives are a common strategy to improve the electrochemical performance of electrodes in the field of battery research, but they are rarely considered in electrocatalysis research. Appropriate electrolyte additives have the potential to adjust the chemical composition or nanostructure of the catalytically active phase at the interface between the electrode and the electrolyte, but this potential has not yet been developed. Summary of the invention

[0003] The electrolyte modification method provided by the present invention has a simple process and a short operation cycle. The modified electrolyte system effectively reduces the electrode overpotential, improves the energy efficiency of the water electrolysis reaction, and has excellent water electrolysis hydrogen production performance.

[0004] A method for modifying an electrolyte to improve the performance of an alkaline water electrolysis electrode material comprises the following steps:

[0005] S1. Weigh a certain amount of water-soluble sulfide and dissolve it in alkaline electrolyte;

[0006] S2. Activating the electrode in the above-mentioned sulfur-containing alkaline electrolyte can produce a modified alkaline electrolyte.

[0007] Furthermore, in S1, the water-soluble sulfide is one or more of lithium sulfide, sodium sulfide, potassium sulfide, and ammonium sulfide.

[0008] Furthermore, in S1, the alkaline electrolyte is alkaline water or saline water.

[0009] Furthermore, in S1, the concentration of the water-soluble sulfide dissolved in the electrolyte is 0.001 to 1 mol·L -1 .

[0010] Further, in S2, the electrode material is a nickel-based, cobalt-based or iron-based material.

[0011] Further, in S2, the activation method is standing or using cyclic voltammetry.

[0012] Furthermore, the static time condition is 1min~1d ；

[0013] If cyclic voltammetry is used, the scan rate should be 0.005 to 0.5 V·s -1 The number of circles is 1 to 1000.

[0014] Furthermore, the electrochemical performance of the modified alkaline electrolyte in S2 was tested by electrocatalytic hydrogen evolution, electrocatalytic oxygen evolution or full water electrolysis reaction.

[0015] The alkaline electrolyte treated by the alkaline electrolyte modification method.

[0016] The application of the above alkaline electrolyte in the field of hydrogen production by water electrolysis.

[0017] The beneficial effects of the present invention are as follows: the electrolyte modification method provided by the present invention can be used as an effective means to improve the performance of water electrolysis electrodes and alkaline water electrolysis hydrogen production systems. The electrolyte modification method has low raw material prices, simple operation methods, and can be scaled up. In particular, the sulfide additive is 0.001 to 10 mol·L -1 The concentration range is adjustable, and for different electrode materials or complex working environments, this method can significantly reduce the overpotential of the electrode reaction and improve the energy efficiency of the alkaline water electrolysis system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The Ni(OH) 2 SEM images of electrodes;

[0019] Figure 2 The Ni(OH) 2 Hydrogen evolution polarization curve of the electrode;

[0020] Figure 3 The Ni(OH) 2 Scanning electron microscope image of electrode;

[0021] Figure 4 The Ni(OH) 2 Electrode hydrogen evolution polarization curve. DETAILED DESCRIPTION

[0022] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0023] The present invention provides an electrolyte modification method for improving the performance of an alkaline water electrolysis electrode material, comprising the following steps:

[0024] S1. Weigh a certain amount of water-soluble sulfide and dissolve it in an alkaline electrolyte; wherein the water-soluble sulfide is one or more of lithium sulfide, sodium sulfide, potassium sulfide, and ammonium sulfide. The alkaline electrolyte is alkaline water (such as 1M KOH, 30wt% KOH, 1M NaOH, etc.) or saline water (such as seawater + 1M KOH, seawater + 30wt% KOH, etc.). The concentration of the water-soluble sulfide after dissolving in the electrolyte is 0.001 to 1 mol·L -1 , specifically, it can be 0.001 mol·L -1 , 0.01mol·L -1 , 0.05mol·L -1 , 0.1 mol·L -1 , 0.5mol·L -1 , 1mol·L -1 .

[0025] S2. Activate the electrode in the above-mentioned sulfur-containing alkaline electrolyte; wherein the electrode material is nickel-based, cobalt-based or iron-based. The activation method is to stand for 1 minute to 1 day, or to test using cyclic voltammetry in the selected voltage range at a scan rate of 0.005 to 0.5 V·s -1 , the number of turns is 1 to 1000. Specifically, the standing time of the present invention can be 1 min, 30 min, 60 min, 120 min, 240 min, 480 min, 960 min, 1440 min; the scanning speed can be 0.005 V·s -1 , 0.025V·s -1 , 0.05V·s -1 , 0.2V·s -1 , 0.25V·s -1 , 0.5V·s -1 ; The number of circles can be 1 circle, 100 circles, 250 circles, 500 circles, 750 circles, and 1000 circles.

[0026] S3. Testing the electrochemical performance of the activated electrode material in a sulfur-containing alkaline electrolyte; wherein the electrochemical performance may be electrocatalytic hydrogen evolution, electrocatalytic oxygen evolution or full electrolysis of water reaction, wherein electrocatalytic hydrogen evolution, electrocatalytic oxygen evolution or full electrolysis of water reaction are all prior arts.

[0027] The present invention also aims to protect the alkaline electrolyte obtained by the above-mentioned modification method.

[0028] The present invention also aims to protect the application of the modified alkaline electrolyte in the field of hydrogen production by electrolysis of water.

[0029] <Comparative Example 1>

[0030] A method for preparing an electrolyte without electrolyte additives comprises the following steps:

[0031] S1, without using sulfide additives, directly prepare 1mol·L -1 NaOH alkaline electrolyte;

[0032] S2. In the above alkaline electrolyte, Ni(OH) 2 The electrode was activated at a voltage range of -1.0 V to 0 V (relative to the reversible hydrogen electrode) at a rate of 0.2 V·s -1 100 cycles of cyclic voltammetry were performed at a scan rate of 100 cycles;

[0033] S3, the activated electrode was heated to 1 mol·L -1 The electrochemical hydrogen evolution performance was tested in NaOH electrolyte.

[0034] Using the Ni(OH) 2 The scanning electron microscope image of the electrode is shown in Figure 1 As shown, the figure shows that Ni(OH) 2 The active material presents a typical nanosheet structure with a relatively flat and smooth surface. Its electrochemical hydrogen evolution performance is as follows Figure 2 The polarization curves show that at 10 mA cm -2 At a current density of , its electrode overpotential is 273mV.

[0035] <Example 1>

[0036] A method for modifying an electrolyte to improve the performance of an alkaline water electrolysis electrode material comprises the following steps:

[0037] S1, weigh 1.2009g Na 2 S.9H 2 O, and dissolve it all in 0.1L 1mol·L -1 In NaOH solution, a sulfur-containing alkaline electrolyte is prepared;

[0038] S2, in the above sulfur-containing alkaline electrolyte, Ni(OH) 2 The electrode was activated at a voltage range of -1.0 V to 0 V (relative to the reversible hydrogen electrode) at a rate of 0.2 V·s -1 100 cycles of cyclic voltammetry were performed at a scan rate of 100 cycles;

[0039] S3. Conducting an electrochemical hydrogen evolution performance test on the activated electrode in a sulfur-containing alkaline electrolyte.

[0040] Obtaining Ni(OH) using the electrolyte modification method in Example 1 2The scanning electron microscope image of the electrode shows Figure 3 As shown, the figure shows that Ni(OH) 2 The active material still has a nanosheet structure, and its surface becomes obviously rough, indicating that the specific surface area of ​​the electrode has been increased to a certain extent. Figure 4 The polarization curves are shown in Figure 1. At 10 mA cm -2 At a current density of , the electrode overpotential is only 196 mV. Compared with the electrode in Comparative Example 1, its overpotential is reduced by 77 mV. The above results show that the electrode using the electrolyte modification method of Example 1 has a larger specific surface area and significantly improved electrocatalytic hydrogen evolution performance.

[0041] <Example 2>

[0042] A method for modifying an electrolyte to improve the performance of an alkaline water electrolysis electrode material comprises the following steps:

[0043] S1, weigh 2.4018g Na 2 S·9H 2 O, and dissolve it all in 0.1L 1mol·L -1 In NaOH solution, a sulfur-containing alkaline electrolyte is prepared;

[0044] S2, in the above sulfur-containing alkaline electrolyte, Ni(OH) 2 The electrode was activated at a voltage range of -1.0 V to 0 V (relative to the reversible hydrogen electrode) at a rate of 0.2 V·s -1 100 cycles of cyclic voltammetry were performed at a scan rate of 100 cycles;

[0045] S3. Conducting an electrochemical hydrogen evolution performance test on the activated electrode in a sulfur-containing alkaline electrolyte.

[0046] This Example 2 changes the Na 2 S·9H 2 O addition, the concentration of sulfide additives was increased, and the electrochemical hydrogen evolution performance of the electrode after electrolyte modification was tested. -2 At a current density of , the electrode overpotential is 221 mV. Compared with comparative example 1, its electrocatalytic hydrogen evolution performance is improved.

[0047] <Example 3>

[0048] A method for modifying an electrolyte to improve the performance of an alkaline water electrolysis electrode material comprises the following steps:

[0049] S1, weigh 1.2009g Na 2 S·9H 2 O, and dissolve it all in 0.1L 1mol·L -1In NaOH solution, a sulfur-containing alkaline electrolyte is prepared;

[0050] S2, in the above sulfur-containing alkaline electrolyte by standing for 1h to react Ni(OH) 2 The electrode is activated;

[0051] S3. Conducting an electrochemical hydrogen evolution performance test on the activated electrode in a sulfur-containing alkaline electrolyte.

[0052] In this embodiment 3, the electrode activation method is changed, and the electrochemical hydrogen evolution performance test is carried out on the electrode after the electrolyte modification. -2 At a current density of , the electrode overpotential is 232 mV. Compared with comparative example 1, its electrocatalytic hydrogen evolution performance is improved.

[0053] <Example 4>

[0054] A method for modifying an electrolyte to improve the performance of an alkaline water electrolysis electrode material comprises the following steps:

[0055] S1, weigh 1.2009g Na 2 S.9H 2 O and 0.5513 g K 2 S, dissolve all of it in 0.1L 1mol·L -1 In NaOH solution, a sulfur-containing alkaline electrolyte is prepared;

[0056] S2, in the above sulfur-containing alkaline electrolyte, Ni(OH) 2 The electrode was activated at a voltage range of -1.0 V to 0 V (relative to the reversible hydrogen electrode) at a rate of 0.2 V·s -1 100 cycles of cyclic voltammetry were performed at a scan rate of 100 cycles;

[0057] S3. Conducting an electrochemical hydrogen evolution performance test on the activated electrode in a sulfur-containing alkaline electrolyte.

[0058] In Example 4, a composition of multiple sulfide additives was used, and the electrochemical hydrogen evolution performance of the electrode after the electrolyte modification was tested. -2 At a current density of , the electrode overpotential is 219 mV. Compared with comparative example 1, its electrocatalytic hydrogen evolution performance is improved.

[0059] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for modifying an electrolyte to improve the performance of an alkaline water electrolysis electrode material, characterized in that: The following steps are involved: S1. Weigh a certain amount of water-soluble sulfide and dissolve it in alkaline electrolyte; S2. Activating the electrode in the above-mentioned sulfur-containing alkaline electrolyte can produce a modified alkaline electrolyte.

2. The alkaline electrolyte modification method for improving the performance of alkaline water electrolysis electrode materials according to claim 1, characterized in that: In S1, the water-soluble sulfide is one or more of lithium sulfide, sodium sulfide, potassium sulfide, and ammonium sulfide.

3. The alkaline electrolyte modification method for improving the performance of alkaline water electrolysis electrode materials according to claim 1, characterized in that: In S1, the alkaline electrolyte is alkaline water or saline water.

4. The method for modifying an electrolyte for improving the performance of an alkaline water electrolysis electrode material according to claim 1, characterized in that: In S1, the concentration of water-soluble sulfide dissolved in the electrolyte is 0.001 to 1 mol·L -1 .

5. The method for modifying an electrolyte for improving the performance of an alkaline water electrolysis electrode material according to claim 1, characterized in that: In S2, the electrode material is nickel-based, cobalt-based or iron-based material.

6. The method for modifying an electrolyte for improving the performance of an alkaline water electrolysis electrode material according to claim 1, characterized in that: In S2, the activation method is static or cyclic voltammetry.

7. The method for modifying an electrolyte for improving the performance of an alkaline water electrolysis electrode material according to claim 6, characterized in that: The static time condition is 1min~1d ； If cyclic voltammetry is used, the scan rate should be 0.005 to 0.5 V·s -1 The number of circles is 1 to 1000.

8. The method for modifying an electrolyte for improving the performance of an alkaline water electrolysis electrode material according to claim 1, characterized in that: The electrochemical performance of the modified alkaline electrolyte in S2 was tested by electrocatalytic hydrogen evolution, electrocatalytic oxygen evolution or full water electrolysis reaction.

9. An alkaline electrolyte treated by the alkaline electrolyte modification method according to any one of claims 1 to 8.

10. Use of the alkaline electrolyte according to claim 9 in the field of hydrogen production by water electrolysis.

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