Photocatalyst for killing and inhibiting growth of microorganisms on surface of stone cultural relics

Abstract

The application discloses a kind of photocatalyst for killing microorganism on the surface of stone cultural relics and inhibiting its growth, the catalyst is BiVO4 / TiO2-Ti2N (MXene) ternary photocatalytic material;Scanning electron microscope is observed to 20 times to the catalytic material is enlarged, Ti2N (MXene) is two-dimensional layered structure, and TiO2 is attached to the surface of Ti2N (MXene), BiVO4 is spherical structure and is dispersed in the surface and around of Ti2N (MXene) and TiO2.The photocatalyst of the application is coated on the surface of stone cultural relics, not only can effectively kill microorganism on the surface of stone cultural relics and inhibit the growth of microorganism, but also can improve the hydrophobic property of stone cultural relics, to realize the effective preventive protection of stone cultural relics.The photocatalyst of the application has simple manufacturing process, mild reaction condition, low cost, is suitable for mass production and widely used in the preventive protection of stone cultural relics microbial disease.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor photocatalysts, in particular to a photocatalyst for killing and inhibiting the growth of microorganisms on the surface of stone cultural relics. BACKGROUND

[0002] Cultural relics are the crystallization of human wisdom, the carrier of brilliant civilization and excellent historical culture, the precious heritage left by our ancestors, and the spiritual strength for human to forge ahead on a new journey. Among China's historical and cultural heritage, stone cultural relics are a very important type of cultural relics. They have a long history and are widely distributed, and have important historical and scientific value, which is of great significance for understanding and studying ancient civilization.

[0003] However, most stone cultural relics are preserved in outdoor environments and are in close contact with the biosphere, making them prone to microbial colonization. The pigments produced by microbial metabolism will change the color and appearance of the cultural relics, and the acidic substances secreted by the microorganisms will cause chemical corrosion to the stone cultural relics. The acidolysis reaction between the acidic substances and the rock will dissolve the rock, causing local cavities and crushing, and even large-scale peeling, thereby causing irreversible damage to the stone cultural relics. Therefore, effectively removing the microorganisms on the surface of the cultural relics and effectively inhibiting the growth of the microorganisms on the surface of the cultural relics has great significance for effectively preventing and treating microbial erosion of stone cultural relics.

[0004] In the prior art, the methods for removing microorganisms on the surface of stone cultural relics mainly include mechanical removal, gamma radiation, laser cleaning, thermal shock, microwave and dry ice treatment. Among them, the mechanical removal is to remove the microorganisms on the surface of stone cultural relics by using surgical knives or shovels and the like, which can only be effective in the short term, and frequent operation is required because it cannot inhibit the growth of microorganisms. More importantly, this method can damage the cultural relics, and is less used. Gamma radiation, laser cleaning, thermal shock, microwave and dry ice treatment can hardly remove the microorganisms in the rock fissures, and the removal efficiency is low, and it cannot inhibit the growth of microorganisms and can damage the cultural relics. In order to effectively inhibit the growth of microorganisms on the surface of stone cultural relics, biological and chemical methods are used. The biological method is to remove or inhibit the growth of harmful microorganisms on stone cultural relics through competition and predation between different microorganisms, but the biological method has less selectivity, high implementation difficulty and narrow use range, and is rarely used. The chemical method mainly uses bacteriostatic agents, antibacterial agents, natural plant essential oils and the like to kill the microorganisms on the surface of stone cultural relics, and is the method commonly used at present, but has the problems of short drug effect, development of drug resistance of microorganisms after long-term use, environmental pollution caused by large-scale use and change of appearance of cultural relics. Therefore, there is no method and reagent that can effectively remove and inhibit the growth of microorganisms on the surface of stone cultural relics at present, and it is very important to construct and develop a method and reagent that can effectively kill and inhibit the growth of microorganisms on the surface of stone cultural relics, which is the key to the preventive protection of microbial diseases of stone cultural relics. SUMMARY

[0005] In view of the above problems in the prior art, the purpose of the present application is to provide a photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics, so as to solve the problems that the chemical agents used in the prior art can easily cause microorganisms to develop drug resistance, can cause environmental pollution and can change the appearance of cultural relics when used in large quantities.

[0006] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0007] The photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics is a BiVO4 / TiO2-Ti2N (MXene) ternary photocatalytic material. The scanning electron microscope is used to observe the catalytic material at 20 times magnification, the Ti2N (MXene) has a two-dimensional layered structure, and the TiO2 is attached to the surface of the Ti2N (MXene), the BiVO4 has a spherical structure and is dispersed on the surface and around the Ti2N (MXene) and the TiO2.

[0008] Preferably, the Ti2N (MXene) is directly coupled with the titanium dioxide as a photocatalyst substrate, and BiVO4 is doped in the TiO2-Ti2N (MXene) to obtain the BiVO4 / TiO2-Ti2N (MXene) ternary photocatalytic material.

[0009] Preferably, the BiVO4 / TiO2-Ti2N (MXene) ternary photocatalytic material is prepared by the following steps:

[0010] The Ti2N (MXene) and TiO2 are dissolved in water and stirred for 5-8 h, wherein the weight ratio of Ti2N (MXene) to TiO2 is 1: (10-20) ; then, centrifugal treatment is performed and the supernatant is removed; then, the solid after centrifugal treatment is vacuum dried at 60-100 ℃ for 10-14 h to obtain the TiO2-Ti2N (MXene) composite material; then, BiVO4 and the TiO2-Ti2N (MXene) composite material are added to water and dissolved and stirred for 6-10 h, and the weight ratio of BiVO4 to TiO2-Ti2N (MXene) is (1-3) : 10; then, centrifugal treatment is performed and the supernatant is removed, and the obtained solid is vacuum dried at 95-110 ℃ for 10-14 h to obtain the BiVO4 / TiO2-Ti2N (MXene) composite material.

[0011] Preferably, the TiO2 is treated as follows:

[0012] The TiO2 powder is calcined at 450 ℃ for 2-4 h before use.

[0013] Preferably, the Ti2N (MXene) is prepared by the following method:

[0014] Potassium fluoride is added to hydrochloric acid until the potassium fluoride is completely dissolved to obtain a mixture, wherein the concentration of hydrochloric acid in the mixture is 0.3-1.2 mol / mL, and the concentration of potassium fluoride is 0.015-0.2 g / mL; titanium aluminum nitride is soaked in the mixture to form a suspension, and the concentration of titanium aluminum nitride in the suspension is 0.025-0.6 g / mL; the suspension is reacted at 30-50 ℃ for 0.5-2 h while ultrasonic bath treatment is performed, and the supernatant is removed to obtain a powder; the powder is added to water and centrifuged, and this process is repeated until the pH of the supernatant is 6-7; the powder is added to isopropanol and centrifuged, filtered and dried to obtain the Ti2N (MXene).

[0015] Preferably, the BiVO4 is prepared by the following method:

[0016] Bismuth vanadate pentahydrate was dissolved in nitric acid, and citric acid was added. The mixture was stirred until colorless to obtain solution A. In solution A, the concentration of bismuth vanadate pentahydrate was 0.001–0.003 mol / mL, the concentration of citric acid was 0.0001–0.0008 mol / mL, and the mass fraction of hydrochloric acid was 10%. Ammonium metavanadate was dissolved in water and heated to 60–90 °C with continuous stirring until a transparent lemon-yellow solution was obtained. Citric acid was then added and stirring continued until a brown solution B was obtained. In solution B, ammonium metavanadate... The concentration of the solution was 0.001–0.003 mol / mL, and the concentration of citric acid was 0.0001–0.0008 mol / mL. Solution A was then added dropwise to solution B to obtain a mixed solution, and the pH of the mixed solution was adjusted to 6–7 with ammonium hydroxide. The adjusted mixed solution was kept at 60–90 °C and stirred continuously until gel formed. The gel was then dried to obtain powder, and the obtained powder was calcined at 450–550 °C for 1.5–3.0 h to obtain a bright yellow BiVO4 powder.

[0017] Preferably, the photocatalyst is used to kill microorganisms on the surface of stone artifacts and inhibit their growth.

[0018] Preferably, the photocatalyst is made into a gel and coated onto the surface of the stone artifact.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The photocatalyst described in this invention is a BiVO4 / TiO2-Ti2N(MXene) ternary composite photocatalyst, which can effectively compensate for the shortcomings of TiO2 in terms of low light utilization and high recombination rate of photogenerated carriers. This invention synthesizes and prepares the BiVO4 / TiO2-Ti2N(MXene) ternary photocatalytic material through etching and sol-gel methods. First, using titanium dioxide as the substrate of the photocatalyst, Ti2N(MXene) is directly coupled to titanium dioxide. The two-dimensional layered structure of Ti2N(MXene) can increase the specific surface area of ​​the photocatalyst and increase the number of active sites. Then, BiVO4 is doped into TiO2-Ti2N(MXene) to improve the light energy utilization efficiency and charge transfer capability of the photocatalyst, enhance the photocatalytic activity, and thus produce more active oxygen groups for killing microorganisms.

[0021] 2. The photocatalyst described in this invention is easy to use. Applying the photocatalyst of this invention to the surface of stone cultural relics can not only effectively kill microorganisms on the surface of stone cultural relics and inhibit their growth, but also improve the hydrophobic properties of stone cultural relics, thereby achieving preventive protection against microbial diseases of stone cultural relics. Attached Figure Description

[0022] Figure 1SEM photos of BiVO4 / TiO2-Ti2N (MXene) prepared for Example 7.

[0023] Figure 2 Photos of the rock without coating and coated with TiO2, TiO2-Ti2N (MXene), BiVO4 / TiO2-Ti2N (MXene) semiconductor photocatalyst after 28 days of cultivation.

[0024] Figure 3 For every 7 days, the absorbance of microalgae at a wavelength of 680 nm corresponds to the absorbance intensity, and the greater the absorbance indicates the greater the biomass of microalgae. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the present application belong to the scope of protection of the present application.

[0026] Unless otherwise specified in specific cases, the numerical ranges listed in the present application include the upper and lower limits, and all integers and fractions within the range, and are not limited to the specific values listed in the defined range.

[0027] I. Photocatalyst for killing and inhibiting growth of microorganisms on the surface of stone cultural relics

[0028] The catalyst described in the present application is a BiVO4 / TiO2-Ti2N (MXene) ternary photocatalytic material. The scanning electron microscope is used to observe the catalyst material at 20 times magnification. Ti2N (MXene) is a two-dimensional layered structure, and TiO2 is attached to the surface of Ti2N (MXene). BiVO4 is a spherical structure and is dispersed on the surface and around Ti2N (MXene) and TiO2.

[0029] In order to effectively prevent microbial diseases of stone cultural relics, the application makes in-depth research on photocatalysts and finds that the purpose of killing microorganisms and inhibiting microbial growth can be achieved by promoting semiconductor photocatalysts to produce active oxygen groups. However, the TiO2 catalyst in the prior art has the shortcomings of low light utilization rate and fast recombination rate of photo-generated carriers, so the TiO2 catalyst in the prior art is improved, Ti2N (MXene) is directly coupled with titanium dioxide, the two-dimensional layered structure of Ti2N (MXene) can increase the specific surface area of the photocatalyst and increase the active sites, then BiVO4 is doped in TiO2-Ti2N (MXene) to improve the light energy utilization efficiency and charge transfer ability of the photocatalyst, and the photocatalytic activity of the photocatalyst is enhanced, so that more active oxygen groups are produced for killing microorganisms.

[0030] In some embodiments, the BiVO4 / TiO2-Ti2N (MXene) ternary photocatalytic material is prepared by the following steps:

[0031] Ti2N (MXene) and TiO2 are dissolved with water and stirred for 5-8h, wherein the weight ratio of Ti2N (MXene) to TiO2 is 1:(10-20); then, centrifugal treatment is performed and the supernatant is removed; then, the solid after centrifugal treatment is vacuum dried at 60-100℃ for 10-14h to obtain TiO2-Ti2N (MXene) composite material; then, BiVO4 and TiO2-Ti2N (MXene) composite material are added to water and dissolved and stirred for 6-10h, the weight ratio of BiVO4 to TiO2-Ti2N (MXene) is (1-3):10; then, centrifugal treatment is performed and the supernatant is removed, and the obtained solid is vacuum dried at 95-110℃ for 10-14h to obtain BiVO4 / TiO2-Ti2N (MXene) composite material. Therefore, the weight ratio of Ti2N (MXene) to TiO2 can be 1:10, 1:19, 1:20, etc., and all ranges and subranges between the above-mentioned values. The weight ratio of BiVO4 to TiO2-Ti2N (MXene) can be 1:10, 1.1:10, 3:10, etc., and all ranges and subranges between the above-mentioned values. It should be understood that in embodiments, any of the above-mentioned ranges can be combined with any other range. Among them, before the use of TiO2, the TiO2 powder is calcined at 450℃ for 2-4h before use. The calcination time of TiO2 at 450℃ can be 2h, 3h, 4h, etc., and all ranges and subranges between the above-mentioned values. It should be understood that in embodiments, any of the above-mentioned ranges can be combined with any other range.

[0032] In some embodiments, the Ti2N (MXene) is prepared by the following method:

[0033] Potassium fluoride is added to hydrochloric acid until the potassium fluoride is completely dissolved to obtain a mixture, in which the concentration of hydrochloric acid is 0.3-1.2 mol / mL, and the concentration of potassium fluoride is 0.015-0.2 g / mL; titanium aluminum nitride is soaked in the mixture to form a suspension, in which the concentration of titanium aluminum nitride is 0.025-0.6 g / mL; the suspension is reacted at 30-50°C for 0.5-2 h, while ultrasonic bath treatment is performed, and the supernatant is removed to obtain a powder; the powder is added to water and centrifuged, and this process is repeated until the pH of the supernatant is 6-7; the powder is added to isopropanol and centrifuged, and dried after filtration to obtain Ti2N (MXene). The Ti2N (MXene) prepared by the method of the present application has a two-dimensional layered structure, which can significantly increase the specific surface area of the photocatalyst and increase the active sites. If the raw material ratio and the reaction conditions are not within the range of the method of the present application, the product obtained may not have a two-dimensional layered structure, or the specific surface area of the photocatalyst may be insufficient and the active sites may be too few.

[0034] In some embodiments, the BiVO4 is prepared by the following method:

[0035] Bismuth vanadate pentahydrate is dissolved in nitric acid, citric acid is added, and stirred until colorless to obtain solution A; in solution A, the concentration of bismuth vanadate pentahydrate is 0.001-0.003 mol / mL, the concentration of citric acid is 0.0001-0.0008 mol / mL, and the mass fraction of hydrochloric acid is 10%; ammonium metavanadate is dissolved in water, and heated to 60-90°C for continuous stirring until a transparent citrine solution is obtained, then citric acid is added and stirred until a brown solution B is obtained; in solution B, the concentration of ammonium metavanadate is 0.001-0.003 mol / mL, and the concentration of citric acid is 0.0001-0.0008 mol / mL; then solution A is added dropwise into solution B to obtain a mixed solution, and the pH of the mixed solution is adjusted to 6-7 with ammonium hydroxide; the adjusted mixed solution is kept at 60-90°C for continuous stirring until a gel is formed; then the gel is dried to obtain a powder, and the obtained powder is calcined at 450-550°C for 1.5-3.0 h to obtain a bright yellow powder BiVO4. The BiVO4 prepared by the method of the present application has good response to visible light, and can be used to improve the light energy utilization efficiency and charge transfer ability of the photocatalyst, thereby enhancing the photocatalytic activity of the photocatalyst to produce more active oxygen groups to kill microorganisms.

[0036] In some embodiments, the photocatalyst is used to kill and inhibit the growth of microorganisms on the surface of stone cultural relics. Specifically, the photocatalyst is made into a gel and coated on the surface of stone cultural relics. However, this is only one embodiment, and the photocatalyst can also be made into other forms of products to cover the surface of stone cultural relics, which can also kill and inhibit the growth of microorganisms, and at the same time improve the hydrophobicity of stone cultural relics, thereby achieving multi-angle and effective protective protection of stone cultural relics.

[0037] The preparation of BiVO4 / TiO2-Ti2N (MXene) gel is as follows: first, 0.2-0.4 mol of ethylene glycol is added to a glass volumetric flask, and heated in a water bath to 55-65°C, continuously stirred at a stirring speed of 200-600 rpm, then 0.02-0.3 mol of titanium isopropoxide is added to the mixed solution of ethylene glycol, and the water bath is heated to 85-95°C; then 0.03-0.12 mol of citric acid monohydrate is added, and continuously stirred until the solution becomes clear, at a stirring speed of 300 rpm; finally, 3-6 g of BiVO4 / TiO2-Ti2N (MXene) powder is added, stirred for 0.5-2.5 h, and taken out to store in the dark, to obtain BiVO4 / TiO2-Ti2N (MXene) gel. The gel preparation method is only illustrative, and the present application is not limited to making the catalyst into a gel.

[0038] II. Examples and Comparative Examples

[0039] Example 1

[0040] Preparation of Ti2N (MXene): 0.3 g of potassium fluoride was dissolved in 5 ml of 6 mol hydrochloric acid and stirred until the potassium fluoride was completely dissolved. Aluminum titanium nitride (0.5 g) was soaked in 5 ml of the mixture of potassium fluoride and hydrochloric acid and stirred at room temperature for 3.5 h. The suspension was further heated at 30°C for 0.5 h while being treated in an ultrasonic bath to promote exfoliation and intercalation. The supernatant was removed to obtain a powder, deionized water was added to the powder, and centrifuged at 3500 rad / min for 3-8 min to remove soluble fluorides. This process was repeated until the pH of the supernatant was close to 6-7. After changing the bottle, isopropyl alcohol was added and centrifuged at 3500 rad / min for 20-50 min, and then dried for 8-15 h after filtration to obtain Ti2N (MXene).

[0041] Example 2

[0042] Based on Example 1, the difference is that the amount of potassium fluoride is 0.5 g, the amount of hydrochloric acid is 15 mL of 6 mol, the amount of aluminum titanium nitride is 2.5 g, and the suspension is heated at 40°C for 1 h. The other steps are completely consistent, and Ti2N (MXene) is prepared.

[0043] Example 3

[0044] Improvement was made on the basis of Example 1, the difference is that the amount of incubator is 1.0 g, the amount of hydrochloric acid is 20 mL 6 mol, the amount of titanium aluminum nitride is 3.0 g, and the suspension is heated at 50°C for 2h. Other steps are exactly the same, and Ti2N (MXene) is prepared.

[0045] Example 4

[0046] Preparation of BiVO4: 0.08 mol of bismuth vanadate pentahydrate was dissolved in 45 ml of 10% nitric acid, 0.01 mol of citric acid was added, and the mixture was stirred until a colorless solution (solution A) was obtained. In another beaker, 0.08 mol of ammonium metavanadate was dissolved in 45 ml of deionized water, then heated at 60°C with magnetic stirring until a transparent lemon yellow solution was obtained. Then 0.01 mol of citric acid was added until a brown solution (solution B) was obtained. Then solution A was added dropwise into solution B to obtain the final mixed solution, which was strongly blue. Then adjust the pH value with ammonium hydroxide solution until the pH value of the mixture reaches 6-7. The mixture was kept at the same temperature and continuously stirred until the gel was formed. Then dry at 90-110°C overnight, the obtained powder was calcined in a muffle furnace at a temperature increasing rate of 5°C / min to 450°C for 1.5h to obtain bright yellow powder BiVO4.

[0047] Example 5

[0048] Improvement was made on the basis of Example 4, the difference is that when preparing solution A, the amount of bismuth vanadate pentahydrate is 0.1 mol, the amount of 10% nitric acid is 50 ml, and the amount of citric acid is 0.02 mol. When preparing solution B, the amount of ammonium metavanadate is 0.1 mol, the amount of deionized water is 50 ml, and the amount of citric acid is 0.02 mol, and the reaction is carried out at 80°C. The powder calcination temperature is 500°C, and the calcination time is 2h, to obtain bright yellow powder BiVO4.

[0049] Example 6

[0050] Improvement was made on the basis of Example 4, the difference is that when preparing solution A, the amount of bismuth vanadate pentahydrate is 0.12 mol, the amount of 10% nitric acid is 60 ml, and the amount of citric acid is 0.035 mol. When preparing solution B, the amount of ammonium metavanadate is 0.12 mol, the amount of deionized water is 60 ml, and the amount of citric acid is 0.035 mol, and the reaction is carried out at 90°C. The powder calcination temperature is 550°C, and the calcination time is 3h, to obtain bright yellow powder BiVO4.

[0051] Example 7

[0052] Preparation of BiVO4 / TiO2-Ti2N (MXene) photocatalytic material: First, titanium dioxide powder was calcined at 450°C for 3h, 0.1 g of Ti2N (MXene), 1.9 g of TiO2 were weighed and dissolved in deionized water and stirred for 6h. Centrifuged at 5400 rad / min for 5 min, remove the supernatant, then vacuum dried at 80°C for 12h to obtain TiO2-Ti2N (MXene) composite material. 0.2 g of BiVO4, 1.8 g of TiO2-Ti2N (MXene) were weighed and dissolved in deionized water and stirred for 8h. Centrifuged at 4000 rad / min for 5 min, remove the supernatant, then vacuum dried at 100°C for 12h to obtain BiVO4 / TiO2-Ti2N (MXene) composite material. In this example, Ti2N (MXene) is from Example 1, and BiVO4 is from Example 4.

[0053] Example 8

[0054] Based on Example 7, the difference is that the titanium dioxide powder is calcined at 450°C for 2h. The amount of Ti2N (MXene) is 0.1 g, and Ti2N (MXene) is from Example 2. The amount of TiO2 is 1.0 g. BiVO4 is from Example 5, BiVO4 is 0.1 g, and the amount of TiO2-Ti2N (MXene) is 1.0 g. BiVO4 / TiO2-Ti2N (MXene) composite material is prepared.

[0055] Example 9

[0056] Based on Example 7, the difference is that the titanium dioxide powder is calcined at 450°C for 4h. The amount of Ti2N (MXene) is 0.1 g, and Ti2N (MXene) is from Example 3. The amount of TiO2 is 2.0 g. BiVO4 is from Example 6, BiVO4 is 0.3 g, and the amount of TiO2-Ti2N (MXene) is 1.0 g. BiVO4 / TiO2-Ti2N (MXene) composite material is prepared.

[0057] Example 10

[0058] Preparation of BiVO4 / TiO2-Ti2N (MXene) gel: first, 0.2 mol of ethylene glycol was taken into a glass volumetric flask, and heated in a water bath to 55°C, constantly stirring at a stirring speed of 200 rpm, then 0.02 mol of titanium isopropoxide was added to the ethylene glycol mixed solution, and the water bath was heated to 85°C; then 0.03 mol of citric acid monohydrate was added, and constantly stirred until the solution became clear, at a stirring speed of 300 rpm; finally, 3 g of BiVO4 / TiO2-Ti2N (MXene) powder (from Example 7) was added, stirred for 0.5-2.5 h, and then removed for light shielding storage, to obtain the BiVO4 / TiO2-Ti2N (MXene) gel.

[0059] Example 11

[0060] On the basis of Example 10, the difference is that the BiVO4 / TiO2-Ti2N (MXene) powder prepared in Example 8 is used in an amount of 5 g, and the other steps are the same, to prepare the BiVO4 / TiO2-Ti2N (MXene) gel.

[0061] Example 12

[0062] On the basis of Example 10, the difference is that the BiVO4 / TiO2-Ti2N (MXene) powder prepared in Example 9 is used in an amount of 6 g, and the other steps are the same, to prepare the BiVO4 / TiO2-Ti2N (MXene) gel.

[0063] Comparative Example 1

[0064] The TiO2 prepared in Example 7 is used as a catalyst to treat the surface of stone cultural relics, and its effect on killing microorganisms is compared with that of Examples 7-9. The same gel as in Example 10 is prepared and used.

[0065] Comparative Example 2

[0066] The TiO2-Ti2N (MXene) prepared in Example 7 is used as a catalyst to treat the surface of stone cultural relics, and its effect on killing microorganisms is compared with that of Examples 7-9. The same gel as in Example 10 is prepared and used.

[0067] III. Performance Comparison

[0068] 1. Morphology analysis

[0069] The catalysts prepared in Examples 7-9 are subjected to morphology analysis, Figure 1 SEM photograph of BiVO4 / TiO2-Ti2N (MXene) prepared in Example 7. Figure 1It is shown that the two-dimensional layered structure of Ti2N (MXene) is well preserved, and part of TiO2 is attached to the surface of Ti2N (MXene); BiVO4 is in a spherical structure and is well dispersed on the surface and around Ti2N (MXene) and TiO2; it is shown that the BiVO4 / TiO2-Ti2N (MXene) semiconductor photocatalyst is successfully synthesized. After observing the catalysts prepared in Examples 8 and 9, the same morphology as Example 7 can also be found, which also shows that the BiVO4 / TiO2-Ti2N (MXene) semiconductor photocatalysts are prepared in Examples 8 and 9.

[0070] 2. Comparison of microbial killing effect

[0071] Selection and coating of rock samples: In order to facilitate the colonization of microalgae, large-pore sandstone with a size of 12*4 cm was selected as the experimental sample. First, the sample was polished with sandpaper, washed with deionized water and dried in a drying oven at 150°C for 30 min, then the surface of the sample was wiped clean with anhydrous ethanol and naturally air-dried at room temperature. Finally, 1.5 ml of gel was evenly spread on the sandstone with a pipette, and placed in a drying oven at a temperature of 150°C for 4.5 h to obtain a rock coated with a photocatalyst. The BiVO4 / TiO2-Ti2N (MXene) gel coating thickness was about 120 μm.

[0072] Preventive protection performance test of microbial diseases of stone cultural relics: In order to test the preventive protection performance of BiVO4 / TiO2-Ti2N (MXene) on microbial diseases of stone cultural relics, 5 ml of biomass concentration OD 680 = 0.1168 g / L microalgae was planted on the surface of the rock without coating and coated with BiVO4 / TiO2-Ti2N (MXene) semiconductor photocatalyst with a pipette. Then the rock sample with microalgae was naturally air-dried, and then placed in an experimental box with a full-spectrum LED light strip with a light intensity of 18 W. The temperature of the experimental box was set to 25°C, and the light irradiation time was 12 h and the dark time was 12 h. The sample was cultured in this experimental environment for 28 days. Subsequently, the same method was used to coat the same thickness of TiO2 catalyst prepared in Comparative Example 1 and Ti2N (MXene) catalyst prepared in Comparative Example 2 on the surface of the same sandstone.

[0073] Figure 2 a shows that the microalgae on the surface of the rock without coating BiVO4 / TiO2-Ti2N (MXene) semiconductor photocatalyst grows normally. Figure 2b shows that the growth of microalgae on the rock surface coated with the catalyst prepared in Comparative Example 1 is affected to a certain extent, but the effect is not obvious, and only a small amount of microalgae dies, which also shows that the TiO2catalyst does not have a killing effect on microalgae. Figure 2 c shows that TiO2-Ti2N(MXene) has a more obvious effect on the growth of microalgae, and the number of dead microalgae is significantly higher than Figure 2 b, which also shows that the adverse effect of TiO2-Ti2N(MXene) on the growth of microalgae is more significant than that of the TiO2catalyst, but there is still a significant gap compared with the examples. Figure 2 d shows that the microalgae on the rock surface coated with the BiVO4 / TiO2-Ti2N(MXene) semiconductor photocatalyst gel prepared in Examples 10-12 turn yellow, and the surface microalgae have completely died.

[0074] Figure 3 It is shown that with the increase of microalgae culture time, the growth rate of microalgae on the rock without coating BiVO4 / TiO2-Ti2N(MXene) semiconductor photocatalyst is the fastest, faster than the growth rate of microalgae on the rock in the examples and comparative examples, and very rapid reproduction occurs before 20 days. On the rock coated with the TiO2semiconductor photocatalyst prepared in Comparative Example 1, the growth rate of microalgae has a very significant decrease compared with that without coating, but the growth of microalgae is not obviously inhibited, and the growth of microalgae is still continuous as a whole. On the rock coated with the TiO2-Ti2N(MXene) semiconductor photocatalyst prepared in Comparative Example 2, the growth of microalgae has only a small decrease compared with the effect of coating the catalyst of Comparative Example 1, and the growth of microalgae is not inhibited. At the same time, on the rock surface coated with the BiVO4 / TiO2-Ti2N(MXene) semiconductor photocatalyst gel prepared in Examples 10-12, the growth of microalgae is very obviously inhibited from the beginning, and it can be seen that the amount of microalgae reproduction is very small, and the microalgae stop growing after less than 15 days. The reason is that the photocatalyst generates electron-hole pairs on the surface of the photocatalyst by light irradiation, and then generates active oxygen groups, i.e. superoxide free radicals (·O 2- ) and hydroxyl free radicals (·OH) with oxygen, water and hydroxyl ions; the active oxygen groups have strong oxidizing ability, and when the active oxygen groups contact the microbial cells, they will cause the microalgae cells to break the wall, thereby killing the microbial cells and inhibiting the growth of the microbial cells, which further proves that the catalysts described in the present application can inhibit the growth of microorganisms.

[0075] Finally, it needs to be explained that the above examples are only used to illustrate the technical solutions of the present application but not to limit the technical solutions, and those of ordinary skill in the art should understand that the technical solutions of the present application are modified or equivalently replaced without departing from the purpose and scope of the technical solutions, which should be covered in the scope of claims of the present application.

Claims

1. A photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone artifacts, characterized in that, The catalyst is a BiVO4 / TiO2-Ti2N ternary photocatalytic material. The catalytic material was observed by scanning electron microscopy at 20x magnification. Ti2N has a two-dimensional layered structure of MXene phase, and TiO2 is attached to the surface of Ti2N of MXene phase. BiVO4 has a spherical structure and is dispersed on the surface and around Ti2N and TiO2. The BiVO4 / TiO2-Ti2N ternary photocatalytic material was prepared by the following steps: MXene phase Ti2N and TiO2 were dissolved in water and stirred for 5-8 h, wherein the weight ratio of MXene phase Ti2N to TiO2 was 1:(10-20); then, the mixture was centrifuged and the supernatant was removed; then, the centrifuged solid was vacuum dried at 60-100℃ for 10-14 h to obtain TiO2-Ti2N composite material; then, BiVO4 and TiO2-Ti2N composite material were dissolved in water and stirred for 6-10 h, wherein the weight ratio of BiVO4 to TiO2-Ti2N was (1-3):10; then, the mixture was centrifuged and the supernatant was removed, and the obtained solid was vacuum dried at 95-110℃ for 10-14 h to obtain BiVO4 / TiO2-Ti2N composite material; The TiO2 was treated as follows: The TiO2 powder is calcined at 450℃ for 2-4 hours before use.

2. The photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics according to claim 1, characterized in that, Using titanium dioxide as the substrate of the photocatalyst, Ti2N of the MXene phase is directly coupled with titanium dioxide, and then BiVO4 is doped into TiO2-Ti2N to obtain the BiVO4 / TiO2-Ti2N ternary photocatalytic material.

3. The photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics according to claim 2, characterized in that, The MXene phase Ti2N was prepared by the following method: Potassium fluoride was added to hydrochloric acid until it was completely dissolved to obtain a mixture, wherein the concentration of hydrochloric acid in the mixture was 0.3~1.2 mol / mL and the concentration of potassium fluoride was 0.015~0.2 g / mL; titanium aluminum nitride was immersed in the mixture and stirred to form a suspension, wherein the concentration of titanium aluminum nitride in the suspension was 0.025~0.6 g / mL; the suspension was reacted at 30~50℃ for 0.5~2 h, and simultaneously subjected to ultrasonic bath treatment, and the supernatant was removed to obtain powder; the powder was added to water and centrifuged, and this process was repeated until the pH of the supernatant was 6~7; the powder was added to isopropanol, centrifuged, filtered, and dried to obtain MXene phase Ti2N.

4. The photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics according to claim 2, characterized in that, The BiVO4 was prepared by the following method: Bismuth vanadate pentahydrate was dissolved in nitric acid, and citric acid was added. The mixture was stirred until colorless to obtain solution A. In solution A, the concentration of bismuth vanadate pentahydrate was 0.001–0.003 mol / mL, and the concentration of citric acid was 0.0001–0.0008 mol / mL. Ammonium metavanadate was dissolved in water and heated to 60-90°C with continuous stirring until a transparent lemon-yellow solution was obtained. Citric acid was then added and stirring continued until a brown solution B was obtained. In solution B, the concentration of ammonium metavanadate was 0.001-0.003 mol / mL and the concentration of citric acid was 0.0001-0.0008 mol / mL. Solution A was then added dropwise to solution B to obtain a mixed solution, and the pH of the mixed solution was adjusted to 6-7 with ammonium hydroxide. The adjusted mixed solution was kept at 60-90°C with continuous stirring until gelation occurred. The gel was then dried to obtain a powder, and the obtained powder was calcined at 450-550°C for 1.5-3.0 h to obtain a bright yellow BiVO4 powder.

5. The photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics according to any one of claims 1 to 4, characterized in that, The photocatalyst is used to kill microorganisms on the surface of stone artifacts and inhibit their growth.

6. The photocatalyst for killing microorganisms and inhibiting their growth on the surface of stone cultural relics according to claim 5, characterized in that, The photocatalyst was made into a gel and coated onto the surface of a stone artifact.

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