CN114507877A - A kind of preparation method and application of photoelectrode film with graphitic carbon nitride as base material - Google Patents

Abstract

The invention relates to a preparation method and application of a photoelectrode film using graphitic carbon nitride as a base material, and belongs to the technical field of photoelectrochemistry. Put melamine into distilled water, heat it on a stirrer until the solution is clear, add terephthalaldehyde powder, stir for a period of time, put it into an oven to dry to obtain a precursor, and calcine the precursor at high temperature in a nitrogen environment, Obtain the target product, grind the target product into powder, then take an appropriate amount of powder and disperse it in acetone containing I, and ultrasonically vibrate to obtain an electrophoretic deposition suspension, and immerse _two transparent conductive glasses with equal areas face to face and parallel to each other in the electrophoretic deposition suspension. , Electrodeposition preparation of photoelectrode thin films. The photoelectrode film with graphitic carbon nitride as the base material prepared by the method of the present invention can effectively separate the electron-hole pair, reduce the recombination rate of the electron-hole, thereby effectively improving the photoelectrochemical performance and achieving efficient decomposition purpose of water.

Description

A kind of preparation method and application of photoelectrode film with graphitic carbon nitride as base material

technical field

The invention relates to a preparation method and application of a photoelectrode film using graphitic carbon nitride as a base material, and belongs to the technical field of photoelectrochemistry.

Background technique

With the development of human society, the burning of fossil fuels has caused a series of serious environmental problems. Photoelectrochemical cells to solve environmental pollution and energy shortage have become the focus of attention. Photoelectrochemical water splitting to produce hydrogen, which converts solar energy into storable chemical energy, is the main means to solve environmental and energy problems in the 21st century. Graphitized carbonitride photocatalyst is a photocatalytic material with low price, abundant resources and good stability, and is considered as a photocatalytic material with the prospect of purifying pollution and saving energy. However, unmodified graphitic carbon nitride limits its practical application due to its relatively inefficient light absorption, low electron-hole separation efficiency, and fewer active sites.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems, the purpose of the present invention is to provide a preparation method and application of a photoelectrode film with graphitic carbon nitride as a base material, which is easy to operate, simple, convenient, low in cost, mild in conditions, and conducive to large-scale production. Production.

The technical scheme adopted in the present invention is: a preparation method of a photoelectrode film with graphitic carbon nitride as a base material, comprising the following steps:

1) adding melamine into distilled water, heating and magnetic stirring until the solution is clarified, then adding terephthalaldehyde, continuing to heating magnetic stirring, and putting the obtained mixed solution into an oven for drying to obtain a precursor;

2) calcining the precursor obtained in step 1) at a high temperature in a nitrogen environment to obtain the target product;

3) grinding the target product obtained in step 2) into powder, taking an appropriate amount of powder and dispersing it in acetone, then adding I ₂ , and sealing with ultrasonic vibration to obtain an electrophoretic deposition suspension;

4) Use two transparent conductive glass (FTO) with equal area as positive and negative electrodes, immerse the two electrodes face to face and parallel to each other in the electrophoretic deposition suspension obtained in step 3), and apply a certain DC voltage between the two electrodes to set Deposition time, after the deposition is completed, the current is cut off, the two electrodes are taken out from the electrophoretic deposition suspension, and dried at room temperature to obtain a photoelectrode film with graphitic carbon nitride as the base material.

Further, in the above preparation method, in step 1), by mass ratio, terephthalaldehyde:melamine=1～20:300.

Further, in the above preparation method, in step 1), the heating temperature is 100°C.

Further, in the above preparation method, in step 1), the drying temperature is 50-100°C.

Further, in the above preparation method, in step 2), the calcination temperature is 500-600°C, and the heating rate is 5°C/min.

Further, in the above preparation method, in step 2), the calcination time is 4h.

Further, in the above preparation method, in step 3), the added amount of the powder is 0.05-0.1 g.

Further, in the above preparation method, in step 3), the acetone is 25 mL.

Further, in the above preparation method, in step 4), the DC voltage is 25V, and the deposition time is 1-5min.

Application of a photoelectrode film with graphitic carbon nitride as base material prepared according to the above preparation method in photoelectrochemical water splitting.

The beneficial effects of the present invention are:

1. The photoelectrode film with graphitic carbon nitride as the base material provided by the present invention is easier to effectively separate the photogenerated electron holes, reduce the recombination rate, and can effectively improve the photoelectrochemical performance.

2. The photoelectrode film with graphitic carbon nitride as the base material provided by the present invention has a photocurrent density that is 4.85 times that of pure graphitic carbon nitride under visible light.

3. The preparation method of the photoelectrode film with graphitic carbon nitride as the base material provided by the present invention has cheap and easy-to-obtain raw materials, simple and convenient operation, greatly reduces the cost, provides a new catalytic material for the decomposition of water, alleviates the In today's tense environment and energy situation, there are good prospects for development.

Description of drawings

Figure 1 shows the XRD comparison of the photoelectrode film based on graphitic carbon nitride and the pure graphitic carbon nitride photoelectrode film.

FIG. 2 is a photocurrent comparison diagram of a photoelectrode film based on graphitic carbon nitride and a pure graphitic carbon nitride photoelectrode film.

FIG. 3 is a comparison diagram of the impedance spectra of the photoelectrode film with graphitic carbon nitride as the base material and the pure graphitic carbon nitride photoelectrode film.

Among them, 1 represents the photoelectrode film with graphitic carbon nitride as the base material, and 0 represents the pure graphitic carbon nitride photoelectrode film.

Detailed ways

Example 1

(1) Preparation of photoelectrode thin films with graphitic carbon nitride as base material

1. Add 3g of melamine into 200mL of distilled water, stir magnetically at 100°C until the solution is clear, then add 0.13g of terephthalaldehyde powder, continue stirring for 1.5h, put the resulting mixed solution in an oven, dry at 90°C for 20h, get the precursor.

2. After grinding the obtained precursor, in a nitrogen environment, the temperature is raised to 550°C at a heating rate of 5°C/min, and calcined for 4 hours to obtain the target product.

3. Grind the target product into powder, take 0.06g of the powder and place it in 25mL of acetone solution, seal and ultrasonicate for 90min until the solution is uniformly dispersed, add 0.012g of I ₂ to the obtained uniform dispersion, and seal and ultrasonically oscillate for 30min to obtain an electrophoretic deposition suspension. liquid.

4. Use two transparent conductive glass (FTO) with equal area as positive and negative electrodes, immerse the two electrodes into the electrophoretic deposition suspension in parallel to each other, and apply a DC voltage of 25V between the two electrodes for 5 minutes; The two electrodes are taken out from the electrophoretic deposition suspension and dried at room temperature to obtain a photoelectrode film with graphitic carbon nitride as the base material. (2) Comparative example: Preparation of pure graphitic carbon nitride photoelectrode film

1. Add 3g of melamine to 200mL of distilled water, stir magnetically at 100°C for 1.5h, put the resulting solution in an oven, and dry at 90°C for 20h to obtain the precursor.

2. After grinding the obtained precursor, in a nitrogen environment, the temperature is raised to 550°C at a heating rate of 5°C/min, and calcined for 4 hours to obtain the target product.

3. Grind the target product into powder, take 0.06g of the powder and place it in 25mL of acetone solution, seal and ultrasonicate for 90min until the solution is uniformly dispersed, add 0.012g of I ₂ to the obtained uniform dispersion, and seal and ultrasonically oscillate for 30min to obtain an electrophoretic deposition suspension. liquid.

4. Use two transparent conductive glass (FTO) with equal area as positive and negative electrodes, immerse the two electrodes into the electrophoretic deposition suspension in parallel to each other, and apply a DC voltage of 25V between the two electrodes for 5 minutes; The two electrodes were taken out from the electrophoretic deposition suspension and dried at room temperature to obtain a pure graphitic carbon nitride photoelectrode film.

(3) Detection

Figure 1 is the XRD test chart of the photoelectrode film with graphitic carbon nitride as the base material and the pure graphitic carbon nitride photoelectrode film in powder form. There are two diffraction peaks at 27.6°, which are consistent with the diffraction peaks of pure graphite carbon nitride, but compared with pure graphite carbon nitride, the XRD diffraction peak intensity of the material treated with terephthalaldehyde decreases, and the crystallinity of the sample changes. Small.

Embodiment 2 A kind of photoelectrode film with graphitic carbon nitride as base material in photoelectrochemical water splitting

The photoelectrode film prepared in Example 1 with graphitic carbon nitride as the base material and the pure graphitic carbon nitride photoelectrode film were respectively tested for photoelectrochemical performance of photocurrent and impedance.

All electrochemical experimental testing procedures were carried out in an electrochemical workstation (Princeton Applied Research 2273) with a three-electrode system. The photoelectrode film with graphitic carbon nitride as the base material or the pure graphitic carbon nitride photoelectrode film is used as the working electrode, the platinum sheet is used as the counter electrode, Ag/AgCl is used as the reference electrode, the electrolyte is 0.5M sodium sulfate, and the sample is irradiated with light. The area is 1 cm ² .

Photocurrent test: The light source is a 300W xenon lamp, and the bias voltage is 1.23V vs. RHE. The test results are shown in Figure 2. The results show that the photocurrent density of the photoelectrode film with graphite carbon nitride as the base material is greater than that of pure graphite nitride. The carbon photoelectrode film shows that the photoelectrochemical performance of the sample treated with graphitic carbon nitride as the base material is improved.

Electrochemical Impedance Spectroscopy (EIS) test: The fixed voltage is 0V vs. Voc, and the frequency range is 0.1-105Hz. The test results are shown in Figure 3. The photoelectrode film sample treated with graphitic carbon nitride as the base material has a relatively high impedance. is smaller, and the photocurrent is the largest, which is consistent with Figure 3.

Claims (10)

1. a preparation method of the photoelectrode film with graphitic carbon nitride as base material, is characterized in that, comprises the steps: 1) adding melamine into distilled water, heating and magnetic stirring until the solution is clarified, then adding terephthalaldehyde, continuing to heating magnetic stirring, and putting the obtained mixed solution into an oven for drying to obtain a precursor; 2) calcining the precursor obtained in step 1) at a high temperature in a nitrogen environment to obtain the target product; 3) grinding the target product obtained in step 2) into powder, taking an appropriate amount of powder and dispersing it in acetone, then adding I ₂ , and sealing with ultrasonic vibration to obtain an electrophoretic deposition suspension; 4) Use two transparent conductive glass (FTO) with equal area as positive and negative electrodes, immerse the two electrodes face to face and parallel to each other in the electrophoretic deposition suspension obtained in step 3), and apply a certain DC voltage between the two electrodes to set Deposition time, after the deposition is completed, the current is cut off, the two electrodes are taken out from the electrophoretic deposition suspension, and dried at room temperature to obtain a photoelectrode film with graphitic carbon nitride as the base material. 2. preparation method according to claim 1 is characterized in that, in step 1), by mass ratio, terephthalaldehyde:melamine=1～20:300. 3. The preparation method according to claim 1, wherein in step 1), the heating temperature is 100°C. 4. The preparation method according to claim 1, wherein in step 1), the drying temperature is 50-100°C. 5 . The preparation method according to claim 1 , wherein in step 2), the calcination temperature is 500-600° C., and the heating rate is 5° C./min. 6 . 6. The preparation method according to claim 1, wherein in step 2), the calcination time is 4h. 7. The preparation method according to claim 1, wherein in step 3), the addition amount of the powder is 0.05-0.1 g. 8. preparation method according to claim 1 is characterized in that, in step 3), described acetone is 25mL. 9. The preparation method according to claim 1, wherein in step 4), the DC voltage is 25V, and the deposition time is 1-5min. 10. The application of the photoelectrode film prepared by the preparation method according to any one of claims 1 to 9 with graphitic carbon nitride as the base material in photoelectrochemical water splitting.

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