Application of metal-oxygen cluster-modified ultrathin carbon nitride nanosheets in promoting plant growth through artificial photosynthesis

Abstract

The invention relates to the application of ultrathin carbon nitride nanosheets modified by metal oxoclusters in promoting plant growth through artificial photosynthesis, which relates to the field of nano-agricultural technology. The purpose of the invention is to solve the problem of low photosynthesis efficiency caused by the low utilization rate of the solar spectrum of plants. Method: The ultrathin carbon nitride nanosheets modified by metal oxoclusters are configured into an aqueous dispersion of a certain concentration, and then the dispersion of the ultrathin carbon nitride nanosheets modified by metal oxoclusters is sprayed onto the leaves of the plants, which has a good growth-promoting effect on the plants; the fresh weight and dry weight of the plants are significantly increased. And its growth-promoting effect on plants is positively correlated with the water oxidation performance of the photocatalyst. Ultrathin carbon nitride nanosheets modified by metal oxoclusters are eco-friendly and environmentally friendly due to their good stability, wide sources and good biocompatibility, meet the requirements of sustainable development, and can be widely used in crop planting. The present invention provides a new method for improving the photosynthesis efficiency of plants and promoting crop yield and income.

Description

Technical Field

[0001] The present invention relates to the field of nano-agricultural technology, and in particular to an application of a metal oxide cluster-modified ultrathin carbon nitride nanosheet in promoting plant growth through artificial photosynthesis. Background Art

[0002] The shortage of fossil energy and increasing environmental pollution have fueled a growing desire for efficient solar energy utilization. Natural photosynthesis is one of nature's most successful ways of harnessing solar energy. However, plants' low efficiency in converting light energy results in low photosynthesis efficiency. Therefore, developing green and feasible methods to improve plant photosynthesis efficiency and promote increased plant production and income is of great significance.

[0003] Photocatalytic technology (also known as artificial photosynthesis) works by exciting a semiconductor with light to produce photogenerated electron-hole pairs. These pairs migrate to the surface of the catalyst, initiating a series of redox reactions, such as H₂O decomposition, CO₂ reduction, and N₂ fixation. Therefore, artificial photosynthesis promotes natural photosynthesis by expanding the spectral range utilized by natural photosynthesis and, through improved water oxidation performance of photocatalysts, transferring the long-lived photogenerated electrons to plant chloroplasts. This is expected to increase the efficiency of natural photosynthesis and promote plant growth.

[0004] Carbon nitride (CN) is a widely used semiconductor photocatalyst. Due to its good stability, wide availability, and good biocompatibility, it is eco-friendly and environmentally friendly, meets the requirements of sustainable development, and can be widely used in crop cultivation. Currently, there are reports that carbon nitride promotes plant photosynthesis through fluorescence conversion. However, there is still the problem of low spectral utilization leading to low photosynthesis efficiency. There are no reports on metal oxygen cluster-modified ultrathin carbon nitride expanding the utilization of the solar spectrum of plants and promoting their growth by accelerating the transfer of long-lived photogenerated electrons generated by the water oxidation performance of photocatalysts to plant chloroplasts. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of low photosynthesis efficiency caused by low utilization of the solar spectrum of plants, and to provide an application of metal oxide cluster modified ultrathin carbon nitride nanosheets in artificial photosynthesis to promote plant growth.

[0006] Artificial photosynthesis using ultrathin carbon nitride nanosheets modified with metal oxoclusters (M-COS-CN) is used to promote plant growth. Carbon nitride, due to its strong ultraviolet light absorption ability, can expand plants' utilization of the solar spectrum. In addition, by improving the water oxidation performance of carbon nitride-based photocatalysts through metal oxoclusters, long-lived photogenerated electrons are generated, which are further transferred to the plant's chloroplasts, increasing the electron transfer rate in the electron transport chain and promoting its growth. Therefore, the present invention's use of a series of ultrathin carbon nitride nanosheets modified with metal oxoclusters to promote plant growth has certain application prospects.

[0007] A metal oxide cluster-modified ultrathin carbon nitride nanosheet is used to promote plant growth, specifically comprising the following steps:

[0008] The metal oxide cluster modified ultrathin carbon nitride nanosheets are prepared into a water dispersion of a certain concentration, and then the water dispersion of the metal oxide cluster modified ultrathin carbon nitride nanosheets is sprayed onto the leaves of the plants;

[0009] The metal oxide cluster modified ultrathin carbon nitride nanosheets are: manganese oxide cluster modified ultrathin carbon nitride nanosheets, ruthenium oxide cluster modified ultrathin carbon nitride nanosheets, manganese oxide cluster modified ultrathin boron doped carbon nitride nanosheets or ruthenium oxide cluster modified ultrathin boron doped carbon nitride nanosheets.

[0010] Beneficial effects of the present invention:

[0011] (1) Foliar spraying of photocatalysts greatly promoted plant growth. After treatment with ultrathin carbon nitride nanosheets modified with manganese oxide clusters, the fresh weight of tobacco increased by 21.9% and the dry weight increased by 17.8%; the fresh weight of sugar beets increased by 25.1% and the dry weight increased by 57.8%;

[0012] (2) The metal oxide cluster-modified ultrathin carbon nitride nanosheets prepared by the present invention have the characteristics of stable structure, good optical properties, and low toxicity, especially strong absorption in the ultraviolet region of 300-400nm, and good water oxidation performance;

[0013] (3) The preparation method of the metal oxide cluster modified ultrathin carbon nitride nanosheets of the present invention is simple and suitable for large-scale synthesis;

[0014] (4) The metal oxide cluster-modified ultrathin carbon nitride nanosheets of the present invention are eco-friendly and environmentally friendly due to their good stability, wide availability, and good biocompatibility, meeting the requirements of sustainable development and can be widely used in crop cultivation. The present invention provides a new method for improving plant photosynthesis efficiency and promoting crop yield and income growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Structural characterization of the ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 1;

[0016] Figure 2 The morphology and thickness of the ultrathin carbon nitride nanosheet modified with ruthenium oxide clusters prepared in Example 1;

[0017] Figure 3 To investigate the effect of the ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 1 on tobacco growth;

[0018] Figure 4 The effect of ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 1 at different concentrations on tobacco growth in Application Example 2 is described.

[0019] Figure 5 Structural characterization of the ultrathin carbon nitride nanosheets modified with manganese oxide clusters prepared in Example 3;

[0020] Figure 6 The effect of the ultrathin carbon nitride nanosheets modified with manganese oxo clusters prepared in Example 3 on tobacco growth in Example 4 is investigated;

[0021] Figure 7 The effect of the ultrathin carbon nitride nanosheets modified with manganese oxide clusters prepared in Example 3 on the growth of sugar beets was investigated in Example 5. DETAILED DESCRIPTION

[0022] The following examples further illustrate the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention.

[0023] Specific embodiment 1: This embodiment is an application of ultrathin carbon nitride nanosheets modified with metal oxoclusters in promoting plant growth through artificial photosynthesis. The ultrathin carbon nitride nanosheets modified with metal oxoclusters in artificial photosynthesis are used to promote plant growth, specifically comprising the following steps:

[0024] The metal oxide cluster modified ultrathin carbon nitride nanosheets are prepared into a water dispersion of a certain concentration, and then the water dispersion of the metal oxide cluster modified ultrathin carbon nitride nanosheets is sprayed onto the leaves of the plants;

[0025] The metal oxide cluster modified ultrathin carbon nitride nanosheets are: manganese oxide cluster modified ultrathin carbon nitride nanosheets, ruthenium oxide cluster modified ultrathin carbon nitride nanosheets, manganese oxide cluster modified ultrathin boron doped carbon nitride nanosheets or ruthenium oxide cluster modified ultrathin boron doped carbon nitride nanosheets.

[0026] Specific Embodiment 2: This embodiment differs from Specific Embodiment 1 in that the process for preparing the metal-oxo-cluster-modified ultrathin carbon nitride nanosheets into an aqueous dispersion of a certain concentration is as follows: the metal-oxo-cluster-modified ultrathin carbon nitride nanosheets are added to water, and then ultrasonicated at a power of 100 W for 10 to 60 minutes to obtain an aqueous dispersion of the metal-oxo-cluster-modified ultrathin carbon nitride nanosheets; the concentration of the aqueous dispersion of the metal-oxo-cluster-modified ultrathin carbon nitride nanosheets is 50 mg / L to 200 mg / L. Other steps are the same as those in Specific Embodiment 1.

[0027] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the plant is tobacco, sugar beet, rice, corn or soybean. The other steps are the same as those of specific embodiment 1 or 2.

[0028] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the plants are cultivated in a soil culture mode. The other steps are the same as those of specific embodiments 1 to 3.

[0029] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the method for preparing the ultra-thin carbon nitride modified with manganese oxide clusters is specifically completed according to the following steps:

[0030] 1. Preparation of ultrathin carbon nitride nanosheets and ultrathin boron-doped carbon nitride nanosheets:

[0031] The urea is placed in an alumina crucible and transferred to a muffle furnace for primary calcination, naturally cooled to room temperature, and then ground to obtain product I; the product I is placed in a semi-enclosed magnetic boat, then placed in a muffle furnace for secondary calcination, naturally cooled to room temperature, and then ground to obtain product II; the product II is placed in a round-bottom flask, acidified after adding acid, cooled to room temperature, centrifuged, washed with water until neutral, and dried to obtain ultrathin carbon nitride nanosheets; the product I is mixed with sodium borohydride, ground for a period of time, and then placed in a vacuum tube furnace for calcination. The product obtained after calcination is washed with water and dried to obtain ultrathin boron-doped carbon nitride nanosheets;

[0032] 2. placing ultrathin carbon nitride nanosheets or ultrathin boron-doped carbon nitride nanosheets and chitosan oligosaccharide in a beaker, adding a certain amount of deionized water and mixing to obtain a mixture; after stirring the mixture for several hours, placing it in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction, cooling it to room temperature, centrifuging, washing, and drying to obtain chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets;

[0033] Third, the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets are dispersed in deionized water, and a metal source is added. After stirring for several hours, the mixture is placed in a polytetrafluoroethylene-lined autoclave for reaction. After cooling to room temperature, the mixture is centrifuged, washed, and dried to obtain metal oxide cluster-modified ultrathin carbon nitride nanosheets. The remaining steps are the same as those in Specific Embodiments 1 to 4.

[0034] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that: the process of the primary calcination described in step 1 is as follows: in air, the temperature is increased from room temperature to 400°C to 600°C at a heating rate of 0.1°C / min to 1°C / min, and then calcined at 400°C to 600°C for 2h to 4h; the process of the secondary calcination described in step 1 is as follows: in air, the temperature is increased from room temperature to 400°C to 600°C at a heating rate of 5°C / min to 10°C / min, and then calcined at 400°C to 600°C for 2h to 4h; the acid described in step 1 is 1mol / L to 5mol / L nitric acid; the temperature of the acidification treatment described in step 1 is 100°C to 120°C, and the acidification treatment time is 1h to 3h; the mass ratio of the product II described in step 1 to the acid is (1g to 2g): (100mL to 200mL). The other steps are the same as specific embodiments 1 to 5.

[0035] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the mass ratio of product I to sodium borohydride in step 1 is (0.2-0.4):(0.1-0.3); in step 1, product I and sodium borohydride are mixed and ground for 2-5 minutes, then calcined in a vacuum tube furnace at a temperature of 450°C to 550°C for 1-3 hours. The calcined product is washed with water 3-5 times to obtain ultrathin boron-doped carbon nitride nanosheets. The other steps are the same as those in specific embodiments 1 to 6.

[0036] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that: the mass ratio of chitosan oligosaccharide to ultrathin carbon nitride nanosheets or ultrathin boron-doped carbon nitride nanosheets in the mixture described in step 2 is (1-5):100; the volume ratio of the mass of ultrathin carbon nitride nanosheets or ultrathin boron-doped carbon nitride nanosheets in the mixture described in step 2 to deionized water is (0.2g-0.3g):(20mL-30mL); and the stirring time described in step 2 is 5h-8h. The other steps are the same as specific embodiments 1 to 7.

[0037] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: the hydrothermal reaction temperature in step 2 is 100°C to 120°C, and the hydrothermal reaction time is 2 to 4 hours; the centrifugation process in step 2 is: centrifugation at a speed of 3000 to 4000 r / min for 3 to 5 minutes, and then the supernatant is removed to obtain a solid material; the washing in step 2 is: washing with deionized water 3 to 5 times; the drying temperature in step 2 is 60°C to 80°C, and the drying time is 10 to 24 hours. The other steps are the same as specific embodiments 1 to 8.

[0038] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that: the metal source described in step 3 is manganese nitrate or ruthenium chloride; the mass ratio of the metal element in the metal source described in step 3 to the mass of the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets is (1-3):100; the mass ratio of the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets to deionized water in step 3 is (0.2g-0.3g):(20mL-30mL); the centrifugation process described in step 3 is: centrifugation at a centrifugal speed of 3000r / min-4000r / min for 3min-5min, and then removing the supernatant to obtain a solid substance; the washing described in step 3 is: washing with deionized water 3 to 5 times; the drying temperature described in step 3 is 60℃-80℃, and the drying time is 10h-24h. The other steps are the same as specific embodiments 1 to 9.

[0039] The following examples are used to verify the beneficial effects of the present invention:

[0040] Example 1: Preparation of ruthenium oxide cluster-modified ultrathin carbon nitride nanosheets (Ru-COS-CN), specifically completed by the following steps:

[0041] 1. Preparation of ultrathin carbon nitride nanosheets and ultrathin boron-doped carbon nitride nanosheets:

[0042] 35 g of urea was placed in an alumina crucible and transferred to a muffle furnace for primary calcination, naturally cooled to room temperature, and then ground to obtain product I; product I was placed in a semi-enclosed magnetic boat, then placed in a muffle furnace for secondary calcination, naturally cooled to room temperature, and then ground to obtain product II; product II was placed in a round-bottom flask, acid was added, and the mixture was refluxed at 120° C. for 2 h. After cooling to room temperature, the mixture was centrifuged, and the collected solid matter was washed with deionized water until neutral, and then dried at 80° C. for 24 h to obtain ultrathin carbon nitride nanosheets (CN);

[0043] The primary calcination process in step 1 is as follows: heating from room temperature to 550°C at a heating rate of 0.5°C / min in air, and then calcining at 550°C for 3h;

[0044] The secondary calcination process described in step 1 is as follows: heating from room temperature to 500°C at a heating rate of 5°C / min in air, and then calcining at 500°C for 2h;

[0045] The acid described in step 1 is 5 mol / L nitric acid;

[0046] The mass ratio of the product II described in step 1 to the volume ratio of the acid is 1 g:100 mL;

[0047] 2. Place 0.2 g of ultrathin carbon nitride nanosheets and 0.01 g of chitosan oligosaccharide in a beaker, add 25 mL of deionized water to obtain a mixture; after stirring the mixture for 5 h, place it in a polytetrafluoroethylene-lined autoclave and react at 120 ° C for 2 h. After cooling to room temperature, centrifuge and wash, and then dry at 80 ° C for 24 h to obtain chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets (COS-CN);

[0048] The centrifugation process described in step 2 is: centrifugation at a centrifugal speed of 3000 r / min for 5 minutes, and then removing the supernatant to obtain a solid substance; the washing process described in step 2 is: washing with deionized water 3 times;

[0049] 3. Disperse 0.2 g of chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets in deionized water, then add a metal source, stir for 5 h, and then place in a polytetrafluoroethylene-lined autoclave for reaction at 120 ° C for 2 h. After cooling to room temperature, centrifuge and wash, and then dry at 80 ° C for 24 h to obtain ruthenium oxide cluster-modified ultrathin carbon nitride nanosheets (Ru-COS-CN);

[0050] The metal source in step 3 is a ruthenium chloride aqueous solution with a concentration of 1 g / L, and the mass ratio of the ruthenium element in the ruthenium chloride to the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets is 2:100;

[0051] The volume ratio of the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets to deionized water in step 3 is 0.2 g:25 mL;

[0052] The centrifugation process described in step 3 is: centrifugation at a centrifugal speed of 3000 r / min for 5 minutes, and then removing the supernatant to obtain a solid substance; the washing process described in step 3 is: washing with deionized water 3 times.

[0053] Figure 1 Structural characterization of the ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 1;

[0054] from Figure 1 It can be seen that the material prepared in Example 1 is Ru-COS-CN.

[0055] Figure 2 The morphology and thickness of the ultrathin carbon nitride nanosheet modified with ruthenium oxide clusters prepared in Example 1;

[0056] from Figure 2 It can be seen that the Ru-COS-CN prepared in Example 1 is a two-dimensional ultra-thin layer structure with a thickness of ∼3.0 nm.

[0057] Application Example 1: Application of the ruthenium oxide cluster-modified ultrathin carbon nitride nanosheets prepared in Example 1 in promoting tobacco growth comprises the following steps:

[0058] (1) Tobacco (Nicotiana tabacum L.) seeds from the College of Life Sciences of Heilongjiang University, Heilongjiang Province, were sterilized in a sodium hypochlorite solution (5 wt.%) for 20 minutes and then rinsed three times with deionized water to obtain sterilized seeds;

[0059] (2) Place the sterilized seeds in deionized water and soak them in a refrigerator at 4°C for 24 hours to obtain expanded tobacco seeds;

[0060] (3) Use plastic pots (12 cm top edge, 8.5 cm bottom edge, 10.5 cm high) as cultivation containers, each pot is filled with 700 g of soil, and the expanded tobacco seeds are sown in the sterilized soil. The pots are placed in a controlled environment with a relative humidity of 60%, a temperature of 23-24°C, and no light for 24 hours. Then, the pots are placed under a plant cultivation lamp with an average light intensity of 14 hours per day and 10 hours at night. After 5-6 days, the tobacco seedlings begin to germinate.

[0061] (4) The metal oxo cluster modified ultrathin carbon nitride nanosheets (Ru-COS-CN) prepared in Example 1 was added to water, and then ultrasonicated at an ultrasonic power of 100 W for 60 min to obtain an aqueous dispersion of the metal oxo cluster modified ultrathin carbon nitride nanosheets with a concentration of 100 mg / L; when the tobacco grew to 3-4 true leaves, tobacco seedlings of similar growth were selected for foliar spraying, and the foliar spraying was performed once every 5 days with an aqueous dispersion of the metal oxo cluster modified ultrathin carbon nitride nanosheets with a concentration of 100 mg / L (2 mL per plant per spray). The tobacco was harvested on the 20th day after the catalyst spraying, and the fresh weight and dry weight were tested.

[0062] Figure 3 To investigate the effect of the ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 1 on tobacco growth;

[0063] from Figure 3It can be seen that Ru-COS-CN has a significant effect on promoting tobacco growth. Compared with CK (control group), the fresh weight of tobacco treated with Ru-COS-CN ultrathin nanosheets increased by 35.3% and the dry weight increased by 37.6%.

[0064] Application Example 2: This application example differs from Application Example 1 in that the concentration of the aqueous dispersion of metal oxo-cluster-modified ultrathin carbon nitride nanosheets in step (4) is adjusted to 0 (CK), 50 mg / L, 100 mg / L, or 200 mg / L; and the aqueous dispersion of metal oxo-cluster-modified ultrathin carbon nitride nanosheets at a concentration of 0 (CK), 50 mg / L, 100 mg / L, or 200 mg / L is sprayed on tobacco leaves. The other steps and parameters are the same as those in Application Example 1.

[0065] Figure 4 The effect of ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 1 at different concentrations on tobacco growth in Application Example 2 is described.

[0066] from Figure 4 It can be seen that the ultrathin carbon nitride nanosheets modified with ruthenium oxide clusters (Ru-COS-CN) prepared in Example 1 with different concentrations have a significant effect on promoting tobacco growth. Compared with CK, when the concentration of Ru-COS-CN is 100 mg / L, the effect of promoting tobacco growth is most obvious.

[0067] Example 2: Preparation of ruthenium oxide cluster modified ultrathin boron-doped carbon nitride nanosheets (Ru-COS-BCN), specifically completed by the following steps:

[0068] 1. Preparation of ultra-thin boron-doped carbon nitride nanosheets:

[0069] 35 g of urea was placed in an alumina crucible and transferred to a muffle furnace for calcination, naturally cooled to room temperature, and then ground to obtain product I; product I was mixed with sodium borohydride, ground for a period of time, and then placed in a vacuum tube furnace for calcination. The calcined product was washed with water and dried to obtain ultrathin boron-doped carbon nitride nanosheets (BCN);

[0070] The mass ratio of the product I described in step 1 to sodium borohydride is 0.4:0.24;

[0071] In step 1, product I was mixed with sodium borohydride, ground for 5 minutes, and then calcined in a vacuum tube furnace at a temperature of 500°C for 2 hours. The calcined product was washed with water three times and then dried at a temperature of 80°C for 24 hours to obtain ultrathin boron-doped carbon nitride nanosheets (BCN);

[0072] The primary calcination process in step 1 is as follows: heating from room temperature to 550°C at a heating rate of 0.5°C / min in air, and then calcining at 550°C for 3h;

[0073] 2. Place 0.2 g of ultrathin boron-doped carbon nitride nanosheets and 0.01 g of chitosan oligosaccharide in a beaker, add 25 mL of deionized water to obtain a mixture; after stirring the mixture for 5 hours, place it in a polytetrafluoroethylene-lined high-pressure reactor, react at 120°C for 2 hours, cool to room temperature, centrifuge, wash, and then dry at 80°C for 24 hours to obtain chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets (COS-BCN);

[0074] The centrifugation process described in step 2 is: centrifugation at a centrifugal speed of 3000 r / min for 5 minutes, and then removing the supernatant to obtain a solid substance; the washing process described in step 2 is: washing with deionized water 3 times;

[0075] 3. Disperse 0.2 g of chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets in deionized water, then add a metal source, stir for 5 hours, and then place in a polytetrafluoroethylene-lined autoclave for reaction at 120°C for 2 hours. After cooling to room temperature, centrifuge and wash, and then dry at 80°C for 24 hours to obtain ruthenium oxide cluster-modified ultrathin boron-doped carbon nitride nanosheets (Ru-COS-BCN);

[0076] The metal source in step 3 is a ruthenium chloride aqueous solution with a concentration of 1 g / L, and the mass ratio of the ruthenium element in the ruthenium chloride to the chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets is 2:100;

[0077] The volume ratio of the chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets to deionized water in step 3 is 0.2 g:25 mL;

[0078] The centrifugation process described in step 3 is: centrifugation at a centrifugal speed of 3000 r / min for 5 minutes, and then removing the supernatant to obtain a solid substance; the washing process described in step 3 is: washing with deionized water 3 times.

[0079] Application Example 3: This application example differs from Application Example 1 in that, in step (4), the ruthenium oxide cluster-modified ultrathin boron-doped carbon nitride nanosheets (Ru-COS-BCN) prepared in Example 2 are added to water, and then ultrasonicated at a power of 100 W for 60 minutes to obtain an aqueous dispersion of the ruthenium oxide cluster-modified ultrathin boron-doped carbon nitride nanosheets having a concentration of 100 mg / L; and the aqueous dispersion of the ruthenium oxide cluster-modified ultrathin boron-doped carbon nitride nanosheets having a concentration of 100 mg / L is sprayed on tobacco leaves. The other steps and parameters are the same as those in Application Example 1.

[0080] Table 1 shows the improvement (percentage) of the growth-promoting effect of the ultrathin boron-doped carbon nitride nanosheets modified with ruthenium oxide clusters prepared in Example 2 on tobacco;

[0081] Table 1

[0082]

[0083] As can be seen from Table 1, Ru-COS-BCN has a significant effect on promoting tobacco growth, and its promoting effect is significantly higher than that of ruthenium oxide cluster-modified ultrathin carbon nitride nanosheets.

[0084] Example 3: The difference between this example and Example 1 is that the metal source described in step 3 is manganese nitrate with a concentration of 1 g / L, and the mass ratio of the manganese element in manganese nitrate to the ultra-thin carbon nitride nanosheets modified with chitosan oligosaccharide is 2:100; the product obtained in step 3 is ultra-thin carbon nitride nanosheets modified with manganese oxo clusters (Mn-COS-CN).

[0085] Figure 5 Structural characterization of the ultrathin carbon nitride nanosheets modified with manganese oxide clusters prepared in Example 3;

[0086] from Figure 5 It can be seen that the material prepared in Example 3 is Mn-COS-CN.

[0087] Application Example 4: This application example differs from Application Example 1 in that: in step (4), the manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) prepared in Example 3 are added to water, and then ultrasonicated at a power of 100 W for 60 minutes to obtain an aqueous dispersion of the manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) at a concentration of 100 mg / L; and the 100 mg / L aqueous dispersion of the manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) is sprayed on tobacco leaves. The other steps and parameters are the same as those in Application Example 1.

[0088] Figure 6 The effect of the ultrathin carbon nitride nanosheets modified with manganese oxo clusters prepared in Example 3 on tobacco growth in Example 4 is investigated;

[0089] from Figure 6 It can be seen that the manganese oxo cluster modified ultrathin carbon nitride nanosheets (Mn-COS-CN) prepared in Example 3 have a significant growth-promoting effect on tobacco. Compared with CK, the fresh weight of tobacco treated with Mn-COS-CN nanosheets increased by 21.9% and the dry weight increased by 17.8%.

[0090] Application Example 5: Ultrathin carbon nitride nanosheets modified with manganese oxide clusters (Mn-COS-CN) prepared in Example 3

[0091] The application in promoting the growth of sugar beets includes the following steps:

[0092] (1) Sugar beet (7748) seeds were obtained from the Agricultural College of Heilongjiang University, Heilongjiang Province. The seeds were pelleted seeds from KWS Company, Germany.

[0093] (2) Sow the beet seeds in fertilized soil using plastic pots (12 cm top edge, 8.5 cm bottom edge, 10.5 cm high) as cultivation containers. Each pot is filled with 700 g of substrate soil, compacted evenly, and the seeds are placed in the pot, and then covered with 200 g of substrate soil. The light radiation intensity in the culture room is 450 μmol / m 2 / s. Average daily light intensity is 14 hours, temperature is 25±1°C, nighttime is 10 hours, temperature is 20±1°C, and relative humidity is 40%-50%. After 4-5 days, the beet seedlings will begin to germinate. Before germination, spray with a solution of oxadiazine to prevent damping-off disease.

[0094] (3) Starting from the seventh day, the seedlings were transplanted several times until there were two plants in each pot on the thirteenth day. Then, 100g of soil was added to each tray.

[0095] (4) The manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) prepared in Example 3 were added to water and ultrasonicated at 100 W for 60 min to obtain an aqueous dispersion of the manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) at a concentration of 100 mg / L. The dispersion was then sprayed onto the leaves of the sugar beets when the second pair of true leaves had unfolded. The leaves were sprayed with a 100 mg / L aqueous dispersion of the manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) every three days (2.5 mL per plant per spray).

[0096] Figure 7 The effect of the ultrathin carbon nitride nanosheets modified with manganese oxide clusters prepared in Example 3 on the growth of sugar beet in Example 5 is investigated;

[0097] from Figure 7 It can be seen that the manganese oxide cluster-modified ultrathin carbon nitride nanosheets (Mn-COS-CN) prepared in Example 3 have a significant effect on promoting sugar beet growth. Compared with CK, the fresh weight of sugar beets treated with Mn-COS-CN increased by 25.1% and the dry weight increased by 57.8%.

[0098] Comparative Example 1: A method for preparing ultrathin carbon nitride nanosheets, comprising the following steps:

[0099] 35 g of urea was placed in an alumina dry pot and transferred to a muffle furnace, heated to 550 ° C at a heating rate of 0.5 ° C / min in air, calcined at 550 ° C for 3 hours, then naturally cooled to room temperature, and then ground to obtain product I; product I was placed in a semi-closed magnetic boat, and then placed in a muffle furnace, heated to 500 ° C at a heating rate of 5 ° C / min in air, calcined at 500 ° C for 2 hours, naturally cooled to room temperature, and ground to obtain product II; a certain amount of product II was placed in a round-bottom flask, refluxed at 120 ° C for 2 hours using 5 mol / L nitric acid, cooled to room temperature, centrifuged, washed, and dried at 80 ° C for 24 hours to obtain ultrathin carbon nitride nanosheets (CN).

[0100] Comparative Application Example 1: This comparative example differs from Application Example 1 in that, in step (4), the ultrathin carbon nitride nanosheets (CN) prepared in Comparative Example 1 were added to water, and then ultrasonicated at a power of 100 W for 60 minutes to obtain an aqueous dispersion of ultrathin carbon nitride nanosheets (CN) having a concentration of 100 mg / L; and the 100 mg / L aqueous dispersion of ultrathin carbon nitride nanosheets (CN) was sprayed on tobacco leaves. Other steps and parameters were the same as those in Application Example 1.

[0101] Comparative Application Example 2: This comparative example differs from Application Example 5 in that: in step (4), the ultrathin carbon nitride nanosheets (CN) prepared in Comparative Example 1 are added to water, and then ultrasonicated at an ultrasonic power of 100 W for 60 minutes to obtain an aqueous dispersion of ultrathin carbon nitride nanosheets (CN) with a concentration of 100 mg / L; when the beets grow to the point where the second pair of true leaves unfold, the leaves are sprayed with the 100 mg / L aqueous dispersion of ultrathin carbon nitride nanosheets (CN). The leaves are sprayed with the 100 mg / L aqueous dispersion every three days. The other steps and parameters are the same as those in Application Example 5.

[0102] Table 2: Improvement in the growth-promoting effect of the ultrathin carbon nitride nanosheets (CN) prepared in Comparative Example 1 on tobacco and sugar beets (percentage);

[0103] Table 2

[0104]

[0105] It can be seen from Table 2 that the ultrathin carbon nitride nanosheets (CN) prepared in Control Example 1 have a significant growth-promoting effect on tobacco and sugar beets, but their promoting effect is significantly lower than that of the ultrathin carbon nitride nanosheets modified with manganese oxide clusters.

[0106] Comparative Example 2: A method for preparing ultrathin boron-doped carbon nitride nanosheets (BCN), comprising the following steps:

[0107] 35g of urea was placed in an alumina dry pan and transferred to a muffle furnace. The temperature was raised to 550°C in air at a heating rate of 0.5°C / min. The mixture was calcined at 550°C for 3 hours, cooled naturally to room temperature, and then ground to obtain Product I. 0.4g of Product I was finely ground with 0.24g of sodium borohydride and then calcined at 500°C for 2 hours in a nitrogen atmosphere at a heating rate of 10°C / min. After cooling naturally to room temperature, the mixture was washed with deionized water and ethanol. The mixture was dried at 80°C for 12 hours to obtain ultrathin boron-doped carbon nitride nanosheets (BCN).

[0108] Comparative Application Example 3: This comparative example differs from Application Example 1 in that, in step (4), the ultrathin boron-doped carbon nitride nanosheets (BCN) prepared in Comparative Example 2 were added to water, and then ultrasonicated at a power of 100 W for 60 min to obtain an aqueous dispersion of ultrathin boron-doped carbon nitride nanosheets (BCN) having a concentration of 100 mg / L; and the aqueous dispersion of ultrathin boron-doped carbon nitride nanosheets (BCN) having a concentration of 100 mg / L was sprayed on tobacco leaves. Other steps and parameters were the same as those in Application Example 1.

[0109] Comparative Application Example 4: This comparative example differs from Application Example 5 in that: in step (4), the ultrathin boron-doped carbon nitride nanosheets (BCN) prepared in Comparative Example 2 are added to water, and then ultrasonicated at an ultrasonic power of 100 W for 60 minutes to obtain an aqueous dispersion of ultrathin boron-doped carbon nitride nanosheets (BCN) with a concentration of 100 mg / L; when the beets grow to the point where the second pair of true leaves unfold, foliar spraying is performed. Spray the leaves with an aqueous dispersion of ultrathin boron-doped carbon nitride nanosheets (BCN) with a concentration of 100 mg / L every three days. The other steps and parameters are the same as those in Application Example 5.

[0110] Table 3 Improvement in the growth-promoting effect of the ultrathin boron-doped carbon nitride nanosheets (BCN) prepared in Comparative Example 2 on tobacco and sugar beets (percentage);

[0111] Table 3

[0112]

[0113] It can be seen from Table 3 that BCN has a significant growth-promoting effect on tobacco and sugar beets, and its promoting effect is higher than that of ultrathin carbon nitride nanosheets, but its promoting effect is significantly lower than that of manganese oxide cluster-modified ultrathin carbon nitride nanosheets, ruthenium oxide cluster-modified ultrathin carbon nitride nanosheets and ruthenium oxide cluster-modified ultrathin boron-doped carbon nitride nanosheets.

[0114] Table 4 Water oxidation activity of ultrathin carbon nitride and metal oxygen cluster modified ultrathin carbon nitride photocatalysts

[0115]

[0116] In summary, a series of ultrathin carbon nitride and metal oxygen cluster modified ultrathin carbon nitride photocatalysts can promote plant growth, and the plant growth promotion effect is positively correlated with the water oxidation performance of the photocatalyst.

Claims

1. Application of ultrathin carbon nitride nanosheets modified with metal oxide clusters in promoting plant growth through artificial photosynthesis, characterized in that In artificial photosynthesis, the metal oxygen cluster-modified ultrathin carbon nitride nanosheets are used to promote the growth of sugar beets, which are cultured in a soil culture mode, specifically including the following steps: The metal oxide cluster modified ultrathin carbon nitride nanosheets are prepared into a water dispersion of a certain concentration, and then the water dispersion of the metal oxide cluster modified ultrathin carbon nitride nanosheets is sprayed onto the leaves of the plants; The metal oxide cluster modified ultrathin carbon nitride nanosheets are: manganese oxide cluster modified ultrathin carbon nitride nanosheets, ruthenium oxide cluster modified ultrathin carbon nitride nanosheets, manganese oxide cluster modified ultrathin boron doped carbon nitride nanosheets or ruthenium oxide cluster modified ultrathin boron doped carbon nitride nanosheets; The process for preparing the metal oxo cluster-modified ultrathin carbon nitride nanosheets into an aqueous dispersion of a certain concentration is as follows: the metal oxo cluster-modified ultrathin carbon nitride nanosheets are added to water, and then ultrasonicated at an ultrasonic power of 100 W for 10 minutes to 60 minutes to obtain an aqueous dispersion of the metal oxo cluster-modified ultrathin carbon nitride nanosheets; the concentration of the metal oxo cluster-modified ultrathin carbon nitride aqueous dispersion is 50 mg / L to 200 mg / L.

2. The use of a metal oxygen cluster modified ultrathin carbon nitride in promoting plant growth through artificial photosynthesis according to claim 1, characterized in that The method for preparing the metal oxide cluster modified ultrathin carbon nitride nanosheets is specifically completed according to the following steps:

1. Preparation of ultrathin carbon nitride nanosheets and ultrathin boron-doped carbon nitride nanosheets: The urea is placed in an alumina crucible and transferred to a muffle furnace for primary calcination, naturally cooled to room temperature, and then ground to obtain product I; the product I is placed in a semi-enclosed magnetic boat, then placed in a muffle furnace for secondary calcination, naturally cooled to room temperature, and then ground to obtain product II; the product II is placed in a round-bottom flask, acidified after adding acid, cooled to room temperature, centrifuged, washed with water until neutral, and dried to obtain ultrathin carbon nitride nanosheets; the product I is mixed with sodium borohydride, ground for a period of time, and then placed in a vacuum tube furnace for calcination. The product obtained after calcination is washed with water and dried to obtain ultrathin boron-doped carbon nitride nanosheets; 2. placing ultrathin carbon nitride nanosheets or ultrathin boron-doped carbon nitride nanosheets and chitosan oligosaccharide in a beaker, adding a certain amount of deionized water and mixing to obtain a mixture; after stirring the mixture for several hours, placing it in a polytetrafluoroethylene-lined high-pressure reactor for hydrothermal reaction, cooling it to room temperature, centrifuging, washing, and drying to obtain chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets; 3. Disperse the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets in deionized water, then add a metal source, stir for several hours, and then place in a polytetrafluoroethylene-lined high-pressure reactor for reaction. After cooling to room temperature, centrifuge, wash, and dry to obtain metal oxide cluster-modified ultrathin carbon nitride nanosheets.

3. The use of a metal oxygen cluster modified ultrathin carbon nitride in promoting plant growth through artificial photosynthesis according to claim 2, characterized in that The process of the primary calcination described in step 1 is as follows: heating from room temperature to 400°C~600°C at a heating rate of 0.1°C / min~1°C / min under air, and then calcining at 400°C~600°C for 2h~4h; the process of the secondary calcination described in step 1 is as follows: heating from room temperature to 400°C~600°C at a heating rate of 5°C / min~10°C / min under air, and then calcining at 400°C~600°C for 2h~4h; the acid described in step 1 is 1mol / L~5mol / L nitric acid; the temperature of the acidification treatment described in step 1 is 100°C~120°C, and the time of the acidification treatment is 1h~3h; the mass ratio of the product II described in step 1 to the acid is (1g~2g):(100mL~200mL).

4. The use of a metal oxygen cluster modified ultrathin carbon nitride in promoting plant growth through artificial photosynthesis according to claim 2, characterized in that The mass ratio of the product I described in step 1 to sodium borohydride is (0.2-0.4):(0.1-0.3); in step 1, the product I is mixed with sodium borohydride, ground for 2-5 minutes, and then placed in a vacuum tube furnace at a temperature of 450° C. to 550° C. for calcination for 1-3 hours. The product obtained after calcination is washed with water 3-5 times to obtain ultrathin boron-doped carbon nitride nanosheets.

5. The use of a metal oxygen cluster modified ultrathin carbon nitride in promoting plant growth through artificial photosynthesis according to claim 2, characterized in that The mass ratio of chitosan oligosaccharide to ultrathin carbon nitride nanosheets or ultrathin boron-doped carbon nitride nanosheets in the mixture described in step 2 is (1-5):100; the volume ratio of the mass of ultrathin carbon nitride nanosheets or ultrathin boron-doped carbon nitride nanosheets in the mixture described in step 2 to deionized water is (0.2g-0.3g):(20mL-30mL); the stirring time described in step 2 is 5h-8h.

6. The use of a metal oxygen cluster modified ultrathin carbon nitride in promoting plant growth through artificial photosynthesis according to claim 2, characterized in that The temperature of the hydrothermal reaction described in step 2 is 100°C~120°C, and the hydrothermal reaction time is 2h~4h; the centrifugation process described in step 2 is: centrifugation at a centrifugal speed of 3000r / min~4000r / min for 3min~5min, and then removing the supernatant to obtain a solid substance; the washing described in step 2 is: washing with deionized water 3 times~5 times; the drying temperature described in step 2 is 60°C~80°C, and the drying time is 10h~24h.

7. The use of a metal oxygen cluster modified ultrathin carbon nitride in promoting plant growth through artificial photosynthesis according to claim 2, characterized in that The metal source described in step three is manganese nitrate or ruthenium chloride; the mass ratio of the metal element in the metal source described in step three to the mass ratio of the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or the chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets is (1~3):100; the mass ratio of the chitosan oligosaccharide-modified ultrathin carbon nitride nanosheets or the chitosan oligosaccharide-modified ultrathin boron-doped carbon nitride nanosheets to deionized water is (0.2g~0.3g):(20mL~30mL); the centrifugation process described in step three is: centrifugation at a centrifugal speed of 3000r / min~4000r / min for 3min~5min, and then removing the supernatant to obtain a solid substance; the washing described in step three is: washing with deionized water 3 times~5 times; the drying temperature described in step three is 60℃~80℃, and the drying time is 10h~24h.

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