CN112126951A - Preparation method of oxygen evolution reaction electrocatalyst - Google Patents

Abstract

_The invention discloses a preparation method of an _{electrocatalyst} for _{oxygen evolution} reaction. _Carbon paper is treated under the condition of concentrated _{sulfuric acid ; 4} · 2H ₂ O, Na ₂ WO ₄ · 2H ₂ O, boric acid, ascorbic acid, and FeSO ₄ · 7H ₂ O The reagents were dissolved in deionized water in the order to obtain a ready-to-use plating solution; then the carbon paper was placed in the plating solution for constant temperature. Potential deposition, after the reaction is over, the obtained sample is rinsed with deionized water and anhydrous alcohol, and dried with cold air, to obtain the electrocatalyst for the oxygen evolution reaction of the iron-based alloy. The method has the advantages of low implementation cost, stable structure, simple operation and short preparation period, and is an efficient and economical synthesis method.

Description

A kind of preparation method of oxygen evolution reaction electrocatalyst

technical field

The invention relates to the technical field of iron-based alloy oxygen evolution reaction electrocatalysts, and more particularly, to a preparation method of iron-based alloy oxygen evolution reaction electrocatalysts and its application in electrocatalytic oxygen evolution in alkaline solution.

Background technique

Traditional fossil fuels are not renewable in a short period of time, and they will bring a series of environmental problems after use. Hydrogen energy is a renewable and clean energy that is expected to become an alternative energy to fossil fuels. Hydrogen production by electrolysis of water is an effective way to produce hydrogen. Hydrogen production from water electrolysis consists of two half-reactions: hydrogen evolution at the cathode and oxygen evolution at the anode. Since the oxygen evolution reaction needs to undergo a four-electron transfer process, the kinetic process is slower and becomes a bottleneck limiting the efficiency of water electrolysis. Precious metal compounds such as ruthenium and iridium are the most efficient oxygen evolution catalysts at present, but the high cost and resource shortage limit their application and promotion. Therefore, it is urgent to develop a cheap and energy-saving oxygen evolution catalyst with low overpotential. The high specific surface area and the synergistic effect between elements are beneficial to improve the catalytic performance of the material, and the electrodeposition method is simple and easy to operate, which is convenient for industrial production. The high specific surface area iron-based alloy oxygen evolution electrocatalyst prepared by the electrodeposition method uses the synergistic effect between elements to improve the oxygen evolution catalytic performance, and the elements contained are all base metals, which are cheap and easy to obtain. Therefore, it is necessary and reasonable to study the preparation of Fe-based alloy electrocatalysts for oxygen evolution by electrodeposition.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a preparation method of an oxygen evolution reaction electrocatalyst, which is low in cost, simple in preparation process, low in implementation cost and easy to operate.

The technical purpose of the present invention is achieved through the following technical solutions.

A preparation method of an oxygen evolution reaction electrocatalyst is carried out according to the following steps:

Using carbon paper as the working electrode, a three-electrode system was used for potentiostatic deposition in the plating solution to obtain an electrocatalyst for the oxygen evolution reaction on the carbon paper; the deposition potential range was -1.0V～-1.5V vs SCE, and the deposition time was 10～ 40min; deionized water is used as solvent in the plating solution, and the concentration of each solute is 0.2～0.6mol·L -1 of sodium citrate, 0.1～0.4mol·L ^-1 of ferric sulfate, 0.1～0.4mol·L ^{-1 of} nickel sulfate ^1. Sodium molybdate 0.01～0.1mol·L ^-1 , sodium tungstate 0.01～0.1mol·L ^-1 , boric acid 0.2～0.5mol·L ^-1 and ascorbic acid 0.1～0.3mol·L ^-1 , pH 4 ~7.

In the above technical solution, the deposition potential ranges from -1.0V to -1.3V vs SCE, the deposition time is 10 to 30 minutes, and the deposition temperature is 20 to 25 degrees Celsius at room temperature.

In the above technical solution, the platinum mesh is used as the counter electrode, and the saturated calomel electrode is used as the reference electrode.

In the above technical scheme, after the constant potential deposition, the obtained product is washed with deionized water and alcohol, and then blown dry with cold air, so as to obtain the electrocatalyst for the oxygen evolution reaction of the iron-based alloy.

In the above technical solution, the concentration of each solute in the plating solution is 0.3-0.5 mol·L -1 of sodium citrate, 0.1-0.3 mol·L ^-1 of ferric sulfate, 0.2-0.4 mol·L ^-1 of nickel sulfate, and 0.2 to 0.4 mol·L ^-1 of molybdenum. Sodium 0.04～0.07mol·L ^-1 , sodium tungstate 0.05～0.08mol·L ^-1 , boric acid 0.3～0.5mol·L ^-1 and ascorbic acid 0.1～0.2mol·L ^-1 .

In the above technical solution, according to Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NiSO ₄ ·6H ₂ O, Na ₂ MoO ₄ ·2H ₂ O, Na ₂ WO ₄ ·2H ₂ O, boric acid, ascorbic acid and FeSO _4. The order and concentration of 7H ₂ O require that the reagents be dissolved in a 200ml beaker, deionized water to make up to 200ml, fully stirred to dissolve, and then allowed to stand for 2 hours to prepare a plating solution.

In the above technical solution, the carbon paper is a hydrophilic carbon paper, and the carbon paper is selected to be treated in concentrated sulfuric acid to improve the hydrophilicity of the carbon paper and to form hydroxyl, carboxyl or aldehyde functional groups on the surface. The concentrated sulfuric acid used It is 95-98wt% sulfuric acid, the treatment time is 5-8 hours, and the treatment temperature is 20-50 degrees Celsius.

The invention also discloses the iron-based alloy oxygen evolution reaction electrocatalyst obtained according to the above method and its application in the electrolysis of water to produce oxygen.

Compared with the prior art, the beneficial effects of the present invention are as follows: the iron-based alloy oxygen evolution reaction electrocatalyst has high electrocatalytic oxygen evolution activity and stability; the synthesis method of the present invention adopts an electrodeposition method to obtain the iron-based alloy precipitation. The oxygen reaction electrocatalyst has the advantages of simple process, mild conditions, short reaction time, good reproducibility, safe operation and high yield, and can be suitable for large-scale production.

Description of drawings

FIG. 1 is a SEM photograph of the electrocatalyst for the oxygen evolution reaction of the iron-based alloy prepared in Example 1 of the present invention.

Fig. 2 is the morphology-EDS-XRD spectrum diagram of the iron-based alloy oxygen evolution reaction electrocatalyst prepared in Example 1 of the present invention, wherein a is the SEM photo of the sample; b is the STEM photo of the sample; c is the HRSEM photo of the sample; d is the sample The SAED pattern of the sample; e is the transmission EDS pattern of the sample; f is the element surface distribution of the sample; g is the phase structure (XRD) of the sample and blank carbon paper.

Fig. 3 is the electrochemical performance test curve diagram of the iron-based alloy oxygen evolution reaction electrocatalyst prepared in Example 1 of the present invention, wherein a is the iron-based alloy oxygen evolution catalyst in 1 mol·L ^-1 KOH solution with a scan rate of 10/20 /40/60/80/100/120/140/160/180/200mV·s ^-1 (in the direction of the arrow in the figure) scanning cyclic voltammetry curve, b is the relationship between capacitive current and scanning speed.

Fig. 4 is a linear sweep voltammogram of the iron-based alloy oxygen evolution catalyst prepared in Example 1 of the present invention in 1 mol·L ^-1 KOH solution scanned at 2 mV·s ^-1 .

Fig. 5 is a graph showing the stability test of the iron-based alloy oxygen evolution catalyst prepared in Example 1 of the present invention, wherein a is the scanning rate of the iron-based alloy oxygen evolution catalyst in 1 mol·L ^-1 KOH solution at 100mV·s ^-1 Stability test curve, b is the constant current stability test curve of Fe-based alloy precipitation catalyst at 10 mA·cm ^-1 .

Detailed ways

The method of the present invention will be further described below in conjunction with specific embodiments. A three-electrode system was used, the working electrode was Japan's Toray TGP-H-060 hydrophilic carbon paper, the counter electrode was a platinum mesh, and the reference electrode was a saturated calomel electrode (SCE), which was deposited in a potentiostatic mode. Japan Hitachi S-4800 scanning electron microscope, Japan Electron 2100F transmission electron microscope to observe the morphology of the sample; Japan Rigaku MiniFlex600 X-ray diffractometer to detect the phase structure of the sample; the deposition process and oxygen evolution performance tests are all using the American Gamry Interface 1000 electrochemical workstation.

Example 1:

The method for preparing iron-based alloy oxygen evolution reaction electrocatalyst, the preparation steps are as follows:

Step 1, heating the carbon paper to 40 degrees Celsius in concentrated sulfuric acid for 8h;

Step _2. According to _{Na3C6H5O7 · 2H2O} , _{NiSO4 ·} 6H2O, _{Na2MoO4 ·} 2H2O, _{Na2WO4 ·} 2H2O, boric _acid , ascorbic _acid and _FeSO4 · _7H Dissolve the reagents in a 200ml beaker in the order of ₂ O, dilute the volume to 200ml with deionized water, fully stir to dissolve and let stand for 2h, sodium citrate 0.5mol·L ^-1 , ferric sulfate 0.3mol·L ^-1 , nickel sulfate 0.1 mol·L ^-1 , sodium molybdate 0.05mol·L ^-1 , sodium tungstate 0.05mol·L ^-1 , boric acid 0.5mol·L ^-1 , ascorbic acid 0.1mol·L ^-1 ; the pH of the plating solution is 6;

Step 3. Use the carbon paper processed in step 1 as a working electrode, a platinum mesh as a counter electrode, and a saturated calomel electrode as a reference electrode, and in the plating solution obtained in step 2, the three-electrode system is used for constant potential deposition, and the obtained products are deionized water and alcohol. After cleaning with cold air and drying, the electrocatalyst for the oxygen evolution reaction of iron-based alloys can be obtained. The deposition potential is -1.3V vs SCE; the deposition time is 20 min.

Example 2:

The preparation process is basically the same as that of Example 1, and the only difference is that in step 2, the deposition potential is -1.2Vvs SCE.

Example 3:

The preparation process is basically the same as that of Example 1, except that in step 1, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O 0.4mol·L ^-1 , and the deposition potential is -1.1V vs SCE.

Example 4:

The preparation process is basically the same as that of Example 1, and the only difference is that: in step 1, the deposition potential is -1.0Vvs SCE. It can be seen from Figure 1 and Figure 2a that the FeNiMoW alloy grows uniformly on the surface of the carbon fiber in a sheet-like structure. It can be seen from Figure 2b that the FeNiMoW sheet-like structure is full of wrinkles. From Figure 2c, it can be seen that the FeNiMoW alloy is an amorphous matrix with 4-6 nm distributed on it. The XRD results show that the nanocrystals are amorphous (Fig. 2g), and some diffraction spots are distributed in the amorphous halo of the selected area electron diffraction pattern (Fig. 2d). All elements are indeed deposited successfully on the surface, and it can be seen from Figure 2f that the four elements are uniformly distributed in the sample. The electrochemical active specific surface area of the sample was detected by the cyclic voltammetry curve in Figure 3. It can be seen from Figure 3b that the slope is 73.21mF·cm ^-2 , indicating that the sample has more electrochemical reaction active sites. It has a small oxygen evolution reaction overpotential of 299.14 mV at the cm ^-1 current density. It can be seen from Fig. 5a that the difference between the first and the 5000th cycle of the 5000-cycle linear sweep voltammetry stability test is very small, indicating the oxygen evolution stability of the sample. Better, it can be seen from Fig. 5b that oxygen evolution is continuous at a current density of 10 mA·cm ^-1 for 40 hours, and the potential change of the oxygen evolution electrode of the sample is less than 0.01 mV, and the stability is good.

By adjusting the process parameters according to the content of the present invention, the preparation of the catalyst of the present invention can be realized, and the performance is basically consistent with that of the present invention, that is, the obtained electrocatalyst for the oxygen evolution reaction of the iron-based alloy has a small overpotential for the electrolysis of water and the production of oxygen. Under the current density of 10 mA·cm ^-1 , the average overpotential of the oxygen evolution reaction is 298-302 mV, indicating that the prepared material has a good application prospect in the field of electrolysis of water. The present invention has been exemplarily described above. It should be noted that, without departing from the core of the present invention, any simple deformation, modification, or other equivalent replacements that can be performed by those skilled in the art without any creative effort fall into the scope of the present invention. the scope of protection of the invention.

Claims (9)

1. The preparation method of the oxygen evolution reaction electrocatalyst is characterized by comprising the following steps of:

taking carbon paper as a working electrode, and carrying out constant potential deposition in a plating solution by using a three-electrode system to obtain an oxygen evolution reaction electrocatalyst on the carbon paper; the deposition potential range is-1.0V to-1.5V vs SCE, and the deposition time is 10-40 min; deionized water is used as a solvent in the plating solution, and the concentration of each solute is 0.2-0.6 mol.L of sodium citrate^-10.1 to 0.4 mol/L of iron sulfate^-10.1 to 0.4 mol/L of nickel sulfate^-10.01 to 0.1 mol/L of sodium molybdate^-10.01 to 0.1 mol/L sodium tungstate^-10.2 to 0.5 mol/L boric acid^-1And ascorbic acid 0.1 to 0.3 mol.L^-1The pH value is 4-7.

2. The method of claim 1, wherein the concentration of each solute in the plating solution is 0.3-0.5 mol.L sodium citrate^-10.1 to 0.3 mol/L of iron sulfate^-10.2 to 0.4 mol/L of nickel sulfate^-10.04 to 0.07 mol/L sodium molybdate^-10.05-0.08 mol/L sodium tungstate^-10.3 to 0.5 mol/L boric acid^-1And ascorbic acid 0.1 to 0.2 mol.L^-1。

3. The method for preparing the oxygen evolution reaction electrocatalyst according to claim 1 or 2, wherein the deposition potential range is-1.0V to-1.3V vs SCE, the deposition time is 10 to 30min, and the deposition temperature is 20 to 25 ℃ at room temperature.

4. The method for preparing an oxygen evolution reaction electrocatalyst according to claim 1 or 2, wherein a platinum mesh counter electrode and a saturated calomel electrode are used as reference electrodes.

5. The method of claim 1 or 2, wherein the carbon paper is hydrophilic carbon paper.

6. The method of claim 5, wherein the carbon paper is treated in concentrated sulfuric acid to improve hydrophilicity of the carbon paper and form hydroxyl, carboxyl or aldehyde functional groups on the surface of the carbon paper, the concentrated sulfuric acid is 95-98 wt% sulfuric acid, the treatment time is 5-8 hours, and the treatment temperature is 20-50 ℃.

7. An iron-based alloy oxygen evolution reaction electrocatalyst obtained by the method for preparing an oxygen evolution reaction electrocatalyst according to claim 1 or 2.

8. The iron-based alloy oxygen evolution reaction electrocatalyst according to claim 7, wherein the FeNiMoW alloy uniformly grows on the surface of the carbon fiber in a sheet structure, four elements of Fe, Ni, Mo and W are uniformly distributed, the FeNiMoW sheet structure is fully folded, and 4-6 nm of nanocrystals are distributed on an amorphous matrix of the FeNiMoW alloy.

9. The use of the iron-based alloy oxygen evolution reaction electrocatalyst obtained by the method for preparing an oxygen evolution reaction electrocatalyst according to claim 1 or 2, for electrolysis of water to produce oxygen, characterized in that it is used at 10 mA-cm^-1The overpotential of oxygen evolution reaction under current density can be 298-302 millivolts.

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