Application of a gossypol / TiO2 composite photocatalytic material

Abstract

The present invention discloses the use of a gossypol / TiO2 composite photocatalytic material in photocatalysis. The gossypol / TiO2 composite photocatalytic material is obtained by compounding gossypol with TiO2 via a sol-gel method. The gossypol / TiO2 composite photocatalytic material, obtained by compounding organic gossypol with inorganic TiO2 via a sol-gel method, significantly enhances the synergistic effect between the organic and inorganic components, effectively improving the visible light response capability and utilization range (extending the visible light utilization range to approximately 800 nm), and enhancing photocatalytic activity. The material has significant 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 polyphenol compound that is widely found in the pigment glands of the roots, stems and seeds of cotton, a plant of the Malvaceae family. It is a yellow and toxic phenolic substance that can not only resist pest infestation, but has also been proven to have natural medicinal 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, it has a planar structure and electronic structure with a unique π-conjugation effect. Its excellent photoreactivity allows it to be used as an organic dye. It can serve as a light-capturing unit and charge-transfer module in photofunctional composite materials, playing a role in light response, charge separation and transmission. It has certain potential application value in luminescence, supramolecular self-assembly, photoelectrocatalysis, photocatalytic reduction of carbon dioxide and hydrogen production, and photocatalytic degradation of pollutants. However, gossypol, as a polyhydroxy aromatic ring structure compound, is very unstable under light conditions and is prone to structural alienation, which limits its development and utilization. Therefore, how to make full use of the photofunctional effect caused by its structural alienation, enhance the photofunctional application value of gossypol-based active molecules, and develop their commercial application potential. Currently, there are few related research reports. Therefore, it is necessary to construct gossypol-based photofunctional materials through effective synthetic strategies and methods, explore its application value in photocatalysis, and expand the application range of photoactive organic components in nature, 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] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] 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.

[0007] Furthermore, the application includes photocatalytic decomposition of water to produce hydrogen, and the light includes visible light.

[0008] Furthermore, the TiO2 in the gossypol / TiO2 composite photocatalytic material has an anatase crystal structure, a size of 10-50 nm, and micro-mesopores; the gossypol is dispersed around the TiO2 nanoparticles in an amorphous state.

[0009] Furthermore, the mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 0<gossypol%≤16%.

[0010] Furthermore, the mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 2≤gossypol%≤8%.

[0011] Furthermore, the mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 4%.

[0012] Furthermore, the gossypol / TiO2 composite photocatalytic material is prepared by the following steps: adding a TiO2 precursor dropwise into a solvent under stirring, adding water and an acidifying agent under stirring to form a titanium dioxide sol, then adding a gossypol-solvent solution dropwise under stirring, heating under stirring, maintaining the temperature reached, stirring until a gel is formed, then drying, performing Soxhlet extraction in an aqueous phase, and finally vacuum drying to obtain the gossypol / TiO2 composite photocatalytic material.

[0013] Furthermore, the TiO2 precursor is tetrabutyl titanate; the solvent is N,N-dimethylformamide; and the acidifying agent is acetic acid.

[0014] Furthermore, the temperature is raised to 30-100° C. under stirring, and the temperature is maintained and stirred until a gel is formed. The mixture is then allowed to stand and dry at room temperature for 6-12 h, and then Soxhlet extracted in an aqueous phase at 100-160° C. for 12-72 h.

[0015] Beneficial effects of the present invention:

[0016] 1) The gossypol / TiO2 composite photocatalytic material of the present invention is obtained by compounding organic gossypol and inorganic TiO2 through a sol-gel method. The synergistic effect between the organic and inorganic components 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), enhance the photocatalytic activity, and has very important application potential in the field of photocatalysis.

[0017] 2) The gossypol / TiO2 composite photocatalytic material of the present invention is applied to the photocatalytic decomposition of water to produce hydrogen. Compared with the TiO2 photocatalytic material, it has stronger spectral response capability and visible light utilization rate, better photocatalytic activity, and higher hydrogen production, and has good application potential in the field of photocatalytic decomposition of water to produce hydrogen.

[0018] 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 reaction active sites, which can effectively increase the amount of hydrogen produced by photocatalytic water decomposition.

[0019] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The X-ray diffraction spectra of the gossypol / TiO2 composite photocatalytic materials with different gossypol contents prepared in various examples are shown.

[0021] Figure 2 This is a scanning electron microscope image of the gossypol / TiO2 composite photocatalytic material prepared in Example 3. Figure 2 (a) is a scanning electron microscope image at low magnification. Figure 2 (b) is a scanning electron microscope image at high magnification.

[0022] Figure 3 This is a transmission electron microscope image 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.

[0023] Figure 4 This is a nitrogen adsorption-desorption diagram of the gossypol / TiO2 composite photocatalytic material prepared in Example 3.

[0024] Figure 5 This is the pore size distribution diagram of the gossypol / TiO2 composite photocatalytic material prepared in Example 3.

[0025] Figure 6 Gossypol / TiO2 composite photocatalytic materials with different gossypol contents prepared in various examples and UV-visible absorption spectra of gossypol.

[0026] Figure 7 Graph showing the gossypol / TiO2 composite photocatalytic materials with different gossypol contents prepared in various embodiments and the amount of hydrogen produced by the photocatalytic decomposition of water by gossypol. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below through specific embodiments and drawings, but the protection scope of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] Preparation of 0% (wt) gossypol / TiO2 (i.e., TiO2) photocatalytic material: 10 mL of precursor tetrabutyl titanate was added dropwise to 10 mL of N,N-dimethylformamide (DMF) while stirring, and 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 and stirred until a gel was formed. The sol was then dried overnight (12 h) at room temperature to obtain light yellow solid particles. The sol was extracted with Soxhlet extraction in an aqueous phase at 140°C for 48 h. After the Soxhlet extraction, the sample was placed in a vacuum drying oven and maintained at room temperature for 10 -3 Pa vacuum drying for 12 h to obtain a light yellow solid granular sample.

[0030] Example 2

[0031] Preparation of 2% (wt) gossypol / TiO2 composite photocatalytic material: 10 mL of precursor tetrabutyl titanate was added dropwise to 10 mL of DMF while stirring, 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol, and 10 mL of gossypol (46 mg) DMF solution was added dropwise under stirring to form a transparent dark red sol, and 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, and then allowed to stand and dry overnight (12 h) at room temperature to obtain light brown solid particles, which were Soxhlet extracted in an aqueous phase at 140°C for 48 h. After the Soxhlet extraction, the sample was placed in a vacuum drying oven and maintained at room temperature for 10 -3 Pa vacuum drying for 12 h to obtain a light brown solid granular sample.

[0032] Example 3

[0033] Preparation of 4% (wt) gossypol / TiO2 composite photocatalytic material: 10 mL of precursor tetrabutyl titanate was added dropwise to 10 mL of DMF while stirring, 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol, and 10 mL of gossypol (92 mg) DMF solution was added dropwise under stirring to form a transparent dark red sol, and 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, and then allowed to stand and dry overnight (12 h) at room temperature to obtain brown solid particles, which were Soxhlet extracted in an aqueous phase at 140°C for 48 h. After the Soxhlet extraction, the sample was placed in a vacuum drying oven and maintained at room temperature for 10 -3 Pa vacuum drying for 12 h to obtain a brown solid granular sample.

[0034] Example 4

[0035] Preparation of 8% (wt) gossypol / TiO2 composite photocatalytic material: 10 mL of precursor tetrabutyl titanate was added dropwise to 10 mL of DMF while stirring, 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol, and 10 mL of gossypol (184 mg) DMF solution was added dropwise under stirring to form a transparent dark red sol, and 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, and then allowed to stand and dry overnight (12 h) at room temperature to obtain dark brown solid particles, which were Soxhlet extracted in an aqueous phase at 140°C for 48 h. After the Soxhlet extraction, the sample was placed in a vacuum drying oven and maintained at room temperature for 10 -3 Pa vacuum drying for 12 h to obtain a dark brown solid granular sample.

[0036] Example 5

[0037] Preparation of 16% (wt) gossypol / TiO2 composite photocatalytic material: 10 mL of precursor tetrabutyl titanate was added dropwise to 10 mL of DMF while stirring, 1 mL of water and 1 mL of acetic acid were added under stirring to form a transparent light yellow sol, and 10 mL of gossypol (368 mg) DMF solution was added dropwise under stirring to form a transparent dark red sol, and 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, and then allowed to stand and dry overnight (12 h) at room temperature to obtain dark brown solid particles, which were Soxhlet extracted in an aqueous phase at 140°C for 48 h. After the Soxhlet extraction, the sample was placed in a vacuum drying oven and maintained at room temperature for 10 -3 Pa vacuum drying for 12 h to obtain a dark brown solid granular sample.

[0038] like Figure 1 As shown in the X-ray diffraction (XRD) spectra, in the gossypol / TiO2 composite photocatalytic materials prepared in Example 2, Example 3, Example 4 and Example 5, the signal peaks such as 18.98°, 28.94°, 34.50°, 40.26°, 47.30°, 53.46°, and 59.27° belong to anatase-type TiO2. Therefore, the presence of gossypol does not change the TiO2 crystal structure. In addition, as the gossypol content increases, the intensity of the TiO2 signal peak increases within a certain range, indicating that the introduction of gossypol can improve the crystallinity of the composite material to a certain extent.

[0039] like Figure 2 As shown in the scanning electron microscope (SEM) image, in the gossypol / TiO2 composite photocatalytic material prepared in Example 3, gossypol and TiO2 nanoparticles are tightly combined, wherein the titanium dioxide is composed of spherical nanoparticles, is evenly dispersed, has a rich pore structure, and has the characteristics of a typical TiO2 structural morphology; in addition, the edge surface of the spherical particles is covered with a layer of amorphous tissue structure, which is presumed to be gossypol, further confirming the formation of the composite structure.

[0040] like Figure 3 As shown in the transmission electron micrograph, after in situ photoloading of platinum nanoparticles, the structure of the gossypol / TiO2 composite photocatalytic material prepared in Example 3 did not change much, the TiO2 was still spherical TiO2 nanoparticles with a size of 10-40 nm, and the loaded platinum nanoparticles had a size of 3-6 nm.

[0041] like Figure 4 、 Figure 5As shown in Table 1, there are nitrogen adsorption-desorption diagram, pore size distribution diagram and relevant parameter value summary table of the gossypol / TiO2 composite photocatalytic material prepared in Example 3. Analysis shows that the gossypol / TiO2 composite photocatalytic material prepared in Example 3 has micro-mesoporous pore size and morphological characteristic structure, and the BET specific surface area is 166.9 m 2 / g, which is larger than the specific surface area of ​​commercial P25 titanium dioxide (35-65 m 2 / g) is much larger.

[0042]

[0043] Figure 6 The figures are UV-visible absorption spectra of the gossypol photocatalytic material of the control group, the TiO2 photocatalytic material prepared in Example 1, and the gossypol / TiO2 composite photocatalytic materials prepared in Examples 2-6. As can be seen from the figures, the TiO2 photocatalytic material mainly absorbs in the ultraviolet part, with the longest absorption sideband at 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 be extended to around 800 nm, indicating that the gossypol / TiO2 composite photocatalytic materials prepared in the present invention have excellent light absorption capacity.

[0044] The photocatalytic decomposition of water and hydrogen production performance of the gossypol photocatalytic material in the control group, the TiO2 photocatalytic material prepared in Example 1, and the gossypol / TiO2 composite photocatalytic material prepared in Examples 2-5 were evaluated. A 500W xenon lamp was used as a light source for in-situ photoloading of platinum nanoparticles: 20 mg of the photocatalytic material (the TiO2 photocatalytic material prepared in Example 1, the gossypol / TiO2 composite photocatalytic material prepared in Examples 2-6), 10 mL of water, 10 mL of methanol, and 52 μL of a 10 mM potassium chloroplatinite aqueous solution were added to a photocatalytic reactor equipped with a quartz lid. The quartz lid was covered, the system was evacuated, and the system was irradiated under full light for 1 h. After centrifugation (10,000 r / min for 3 min), the precipitate was recovered, washed three times with methanol, and maintained at room temperature for 10 -3 The catalyst loaded with platinum nanoparticles was dried under vacuum at 1.5 Pa for 12 hours. 10 mg of the platinum nanoparticle-loaded catalyst, 18 mL of water, and 2 mL of triethanolamine were added to the photocatalytic reactor, which was then re-evacuated. The photocatalytic reaction system was illuminated with a xenon lamp equipped with a cutoff filter (visible light with λ ≥ 420 nm), and the hourly hydrogen production was measured using a gas chromatography online sampling system.

[0045] Depend on Figure 7As can be seen from the graph of hydrogen production from photocatalytic decomposition of water, under the irradiation of visible light, the hydrogen production of the gossypol photocatalytic material in the control group is 0.0029 mmol / g / h, the hydrogen production of the TiO2 photocatalytic material prepared in Example 1 is 0.0037 mmol / g / h, the hydrogen production of the 2% gossypol / TiO2 composite photocatalytic material prepared in Example 2 is 0.45 mmol / g / h, the hydrogen production of the 4% gossypol / TiO2 composite photocatalytic material prepared in Example 3 is 0.48 mmol / g / h, the hydrogen production of the 8% gossypol molecule / TiO2 composite photocatalytic material prepared in Example 4 is 0.27 mmol / g / h, and the hydrogen production of the 16% gossypol molecule / TiO2 composite photocatalytic material prepared in Example 5 is 0.030 mmol / g / h. The addition of gossypol increased the photocatalytic decomposition of water hydrogen production of the composite material to varying degrees, especially the 4% gossypol / TiO2 composite photocatalytic material prepared in Example 3, which had the optimal photocatalytic decomposition of water hydrogen production of 0.48 mmol / g / h, while the hydrogen production of the TiO2 photocatalytic material was only 0.0037 mmol / g / h, the former being more than 129 times that of the latter. The variation in the photocatalytic decomposition of water hydrogen production of the composite material is within a certain range, increasing with the increase of gossypol content, reaching a maximum at a gossypol content of 4%. Further increasing the gossypol content, the photocatalytic decomposition of water hydrogen production will gradually decrease, and at 16% hydrogen production is only 0.030 mmol / g / h, indicating that excessive gossypol content can lead to reduced 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 decomposition of water to produce hydrogen activity of the composite material, but the results are much higher than the photocatalytic decomposition of water to produce hydrogen 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 response ability of the composite material in visible light and improve the photocatalytic decomposition of water to produce hydrogen 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 a sol-gel method, comprising 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 under stirring, maintaining the temperature reached, stirring until a gel is formed, drying, performing Soxhlet extraction in an aqueous phase, and finally vacuum drying to obtain the gossypol / TiO2 composite photocatalytic material; The mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 0<gossypol%≤16%; The application is photocatalytic decomposition of water to produce hydrogen, and the light includes visible light.

2. The use of a gossypol / TiO2 composite photocatalytic material in photocatalysis according to claim 1, characterized in that: The TiO2 in the gossypol / TiO2 composite photocatalytic material has an anatase crystal structure, a size of 10-50 nm, and micro-mesopores; the gossypol is dispersed around the TiO2 nanoparticles in an amorphous state.

3. The use of a gossypol / TiO2 composite photocatalytic material in photocatalysis according to claim 1, characterized in that: The mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 2%≤gossypol%≤8%.

4. The use of a gossypol / TiO2 composite photocatalytic material in photocatalysis according to claim 3, characterized in that: The mass percentage of gossypol in the gossypol / TiO2 composite photocatalytic material is 4%.

5. The use of a gossypol / TiO2 composite photocatalytic material in photocatalysis according to claim 1, characterized in that: The TiO2 precursor is tetrabutyl titanate; the solvent is N,N-dimethylformamide; and the acidifying agent is acetic acid.

6. The use of a gossypol / TiO2 composite photocatalytic material in photocatalysis according to claim 1, characterized in that: The mixture is heated to 30-100°C while stirring, and the temperature is maintained and stirred until a gel is formed. The mixture is then allowed to stand and dry at room temperature for 6-12 h, and then subjected to Soxhlet extraction in an aqueous phase at 100-160°C for 12-72 h.

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