CN104269273A - TiO2 with nanometer hollow thorn ball structure, preparation method and application to solar cell photoanode - Google Patents

Abstract

The invention relates to TiO ₂ with a nanometer hollow thorn ball structure, a preparation method and its application as a photoanode material of a dye-sensitized solar cell, belonging to the field of dye-sensitized solar cells. The first step is to synthesize the SiO ₂ nanosphere template, then coat a layer of TiO ₂ on the surface of the SiO ₂ nanosphere, and finally remove the SiO ₂ template in one step by hydrothermal reaction with a certain concentration of NaOH aqueous solution, and effectively corrode the TiO ₂ surface, finally A TiO ₂ material with a nano-hollow thorn ball structure is obtained. A solar cell assembled from the photoanode film prepared by this material has a photoelectric conversion efficiency of 5.48%. The preparation method has high production efficiency, low cost, simple method, short experiment period, easy realization of large-area production, and improved battery stability.

Description

TiO2 with nanometer hollow thorn ball structure, preparation method and application to solar cell photoanode

technical field

The invention belongs to the technical field of dye-sensitized solar cells, and in particular relates to TiO ₂ with a nanometer hollow thorn ball structure, a preparation method and its application as a photoanode material of dye-sensitized solar cells.

Background technique

Environmental pollution and lack of renewable energy are two major challenges facing mankind. As the most important renewable green energy, solar energy has attracted more and more people's attention. Among them, dye-sensitized solar cells have quickly become the representative of the new generation of solar cells due to their low power consumption, simple process, environmental friendliness and high conversion efficiency. In the past two decades, scientists have done a lot of research, especially the research on nanoporous titanium dioxide materials has made many breakthroughs. As we all know, titanium dioxide nanocrystalline film is used as a battery photoanode, and its crystal structure, crystal size and material morphology (such as: nanowires, nanosheets, nanotubes, nanoflowers, nanospheres, etc.) have a great influence on the photoelectric performance of the battery. Although the one-dimensional nanostructured titanium dioxide has the advantages of low transfer resistance, long electron lifetime, and few grain boundaries as the bottom layer of the photoanode layered structure, but its light scattering ability is low, and because the specific surface area is relatively small compared with the three-dimensional nanostructure, so The dye adsorption ability is weak, which limits the further improvement of its photoelectric performance. Therefore, titanium dioxide nanomaterials with high light scattering efficiency and large specific surface area have become the target of photoanode materials for dye-sensitized solar cells. Designing and synthesizing titanium dioxide materials with special morphology to meet the above requirements has far-reaching research significance and broad application prospects as an effective method to improve battery performance.

Contents of the invention

Aiming at the pursuit of titanium dioxide material with special appearance and advantages in the background technology, the present invention provides a preparation method of titanium dioxide material with nano-hollow thorn ball structure and the application of the material as photoanode of dye-sensitized solar cells. The titanium dioxide prepared by the method can also be widely used in photocatalysis, photochemistry, lithium batteries and other fields.

The dye-sensitized solar cell of the present invention is composed of an anode conductive glass FTO, a dye-sensitized TiO ₂ nanocrystalline film electrode, an electrolyte solution (I ⁻ /I ₃ ⁻ ), and a Pt counter electrode; method to inject the battery. The structure is shown in Fig. 1, and it is characterized in that: the photoanode material is the titanium dioxide of the nano-hollow thorn ball structure prepared by the present invention, and the porous _TiO2 nanocrystalline film prepared by this material has good light scattering effect. When the incident light passes through the conductive glass FTO and enters the _TiO2 nanocrystalline film, because the prepared material has a special porous structure, it can reflect multiple times and effectively absorb the incident light, thereby greatly improving the utilization rate of the incident light. At the same time, due to its special nanostructure, the specific surface area of the material is increased, which is conducive to the adsorption of more dyes, thereby achieving the purpose of improving the photoelectric conversion efficiency.

The TiO ₂ material with the nano hollow thorn ball structure described in the present invention is synthesized by means of a hard template. First, the SiO ₂ nanosphere template is synthesized by chemical co-precipitation, and then a layer of TiO ₂ is coated on the surface of the SiO ₂ . The hydrothermal reaction with a certain concentration of NaOH aqueous solution removes the _SiO2 template in one step, and effectively corrodes the _TiO2 surface, and finally obtains a _TiO2 material with a nano-hollow thorn ball structure. Among them, the SiO ₂ nanosphere template is prepared by the co-precipitation method, which can prepare SiO ₂ nanospheres with excellent monodispersity, and the diameter can be accurately controlled; the TiO ₂ layer can be prepared by chemical coating.

A kind of preparation method of titanium dioxide with nanometer hollow barbed ball structure according to the present invention, its steps are as follows:

(1) Measure 3-7mL tetraethyl orthosilicate (Beijing Fine Chemical Co., Ltd.), add it to 45mL ethanol to obtain solution A, and stir magnetically for 10-20min;

(2) Measure 2-6mL ammonia water (concentration 25-28wt.%) (Beijing Fine Chemical Co., Ltd.), add it to a mixed solution consisting of 10mL deionized water and 35mL ethanol to obtain solution B, and stir magnetically for 10-20min;

(3) Add solution A to solution B, and fully stir in a water bath at 40-60°C for 2-3 hours to obtain a white suspension;

(4) Wash the white suspension in step (3) with ethanol for 3 to 5 times, then put the cleaned product in a vacuum oven at 60 to 80°C, and take it out after drying for 5 to 10 hours to obtain SiO ₂ sample;

(5) Measure 0.2-0.4g of the _SiO2 sample described in step (4), add it to 100mL of ethanol, and ultrasonically dissolve it for 10-20min to obtain suspension C;

(6) Measure 2-3 mL of tetrabutyl titanate (Beijing Fine Chemical Co., Ltd.), add it to 100 mL of ethanol, and stir magnetically for 5-10 minutes to obtain solution D;

(7) Add solution D to suspension C, add 1-2mL ammonia water (concentration: 25-28wt.%) at the same time, stir in a water bath at 40-60°C for 2-4 hours, and obtain a white suspension;

(8) Wash the white suspension in step (7) with ethanol for 3 to 5 times, then put the washed product in a vacuum oven at 60 to 80°C, and take it out after drying for 5 to 10 hours to obtain a diameter of about A SiO ₂ sample coated with TiO ₂ of 400-600nm;

(9) Measure 0.04-0.1 g of the TiO _2- coated SiO ₂ sample described in step (8), add it to 30 mL, 1-5 mol/L NaOH solution, and dissolve it by ultrasonication for 20-30 minutes to obtain a white suspension liquid;

(10) Pour the white suspension in step (9) into a polytetrafluoroethylene-lined autoclave, react at 80-120°C for 3-6 hours, and cool to room temperature naturally;

(11) Wash the reaction product in step (10) successively with 0.2 to 0.3 mol/L _HNO3 solution and deionized water repeatedly for 3 to 5 times, and put the washed product into a vacuum oven at 60 to 80°C, Dry it for 5-10 hours and take it out to obtain the TiO ₂ material with the nano hollow thorn ball structure of the present invention.

The reaction product is cleaned by repeated centrifugation, the centrifugation speed is 8000-10000 rpm, and the centrifugation time is 10-20 minutes.

The present invention provides a titanium dioxide material prepared by the above method. The XRD characterization diagram of titanium dioxide, its 2θ are 25.28, 37.80, 48.05, 53.89, 55.06, 62.69, 68.76, 70.31 and 75.03, respectively, which can be known as anatase structure from the standard card (JCPDS card no.21-1272). No characteristic peak of _SiO2 appeared in it, indicating that the _SiO2 template had been removed.

The titanium dioxide material with the nano hollow thorn ball structure of the present invention has good monodispersity, and the diameter of the nano hollow thorn ball is about 400-600 nm. As shown in Figure 2, the spherical shell is composed of dense nanosheets. The size of the nanosheets is about 50-100nm. The nanosheets overlap and stagger to form a rough spherical shell surface. This unique mesoporous structure can effectively improve the The specific surface area of the material increases the amount of dye adsorption. At the same time, because the material has a hollow structure, when the light enters its interior, multiple diffuse reflections will occur, and the energy of the light is continuously absorbed by the _TiO2 material, thereby further increasing the light capture rate and achieving the purpose of improving the photoelectric conversion efficiency.

The titanium dioxide material described in the present invention can be used as a photoanode material of a dye-sensitized solar cell. The obtained _TiO2 powder material is made into a slurry, uniformly scraped and coated on the FTO, dried in a vacuum oven at 80°C for 1 hour, then placed in a high-temperature resistance furnace and calcined at 500°C for 30 minutes, and the solar energy described in the present invention can be obtained. The photoanode of the battery.

The advantages of the invention: the preparation method has the advantages of high production efficiency, low cost, simple method and short experiment period. The prepared titanium dioxide material can be used as a photoanode in a dye-sensitized solar cell, and the photoelectric conversion efficiency obtained by assembling it into a cell can reach 5.48%.

Description of drawings

Fig. 1: dye-sensitized solar cell structure schematic diagram of the present invention; As shown in Fig. 1, each part name is: ammeter ₁ , has the TiO of nanometer hollow thorn ball structure The porous nanocrystalline film (film thickness is about 24 μm) 2, Pt counter electrode 3, electrolyte solution (I ⁻ /I ₃ ⁻ ) 4, conductive glass FTO 5 .

Fig. 2: the _TiO2 material that the present invention prepares has nanometer hollow thorn ball structure SEM image; Hollow structure; as shown in Figure 2(b), it is a single nano hollow spine ball with a diameter of about 600nm, and the spherical shell is composed of many nanosheets.

Figure 3: XRD pattern of the titanium dioxide material prepared by the present invention; it can be known from the standard card that the material is anatase structure.

Figure 4: N ₂ adsorption-desorption curve and pore size distribution diagram of the titania material prepared by the present invention; the specific surface area of the material is as high as 100.3m ² g ^-1 and the average pore size is 29.6nm according to the experiment.

Fig. 5: The diffuse reflectance spectrogram of commercial titanium dioxide (P25) and titanium dioxide (THS) prepared by the present invention; In the visible light wavelength range (400～800nm), THS has stronger reflection ability, makes THS more suitable as reflective layer thereby improves Utilization of incident light.

Fig. 6: the cell JV graph that uses commercial titanium dioxide (P25 ⁾ and titanium dioxide (THS) prepared by the present invention as the photoanode material to make; ) increased to 13.20 mA/cm ² .

Detailed ways

Embodiment 1: Prepare the titanium dioxide material of nanometer hollow barbed ball structure with one-step hydrothermal synthesis method, specific process is as follows

(1) Measure 5 mL of ethyl orthosilicate (Beijing Fine Chemical Co., Ltd.), add it into 45 mL of ethanol to obtain solution A, and stir it magnetically for 10 min.

(2) Measure 5 mL of ammonia water (concentration 25 wt.%) (Beijing Fine Chemical Co., Ltd.), add it to a mixed solution consisting of 10 mL of deionized water and 35 mL of ethanol to obtain solution B, and stir magnetically for 10 min.

(3) Add solution A to solution B, and fully stir in a 40°C water bath for 2.5 hours to obtain a white suspension.

(4) Wash the white suspension in step (3) 3 times with ethanol, then put the washed product in a vacuum oven at 80°C, and take it out after drying for 8 hours, which is _SiO with a diameter of about 400nm sample.

(5) Measure 0.3 g of the SiO ₂ sample described in step (4), add it into 100 mL of ethanol, and dissolve it ultrasonically for 10 min to obtain suspension C.

(6) Measure 2 mL of tetrabutyl titanate (Beijing Fine Chemical Co., Ltd.), add it to 100 mL of ethanol to obtain solution D, and stir magnetically for 10 min.

(7) Add solution D to suspension C, and at the same time add 1.5mL ammonia water, stir thoroughly in a 60°C water bath for 3 hours to obtain a white suspension.

(8) Wash the white suspension in step (7) 3 times with ethanol, then put the washed product in a vacuum oven at 80°C, and take it out after drying for 8 hours, which is _TiO with a diameter of about 500nm Coated _SiO2 samples;

(9) Measure 0.05 g of the TiO ₂ -coated SiO ₂ sample described in step (8), add it into 30 mL of 2 mol/L NaOH solution, and ultrasonically dissolve it for 30 min to obtain a white suspension.

(10) Pour the white suspension in step (9) into a polytetrafluoroethylene-lined autoclave (volume 45 mL), react at 100° C. for 4 hours, and cool to room temperature naturally.

(11) The reaction product in step (10) was washed with 0.2mol/L HNO ₃ solution and deionized water repeatedly for 3 times. Put the washed product into a vacuum oven at 80° C., dry it for 8 hours, and take it out to obtain the TiO ₂ material with the nano hollow thorn ball structure of the present invention.

Table 1: Comparison of various battery performance parameters of dye-sensitized solar cells prepared with P25 as photoanode and THS as photoanode

Table 1 lists the performance parameters of the cells with P25 and THS as the photoanode material respectively, where J _sc is the short circuit current, V _oc is the open circuit voltage, FF is the fill factor, and η is the photoelectric conversion efficiency; R ₁ , R ₂ and R ₃ are the fitting parameters of the equivalent circuit of complex impedance spectroscopy (EIS), reflecting the electron transport characteristics of the battery; Dye adsorption is the amount of dye adsorbed by the photoanode during the dye sensitization process. It can be seen from the table that by using THS as the photoanode material, the dye adsorption capacity of the battery is significantly increased, so the short-circuit current of the battery is significantly improved. The photoelectric conversion efficiency of the battery is 5.48%, which is 34.6% higher than that of the battery (4.07%) using P25 as the photoanode material.

Claims (3)

1. have a preparation method for the titanium dioxide of hollow nano acanthosphere structure, its step is as follows:

(1) measure 3 ~ 7mL tetraethoxysilane, join in 45mL ethanol and obtain solution A, magnetic agitation 10 ~ 20min;

(2) measure 2 ~ 6mL ammoniacal liquor, concentration 25 ~ 28wt.%, join in the mixed solution be made up of 10mL deionized water and 35mL ethanol and obtain solution B, magnetic agitation 10 ~ 20min;

(3) solution A is joined in solution B, in 40 ~ 60 DEG C of water-baths, fully stir 2 ~ 3h, obtain white suspension-turbid liquid;

(4) by the white suspension-turbid liquid ethanol purge in step (3) 3 ~ 5 times, more cleaned product is put into 60 ~ 80 DEG C of vacuum drying ovens, dry after 5 ~ 10 hours and take out, obtain SiO ₂sample;

(5) SiO described in 0.2 ~ 0.4g step (4) is measured ₂sample, join in 100mL ethanol, ultrasonic dissolution 10 ~ 20min obtains suspension-turbid liquid C;

(6) measure 2 ~ 3mL butyl titanate, join in 100mL ethanol, magnetic agitation 5 ~ 10min obtains solution D;

(7) solution D is joined in suspension-turbid liquid C, add 1 ~ 2mL ammoniacal liquor, concentration 25 ~ 28wt.% simultaneously, in 40 ~ 60 DEG C of water-baths, stir 2 ~ 4h, obtain white suspension-turbid liquid;

(8) by the white suspension-turbid liquid ethanol purge in step (7) 3 ~ 5 times, more washed product is put into 60 ~ 80 DEG C of vacuum drying ovens, dry after 5 ~ 10 hours and take out, obtain the TiO that diameter is about 400 ~ 600nm ₂coated SiO ₂sample;

(9) TiO described in 0.04 ~ 0.1g step (8) is measured ₂coated SiO ₂sample, joins in the NaOH solution of 30mL, 1 ~ 5mol/L, and ultrasonic 20 ~ 30min dissolves, and obtains white suspension-turbid liquid;

(10) pouring white suspension-turbid liquid in step (9) into liner is in the autoclave of polytetrafluoroethylene, reacts 3 ~ 6 hours, naturally cool to room temperature at 80 ~ 120 DEG C;

(11) by the product priority 0.2 ~ 0.3mol/L HNO in step (10) ₃solution and deionized water rinse 3 ~ 5 times repeatedly, and washed product is put in 60 ~ 80 DEG C of vacuum drying ovens, dry the TiO taking out and obtain hollow nano acanthosphere structure for 5 ~ 10 hours ₂material.

2. there is a titanium dioxide for hollow nano acanthosphere structure, it is characterized in that: be prepared by method described in claim 1.

3. as claimed in claim 1 a kind of titanium dioxide with hollow nano acanthosphere structure as the application in the light anode of DSSC.