CN106449099A - Photo-anode film based on ZnO nano powder and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation method of a photo-anode film based on ZnO nano powder. The preparation method includes: calcining a metal organic frame ZIF-8 to obtain the ZnO nano powder, preparing ZnO slurry, and coating the surface of conductive glass with the ZnO slurry to prepare the photo-anode film. In addition, the invention further discloses the photo-anode film prepared by the preparation method. The preparation method is simple in preparation process, controllable in film thickness, adjustable in powder diameter, low in cost, capable of preparing a large-area film, mild in reaction condition, high in controllability and repeatability, suitable for preparing the large-area photo-anode film, beneficial to popularization, application and industrialization, and the like.

Description

A kind of preparation method based on ZnO nanopowder photoanode film and photoanode prepared Polar membrane

technical field

The invention relates to the technical field of energy materials, in particular to a method for preparing a photoanode film of a ZnO-based dye-sensitized solar cell and the prepared photoanode film.

Background technique

Dye-sensitized solar cells have the advantages of low price, environmental friendliness, and simple fabrication, and have become the representative of the third generation of solar cells. A dye-sensitized solar cell consists of three parts: a dye-sensitized photoanode film, a counter electrode and an electrolyte, and the photoanode film is the core component of the cell.

At present, the photoanode film is mainly nanocrystalline _TiO2 film. Since ZnO has similar bandgap width and electron affinity to TiO ₂ , and the electron diffusion coefficient of ZnO is stronger than that of TiO ₂ , ZnO has been placed high expectations as the photoanode film material of dye-sensitive cells. In addition, due to the anisotropic growth of ZnO crystals and various methods of synthesizing ZnO crystals, ZnO is easier to synthesize a variety of nanostructures with different shapes than TiO ₂ , such as linear, flake, Rod etc. ZnO nanopowder, because of its large specific surface area and good light scattering performance, can absorb more dyes and increase the light absorption rate at the same time, so the photoelectric conversion efficiency of the battery based on ZnO nanopowder photoanode film is relatively high. high. However, the existing technology based on ZnO nanopowders to prepare dye-sensitive battery photoanode films generally has problems such as complex process, high cost, poor controllability and repeatability, and it is difficult to prepare large-area photoanode films, and it is difficult to popularize and apply. Therefore, there is an urgent need to research and develop a new method for preparing ZnO nano-powder photoanode film, so as to facilitate the popularization and application and the realization of industrialization.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a method for preparing a photoanode film based on ZnO nano powder, to obtain ZnO nano powder by calcining metal organic framework ZIF-8, and then to prepare ZnO slurry and scrape it The photoanodic film is prepared by coating on the surface of the conductive substrate, so that a large-area photoanodic film can be obtained by a preparation method with simple process, controllability and strong repeatability, so as to facilitate the popularization and application and the realization of industrialization. Another object of the present invention is to provide a photoanode film prepared by the above preparation method.

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

A kind of preparation method based on ZnO nano-powder photoanode film provided by the invention comprises the following steps:

(1) Calcining the metal-organic framework ZIF-8 to obtain ZnO nanopowder;

(2) The ZnO nanopowder is uniformly dispersed in a mixed solution composed of ethyl cellulose, terpineol and ethanol solvent, and is rotary evaporated after oscillation and ultrasonic to obtain a ZnO slurry;

(3) The ZnO slurry is coated on the surface of the conductive substrate, and then calcined after heating to obtain a photoanode film attached to the conductive substrate and composed of ZnO nanopowder.

Further, the calcination temperature in the step (1) of the present invention is 450-750° C.; the particle size of the ZnO nano powder is 30-100 nm.

Further, ethyl cellulose is 10cp ethyl cellulose and 46cp ethyl cellulose in step (2) of the present invention; Described 10cp ethyl cellulose, 46cp ethyl cellulose, terpineol are in ethanol solvent The mass and volume concentrations of the ZnO nano powders are respectively 0.1-0.5 g/cm ³ ; the mass percent concentration of the ZnO nanometer powder in the mixed solution is 1-10 wt%. The time of oscillation in the step (2) is 5 to 10 min; the time of ultrasonic is 20 to 40 min; the number of cycles of oscillation and ultrasonic is 3 to 5 times; the temperature of the rotary evaporation is 70 to 80 ° C, and the time is 25 min. ~60min.

Further, in the step (3) of the present invention, the thickness of the ZnO slurry coated on the surface of the conductive substrate is 7-35 μm; the heating temperature is 80-120° C.; the calcination temperature is 350-450° C.

In the above scheme, the preparation of the metal organic framework ZIF-8 of the present invention is as follows: respectively dissolving zinc nitrate hexahydrate and 2-methylimidazole in a methanol solvent and stirring evenly to obtain methanol solution of zinc nitrate hexahydrate and 2-methylimidazole respectively. imidazole methanol solution; then pour the zinc nitrate hexahydrate methanol solution into 2-methylimidazole methanol solution, stir and react at room temperature, then centrifuge, wash and dry to obtain metal organic framework ZIF-8.

Further, the molar concentration of zinc nitrate hexahydrate in the methanol solution of zinc nitrate hexahydrate in the present invention is 9-30 mM, and the molar concentration of 2-methylimidazole in the methanol solution of 2-methylimidazole is 72-240 mM. The reaction time is 1-3 hours; the drying temperature is 50-70°C.

Another object of the present invention is achieved through the following technical solutions:

For the photoanode film prepared by the above preparation method, the thickness of the photoanode film is 7-35 μm, and the particle size of the ZnO nano powder is 30-100 nm.

The present invention has the following beneficial effects:

(1) The present invention has the characteristics of simple preparation process, controllable film thickness, adjustable powder diameter, low cost, large-area film production, strong controllability and repeatability, and is suitable for preparing large-area photoanode films. It is beneficial to the popularization and application and the realization of industrialization.

(2) The present invention uses zinc nitrate hexahydrate and 2-methylimidazole as raw materials to obtain metal-organic framework ZIF-8 at room temperature, the reaction conditions are mild, and the ZnO nanopowder obtained after calcining is used for the photoanode of dye-sensitized solar cells The preparation of the film, the obtained photoanode film has a large specific surface area and high photoelectric conversion efficiency.

Description of drawings

The present invention will be described in further detail below in conjunction with embodiment and accompanying drawing:

Fig. 1 is the field emission scanning electron microscope surface photo of ZnO photoanode film that the embodiment of the present invention makes;

Fig. 2 is the field emission scanning electron microscope sectional photo of ZnO photoanode film that the embodiment of the present invention makes;

Fig. 3 is a photocurrent-voltage graph of a dye-sensitized solar cell assembled with a ZnO photoanode film prepared in an example of the present invention.

detailed description

An embodiment of the present invention is a method for preparing a photoanode film based on ZnO nano powder, using fluorine-doped tin oxide conductive glass (FTO) or indium tin oxide conductive glass (ITO) as a conductive substrate.

Embodiment one:

A kind of preparation method of the photoanode film based on ZnO nanopowder of the present embodiment, its steps are as follows:

(1) Calcining the metal-organic framework ZIF-8 to obtain ZnO nanopowder

(1-1) Preparation of metal-organic framework ZIF-8: Weigh 2.93g of zinc nitrate hexahydrate and 6.49g of 2-methylimidazole into two beakers respectively, add 200mL of methanol, stir and dissolve to obtain hexahydrate Zinc nitrate hexahydrate methanol solution with a molar concentration of 9.85mM and 2-methylimidazole methanol solution with a molar concentration of 2-methylimidazole of 79.05mM; In the methanol solution, magnetically stir the reaction at room temperature for 1 h. After the reaction, centrifuge, wash with methanol three times, and dry at 50 ° C to obtain the metal organic framework ZIF-8;

(1-2) Grinding the metal-organic framework ZIF-8 and calcining it at a temperature of 500°C with a heating rate of 8°C/min and a holding time of 5h to obtain ZnO nanopowder;

(2) Preparation of ZnO slurry

2.8g ethyl cellulose (46cp), 2.2g ethyl cellulose (10cp) and 3g terpineol were fully dissolved in 10mL ethanol to form a mixed solution; 1g ZnO nanopowder was weighed and poured into the above mixed solution, After oscillating for 5 minutes and ultrasonicating for 20 minutes, repeat this process 4 times to disperse the ZnO nanopowder in the mixed solution evenly; then obtain the ZnO slurry after rotary evaporation at 75°C for 30 minutes;

(3) Preparation of ZnO photoanode film

Apply 4 layers of ZnO slurry with the thickness of the tape to the surface of the FTO substrate by using the doctor blade method, heat it on a heating plate at 120°C for 5 minutes, and then put it into an electric furnace for calcination. Raise the temperature to 450°C at a heating rate of 8°C/min, keep it warm for 30 minutes, and then cool down naturally to prepare a photoanode film composed of ZnO nanopowder attached to a conductive substrate.

As shown in FIG. 1 , the particle size of the ZnO nanopowder in this embodiment is 50 nm. As shown in Figure 2, the thickness of the photoanode film in this embodiment is 30 μm, and the film thickness can increase with the increase of the number of tape layers; and the photoanode film is composed of ZnO nanopowder.

Embodiment two:

A kind of preparation method of the photoanode film based on ZnO nanopowder of the present embodiment, its steps are as follows:

(1) Calcining the metal-organic framework ZIF-8 to obtain ZnO nanopowder

(1-1) Preparation of metal-organic framework ZIF-8: Weigh 5.86g of zinc nitrate hexahydrate and 12.98g of 2-methylimidazole into two beakers respectively, add 200mL of methanol respectively, stir and dissolve to obtain hexahydrate Zinc nitrate hexahydrate methanol solution with a molar concentration of 19.70mM, 2-methylimidazole methanol solution with a molar concentration of 158.10mM; In the methanol solution, the reaction was carried out under magnetic stirring at room temperature for 1 h. After the reaction was completed, centrifuged, washed with methanol three times, and dried at 60° C. to obtain the metal organic framework ZIF-8;

(1-2) Grinding metal-organic framework ZIF-8 and calcining at 550°C with a heating rate of 8°C/min and a holding time of 5h to obtain ZnO nanopowder;

(2) Preparation of ZnO slurry

Fully dissolve 2.8g ethyl cellulose (46cp), 2.2g ethyl cellulose (10cp) and 3.5g terpineol in 10mL ethanol solvent to form a mixed solution; weigh 1.2g ZnO nanopowder and pour it into the above mixing In the solution, oscillate for 5 minutes and then sonicate for 20 minutes, repeat this process 4 times to disperse the ZnO nano powder in the mixed solution evenly; then obtain the ZnO slurry after rotary evaporation at 70°C for 50 minutes;

(3) Preparation of ZnO photoanode film

Apply 4 layers of ZnO slurry with tape thickness to the surface of the FTO substrate by scraper method, heat it on a heating plate at 100°C for 5 minutes, then put it into an electric furnace for calcination, first raise the temperature to 350°C at a rate of 8°C/min, and keep it for 1 hour. Raise the temperature to 450°C at a heating rate of 8°C/min, keep it warm for 30 minutes, and then cool down naturally to prepare a photoanode film composed of ZnO nanopowder attached to a conductive substrate.

Embodiment three:

A kind of preparation method of the photoanode film based on ZnO nanopowder of the present embodiment, its steps are as follows:

(1) Calcining the metal-organic framework ZIF-8 to obtain ZnO nanopowder

(1-1) Preparation of metal-organic framework ZIF-8: Weigh 8.80g of zinc nitrate hexahydrate and 12.98g of 2-methylimidazole into two beakers respectively, add 200mL of methanol respectively, stir and dissolve to obtain hexahydrate Zinc nitrate hexahydrate methanol solution with a molar concentration of 29.58mM, 2-methylimidazole methanol solution with a molar concentration of 237.15mM; In the methanol solution, magnetically stir the reaction at room temperature for 1 h. After the reaction, centrifuge, wash with methanol three times, and dry at 70 ° C to obtain the metal organic framework ZIF-8;

(1-2) Grinding metal-organic framework ZIF-8 and calcining at 600°C with a heating rate of 8°C/min and a holding time of 5 hours to obtain ZnO nanopowder;

(2) Preparation of ZnO slurry

Fully dissolve 2.8g ethyl cellulose (46cp), 2.2g ethyl cellulose (10cp) and 4g terpineol in 10mL ethanol solvent to form a mixed solution; weigh 1.5g ZnO nanopowder and pour into the above mixed solution In the process, oscillate for 5 minutes and then sonicate for 20 minutes, repeat this process 4 times to disperse the ZnO nano powder in the mixed solution evenly; then obtain the ZnO slurry after rotary evaporation at 80°C for 25 minutes;

(3) Preparation of ZnO photoanode film

Apply 4 layers of ZnO slurry with the thickness of the tape to the surface of the FTO substrate by the doctor blade method, heat it on a heating plate at 80°C for 5 minutes, and then put it into an electric furnace for calcination. Raise the temperature to 450°C at a heating rate of 8°C/min, keep it warm for 30 minutes, and then cool down naturally to prepare a photoanode film composed of ZnO nanopowder attached to a conductive substrate.

Using the photoanode film prepared in the embodiment of the present invention, a dye-sensitized solar cell is prepared according to the following method:

After calcination, the ZnO photoanode film cooled to room temperature was immersed in 0.05mM N719 dye for 2h at room temperature, and the photoanode film was taken out and washed with absolute ethanol to wash the N719 dye on the surface, and then the photoanode film adsorbed by N719 dye was dried with The FTO counter electrode of pyrolyzed platinum constitutes an open sandwich structure battery. Add electrolyte solution dropwise between the photoanode film and the counter electrode, the composition of the electrolyte solution is 0.6M 1-butyl-3-methylimidazolium iodide salt, 0.06M LiI, 0.03M I2, 0.5M 4-tert-butylpyridine and 0.1 M guanidine isothiocyanate in acetonitrile. The J-V curve obtained after the test is shown in Figure 3, and the calculated photoelectric conversion efficiency of the cell is 2.85%, indicating that the ZnO photoanode film prepared in the embodiment of the present invention is suitable for dye-sensitized solar cells.

Claims (10)

1. a preparation method based on ZnO nanometer powder photoanode film, is characterized in that comprising the following steps: (1) Calcining the metal-organic framework ZIF-8 to obtain ZnO nanopowder; (2) The ZnO nanopowder is uniformly dispersed in a mixed solution composed of ethyl cellulose, terpineol and ethanol solvent, and is rotary evaporated after oscillation and ultrasonic to obtain a ZnO slurry; (3) The ZnO slurry is coated on the surface of the conductive substrate, and then calcined after heating to obtain a photoanode film attached to the conductive substrate and composed of ZnO nanopowder. 2. The preparation method based on ZnO nano powder photoanode film according to claim 1, characterized in that: the calcination temperature in the step (1) is 450～750°C; the particle diameter of the ZnO nano powder is 30～ 100nm. 3. the preparation method based on ZnO nano powder photoanode film according to claim 1, is characterized in that: in described step (2), ethyl cellulose is 10cp ethyl cellulose and 46cp ethyl cellulose; The mass volume concentrations of 10cp ethylcellulose, 46cp ethylcellulose, and terpineol in ethanol solvent are respectively 0.1 to 0.5g/cm ³ ; the mass percent concentration of the ZnO nanopowder in the mixed solution is 1 ~10 wt%. 4. the preparation method based on ZnO nanometer powder photoanode film according to claim 1, is characterized in that: the time of oscillation in described step (2) is 5～10min; The time of ultrasonic is 20～40min; Oscillation and ultrasonic The number of cycles is 3 to 5 times; the temperature of the rotary evaporation is 70 to 80° C., and the time is 25 to 60 minutes. 5. the preparation method based on ZnO nanometer powder photoanode film according to claim 1, is characterized in that: in described step (3), the thickness that ZnO slurry is coated on conductive substrate surface is 7～35 μ m; Heating temperature is 80～120℃; calcination temperature is 350～450℃. 6. the preparation method based on ZnO nano powder photoanode film according to claim 1, is characterized in that: the preparation of described metal organic framework ZIF-8 is, zinc nitrate hexahydrate and 2-methylimidazole are dissolved in respectively Stir evenly in the methanol solvent to obtain zinc nitrate hexahydrate methanol solution and 2-methylimidazole methanol solution respectively; then pour the zinc nitrate hexahydrate methanol solution into the 2-methylimidazole methanol solution, and carry out the reaction after stirring After centrifugation, washing and drying, the metal-organic framework ZIF-8 is obtained. 7. The preparation method based on ZnO nano powder photoanode film according to claim 6, characterized in that: the molar concentration of zinc nitrate hexahydrate in the methanol solution of zinc nitrate hexahydrate is 9～30mM, 2-methylimidazole The molar concentration of 2-methylimidazole in methanol solution is 72-240mM. 8 . The method for preparing a photoanode film based on ZnO nano powder according to claim 6 , characterized in that: the reaction time is 1-3 hours; the drying temperature is 50-70° C. 9. The photoanode film prepared by the preparation method based on ZnO nano-powder photoanode film according to any one of claims 1-8. 10. The photoanode film based on ZnO nano powder according to claim 9, characterized in that: the thickness of the photo anode film is 7-35 μm, and the particle size of the ZnO nano powder is 30-100 nm.