Application of gossypol / TiO2 composite photocatalytic material

Abstract

The invention discloses an application of a gossypol / TiO2 composite photocatalytic material in photocatalysis. The gossypol / TiO2 composite photocatalytic material is obtained by compounding gossypol and TiO2 through a sol-gel method. The gossypol / TiO2 composite photocatalytic material is obtained by compounding organic gossypol and inorganic TiO2 through a sol-gel method, the synergistic effect between organic components and inorganic components is obviously enhanced, the visible light response capability and the utilization range can be effectively improved (the visible light utilization range is expanded to about 800 nm), the photocatalytic activity is improved, and the photocatalytic effect is good. The method has very important application potential in the field of photocatalysis.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic materials, and in particular to an application of a gossypol / TiO2 composite photocatalytic material. Background Art

[0002] Introducing photocatalytic technology into the development of clean energy and high-value-added chemicals can convert solar energy into thermal and chemical energy, replacing the fossil fuel consumption and resulting environmental pollution of traditional thermal catalysis. This not only fully utilizes the endless supply of sunlight, but also allows for the development of heterogeneous, mild reaction catalytic systems. Hydrogen energy, in particular, has attracted widespread attention as the most valuable green energy source since the beginning of the new century, offering advantages such as high energy density and low carbonization. It holds enormous potential for alleviating environmental pollution and energy shortages. Producing hydrogen through the reduction of protons by water splitting using photocatalytic technology is a promising approach. Currently, numerous materials and systems are being developed to produce hydrogen using photocatalytic water splitting technology. In particular, the development and modification of the inexpensive, readily available, and environmentally friendly photocatalytic material TiO2, with its simple and mature material preparation methods and process flow, holds great potential for application in the field of photocatalysis. However, due to the wide band gap of TiO2, it can only respond to ultraviolet light and has almost no response to visible light or even infrared light. Therefore, it cannot effectively utilize the full spectrum of sunlight, and the utilization of light resources has certain limitations. In addition, various modification methods currently available, such as precious metal / non-precious metal / non-metal doping, metal oxide / sulfide composites, and photofunctional material sensitization / composite modification measures, will introduce a large number of defect sites in the process of optimizing TiO2, which become recombination centers for photogenerated charges, reduce the efficiency of carrier transfer, and thus cause generally low photocatalytic activity, which cannot meet the requirements of industrial applications. Therefore, how to improve the absorption capacity of photocatalysts in the visible and even infrared parts and improve the separation efficiency of photogenerated charges is of great scientific research significance.

[0003] Gossypol is a polyphenolic compound widely present in the color glands of the roots, stems, and seeds of the cotton plant in the Malvaceae family. It is a yellow and highly toxic phenolic substance that can not only resist pest infestations but also has been proven to have natural medical activities such as antioxidant, anti-fertility, and anti-tumor properties. It will also remain in cottonseed cake and edible oil, causing toxicity and pollution to organisms and the environment. As a yellow pigment substance, it has a planar structure and electronic structure with a unique π-conjugation effect. Its excellent photoreactive activity enables it to be used as an organic dye and as a light-harvesting unit and charge transfer module in optical functional composite materials, playing roles in light response, charge separation, and transmission, and having certain potential application values in aspects such as luminescence, supramolecular self-assembly, photoelectrocatalysis, photocatalytic reduction of carbon dioxide and hydrogen production, and photocatalytic degradation of pollutants. However, gossypol, as a compound with a polyhydroxy aromatic ring structure, is very unstable under light conditions and is prone to structural isomerization, which limits its development and utilization. Therefore, how to make full use of the optical functional effects caused by its structural isomerization, enhance the optical functional application value of gossypol-based active molecules, and develop the potential of its commercial applications, and currently, there are few relevant research reports. Therefore, it is necessary to construct gossypol-based optical functional materials through effective synthesis strategies and methods, explore its application value in photocatalysis, and expand the application scope of natural photoactive organic components, which has certain theoretical and technical guiding significance for the design, synthesis, and mechanism exploration of materials in the field of photocatalysis. Summary of the Invention

[0004] The purpose of the present invention is to provide an application of a gossypol / TiO2 composite photocatalytic material to solve the deficiencies of the prior art.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solutions: An application of a gossypol / TiO2 composite photocatalytic material in photocatalysis, wherein the gossypol / TiO2 composite photocatalytic material is obtained by compounding gossypol and TiO2 through the sol-gel method.

[0006] Further, the application includes photocatalytic water splitting for hydrogen production, and the light includes visible light.

[0007] Further, the TiO2 in the gossypol / TiO2 composite photocatalytic material has anatase crystal structure, with a size of 10 - 50 nm and has micro-mesopores; gossypol is dispersed in an amorphous form around the TiO2 nanoparticles.

[0008] Further, the mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 0 < gossypol% ≤ 16%.

[0009] Even further, the mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 2 ≤ gossypol% ≤ 8%.

[0010] Furthermore, the mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 4%.

[0011] Further, the gossypol / TiO2 composite photocatalytic material is prepared by the following steps: dropping a TiO2 precursor into a solvent under stirring, adding water and an acidifying agent under stirring to form a titanium dioxide sol, then dropping a gossypol-solvent solution under stirring, heating up under stirring, maintaining the temperature reached by heating up and stirring until a gel is formed, then drying, performing Soxhlet extraction in an aqueous phase, and then performing vacuum drying to obtain the gossypol / TiO2 composite photocatalytic material.

[0012] Furthermore, the TiO2 precursor is tetrabutyl titanate; the solvent is N,N-dimethylformamide; the acidifying agent is acetic acid.

[0013] Furthermore, heat up to a temperature of 30-100 °C under stirring, maintain the temperature reached by heating up and stir until a gel is formed, then stand and dry at room temperature for 6-12 h, and perform Soxhlet extraction in an aqueous phase at 100-160 °C for 12-72 h.

[0014] Advantages of the present invention: 1) The gossypol / TiO2 composite photocatalytic material of the present invention is obtained by compounding organic gossypol and inorganic TiO2 through the sol-gel method. The synergistic effect between the organic component and the inorganic component is significantly enhanced, which can effectively improve the visible light response ability and utilization range of the composite material (the visible light utilization range is extended to about 800 nm), improve the photocatalytic activity, and has very important application potential in the field of photocatalysis.

[0015] 2) The gossypol / TiO2 composite photocatalytic material of the present invention is applied to photocatalytic water splitting for hydrogen production. Compared with the TiO2 photocatalytic material, it has stronger spectral response ability and visible light utilization rate, better photocatalytic activity, and higher hydrogen production amount, and has good application potential in the field of photocatalytic water splitting for hydrogen production.

[0016] 3) The gossypol / TiO2 composite photocatalytic material of the present invention has a rich pore structure, a large specific surface area and a large number of reactive sites, which can effectively improve the hydrogen production amount of photocatalytic water splitting.

[0017] 4) The preparation method of the gossypol / TiO2 composite photocatalytic material of the present invention is simple, has high operability and repeatability, and the raw material price is relatively low. Description of the drawings

[0018] Figure 1 X-ray diffraction spectra of the gossypol / TiO2 composite photocatalytic materials with different gossypol contents prepared in each example.

[0019] Figure 2Scanning electron micrograph of the gossypol / TiO₂ composite photocatalytic material prepared in Example 3. Figure 2 (a) is the scanning electron micrograph at low magnification, Figure 2 (b) is the scanning electron micrograph at high magnification.

[0020] Figure 3 Transmission electron micrograph of the gossypol / TiO₂ composite photocatalytic material prepared in Example 3. Figure 3 (a), (b), (c), and (d) are transmission electron micrographs at different positions and magnifications.

[0021] Figure 4 N₂ adsorption - desorption isotherm of the gossypol / TiO₂ composite photocatalytic material prepared in Example 3.

[0022] Figure 5 Pore size distribution diagram of the gossypol / TiO₂ composite photocatalytic material prepared in Example 3.

[0023] Figure 6 UV - Vis absorption spectra of the gossypol / TiO₂ composite photocatalytic materials with different gossypol contents and gossypol prepared in each example.

[0024] Figure 7 Photocatalytic hydrogen production amount diagrams of the gossypol / TiO₂ composite photocatalytic materials with different gossypol contents and gossypol prepared in each example. Detailed implementation manners

[0025] The technical solutions of the present invention will be further described below through specific examples and drawings, but the protection scope of the present invention is not limited to the following examples.

[0026] Example 1

[0027] Preparation of 0% (wt) gossypol / TiO₂ (i.e., TiO₂) photocatalytic material: While stirring, 10 mL of the precursor tetrabutyl titanate was added dropwise to 10 mL of N,N - dimethylformamide (DMF). 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol. The temperature was raised to 80 °C at a heating rate of 10 °C / min under stirring, and then maintained at 80 °C with stirring until a gel was formed. Then, it was left to stand and dry overnight (12 h) at room temperature to obtain light yellow solid particles. The sample was subjected to Soxhlet extraction in the aqueous phase at 140 °C for 48 h. After the Soxhlet extraction was completed, the sample was placed in a vacuum drying oven and dried at a vacuum degree of 10 -3 Pa for 12 h to obtain a light yellow solid particle - like sample.

[0028] Example 2

[0029] Preparation of 2% (wt) gossypol / TiO₂ composite photocatalytic material: While stirring, 10 mL of the precursor tetrabutyl titanate was added dropwise to 10 mL of DMF. 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol. Then, a DMF solution of 10 mL of gossypol (46 mg) was added dropwise under stirring to form a transparent dark red sol. The temperature was raised to 80 °C at a heating rate of 10 °C / min under stirring, and then maintained at 80 °C and stirred until a gel was formed. Subsequently, it was left to stand and dry overnight (12 h) at room temperature to obtain light brown solid particles. The sample was subjected to Soxhlet extraction in an aqueous phase at 140 °C for 48 h. After the Soxhlet extraction was completed, the sample was placed in a vacuum drying oven and dried at a vacuum degree of 10 -3 Pa for 12 h to obtain a sample in the form of light brown solid particles.

[0030] Example 3

[0031] Preparation of 4% (wt) gossypol / TiO₂ composite photocatalytic material: While stirring, 10 mL of the precursor tetrabutyl titanate was added dropwise to 10 mL of DMF. 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol. Then, a DMF solution of 10 mL of gossypol (92 mg) was added dropwise under stirring to form a transparent dark red sol. The temperature was raised to 80 °C at a heating rate of 10 °C / min under stirring, and then maintained at 80 °C and stirred until a gel was formed. Subsequently, it was left to stand and dry overnight (12 h) at room temperature to obtain brown solid particles. The sample was subjected to Soxhlet extraction in an aqueous phase at 140 °C for 48 h. After the Soxhlet extraction was completed, the sample was placed in a vacuum drying oven and dried at a vacuum degree of 10 -3 Pa for 12 h to obtain a sample in the form of brown solid particles.

[0032] Example 4

[0033] Preparation of 8% (wt) gossypol / TiO₂ composite photocatalytic material: While stirring, 10 mL of the precursor tetrabutyl titanate was added dropwise to 10 mL of DMF. 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol. Then, a DMF solution of 10 mL of gossypol (184 mg) was added dropwise under stirring to form a transparent dark red sol. The temperature was raised to 80 °C at a heating rate of 10 °C / min under stirring, and then maintained at 80 °C and stirred until a gel was formed. Subsequently, it was left to stand and dry overnight (12 h) at room temperature to obtain dark brown solid particles. The sample was subjected to Soxhlet extraction in an aqueous phase at 140 °C for 48 h. After the Soxhlet extraction was completed, the sample was placed in a vacuum drying oven and dried at a vacuum degree of 10 -3 Pa for 12 h to obtain a sample in the form of dark brown solid particles.

[0034] Example 5

[0035] Preparation of 16% (wt) gossypol / TiO₂ composite photocatalytic material: While stirring, 10 mL of the precursor tetrabutyl titanate was added dropwise to 10 mL of DMF. 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol. Then, a DMF solution of 10 mL of gossypol (368 mg) was added dropwise under stirring to form a transparent dark red sol. The temperature was raised to 80 °C at a heating rate of 10 °C / min under stirring, and then kept at 80 °C and stirred until a gel was formed. After that, it was left to stand and dry overnight (12 h) at room temperature to obtain dark brown solid particles. The sample was subjected to Soxhlet extraction in the aqueous phase at 140 °C for 48 h. After the Soxhlet extraction was completed, the sample was placed in a vacuum drying oven and dried at a vacuum degree of 10 -3 Pa for 12 h to obtain a sample in the form of dark brown solid particles.

[0036] As Figure 1 shown by the X-ray diffraction (XRD) pattern, in the gossypol / TiO₂ composite photocatalytic materials prepared in Example 2, Example 3, Example 4, and Example 5, the signal peaks at 18.98°, 28.94°, 34.50°, 40.26°, 47.30°, 53.46°, 59.27°, etc. belong to anatase-type TiO₂. Therefore, the presence of gossypol does not change the crystal structure of TiO₂. In addition, when the gossypol content increases, the intensity of the TiO₂ signal peaks increases to a certain extent within a certain range, indicating that the introduction of gossypol can improve the crystallinity of the composite material to a certain extent.

[0037] As Figure 2 shown by the scanning electron microscope (SEM) image in

[0038] In the gossypol / TiO₂ composite photocatalytic material prepared in Example 3, gossypol is tightly combined with TiO₂ nanoparticles. Among them, titanium dioxide is composed of spherical nanoparticles, is evenly dispersed, and has a rich pore structure, showing the characteristics of a typical TiO₂ structural morphology. In addition, an amorphous tissue structure is coated on the edge surface of the spherical particles, presumably gossypol, further confirming the formation of this composite structure. Figure 3 shown by the transmission electron microscope image in

[0039] After in-situ photo-loading of platinum nanoparticles, the structure of the gossypol / TiO₂ composite photocatalytic material prepared in Example 3 changes little. TiO₂ is still spherical TiO₂ nanoparticles with a size of 10 - 40 nm, and the loaded platinum nanoparticles have a size of 3 - 6 nm. Figure 4 and Figure 5As shown in Table 1, they are respectively the nitrogen adsorption - desorption isotherm, pore size distribution diagram and the summary table of relevant parameter values of the gossypol / TiO2 composite photocatalytic material prepared in Example 3. It can be analyzed that the gossypol / TiO2 composite photocatalytic material prepared in Example 3 has a micro - mesoporous pore size and morphological characteristic structure, and the BET specific surface area is 166.9 m 2 / g, which is much larger than the specific surface area of commercial P25 titanium dioxide (35 - 65 m 2 / g).

[0040]

[0041] Figure 6 Figure 11 is the UV - Vis absorption spectra of the control group gossypol photocatalytic material, the TiO2 photocatalytic material prepared in Example 1, and the gossypol / TiO2 composite photocatalytic materials prepared in Examples 2 - 6. It can be seen from the figure that the TiO2 photocatalytic material mainly absorbs in the ultraviolet light part, and the longest absorption edge band is around 600 nm. The absorption spectrum of gossypol extends to around 650 nm, while the absorption peaks of the gossypol / TiO2 composite photocatalytic materials prepared in Examples 2, 3, 4, and 5 can extend to around 800 nm, indicating that the gossypol / TiO2 composite photocatalytic material prepared by the present invention has excellent light absorption ability.

[0042] The photocatalytic water - splitting hydrogen - production performance of the control group gossypol photocatalytic material, the TiO2 photocatalytic material prepared in Example 1, and the gossypol / TiO2 composite photocatalytic materials prepared in Examples 2 - 5 was evaluated. A 500W xenon lamp was used as the light source for in - situ photodeposition of platinum nanoparticles: 20 mg of the photocatalytic material (the TiO2 photocatalytic material prepared in Example 1, the gossypol / TiO2 composite photocatalytic materials prepared in Examples 2 - 6), 10 mL of water, 10 mL of methanol, and 52 μL of 10 mM potassium chloroplatinate aqueous solution were added to a photocatalytic reactor equipped with a quartz cover. The quartz cover was covered, the system was evacuated, irradiated under full light for 1 h, then centrifuged (centrifuged at 10000 r / min for 3 min), the precipitate was recovered, and washed three times with methanol, and dried at a vacuum of 10 -3 Pa at room temperature for 12 h to obtain the catalyst loaded with platinum nanoparticles. 10 mg of the above - mentioned catalyst loaded with platinum nanoparticles, 18 mL of water, and 2 mL of triethanolamine were added to the photocatalytic reactor, and then evacuated again. The photocatalytic reaction system was irradiated with a xenon lamp with a cut - off filter (visible light with λ≥420 nm), and the hydrogen production amount per hour was detected by using an on - line gas chromatography sampling system.

[0043] From Figure 7It can be seen from the photocatalytic water splitting hydrogen production amount diagram that under visible light irradiation, the hydrogen production amount of the control group's gossypol photocatalytic material is 0.0029 mmol / g / h, the hydrogen production amount of the TiO2 photocatalytic material prepared in Example 1 is 0.0037 mmol / g / h, the hydrogen production amount of the 2% gossypol / TiO2 composite photocatalytic material prepared in Example 2 is 0.45 mmol / g / h, the hydrogen production amount of the 4% gossypol / TiO2 composite photocatalytic material prepared in Example 3 is 0.48 mmol / g / h, the hydrogen production amount of the 8% gossypol molecule / TiO2 composite photocatalytic material prepared in Example 4 is 0.27 mmol / g / h, and the hydrogen production amount of the 16% gossypol molecule / TiO2 composite photocatalytic material prepared in Example 5 is 0.030 mmol / g / h. The addition of gossypol has improved the photocatalytic water splitting hydrogen production amount of the composite material to varying degrees. Especially for the 4% gossypol / TiO2 composite photocatalytic material prepared in Example 3, it has the optimal photocatalytic water splitting hydrogen production amount of 0.48 mmol / g / h, while the hydrogen production amount of the TiO2 photocatalytic material is only 0.0037 mmol / g / h, and the former is more than 129 times that of the latter. The change in the photocatalytic water splitting hydrogen production amount of the composite material increases within a certain range with the increase of the gossypol content, reaching the maximum when the gossypol content is 4%. Further increasing the gossypol content, the photocatalytic water splitting hydrogen production amount will gradually decrease, and the hydrogen production amount is only 0.030 mmol / g / h at 16%, indicating that too much gossypol content will lead to a decrease in hydrogen production activity. The above results show that different contents of gossypol in the gossypol / TiO2 composite photocatalytic material have a great influence on the photocatalytic water splitting hydrogen production activity of the composite material, but the results are all much higher than the photocatalytic water splitting hydrogen production activity of the TiO2 photocatalytic material. This is because the excellent and unique light response ability of gossypol and the synergistic effect of gossypol and TiO2 can effectively broaden the visible light response ability of the composite material and improve the photocatalytic water splitting hydrogen production activity.

Claims

1. Application of a gossypol / TiO2 composite photocatalytic material in photocatalysis, characterized in that, The gossypol / TiO2 composite photocatalytic material is obtained by compounding gossypol and TiO2 through the sol-gel method.

2. Use of a gossypol / TiO2 composite photocatalytic material according to claim 1 in photocatalysis, characterized in that, The application includes photocatalytic water splitting for hydrogen production, and the light includes visible light.

3. Use of a gossypol / TiO2 composite photocatalytic material according to claim 1 or 2 in photocatalysis, characterized in that, In the gossypol / TiO2 composite photocatalytic material, TiO2 has an anatase crystal structure, with a size of 10 - 50 nm and has micro-mesopores; gossypol is dispersed in an amorphous form around TiO2 nanoparticles.

4. Use of a gossypol / TiO2 composite photocatalytic material according to claim 1 or 2 in photocatalysis, characterized in that, In the gossypol / TiO2 composite photocatalytic material, the mass percentage of gossypol is 0 < gossypol% ≤ 16%.

5. Use of a gossypol / TiO2 composite photocatalytic material according to claim 4 in photocatalysis, characterized in that, In the gossypol / TiO2 composite photocatalytic material, the mass percentage of gossypol is 2 ≤ gossypol% ≤ 8%.

6. Use of a gossypol / TiO2 composite photocatalytic material according to claim 5 in photocatalysis, characterized in that, In the gossypol / TiO2 composite photocatalytic material, the mass percentage of gossypol is 4%.

7. Use of a gossypol / TiO2 composite photocatalytic material according to claim 1 or 2 in photocatalysis, characterized in that, The gossypol / TiO2 composite photocatalytic material is prepared by the following steps: adding a TiO2 precursor dropwise to a solvent under stirring, adding water and an acidifying agent under stirring to form a titanium dioxide sol, then dropwise adding a gossypol-solvent solution under stirring, heating up under stirring, maintaining the temperature reached during heating and stirring until a gel is formed, then drying, performing Soxhlet extraction in an aqueous phase, and then vacuum drying to obtain the gossypol / TiO2 composite photocatalytic material.

8. Use of a gossypol / TiO2 composite photocatalytic material according to claim 7 in photocatalysis, characterized in that, The TiO2 precursor is tetrabutyl titanate; the solvent is N,N-dimethylformamide; the acidifying agent is acetic acid.

9. Use of a gossypol / TiO2 composite photocatalytic material according to claim 7 in photocatalysis, characterized in that, Heat up to a temperature of 30 - 100 °C under stirring, maintain the temperature reached during heating and stir until a gel is formed, then let it stand and dry at room temperature for 6 - 12 h, and perform Soxhlet extraction in an aqueous phase at 100 - 160 °C for 12 - 72 h.

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