Counter electrode materials for dye-sensitized solar cells, preparation methods thereof and applications

Abstract

The present invention discloses a counter electrode material for dye-sensitized solar cells, a preparation method thereof and an application. The preparation method comprises the following steps: S1, activating multi-walled carbon nanotubes, and then washing and drying to obtain activated multi-walled carbon nanotubes; S2, dispersing the activated multi-walled carbon nanotubes and cobalt salt in methanol or ethanol successively to obtain a first solution, dissolving 2-methylimidazole in methanol / ethanol to obtain a second solution, mixing the first solution and the second solution for an aging reaction, and then cleaning and drying to obtain ZIF-67@MWCNTs; S3, taking the ZIF-67@MWCNTs material and selenium powder to carry out high-temperature calcination treatment in a reducing atmosphere, and introducing alcohol vapor as a carbon source, and cooling to room temperature to obtain the counter electrode material for dye-sensitized solar cells. The counter electrode material for dye-sensitized solar cells of the present invention improves the cycle stability of the counter electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular, to a counter electrode material for a dye-sensitized solar cell, a preparation method thereof, and an application thereof. Background Art

[0002] As a new type of green energy that is inexhaustible, widely distributed, and has little environmental impact during use, solar energy has attracted the attention of a large number of researchers.

[0003] Since the dye-sensitized solar cell was invented by Professor M. in Lausanne, Switzerland in 1991, it has been regarded as the most ideal energy conversion device for large-scale solar energy utilization due to its low cost, simple structure, simple production method, and extremely low pollution during production. A typical dye-sensitized solar cell is a device with a sandwich structure composed of a photoanode, an electrolyte, a separator, and a counter electrode. As an important part of the solar cell, the counter electrode plays the role of receiving electrons from the external circuit and transferring the electrons to the oxidized electrolyte to reduce the electrolyte, so as to repeat the process to achieve a complete battery process. The performance of the counter electrode material directly affects the overall photoelectric conversion efficiency of the battery.

[0004] Currently, the counter electrode material most widely used in DSSCs is platinum metal with excellent performance. However, platinum, as a precious metal, has limited reserves, and the purification process is extremely complex, with high production costs. The global annual output is only 170 tons (in 2017), and it is not suitable as a consumable for long-term use. Conductive polymers represented by polythiophene synthesized artificially have high costs due to their complex synthesis routes. Transition metal chalcogenides have good catalytic performance, but poor conductivity and stability; while single carbon materials have good conductivity and stability, but poor catalytic performance. Summary of the Invention

[0005] The present invention aims to provide a counter electrode material for a dye-sensitized solar cell, a preparation method thereof, and an application thereof, so as to solve the technical problem of the high price of platinum counter electrodes in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, a method for preparing a counter electrode material for a dye-sensitized solar cell is provided. The preparation method includes the following steps: S1, activating multi-walled carbon nanotubes with a mixture of concentrated nitric acid and concentrated sulfuric acid, then washing until neutral and drying to obtain activated multi-walled carbon nanotubes; S2, dispersing the activated multi-walled carbon nanotubes and cobalt salt in methanol or ethanol successively to obtain a first solution, dissolving 2-methylimidazole in methanol / ethanol to obtain a second solution, mixing the first solution and the second solution for an aging reaction, and then cleaning and drying to obtain ZIF-67 interpenetrated with multi-walled carbon nanotubes, abbreviated as ZIF-67@MWCNTs; S3, taking the ZIF-67@MWCNTs material and selenium powder for high-temperature calcination treatment in a reducing atmosphere, and introducing alcohol vapor as a carbon source, and cooling to room temperature to obtain a CoSe@NPC / MWCNTs material with carbon nanotubes grown on the surface, which is the counter electrode material for the dye-sensitized solar cell.

[0007] Further, the mass fraction of concentrated nitric acid ≥ 60%, and concentrated sulfuric acid refers to a sulfuric acid solution with a mass fraction ≥ 98%; preferably, the volume ratio of concentrated nitric acid to concentrated sulfuric acid in the mixture of concentrated nitric acid and concentrated sulfuric acid is 2:1 to 5:1.

[0008] Further, the stirring speed during activation is 200 - 300 r / min, the temperature is 70 - 80 °C, and the time is 10 - 20 h.

[0009] Further, obtaining the activated multi-walled carbon nanotubes after washing and drying includes: washing with deionized water until neutral and then separating and drying to obtain the activated multi-walled carbon nanotubes.

[0010] Further, the mixing and dispersion of the activated multi-walled carbon nanotubes, formaldehyde, and cobalt nitrate include: taking the activated multi-walled carbon nanotubes and methanol, ultrasonically dispersing evenly, and then adding cobalt nitrate and continuing to ultrasonically disperse until evenly dispersed.

[0011] Further, the aging time after mixing and stirring the first solution and the second solution for 10 - 30 min is 2 - 24 h; preferably, the cleaning in S2 is carried out with methanol; preferably, the cobalt salt is one or more selected from the group consisting of cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt nitrate hydrate, cobalt sulfate hydrate, and cobalt chloride hydrate; preferably, the alcohol vapor is one or more selected from the group consisting of ethanol, ethylene glycol, methanol, and propanol.

[0012] Further, in S2, when the dosage of the activated multi-walled carbon nanotubes is 20 - 50 mg, the addition amount of methanol is 50 - 80 mL, the addition amount of cobalt nitrate is 3 - 6 mmol, and the dissolution amount of 2-methylimidazole is 12 - 24 mmol.

[0013] Further, the reducing atmosphere in S3 is a reducing atmosphere of H2 / Ar; preferably, in the H2 / Ar gas mixture, the H2 content is 5-10 vol%.

[0014] Further, in S3, the high-temperature calcination treatment is carried out in a multi-stage programmable temperature-controlled tubular furnace; preferably, the temperature of the high-temperature calcination is 500-700 °C, and the time is 3-6 h.

[0015] According to another aspect of the present invention, a counter electrode material for a dye-sensitized solar cell is provided. The counter electrode material for the dye-sensitized solar cell is prepared by any of the above-mentioned preparation methods for the counter electrode material of the dye-sensitized solar cell.

[0016] According to still another aspect of the present invention, a preparation method for a counter electrode of a dye-sensitized solar cell is provided. The counter electrode of the dye-sensitized solar cell is prepared by using the above-mentioned counter electrode material of the dye-sensitized solar cell.

[0017] Further, the preparation method includes: adding a binder and a solvent to the CoSe@NPC / MWCNTs material, grinding until there is no particle feeling, and then scraping and coating on a conductive glass, and drying to obtain the counter electrode of the dye-sensitized solar cell; preferably, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone; preferably, the conductive glass is FTO conductive glass; preferably, the drying temperature is 100-150 °C, and the time is 10-20 h.

[0018] According to still another aspect of the present invention, a counter electrode of a dye-sensitized solar cell is provided. The counter electrode of the dye-sensitized solar cell is prepared by using the above-mentioned preparation method.

[0019] According to still another aspect of the present invention, a dye-sensitized solar cell is provided. The dye-sensitized solar cell includes a counter electrode of the dye-sensitized solar cell, and the counter electrode of the dye-sensitized solar cell is the above-mentioned counter electrode of the dye-sensitized solar cell.

[0020] The counter electrode material of the dye-sensitized solar cell prepared by applying the technical solution of the present invention improves the conductivity of the cobalt selenide counter electrode material through the carbon nanotubes interspersed between the mesoporous carbons; the carbon nanotubes grown on the surface of the mesoporous carbon increase the contact area between the material and the electrolyte, and reduce the concentration polarization on the electrode surface; the nitrogen-doped mesoporous carbon enhances the stability of the connection between the cobalt selenide particles and the carbon material, and improves the cycle stability of the counter electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 The structural schematic diagram of a multi-stage programmable temperature-controlled tubular furnace used in the material preparation process according to an embodiment of the present invention is shown;

[0023] Figure 2 The structural schematic diagram of the counter electrode material CoSe@NPC / MWCNTs prepared according to the present invention is shown;

[0024] Figure 3 The electron microscope photograph of ZIF-67@MWCNTs prepared in Example 3 is shown;

[0025] Figure 4 The electron microscope photograph of CoSe@NPC / MWCNTs prepared in Example 3 is shown;

[0026] Figure 5 The XRD pattern of ZIF-67@MWCNTs prepared in Example 3 is shown;

[0027] Figure 6 The XRD pattern of CoSe@NPC / MWCNTs prepared in Example 3 is shown. Detailed implementation manners

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0029] The currently widely used platinum counter electrode is expensive, and it is necessary to find a counter electrode with low price. In view of this, the present invention proposes the following technical solutions.

[0030] According to a typical embodiment of the present invention, a preparation method of a counter electrode material for a dye-sensitized solar cell is provided. The preparation method includes the following steps: S1, activating multi-walled carbon nanotubes with a mixture of concentrated nitric acid and concentrated sulfuric acid, then washing until neutral and drying to obtain activated multi-walled carbon nanotubes; S2, dispersing the activated multi-walled carbon nanotubes and cobalt salt in methanol or ethanol successively to obtain a first solution, dissolving 2-methylimidazole in methanol to obtain a second solution, mixing the first solution and the second solution for an aging reaction, and then cleaning and drying to obtain a ZIF-67 material interpenetrating multi-walled carbon nanotubes (ZIF-67@MWCNTs is the abbreviation of the ZIF-67 material interpenetrating multi-walled carbon nanotubes); S3, taking the ZIF-67@MWCNTs material and selenium powder for high-temperature calcination treatment in a reducing atmosphere, and introducing alcohol vapor as a carbon source, and cooling to room temperature to obtain a CoSe@NPC / MWCNTs material with carbon nanotubes grown on the surface, which is the counter electrode material for the dye-sensitized solar cell.

[0031] The counter electrode material of the dye-sensitized solar cell prepared by using the technical solution of the present invention has improved conductivity of the counter electrode material through carbon nanotubes interspersed between mesoporous carbons; the carbon nanotubes grown on the surface of the mesoporous carbon increase the contact area between the material and the electrolyte, weakening the adverse effect of concentration polarization on the electrode surface on the electrode reaction; the nitrogen-doped mesoporous carbon enhances the stability of the connection between cobalt selenide particles and the carbon material, improving the cycle stability of the counter electrode material.

[0032] The activated multi-walled carbon nanotubes and cobalt salt are successively dispersed in methanol or ethanol. Among them, to ensure the uniform adsorption of cobalt ions on the activated carbon nanotubes, the carbon nanotubes should be added to the solvent first, and after being dispersed evenly under ultrasonic assistance, the cobalt salt is dissolved in the solvent.

[0033] Preferably, the mass fraction of concentrated nitric acid ≥ 60%, and concentrated sulfuric acid refers to a sulfuric acid solution with a mass fraction ≥ 98%; the volume ratio of concentrated nitric acid to concentrated sulfuric acid in the mixture of concentrated nitric acid and concentrated sulfuric acid is 2:1 - 5:1. It has been proved by experiments that the activation of multi-walled carbon nanotubes can be achieved within this ratio range; preferably, the stirring speed during activation is 200 - 300 r / min, the temperature is 70 - 80 °C, and the time is 10 - 20 h. During the activation process of carbon nanotubes, concentrated nitric acid mainly acts as a strong oxidant, and concentrated sulfuric acid provides a strong acidic condition to enhance this oxidizing property. Heating is also to enhance the oxidizing property of the oxidant, and the temperature is controlled below 80 °C because the boiling point of the nitric acid solution is 83 °C, and it is not advisable to heat above the boiling point of nitric acid for safety reasons. The experimental time is controlled at 10 - 20 h because if the time is too short, the activation degree of MWCNT is insufficient, and too few surface oxygen-containing functional groups will affect the wettability, while if the experimental time is too long, it will lead to over-oxidation of MWCNT, possibly causing some carbon nanotubes to break. More preferably, the dispersion liquid is continuously stirred during the activation process to prevent local solution overheating.

[0034] In a typical embodiment of the present invention, the activated multi-walled carbon nanotubes obtained after washing and drying include: washing with deionized water until neutral and then separating and drying to obtain the activated multi-walled carbon nanotubes.

[0035] Preferably, the mixing and dispersion of the activated multi-walled carbon nanotubes, methanol and cobalt nitrate include: taking the activated multi-walled carbon nanotubes and methanol and mixing them, dispersing them evenly by ultrasonic treatment, and then adding cobalt nitrate and continuing ultrasonic treatment until evenly dispersed. Since the specific surface area of multi-walled carbon nanotubes is relatively large and it is difficult to disperse them evenly, step-by-step dispersion is adopted. First, the carbon nanotubes are dispersed, and then cobalt nitrate is dispersed, so as to obtain a uniformly dispersed and stable solution.

[0036] According to a typical embodiment of the present invention, the aging time after mixing and stirring the first solution and the second solution for 10 to 30 min is 2 to 24 h; preferably, the cleaning in S2 is carried out with methanol. The cobalt salt is one or more selected from the group consisting of cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt nitrate hydrate, cobalt sulfate hydrate, and cobalt chloride hydrate; the alcohol vapor is one or more selected from the group consisting of ethanol, ethylene glycol, methanol, and propanol.

[0037] Preferably, in S2, when the amount of activated multi-walled carbon nanotubes used is 20 to 50 mg, the addition amount of methanol is 50 to 80 mL, the addition amount of cobalt nitrate is 3 to 6 mmol, and the dissolution amount of 2-methylimidazole is 12 to 24 mmol. By matching different addition amounts of the four substances, ZIF-67@MWCNTs can be obtained.

[0038] In a typical embodiment of the present invention, the reducing atmosphere in S3 is a H2 / Ar reducing atmosphere; preferably, in the H2 / Ar gas mixture, the H2 content is 5 to 10 vol%.

[0039] In a typical embodiment of the present invention, the high-temperature calcination treatment in S3 is carried out in a multi-stage programmable temperature tube furnace (as Figure 1 shown); preferably, the temperature of the high-temperature calcination is 500 to 700 °C, and the time is 3 to 6 h. This tube furnace has high temperature control accuracy, and the reaction atmosphere can be controlled and selected.

[0040] According to a typical embodiment of the present invention, a counter electrode material for a dye-sensitized solar cell is provided. Figure 2 The structural schematic diagram of the CoSe@NPC / MWCNTs counter electrode material prepared by the present invention is shown. The counter electrode material for the dye-sensitized solar cell is prepared by the preparation method of the counter electrode material for the dye-sensitized solar cell described above.

[0041] According to a typical embodiment of the present invention, a method for preparing a counter electrode of a dye-sensitized solar cell is provided. The counter electrode of the dye-sensitized solar cell is prepared by using any one of the above-mentioned counter electrode materials for the dye-sensitized solar cell. Preferably, the preparation method includes: adding a binder and a solvent to the CoSe@NPC / MWCNTs material, grinding until there is no particle feeling, then scraping and coating on a conductive glass, and drying to obtain the counter electrode of the dye-sensitized solar cell. Preferably, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone; polyvinylidene fluoride has good chemical corrosion resistance, high temperature resistance, oxidation resistance, good wetting / swelling performance in the electrolyte, and low cost. Polyvinylidene fluoride is easily soluble in N-methylpyrrolidone and has low toxicity and is not easily volatile at room temperature. Preferably, the conductive glass is FTO conductive glass; preferably, the drying temperature is 100-150 °C and the time is 10-20 h. Within this temperature range, the solvent can be fully volatilized to remove the N-methylpyrrolidone solvent in the counter electrode sheet, and the structure of the electrode active material and the binder will not be damaged.

[0042] According to a typical embodiment of the present invention, a counter electrode of a dye-sensitized solar cell is provided. The counter electrode of the dye-sensitized solar cell is prepared by using the above preparation method.

[0043] According to a typical embodiment of the present invention, a dye-sensitized solar cell is provided. The dye-sensitized solar cell includes a counter electrode of the dye-sensitized solar cell, such as the counter electrode of the dye-sensitized solar cell being the above-mentioned counter electrode of the dye-sensitized solar cell.

[0044] The beneficial effects of the present invention will be further described below in conjunction with embodiments.

[0045] Example 1

[0046] 1. Take 200 mg of commercial multi-walled carbon nanotubes and place them in a round-bottom flask. Add an appropriate amount of a mixture of nitric acid with a mass fraction of 68% and sulfuric acid with a mass fraction of 98% with a volume ratio of 2:1. While stirring at 200 r / min, heat up to 70 °C and keep warm for 20 h. After the multi-walled carbon nanotubes are fully activated, cool down to a safe temperature. Pour the mixed solution into a large amount of ice-bathed deionized water, stir and ultrasonicate, then filter. After washing with a large amount of deionized water until neutral, separate and dry to obtain activated multi-walled carbon nanotubes.

[0047] 2. Place the obtained 20 mg of carbon nanotubes in a beaker, add 50 mL of methanol, ultrasonically disperse evenly, then add 3 mmol of cobalt nitrate and continue ultrasonic treatment until evenly dispersed. At the same time, dissolve 12 mmol of 2-methylimidazole in the same amount of methanol, stir well, and under stirring, mix the two solutions evenly. Continue stirring for 10 min and then age for 2 h. Wash with methanol and dry to obtain the ZIF-67 (ZIF-67@MWCNTs) material interpenetrated with multi-walled carbon nanotubes.

[0048] 3. Place 50 mg of ZIF-67@MWCNTs and an appropriate amount of selenium powder in two quartz boats respectively and put them into a multi-stage programmable temperature-controlled tube furnace. Then, under a reducing atmosphere of H2 / Ar (H2: 5 vol%), perform high-temperature calcination treatment at 500 °C for 6 h, and simultaneously introduce an appropriate amount of ethanol vapor into the tube. After natural cooling to room temperature, the obtained black product is CoSe@NPC / MWCNTs with carbon nanotubes grown on the surface.

[0049] 4. Place 20 mg of the obtained CoSe@NPC / MWCNTs material in a mortar, add a mixture of 2 mg of polyvinylidene fluoride and 5 drops of N-methylpyrrolidone as a binder and solvent, grind until there is no particle feeling, and then scrape and coat it on FTO conductive glass. After drying at 150 °C for 10 h, it is the counter electrode of the dye-sensitized solar cell.

[0050] Example 2

[0051] 1. Place 250 mg of commercial multi-walled carbon nanotubes in a round-bottom flask, add an appropriate mixture of a 60% nitric acid solution and a 98% sulfuric acid solution with a volume ratio of 5:1, heat to 80 °C under stirring at 300 r / min, keep warm for 10 h, and cool to a safe temperature after the multi-walled carbon nanotubes are fully activated. Pour the mixed solution into a large amount of ice-bathed deionized water, stir and ultrasonically treat, then filter, wash with a large amount of deionized water until neutral, and then separate and dry to obtain activated multi-walled carbon nanotubes.

[0052] 2. Place the obtained 50 mg of carbon nanotubes in a beaker, add 80 mL of methanol, ultrasonically disperse evenly, then add 6 mmol of cobalt nitrate and continue ultrasonic treatment until evenly dispersed. At the same time, dissolve 24 mmol of 2-methylimidazole in the same amount of methanol, stir well, and under stirring, mix the two solutions evenly. Continue stirring for 30 min and then age for 24 h. Wash with methanol and dry to obtain the ZIF-67 (ZIF-67@MWCNTs) material interpenetrated with multi-walled carbon nanotubes.

[0053] 3. Take 50 mg of ZIF-67@MWCNTs and an appropriate amount of selenium powder and place them in two quartz boats respectively and put them into a multi-stage programmable temperature-controlled tube furnace, and then carry out high-temperature calcination treatment in a reducing atmosphere of H2 / Ar (H2: 10 vol%), and at the same time, introduce an appropriate amount of methanol vapor into the tube; after naturally cooling to room temperature, the black product obtained is CoSe@NPC / MWCNTs with carbon nanotubes on the surface;

[0054] 4. Take 40 mg of the prepared CoSe@NPC / MWCNTs material and place it in a mortar, and add 4 mg of polyvinylidene fluoride and 10 drops of N-methylpyrrolidone mixture as a binder and solvent. Grind until there is no particle feeling, then scrape and apply it on FTO conductive glass. After drying at 100°C for 20 hours, it becomes the counter electrode of the dye-sensitized solar cell.

[0055] Example 3

[0056] 1. Take 300mg of commercial multi-walled carbon nanotubes and place them in a round-bottom flask. Add a proper volume ratio of 3:1 of a mixture of 60% nitric acid solution and 98% sulfuric acid solution. Heat to 78°C under stirring at 250r / min, keep warm for 12h, and cool to a safe temperature after the multi-walled carbon nanotubes are fully activated. Pour the mixture into a large amount of deionized water in an ice bath, stir and filter after ultrasonication, wash with a large amount of deionized water until neutral, and separate and dry to obtain activated multi-walled carbon nanotubes.

[0057] 2. Take 30 mg of the prepared carbon nanotubes and place them in a beaker. Add 60 mL of methanol. After ultrasonic dispersion, add 4 mmol of cobalt nitrate and continue ultrasonic dispersion until uniform. At the same time, take the same amount of methanol to dissolve 16 mmol of 2-methylimidazole. After sufficient stirring, lower the two solutions under stirring to mix evenly. Continue stirring for 30 minutes and then age for 4 hours. Wash and dry with methanol to obtain ZIF-67 (ZIF-67@MWCNTs) material interlaced with multi-walled carbon nanotubes. For electron microscope photos, see Figure 3 , XRD pattern see Figure 5 .

[0058] 3. Take 50 mg of ZIF-67@MWCNTs and an appropriate amount of selenium powder and place them in two quartz boats and put them into a multi-stage programmable temperature-controlled tube furnace. Then, they are calcined at high temperature in a reducing atmosphere of H2 / Ar (H2: 7 vol%), and an appropriate amount of ethylene glycol vapor is introduced into the tube at the same time. After cooling naturally to room temperature, the black product obtained is CoSe@NPC / MWCNTs with carbon nanotubes on the surface. For electron microscope photos, see Figure 4 , XRD pattern see Figure 6 ;

[0059] 4. Take 30 mg of the prepared CoSe@NPC / MWCNTs material and place it in a mortar. Then add a mixture of 3 mg of polyvinylidene fluoride and 10 drops of N-methylpyrrolidone as the binder and solvent, grind until there are no granules, and then scrape and coat it on the FTO conductive glass. After drying at 110 °C for 12 h, it becomes the counter electrode of the dye-sensitized solar cell.

[0060] The detailed assembly process of the DSSC device used is as follows:

[0061] Fabrication of the anode sheet: Add 0.55 mL of TiCl4 to 200 mL of deionized water at 0 °C, stir for 5 min, then pour it into a beaker containing FTO glass with the conductive side facing up, keep it warm at 70 °C for 30 min, take it out, rinse with water and ethanol, and then keep it warm at 450 °C and 500 °C in a muffle furnace for 15 min respectively. Use the doctor blade method to coat 0.1133 cm 2 of titanium dioxide material on the FTO glass and calcine it in the muffle furnace, with the same procedure as above. Then immerse it in a 0.05 mmol / L N719 solution (the volume ratio of acetonitrile to tert-butanol is 1:1) for 24 h.

[0062] The Pt counter electrode is obtained by thermal decomposition of chloroplatinic acid.

[0063] The DSSC electrolyte is an acetonitrile solution of 0.6 mmol / L 1,2-dimethyl-3-propylimidazolium iodide (DMPII), 0.06 mol / L LiI, 0.03 mol / L I2, and 0.5 mol / L 4-tert-butylpyridine (TPB).

[0064] The photoelectric conversion efficiency is tested using the LSV mode of a CHI604E electrochemical workstation. The battery operates under the illumination intensity of AM1.5.

[0065] The performance indicators of the counter electrode of the dye-sensitized solar cell prepared in the above examples were detected, and the results are shown in Table 1:

[0066] Table 1

[0067]

[0068] According to the data in Table 1, it can be seen that the counter electrode material of the dye-sensitized solar cell prepared by the present invention has a unique multi-level structure carbon skeleton, which provides favorable conditions for the electron transport and the infiltration of the electrolyte, and has a photoelectric conversion efficiency superior to that of platinum materials. The preparation method of the present invention is simple and effective, with low preparation cost, mild and controllable preparation conditions, which is conducive to large-scale production and has broad application prospects.

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a counter electrode material for a dye-sensitized solar cell, characterized in that, It includes the following steps: S1, activating multi-walled carbon nanotubes with a mixture of concentrated nitric acid and concentrated sulfuric acid, then washing until neutral and drying to obtain activated multi-walled carbon nanotubes; S2, dispersing the activated multi-walled carbon nanotubes and cobalt salt in methanol successively to obtain a first solution, dissolving 2-methylimidazole in methanol to obtain a second solution, mixing the first solution and the second solution for an aging reaction, and then cleaning and drying to obtain ZIF-67 intercalated with multi-walled carbon nanotubes, abbreviated as ZIF-67@MWCNTs; S3, subjecting the ZIF-67@MWCNTs material and selenium powder to high-temperature calcination treatment in a reducing atmosphere, and introducing alcohol vapor as a carbon source, and cooling to room temperature to obtain a CoSe@NPC / MWCNTs material with carbon nanotubes grown on the surface, which is the counter electrode material for dye-sensitized solar cells.

2. The preparation method according to claim 1, characterized in that, The mass fraction of the concentrated nitric acid ≥ 60%, and the mass fraction of the concentrated sulfuric acid ≥ 98%.

3. The preparation method according to claim 2, characterized in that, The volume ratio of concentrated nitric acid to concentrated sulfuric acid in the mixture of concentrated nitric acid and concentrated sulfuric acid is 2:1 to 5:

1.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The stirring speed during activation is 200 - 300 r / min, the temperature is 70 - 80 °C, and the time is 10 - 20 h.

5. The preparation method according to any one of claims 1 to 3, characterized in that, The activation of multi-walled carbon nanotubes obtained after washing and drying includes: washing with deionized water until neutral and then separating and drying to obtain the activated multi-walled carbon nanotubes.

6. The preparation method according to claim 1, wherein The mixing and dispersion of the activated multi-walled carbon nanotubes, methanol and cobalt salt include: mixing the activated multi-walled carbon nanotubes and methanol, ultrasonically dispersing uniformly, and then adding cobalt salt and continuing to ultrasonically disperse until uniform.

7. The preparation method according to claim 1 or 6, characterized in that, The aging time after mixing and stirring the first solution and the second solution for 10 - 30 min is 2 - 24 h.

8. The preparation method according to claim 7, characterized in that, The cleaning in S2 is carried out with methanol.

9. The preparation method according to claim 7, wherein The cobalt salt is one or more selected from the group consisting of cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt nitrate hydrate, cobalt sulfate hydrate and cobalt chloride hydrate.

10. The preparation method according to claim 7, characterized in that, The alcohol vapor is one or more selected from the group consisting of ethanol, ethylene glycol, methanol and propanol.

11. The preparation method according to claim 1 or 6, characterized in that, In S2, when the dosage of the activated multi-walled carbon nanotubes is 20 - 50 mg, the addition amount of the cobalt salt is 3 - 6 mmol, and the dissolution amount of 2-methylimidazole is 12 - 24 mmol.

12. According to the preparation method described in claim 1, wherein The reducing atmosphere in S3 is a H2 / Ar reducing atmosphere.

13. The preparation method according to claim 12, wherein, In the H2 / Ar gas mixture, the H2 content is 5 - 10 vol%.

14. The preparation method according to claim 1 or 12, characterized in that, In S3, high-temperature calcination treatment is carried out in a multi-stage programmable temperature tube furnace.

15. The preparation method according to claim 14, characterized in that, The temperature of the high-temperature calcination is 500 - 700 °C, and the time is 3 - 6 h.

16. A counter electrode material for a dye-sensitized solar cell, characterized in that, The counter electrode material for dye-sensitized solar cells is prepared by the preparation method of the counter electrode material for dye-sensitized solar cells as described in any one of claims 1 to 15.

17. A preparation method of a counter electrode for a dye-sensitized solar cell, characterized in that, The counter electrode of the dye-sensitized solar cell is prepared using the counter electrode material for dye-sensitized solar cells as described in claim 16.

18. The preparation method according to claim 17, characterized in that, The preparation method includes: adding a binder and a solvent to the CoSe@NPC / MWCNTs material, grinding until there is no particle feeling and then doctor-blading on a conductive glass, and drying to obtain the counter electrode of the dye-sensitized solar cell.

19. The preparation method according to claim 18, characterized in that, The binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone.

20. The preparation method according to claim 19, wherein The conductive glass is FTO conductive glass.

21. The preparation method according to claim 20, characterized in that, The drying temperature is 100 to 150 °C, and the time is 10 to 20 h.

22. A counter electrode for a dye-sensitized solar cell, characterized in that, The counter electrode of the dye-sensitized solar cell is prepared by the preparation method described in any one of claims 17 to 21.

23. A dye-sensitized solar cell, the dye-sensitized solar cell comprising a counter electrode of the dye-sensitized solar cell, characterized in that, The counter electrode of the dye-sensitized solar cell is the counter electrode of the dye-sensitized solar cell described in claim 22.

Images