Novel photocatalytic semiconductor composite coating

Abstract

The invention relates to the field of semiconductor materials, in particular to a novel photocatalytic semiconductor composite coating, which is characterized in that TiO2 and the like are doped and a novel two-dimensional semiconductor is explored from the material design; and a semiconductor-graphene, MOF and other composite systems are constructed to enhance the synergistic effect. The coating quality is improved by improving sol-gel spin coating and spraying processes, and stable performance is guaranteed by matching with real-time monitoring and regulation. The coating is used in the fields of building glass self-cleaning, medical equipment antibiosis and the like, has high photocatalytic efficiency, strong adhesive force and excellent stability, expands low-temperature adaptation, self-repairing and miniaturized customization capabilities, and promotes the practicability of the photocatalytic coating.

Description

Technical Field

[0001] The present invention relates to the field of information management systems, and particularly to a novel photocatalytic semiconductor composite coating. Background Art

[0002] With the increasing prominence of environmental problems and the improvement of people's pursuit of quality of life, the demand for materials with self-cleaning, antibacterial, air and water purification functions is extremely urgent. The photocatalytic semiconductor coating can theoretically meet these demands. Its principle is to use the photo-generated carriers generated by semiconductor materials under light illumination to drive redox reactions to decompose organic pollutants and kill microorganisms. However, traditional photocatalytic coatings face many dilemmas. Most rely on a single wide-bandgap semiconductor, such as titanium dioxide (TiO 2 ₂), which has low utilization rate of visible light and can only absorb ultraviolet light, resulting in a large amount of visible light being wasted and poor actual photocatalytic effect. Moreover, the recombination rate of photo-generated carriers is high, and electrons and holes recombine before participating in the reaction, reducing the catalytic activity. In terms of the bonding between the coating and the substrate, due to the lack of effective chemical bonding or physical anchoring, the adhesion is poor. After long-term exposure to sunlight and rain outdoors or frequent cleaning and wiping indoors, the coating is prone to peeling and falling off, and cannot continuously perform its functions. The complex preparation process raises the cost, limits the large-area promotion and application, and is difficult to meet the large-scale demands of industries such as construction, medical treatment, and automobiles. There is an urgent need for innovative technologies to break through these bottlenecks and make the advantages of photocatalytic coatings truly realized. Summary of the Invention

[0003] The present invention provides a novel photocatalytic semiconductor composite coating, which comprises a doped and modified photocatalytic semiconductor material. The doping modification is to dope bismuth (Bi) element into titanium dioxide (TiO 2 ₂), and the doping amount of bismuth element is 3%-8% of the mass of TiO 2 , and at the same time, lanthanum-containing organic compound lanthanum tris(acetylacetonate) (La(acac) 3 ) accounting for 0.05%-0.15% of the total mass is added.

[0004] Furthermore: It also includes a novel two-dimensional photocatalytic semiconductor, which is based on cadmium sulfide (CdS) and is in-situ doped with selenium element by chemical vapor deposition (CVD) method, and the doping amount of selenium is controlled at 1%-3%.

[0005] Furthermore, it also includes a photocatalytic semiconductor composite system, including a semiconductor-graphene composite system, which is prepared by in-situ growth method to make TiO 2 nanoparticles grow uniformly on the graphene oxide (GO) sheets to form a TiO 2 -graphene composite system, wherein the graphene content is controlled at 1%-5%.

[0006] Furthermore, it also includes a semiconductor-metal organic framework (MOF) composite system. BiVO 4 nanoparticles are uniformly dispersed in the precursor solution of MIL-101(Cr) by solvothermal method, and the content ratio of BiVO 4 is 20%-30%.

[0007] Furthermore, it also includes a preparation process of a photocatalytic semiconductor composite coating. The TiO 2 -based photocatalytic coating is prepared by improving the sol-gel spin coating method. The aging time of the sol is precisely controlled within 24-48 hours, the spin coating speed is set at 1500-3000 rpm, and spin coating is carried out in multiple times. After each spin coating, it is dried at 100-150 °C for 5-10 minutes, and finally annealed at 400-600 °C.

[0008] Furthermore, it also includes the preparation process of the photocatalytic semiconductor composite coating mentioned above. The composite coating is also innovatively prepared by spraying method. A high-pressure airless spraying device is selected, and the precursor solution of the composite coating is uniformly sprayed on the substrate at a flow rate of 0.5-1.5 mL / s, and the spraying distance is maintained at 20-30 cm. During the spraying process, the substrate temperature is kept at 60-80 °C in real time by an infrared heating device.

[0009] Furthermore, it also includes a performance monitoring and regulation system for the photocatalytic semiconductor composite coating, which includes an in-situ photocatalytic degradation and photocurrent density combined test system to track the photocatalytic degradation efficiency and photocurrent density of the coating during the preparation process and the light irradiation aging stage in real time. When the decrease in photocatalytic degradation efficiency exceeds 5%, or the change in photocurrent density exceeds 8%, the subsequent process parameters are automatically adjusted.

[0010] Furthermore, it also includes the performance monitoring and regulation system for the photocatalytic semiconductor composite coating mentioned above. It also includes a microstructure analysis device. By using the combination of scanning electron microscope (SEM) and transmission electron microscope (TEM), the surface morphology and pore condition of the material are captured by SEM, and the internal structure of the crystal grains, nanostructure and interface characteristics of the composite system are analyzed by TEM. Once abnormalities are found, the preparation process is immediately optimized.

[0011] Furthermore, it also includes a product applying the photocatalytic semiconductor composite coating. This product is a self-cleaning coating for architectural glass. The photocatalytic semiconductor composite coating described in the claims is uniformly coated on the glass surface, and the organic stains on the glass surface are decomposed under light irradiation to achieve the self-cleaning function.

[0012] Furthermore, it also includes a product applying the photocatalytic semiconductor composite coating. This product is an antibacterial coating for medical devices. The photocatalytic semiconductor composite coating described in the claims is applied to the surface of medical devices, and bacteria, viruses and other microorganisms attached to the device surface are killed by the photocatalytic performance of the coating.

[0013] Beneficial effects:

[0014] The new photocatalytic semiconductor composite coating, through the fine doping of materials, two-dimensional structure design and composite system construction, has improved by 30%-50% compared with the traditional photocatalytic coating. Taking the degradation test of common organic pollutants as an example, it can decompose pollutants to the standard level in a shorter time, greatly enhancing the purification ability. The coating adhesion is improved by 20%-30% due to the optimized preparation process. Whether it is the building exterior wall glass exposed to wind and rain for a long time or the surface of medical equipment frequently cleaned and disinfected, the coating is not easy to peel off, ensuring long-term use. In terms of stability, after being stored in a humid and hot environment (85°C, 90% RH) for 500 hours, the photocatalytic performance retention rate > 90%, maintaining stable purification and antibacterial functions. The upgrade of the preparation process brings a 30%-50% increase in production efficiency and a 20%-30% increase in the qualified rate, reducing costs. The real-time monitoring system ensures that the performance deviation of each batch of coatings < 3%, and the product quality is highly consistent. In addition, the low-temperature adaptability, self-repair characteristics and miniaturized customization ability further broaden the application scenarios, enabling it to meet the diverse needs from large buildings to micro medical implant devices. Specific implementation manners

[0015] Example 1:

[0016] Bi-TiO 2 Preparation of photocatalytic materials and basic performance testing

[0017] Experimental preparation

[0018] Accurately weigh an appropriate amount of tetrabutyl titanate as the precursor of TiO 2 , and weigh 5% of bismuth nitrate (Bi(NO 2 )) according to the mass of TiO 3 ), and 0.1% of lanthanum tris(acetylacetonate) (La(acac) 3 ). After dissolving bismuth nitrate and La(acac) 3 in an appropriate amount of ethanol solution, slowly drop it into the ethanol solution of tetrabutyl titanate, and continuously stir for 3 hours to form a homogeneous mixture. 3

[0019] Preparation process

[0020] Using the sol-gel method, react the above mixture at a constant temperature of 60°C with stirring for 6 hours to form a sol, and then age the sol for 36 hours. Spin-coat the aged sol on the glass substrate at a speed of 2000 rpm, dry it at 120°C for 8 minutes after each spin-coating, repeat 3 times, and finally anneal at 500°C for 2 hours to obtain the Bi-TiO 2 photocatalytic coating. ​

[0021] Performance Test

[0022] The light absorption performance of the coating was tested using a UV-visible spectrophotometer. It was found that the doping of Bi caused the light absorption edge of TiO 2 to redshift to about 550 nm, significantly expanding the visible light absorption range. Using methyl orange as a simulated pollutant, the photocatalytic degradation efficiency was tested under the irradiation of a 500 W xenon lamp simulating sunlight. The degradation rate of methyl orange reached 40% within 1 hour, which was about 25% higher than that of undoped TiO 2 , preliminarily confirming the enhancement of photocatalytic performance by doping modification.

[0023] Example 2:

[0024] Synthesis and Synergistic Enhancement Analysis of CdS-Se Two-Dimensional Photocatalytic Materials

[0025] Experimental Preparation

[0026] Prepare high-purity cadmium sulfide (CdS) precursor powder and selenium source, ensure the good airtightness of experimental equipment such as a chemical vapor deposition (CVD) reactor, set the heating program and gas flow parameters of the reactor, and prepare argon as the carrier gas.

[0027] Preparation Process

[0028] Place the CdS precursor in the heating zone of the CVD reactor, heat it to 500 °C in an argon atmosphere, and then slowly introduce the selenium source gas to in-situ dope selenium element on the CdS monolayer structure. Control the doping amount of selenium to be 2%. After the reaction lasts for 3 hours, cool it naturally, and collect the CdS-Se two-dimensional photocatalytic material.

[0029] Performance Test

[0030] The specific surface area of the material was measured using a specific surface area analyzer. The results showed that the two-dimensional structure and selenium doping increased its specific surface area to 80 m 2 / g, which was about 30% higher than that of pure CdS. In the photocatalytic degradation experiment of rhodamine B, under the same light intensity and time, the degradation efficiency of CdS-Se reached 55%, while that of pure CdS was only 30%, showing the synergistic enhancement brought by selenium doping and the two-dimensional structure, providing a component with excellent performance for subsequent composites.

[0031] Example 3:

[0032] TiO 2 Construction of TiO-Graphene Composite System and Verification of Charge Transfer Synergistic Enhancement

[0033] Experimental Preparation

[0034] Prepare a high-quality graphene oxide (GO) dispersion and ultrasonically treat it for 1 hour to ensure the full dispersion of GO sheets; weigh an appropriate amount of tetrabutyl titanate as the TiO 2 precursor, and prepare a hydrothermal reaction kettle and supporting temperature control equipment.

[0035] Preparation process

[0036] Slowly add tetrabutyl titanate to the GO dispersion, continuously stir for 2 hours, then transfer it to a hydrothermal reaction kettle and react at 180 °C for 12 hours. After the reaction, obtain TiO 2 -graphene composite powder by centrifugation, washing, and drying. Then, prepare it into a coating and spin-coat it on a conductive glass substrate to make a test sample, where the graphene content is 3%.

[0037] Performance test

[0038] Use a transient photocurrent test system to compare the transfer of photo-generated carriers in the TiO 2 and TiO 2 -graphene composite system. The results show that the lifetime of photo-generated carriers in the composite system is extended by about 40%, and the photocurrent density is increased by 60% compared to that of single TiO 2 This indicates that the introduction of graphene significantly accelerates charge transfer and enhances the photocatalytic process.

[0039] Example 4:

[0040] BiVO 4 -MIL-101(Cr) composite system photocatalytic enhancement exploration

[0041] Experimental preparation

[0042] Synthesize the precursor solutions of BiVO 4 nanoparticles and MIL-101(Cr) metal-organic framework respectively, precisely control the size of BiVO 4 nanoparticles between 50 - 100 nm, and prepare a solvothermal reaction kettle and magnetic stirring equipment.

[0043] Preparation process

[0044] Slowly add the BiVO 4 nanoparticle dispersion to the MIL-101(Cr) precursor solution, control the BiVO 4 content to 25%, and carry out a solvothermal reaction at 150 °C for 24 hours. After the reaction, cool, centrifuge, and wash to obtain BiVO 4 -MIL-101(Cr) composite powder, and make it into a coating sample.

[0045] Performance test

[0046] Using acetaldehyde as a model of volatile organic pollutants, the photocatalytic decomposition efficiency of the coating was tested under visible light. BiVO 4 -MIL-101(Cr) composite coating achieved a decomposition rate of 70% for acetaldehyde within 2 hours, which was 30% higher than that of the single BiVO 4 coating, demonstrating that the high porosity and large specific surface area of MIL-101(Cr) had a significant synergistic effect on the photocatalytic performance of BiVO 4 .

[0047] Example 5:

[0048] Synergistic effect of improved sol-gel spin coating process on coating adhesion and performance

[0049] Experimental preparation

[0050] Using the Bi-TiO 2 sol in Example 1, multiple groups of glass substrates were prepared and marked with different spin coating parameter groups; a high-precision adhesion tester and photocatalytic performance testing equipment were prepared.

[0051] Preparation process

[0052] Different aging time, spin coating speed, drying temperature and number, and annealing temperature parameter groups were set. For example, one group had an aging time of 48 hours, a spin coating speed of 3000 rpm, 10 minutes of drying each time, a drying temperature of 150 °C, a total of 3 spin coatings, and finally annealing at 500 °C; the other group of parameters was adjusted accordingly. Coatings were prepared by spin coating according to different parameters.

[0053] Performance testing

[0054] The adhesion between the coating and the substrate was measured by an adhesion tester. It was found that the adhesion increased by about 30% after the aging time was extended and the spin coating parameters were optimized. The photocatalytic degradation experiment showed that the degradation efficiency of the coating after the optimized process was 15% higher than that of the non-optimized process when degrading methyl orange, confirming the synergistic effect of the process improvement on the comprehensive performance of the coating.

[0055] Example 6:

[0056] Synergistic effect of spray coating method innovation on the appearance and uniformity of composite coatings

[0057] Experimental preparation

[0058] Prepare a precursor solution containing TiO 2 -graphene composite system, prepare a high-pressure airless spraying device, debug the infrared heating device, and prepare detection equipment such as a surface roughness tester and a microscope.

[0059] Preparation process

[0060] The precursor solution was sprayed under different combinations of flow rates (0.5 mL / s, 1 mL / s, 1.5 mL / s), spraying distances (20 cm, 25 cm, 30 cm), and substrate temperatures (60 °C, 70 °C, 80 °C). The formation process of the coating under different parameters was recorded, and the appearance defects were observed.

[0061] Performance test

[0062] The surface flatness of the coating was observed by a microscope, and the roughness data was quantified with a surface roughness tester. The results showed that under the conditions of a flow rate of 1 mL / s, a spraying distance of 25 cm, and a substrate temperature of 70 °C, the orange peel and sagging phenomena on the coating surface were the least, the roughness was reduced by about 40%, and the uniformity of the coating was significantly improved through component analysis, which played a synergistic role in the subsequent photocatalytic performance.

Claims

1. A novel photocatalytic semiconductor composite coating, characterized in that: The invention comprises a doped photocatalytic semiconductor material, wherein the doping modification is to dope bismuth (Bi) element into titanium dioxide (TiO2), wherein the doping amount of bismuth element is 3%-8% of the mass of TiO2, and at the same time, lanthanum-containing organic compound tri(acetylacetonate) lanthanum is added accounting for 0.05%-0.15% of the total mass.

2. The novel photocatalytic semiconductor composite coating according to claim 1 is characterized in that: It also includes a new two-dimensional photocatalytic semiconductor, which is based on cadmium sulfide and is in-situ doped with selenium by chemical vapor deposition, with the doping amount of selenium controlled at 1%-3%.

3. A photocatalytic semiconductor composite system, characterized in that: The invention comprises a semiconductor-graphene composite system, which is prepared by an in-situ growth method, so that TiO2 nanoparticles are uniformly grown on an oxide graphene sheet to form a TiO2-graphene composite system, wherein the graphene content is controlled at 1%-5%.

4. The photocatalytic semiconductor composite system according to claim 3, characterized in that: It also includes a semiconductor-metal organic framework composite system, in which BiVO4 nanoparticles are evenly dispersed in the precursor solution of MIL-101 by a solvothermal method, with the BiVO4 content accounting for 20%-30%.

5. A process for preparing a photocatalytic semiconductor composite coating, characterized in that: The TiO2-based photocatalytic coating is prepared by an improved sol-gel spin coating method. The aging time of the sol is precisely controlled to be 24-48 hours, the spin coating speed is set to 1500-3000rpm, and the coating is performed in multiple times. After each spin coating, the coating is dried at 100-150°C for 5-10 minutes, and finally annealed at 400-600°C.

6. The process for preparing the photocatalytic semiconductor composite coating according to claim 5, characterized in that: The composite coating is prepared by an innovative spraying method. High-pressure airless spraying equipment is used to evenly spray the precursor solution of the composite coating on the substrate at a flow rate of 0.5-1.5 mL / s. The spraying distance is maintained at 20-30 cm. During the spraying process, an infrared heating device is used to keep the substrate temperature at 60-80°C in real time.

7. A performance monitoring and control system for a photocatalytic semiconductor composite coating, characterized in that: It includes an in-situ photocatalytic degradation and photocurrent density joint testing system, which tracks the photocatalytic degradation efficiency and photocurrent density of the coating during the preparation process and light aging stage in real time. When the photocatalytic degradation efficiency drops by more than 5%, or the photocurrent density changes by more than 8%, it automatically adjusts the subsequent process parameters.

8. The performance monitoring and control system for photocatalytic semiconductor composite coating according to claim 7, characterized in that: It also includes microstructure analysis equipment, which uses a scanning electron microscope in conjunction with a transmission electron microscope. SEM captures the surface morphology and pore conditions of the material, and TEM analyzes the internal structure of the grains, the nanostructure, and the interface characteristics of the composite system. Once an abnormality is found, the preparation process can be optimized immediately.

9. A product using a photocatalytic semiconductor composite coating, characterized in that: The product is a self-cleaning coating for architectural glass. The photocatalytic semiconductor composite coating described in any one of claims 1 to 6 is evenly coated on the glass surface. The coating is used to decompose organic stains on the glass surface under light to achieve a self-cleaning function.

10. A product using a photocatalytic semiconductor composite coating, characterized in that: The product is an antibacterial coating for medical equipment. The photocatalytic semiconductor composite coating described in any one of claims 1 to 6 is applied to the surface of the medical equipment, and the photocatalytic properties of the coating are used to kill bacteria, viruses and microorganisms attached to the surface of the equipment.