CN101492477B - Photosensitizer, composite photocatalyst and method for preparing the same - Google Patents

Abstract

The invention belongs to the technical field of materials, and relates to a photosensitizer and a photocatalyst. The photosensitizer is the black powder of 8-hydroxyquinoline-5-sulfonate iron (III) complex, the molecular formula is (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O, where (C ₉ H ₆ NSO ₄ ) ₃ Fe is a six-dentate coordination structure. The composite photocatalyst is a colloidal or powdery material in which (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complexes are adsorbed on the surface of nanometer TiO ₂ . First prepare 8-hydroxyquinoline-5-sodium sulfonate solution; then drop into FeCl ₃ solution, stir and heat in a boiling water bath, then evaporate to dryness; finally extract with absolute ethanol and vacuum dry to obtain the photosensitizer. Add (C ₉ H ₆ NSO ₄ ) ₃ Fe 2H ₂ O to the TiO ₂ suspension, keep stirring and place away from light to obtain a colloidal composite photocatalyst (or stand still, filter, and dry in a low-temperature vacuum to obtain powder shape composite photocatalyst). The photosensitizer has photosensitization performance in the visible light spectrum range; the degradation rate of the composite photocatalyst to methyl orange can reach more than 90% within one hour. The invention can be used for visible light splitting water to produce hydrogen, sensitized solar cells and degradation of organic pollutants.

Description

A kind of photosensitizer, composite photocatalyst and preparation method thereof

technical field

The invention belongs to the technical field of materials, and relates to a photosensitizer, a composite photocatalyst and a preparation method thereof.

Background technique

教授在Nature上首次报道了染料敏化多孔TiO₂纳米薄膜为光阳极的太阳能电池(Dye-sensitized Solar Cells，简写为DSSCs)，它以羧酸联吡啶钌(II)配合物为染料敏化剂，其光电转化效率在AM1.5的模拟太阳光照射下可以达到7.1～7.9％，并且价格较低，因而引起了全世界的关注(B O’Regan，M

Nature，1991，353：737～739)。此后，人们在这种电池的运作机理及电池组成部分的优化性能改进部分作了大量的研究，使DSSCs能向实用化发展。在DSSCs中，染料敏化剂就像捕获天线，起着收集能量的作用，它的性能将直接影响到DSSCs的光电转化效率，具有非常重要的作用。在20多年的研究当中，人们合成了近千种染料，但只有一小部分具有良好的光电敏化性能，其中主要是钌的联吡啶配合物。作为染料敏化剂不但要求其对太阳光具有良好的广泛吸收，高的摩尔消光系数，在半导体上吸附性能良好(有在TiO₂表面吸附良好的基团，如-OH、-COOH、-SO₃H、-PO₃H₂等)，还要有合适的氧化-还原电位，激发态寿命长、光致发光性好以及具有良好的稳定性等。但从目前的研究来看，联吡啶钌系列配合物是目前研究和应用最多的一类染料，这是因为他们具有较宽的可见光吸收谱、理想的氧化还原性能以及高的氧化态稳定性。但由于钌系贵金属，其金属配合物合成难度较大，且易造成环境污染，因此人们开始开发其他配合物的染料敏化剂。现已发现了各种敏化剂，如Rhodamine B、Thionine等纯有机染料，金属酞菁等有机金属配合物(Bae E，Choi W，Park J，Shin H S，Kim S B，Lee J S.J Phys Chem B.2004(108)：14093-14101.)，含有高度共轭结构的聚合物(Lin Song，RongLiang Qiu，Yueqi，etal.Catalysis Communications，2007(8)：429-433)等。目前，光敏化TiO₂催化剂已广泛的应用于可见光分解水制氢、光电太阳能电池和可见光催化降解有机污染物的研究中。但总的来说其可见光催化性能不理想，且易造成环境污染。因此，需要研制新型高效的、环保的光催化剂。In 1991, the Swiss Institute of Technology in Lausanne

The professor reported for the first time in Nature that dye-sensitized porous TiO ₂ nano-films are used as photoanode solar cells (Dye-sensitized Solar Cells, abbreviated as DSSCs), which use carboxylic acid bipyridyl ruthenium (II) complexes as dye sensitizers , its photoelectric conversion efficiency can reach 7.1～7.9% under the simulated sunlight irradiation of AM1.5, and the price is relatively low, thus caused the attention of the whole world (B O'Regan, M

Nature, 1991, 353:737-739). Since then, people have done a lot of research on the operation mechanism of this battery and the optimization and performance improvement of the battery components, so that DSSCs can be developed into practical use. In DSSCs, the dye sensitizer is like a capture antenna, which plays a role in collecting energy, and its performance will directly affect the photoelectric conversion efficiency of DSSCs, which plays a very important role. In more than 20 years of research, nearly a thousand dyes have been synthesized, but only a small part have good photosensitive properties, mainly bipyridine complexes of ruthenium. As a dye sensitizer, it is not only required to have good broad absorption of sunlight, high molar extinction coefficient, and good adsorption performance on semiconductors (with groups that are well adsorbed on the surface of _TiO2 , such as -OH, -COOH, -SO ₃ H, -PO ₃ H ₂ , etc.), but also have a suitable oxidation-reduction potential, long excited state lifetime, good photoluminescence and good stability. However, according to the current research, bipyridyl ruthenium complexes are the most studied and applied dyes because of their broad visible light absorption spectrum, ideal redox performance and high oxidation state stability. However, due to the difficulty in synthesizing the metal complexes of ruthenium-based noble metals, and easy to cause environmental pollution, people began to develop dye sensitizers of other complexes. Various sensitizers have been found, such as pure organic dyes such as Rhodamine B and Thionine, organometallic complexes such as metal phthalocyanines (Bae E, Choi W, Park J, Shin H S, Kim S B, Lee J SJ Phys Chem B .2004(108): 14093-14101.), polymers containing highly conjugated structures (Lin Song, RongLiang Qiu, Yueqi, etal.Catalysis Communications, 2007(8): 429-433), etc. At present, photosensitized _TiO2 catalysts have been widely used in the research of visible light splitting water to produce hydrogen, photoelectric solar cells and visible light catalytic degradation of organic pollutants. But in general, its visible light catalytic performance is not ideal, and it is easy to cause environmental pollution. Therefore, it is necessary to develop new efficient and environmentally friendly photocatalysts.

Contents of the invention

The object of the present invention is to provide a photosensitizer and a preparation method thereof. The photosensitizer has photosensitization performance in the visible light spectrum range; the preparation method of the photosensitizer is simple and easy, and the cost is low. Another object of the present invention is to provide a composite photocatalyst and its preparation method. The composite photocatalyst is formed by absorbing the photosensitizer provided by the present invention with nano-titanium dioxide as the matrix, and can be used for visible light splitting water to produce hydrogen and dye-sensitized solar energy. Batteries and Visible Light Catalytic Degradation of Organic Pollutants. The preparation method of the composite photocatalyst also has the characteristics of simplicity and low cost.

Technical scheme of the present invention is:

A photosensitizer whose main component is black powder of 8-hydroxyquinoline-5-sulfonate iron (III) complex, easily soluble in water to form a dark green solution, slightly soluble in ethanol, and at pH< It has high complexation stability under 8. Its molecular formula is (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O, where the structural formula of (C ₉ H ₆ NSO ₄ ) ₃ Fe is (as shown in Figure 2):

The preparation method of above-mentioned photosensitizer, comprises the following steps:

Step 1: 8-hydroxyquinoline-5-sulfonic acid is dissolved in NaOH hot solution, and the molar ratio of controlling 8-hydroxyquinoline-5-sulfonic acid to NaOH is n _HQS :n _NaOH =1:0.9～1.1, Generate 8-hydroxyquinoline-5-sodium sulfonate solution;

Step 2: drop _FeCl solution in 8-hydroxyquinoline-5-sulfonic acid sodium solution, control 8-hydroxyquinoline-5-sulfonic acid and FeCl _The mol ratio is n _HQS : n _FeCl =3: 0.9 ~1.1; then adjust the pH of the solution to 4~5;

Step 3: Stir and heat the solution obtained in step 2 in a boiling water bath for 0.5 to 4 hours and then evaporate to dryness to obtain 8-hydroxyquinoline-5-sulfonate iron (III) complex (molecular formula: (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O) crude product;

Step 4: The crude product of 8-hydroxyquinoline-5-sulfonate iron (III) complex obtained in step 3 is extracted with absolute ethanol to remove impurities, and then vacuum-dried at 50-100°C to obtain Photosensitizer-(C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex.

The (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex prepared by the above method is a black powder, easily soluble in water to form a dark green solution, slightly soluble in ethanol, and has a strong High complexation stability. Its yield is 70-80%, mp>300°C; elemental analysis experimental value: N% 5.33%, C% 43.51%, H% 3.91%, calculated value N% 5.77%, C% 44.51%, H% 2.88%; BRUKER ¹ H-NMR (D ₂ O, 600MHz): δ=9.17(s, 3H, SO ₃ H), 8.85(d, 3H ₁ ), 8.08(d, 3H ₃ ), 7.88(m, 3H ₄ ), 7.29(d, 3H ₂ ), 7.24(d, 3H ₆ ); FTIR-8400S(KBr): v _OH 3350cm ^-1 ; hydroxyl bending vibration absorption peak δ _OH 1225cm ^-1 ; v _CO 1025cm ^-1 ; v _C=C 1579cm ^-1 , 1549cm ^-1 , 1479cm ^-1 ; v _C=N 1511cm ^-1 ; v _O=S=O 1369cm ^-1 , 1164cm ^-1 ; UV-Vis: 357nm, 459nm, 630nm; TGA: 106°C, 346 ℃, 512°C and 628°C, the weight loss ratio is 2.91:12.23:12.06:13.35 basically satisfying the weight loss ratio of the chemical formula (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O 1:6.22:6.22:6.22, indicating that in its structure It should contain three identical 8-hydroxyquinoline-5-sulfonic acid ligands, and its structure should be a hexadentate coordination based on classical chemical structure theory. Fig. 1 is the XRD spectrum of (C ₉ H ₆ NSO ₄ ) ₃ Fe, which shows a good crystallization degree and regular crystal form.

A composite photocatalyst, which uses nano- _TiO2 as a matrix, and the surface of the matrix absorbs the photosensitizer-(C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex compound colloid or powder Material.

The preparation method of above-mentioned composite photocatalyst adopts following steps to make:

First drop the ethanol solution of TiCl ₄ into the ethanol solution of NaOH and TEA (n _{TiCl 4} : n _TEA : n _NaOH = 1: 1: 4), remove the generated sodium chloride by suction filtration, then add heated water to it, distill out After ethanol, adjust the pH value of the system to below 3; then heat it in water at 100°C for 1-4 hours, then raise the pH to neutral, pour out the supernatant after natural sedimentation, and repeat the operation 2-3 times before further evaporating and concentrating into a TiO ₂ suspension; finally add the photosensitizer-(C _{9 H 6} NSO ₄ ) ₃ Fe 2H ₂ O complex provided by the invention to the TiO 2 suspension, and control the system If the pH is within 3-7, place it away from light to obtain a colloidal composite photocatalyst (or after standing for 12-36 hours, filter and vacuum dry at low temperature to obtain a powdery composite photocatalyst).

The composite mechanism of the above-mentioned composite photocatalyst can be explained as follows: ①The sulfonic acid group and the hydroxyl group produced on the surface of TiO ₂ produce an esterification reaction, and they are similar and compatible; ②TiO ₂ has a very small particle size and a large specific surface area, which can easily Good adsorption of hydrophilic groups such as sulfonic acid groups.

The photosensitizer provided by the present invention has photosensitizing properties in the visible light spectrum range; the composite photocatalyst provided by the present invention takes nano-titanium dioxide as a matrix, and absorbs the photosensitizer provided by the present invention to form, and its visible light catalytic activity is as good as the degradation of methyl orange. To evaluate the rate, it can reach more than 90% within 1 hour. The photosensitizer and composite photocatalyst provided by the invention can be used in visible light splitting water to produce hydrogen, dye-sensitized solar cells and visible light catalytic degradation of organic pollutants. The preparation methods of the two are simple and easy, the cost is low, and the product quality is stable and reliable.

Description of drawings

Figure 1 is the XRD spectrum of (C ₉ H ₆ NSO ₄ ) ₃ Fe.

Fig. 2 is a structure diagram of (C ₉ H ₆ NSO ₄ ) ₃ Fe molecule.

Figure 3 is a schematic diagram of the self-made photocatalytic reactor.

Figure 4 is the XRD spectrum of unsensitized TiO ₂ .

Figure 5 is the SEM image of unsensitized _TiO2 .

Detailed ways

Example 1:

1. Dissolve 8-hydroxyquinoline-5-sulfonic acid in 0.2M NaOH hot solution, control the molar ratio of 8-hydroxyquinoline-5-sulfonic acid to NaOH to be n _HQS :n _NaOH =1:1.0, Generate 8-hydroxyquinoline-5-sodium sulfonate solution;

2, in step 1, drop into 1M FeCl ₃ solution, the mol ratio of controlling 8-hydroxyquinoline-5-sulfonic acid and FeCl ₃ is n _HQS : n _{FeCl 3} = 3: 1.1; Then the pH value of the solution is adjusted to 5;

3. Stir and heat in a boiling water bath for 2 hours, then evaporate the solution to obtain 8-hydroxyquinoline-5-sulfonate iron (III) complex (molecular formula: (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O) crude product;

4. Extract with absolute ethanol to remove impurities such as sodium chloride, and dry at 100°C to obtain (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex;

5. Drop the ethanol solution of TiCl ₄ into the ethanol solution of NaOH and TEA (n _{TiCl 4} : n _TEA : n _NaOH = 1: 1: 4), remove the generated sodium chloride by suction filtration, then drop heated water into it, and distill Adjust the pH value of the system to 2.5 after removing ethanol. After heating in water at 100°C for 2 hours, then raise the pH to neutral, pour out the supernatant after natural sedimentation, and repeat the operation 2 to 3 times before further evaporating and concentrating it to a certain concentration. Concentration TiO ₂ suspension. Add the complex prepared in step 4 to the newly prepared _TiO2 suspension, control the mass ratio as: _TiO2 : sensitizer=1: 0.040, place it in the dark under constant stirring, and adjust the pH value of the system to be 6. A gel-like product was obtained. After standing for 24 hours, filter and vacuum dry at low temperature to obtain a powder product.

6. Add 600 mL of 15 mg·L ^-1 methyl orange solution and 0.6 g of photocatalyst powder to the self-made photocatalytic reactor shown in Figure 3 to make the concentration 1 g·L ^-1 . The degradation rate of methyl orange solution within 1h is shown in Table 1.

Example 2:

1. Dissolve 8-hydroxyquinoline-5-sulfonic acid in 1M NaOH hot solution, control the molar ratio of 8-hydroxyquinoline-5-sulfonic acid to NaOH to be n _HQS :n _NaOH =1:1.1, generate 8-hydroxyquinoline-5-sulfonate sodium solution;

2, in step 1, drop into 0.5M FeCl ₃ solution, control 8-hydroxyquinoline-5-sulfonic acid and FeCl The mol ratio is n _HQS : n _{FeCl 3} =3: 1; Then the pH value of the solution is adjusted to 4.5;

3. Stir and heat in a boiling water bath for 4 hours and then evaporate the solution to obtain 8-hydroxyquinoline-5-sulfonate iron (III) complex (molecular formula: (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O) crude product;

4. Extract with absolute ethanol to remove impurities such as sodium chloride, and dry at 60°C to obtain (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex;

5. Drop the ethanol solution of TiCl ₄ into the ethanol solution of NaOH and TEA (n _{TiCl 4} : n _TEA : n _NaOH = 1: 1: 4), remove the generated sodium chloride by suction filtration, then drop heated water into it, and distill Adjust the pH value of the system to 2.8 after removing ethanol. After heating in water at 100°C for 3 hours, raise the pH to neutral, pour out the supernatant after natural sedimentation, and repeat the operation 2 to 3 times before further evaporating and concentrating it to a certain concentration. Concentration TiO ₂ suspension. Then add the complex compound prepared in step 4 to the newly prepared _TiO2 suspension, control the mass ratio: _TiO2 : sensitizer=1: 0.035, place it in the dark under constant stirring, and adjust the pH of the system to be 5. Gel-like product.

6. In the self-made photocatalytic reactor shown in Figure 3, add 600mL of 15mg·L ^-1 methyl orange solution and photocatalyst colloid product to make the concentration 1g·L ^-1 . The degradation rate of methyl orange solution within 1h is shown in Table 1.

Example 3:

1. Dissolve 8-hydroxyquinoline-5-sulfonic acid in 0.5M NaOH hot solution, control the molar ratio of 8-hydroxyquinoline-5-sulfonic acid to NaOH to be n _HQS :n _NaOH =1:0.9, Generate 8-hydroxyquinoline-5-sodium sulfonate solution;

2. Add 0.1M _FeCl3 solution dropwise in step 1, and control the mol ratio of 8-hydroxyquinoline-5-sulfonic acid to _FeCl3 to be n _HQS : n _FeCl3 = 3: 0.9; then adjust the pH value of the solution to 4;

3. Stir and heat in a boiling water bath for 1 hour, then evaporate the solution to obtain 8-hydroxyquinoline-5-sulfonate iron (III) complex (molecular formula: (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O) crude product;

4. Extract with absolute ethanol to remove impurities such as sodium chloride, and dry at 80°C to obtain (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex;

5. Drop the ethanol solution of TiCl ₄ into the ethanol solution of NaOH and TEA (n _{TiCl 4} : n _TEA : n _NaOH = 1: 1: 4), remove the generated sodium chloride by suction filtration, then drop heated water into it, and distill Adjust the pH value of the system to 2.7 after removing ethanol. After heating in water at 100°C for 1 hour, raise the pH to neutral, pour out the supernatant after natural sedimentation, and repeat the operation 2 to 3 times before further evaporating and concentrating it to a certain concentration. Concentration TiO ₂ suspension. Then add the complex compound prepared in step 4 to the newly prepared _TiO2 suspension, control the mass ratio: _TiO2 : sensitizer=1: 0.042, place it in the dark under constant stirring, and adjust the pH of the system to be 4.5. Gel-like product.

6. In the self-made photocatalytic reactor shown in Figure 3, add 600mL of 15mg·L ^-1 methyl orange solution and the photocatalyst colloid product in step 5 to make the concentration 1g·L ^-1 . The degradation rate of methyl orange solution within 1h is shown in Table 1.

Comparative example 1:

The preparation method of unsensitized _TiO2 is an improvement on _the basis of Zhong Yongke et al. in the ethanol solution (n _TiCl4 :n _TEA :n _NaOH = 1:1:4), remove the generated sodium chloride by suction filtration, then drop hot water into it, and adjust the pH value of the system to below 3 after distilling off the ethanol. After heating in water at 100°C for 2.5 hours, raise the pH to neutral, pour out the supernatant after natural sedimentation, repeat the operation 2 to 3 times, and then further evaporate and concentrate it to a suspension containing a certain concentration of TiO ₂ , vacuum After drying, it is calcined at 350°C for 1 hour to obtain the product.

It can be seen from the XRD spectrum (Fig. 3) of the self-made TiO ₂ mentioned above that the characteristic peaks of anatase TiO ₂ appear at diffraction angles such as 2θ of 25.2, 38.709 and 48.62, and there are A very weak brookite phase peak is present. Figure 4 shows that TiO ₂ has a uniform particle size of about 50 nm.

In the self-made photocatalytic reactor shown in Figure 3, 600 mL of 15 mg·L ^-1 methyl orange solution and 0.6 g of self-made TiO ₂ powder were added to make the concentration 1 g·L ^-1 . The degradation rate of methyl orange solution within 1h is shown in Table 1.

Table 1: The degradation rate value of each embodiment methyl orange solution within 1h

serial number 10 minutes 20 minutes 30 minutes 40 minutes 50 minutes 1 hour Example 1 28.00% 48.32% 63.77% 76.22% 87.57% 97.67% Example 2 26.68% 46.95% 64.21% 77.08% 85.68% 92.42% Example 3 29.63% 50.42% 66.37% 78.35% 88.49% 96.73% Comparative example 1 9.30% 15.25% 21.47% 27.32% 32.41% 34.38%

Claims (5)

1. A photosensitizer whose composition is the black powder of 8-hydroxyquinoline-5-sulfonic acid iron (III) complex, soluble in water to form a dark green solution, slightly soluble in ethanol, and at pH It has high complexation stability under 8; its molecular formula is (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O, and the structural formula of (C ₉ H ₆ NSO ₄ ) ₃ Fe is:

2. the preparation method of photosensitizer according to claim 1, is characterized in that, comprises the following steps: Step 1: 8-hydroxyquinoline-5-sulfonic acid is dissolved in NaOH hot solution, and the molar ratio of controlling 8-hydroxyquinoline-5-sulfonic acid to NaOH is n _HQS :n _NaOH =1:0.9～1.1, Generate 8-hydroxyquinoline-5-sodium sulfonate solution; Step 2: drop _FeCl solution in 8-hydroxyquinoline-5-sulfonic acid sodium solution, control 8-hydroxyquinoline-5-sulfonic acid and FeCl _The mol ratio is n _HQS : n _FeCl =3: 0.9 ~1.1; then adjust the pH of the solution to 4~5; Step 3: Stir and heat the solution obtained in step 2 in a boiling water bath for 0.5 to 4 hours and then evaporate to dryness to obtain 8-hydroxyquinoline-5-sulfonate iron (III) complex (molecular formula: (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O) crude product; Step 4: The crude product of 8-hydroxyquinoline-5-sulfonate iron (III) complex obtained in step 3 is extracted with absolute ethanol to remove impurities, and then vacuum-dried at 50-100°C to obtain Photosensitizer-(C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex. 3. A composite photocatalyst is based on nano _TiO2 as a substrate, and a composite colloidal or powdery material of a photosensitizer adsorbed on the surface of the substrate; the photosensitizer is a black powder, and its composition is 8-hydroxyquinoline Phenyl-5-sulfonate iron (III) complex, easily soluble in water to form a dark green solution, slightly soluble in ethanol, and has high complexation stability at pH<8; its molecular formula is (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O, wherein the structural formula of (C ₉ H ₆ N ₈ O ₄ ) ₃ Fe is:

4. the preparation method of composite photocatalyst according to claim 3 is characterized in that, adopts following steps to make: first TiCl ₄ ethanol solution is dropped in the ethanol solution of NaOH and TEA, wherein TiCl ₄ , TEA and The molar ratio of NaOH is 1:1:4, remove the generated sodium chloride by suction filtration, drop hot water into it, distill ethanol and adjust the pH value of the system to below 3; From high pH to neutral, pour out the supernatant after natural sedimentation, repeat the operation 2 to 3 times, and then further evaporate and concentrate it into a _TiO2 suspension; finally add the photosensitizer to the _TiO2 suspension- (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex, under continuous stirring, control the pH of the system within 3 to 7, and place it in the dark to obtain a colloidal composite photocatalyst. 5. the preparation method of composite photocatalyst according to claim 3 is characterized in that, adopts following steps to make: first TiCl ₄ ethanol solution is dropped in the ethanol solution of NaOH and TEA, wherein TiCl ₄ , TEA and The molar ratio of NaOH is 1:1:4, remove the generated sodium chloride by suction filtration, drop hot water into it, distill ethanol and adjust the pH value of the system to below 3; From high pH to neutral, pour out the supernatant after natural sedimentation, repeat the operation 2 to 3 times, and then further evaporate and concentrate it into a _TiO2 suspension; finally add the photosensitizer to the _TiO2 suspension- (C ₉ H ₆ NSO ₄ ) ₃ Fe·2H ₂ O complex, after standing still for 12-36 hours, filter, and vacuum dry at low temperature to obtain powdery composite photocatalyst.

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