A Cu2O / SiC / g-C3N4 ternary composite material, its preparation method and application

Abstract

The application provides a Cu2O / SiC / g-C3N4 ternary composite material and a preparation method and application thereof, and relates to the technical field of catalysts.The p-n junction is constructed between Cu2O and g-C3N4, and the Z-scheme heterojunction is constructed between Cu2O and SiC, the two mechanisms synergistically act, can effectively promote the separation of electrons and holes from the Cu2O photocatalyst, form an equivalent wide band gap, fully utilize the strong oxidizing property of the valence band of SiC and the strong reducing property of the conduction band of Cu2O, thereby greatly improving the photocatalytic performance;the proportion of the Cu2O / SiC / g-C3N4 ternary composite material prepared by the application as a photocatalyst in degrading methyl orange water pollutants within 110min can reach 93.70%.The preparation method of the application can realize the compounding of the three materials by adopting two simple processes of calcination and hydrothermal treatment, has the advantages of less raw materials, simple synthesis process and good repeatability, also has the basic conditions of large-scale production, and higher application potential and use value.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a Cu2O / SiC / g-C3N4 ternary composite material, its preparation method, and its application. Background Technology

[0002] With rapid industrial development, water pollution has become increasingly serious, and the use of solar energy to degrade pollutants has attracted widespread attention. Photocatalysis, as a relatively new technology in the treatment of dye wastewater in recent years, has advantages such as clean products, no secondary pollution, and low treatment costs. It also has a significant impact in fields such as catalytic reduction of CO2 and photocatalytic water splitting for hydrogen production, combining environmental and economic benefits. Cu2O is a typical p-type semiconductor material with a band gap of 1.90–2.2 eV, and its photocatalytic performance can be excited in the visible light range. Cu2O is widely used in optoelectronic fields due to its non-toxicity, environmental friendliness, ease of preparation, low preparation cost, and ideal photoelectric properties. However, it also has some common drawbacks, such as susceptibility to photocorrosion and high carrier recombination rate.

[0003] Utilizing suitable semiconductors and their heterojunction fabrication processes can improve some shortcomings of single semiconductor photocatalytic materials, such as enhancing the absorption range of visible light and promoting the separation of photogenerated carriers to improve the photocatalytic performance of the catalyst. Dai et al. coupled Cu2O and g-C3N4 to synthesize a highly efficient stepped heterojunction Cu2O / g-C3N4 catalyst. Effective interfacial charge separation and transfer resulted in the best catalytic performance of this composite catalyst (see Photocatalytic oxidation of tetracycline, reduction of hexavalent chromium and hydrogenevolution by Cu2O / g-C3N4S-scheme photocatalyst: Performance and mechanism[J]. Applied Surface Science, 2022, 592: 153309.). Li et al. found that Cu2O doping improves the separation of electrons and holes in SiC, prolongs the carrier lifetime, and thus enhances the photocatalytic activity of the photocatalyst (Photocatalytic reduction of carbon dioxide to methanol by Cu2O / SiC nanocrystallite under visible light irradiation[J]. Journal of Natural Gas Chemistry, 2011, 20(2):145-150.). In summary, there are many reports on binary composite materials of Cu2O and semiconductors. Although binary composites of semiconductors and Cu2O can improve the photocatalytic performance of Cu2O to some extent, the degree of improvement is limited. Summary of the Invention

[0004] The purpose of this invention is to provide a Cu2O / SiC / g-C3N4 ternary composite material, its preparation method, and its application, which exhibits higher catalytic activity compared to binary composite materials.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a Cu2O / SiC / g-C3N4 ternary composite material, comprising the following steps:

[0007] SiC and carbon-nitrogen precursors were mixed, and the resulting mixture was calcined to obtain SiC / g-C3N4 powder.

[0008] The SiC / g-C3N4 powder, cationic surfactant, copper source and water are mixed. An alkali metal hydroxide solution is added to the resulting mixture to form a copper hydroxide flocculent precipitate. A reducing agent solution is added to the resulting precipitate solution to reduce the copper hydroxide to cuprous oxide, thus obtaining a solution containing cuprous oxide.

[0009] The cuprous oxide-containing liquid was subjected to a hydrothermal reaction, followed by solid-liquid separation, to obtain a Cu2O / SiC / g-C3N4 ternary composite material.

[0010] Preferably, the carbon-nitrogen precursor includes at least one of melamine, urea, cyanamide, dicyandiamide, and thiourea; the mass ratio of SiC to the carbon-nitrogen precursor is 1:1 to 5.

[0011] Preferably, the roasting temperature is 450–750°C, and the holding time is 3–5 hours.

[0012] Preferably, the mass ratio of copper ions to SiC / g-C3N4 powder in the copper source is 1:3 to 18.

[0013] Preferably, the cationic surfactant comprises hexadecyltrimethylammonium bromide; the molar ratio of copper ions to cationic surfactant in the copper source is 1:0.5-3.

[0014] Preferably, the alkali metal hydroxide solution includes NaOH solution or KOH solution; the molar ratio of copper ions to alkali metal hydroxide in the copper source is 1:5 to 10.

[0015] Preferably, the reducing agent solution is an ascorbic acid solution or a glucose solution; the molar ratio of copper ions in the copper source to the reducing agent in the reducing agent solution is 1:0.25-1.

[0016] Preferably, the hydrothermal reaction is carried out at a temperature of 120–200°C for 7–15 hours.

[0017] This invention provides a Cu2O / SiC / g-C3N4 ternary composite material prepared by the preparation method described above.

[0018] This invention provides the application of the Cu2O / SiC / g-C3N4 ternary composite material described above as a photocatalyst in the degradation of organic pollutants in water.

[0019] This invention provides a method for preparing a Cu2O / SiC / g-C3N4 ternary composite material, comprising the following steps: mixing SiC and a carbon-nitrogen precursor, calcining the resulting mixture to obtain SiC / g-C3N4 powder; mixing the SiC / g-C3N4 powder, a cationic surfactant, a copper source, and water; adding an alkali metal hydroxide solution to the resulting mixture to form a copper hydroxide flocculent precipitate; adding a reducing agent solution to the resulting precipitate solution to reduce the copper hydroxide to cuprous oxide, thereby obtaining a cuprous oxide-containing solution; subjecting the cuprous oxide-containing solution to a hydrothermal reaction and performing solid-liquid separation to obtain the Cu2O / SiC / g-C3N4 ternary composite material.

[0020] This invention allows for the simultaneous preparation of SiC and g-C3N4 in a single step by calcining a mixture of SiC and carbon-nitrogen precursors. The process is simple, uses inexpensive raw materials, and has low preparation costs. Furthermore, the ternary composite material prepared by this invention utilizes the synergistic effect of the pn junction of Cu2O and g-C3N4 and the Z-scheme of Cu2O and SiC to effectively promote the separation of electrons and holes from the Cu2O photocatalyst, inhibiting the photo-self-decomposition of Cu2O. Simultaneously, it forms an equivalent wide bandgap, fully utilizing the strong oxidizing properties of the SiC valence band and the strong reducing properties of the Cu2O conduction band, significantly improving photocatalytic performance. The Cu2O / SiC / g-C3N4 ternary composite material prepared by this invention, as a photocatalyst, achieves a 93.70% degradation rate of methyl orange pollutants in water within 110 minutes. The photocatalytic activity is 60 times higher than that of the SiC / g-C3N4 binary material, and 8.07 times and 0.21 times higher than that of Cu2O / SiC and Cu2O / g-C3N4, respectively.

[0021] The Cu2O / SiC / g-C3N4 ternary composite material prepared by this invention can still maintain a degradation rate of nearly 90% after three cycles, demonstrating good reusability and no secondary pollution to the environment. Attached Figure Description

[0022] Figure 1 SEM image of Cu2O / SiC / g-C3N4 composite photocatalyst;

[0023] Figure 2 TEM image of Cu2O / SiC / g-C3N4 composite photocatalyst;

[0024] Figure 3 PL diagrams of Cu2O / SiC / g-C3N4 composite photocatalyst, Cu2O, g-C3N4, and SiC;

[0025] Figure 4 The degradation rate curves of methyl orange for different catalysts are shown.

[0026] Figure 5 The graph shows the degradation rate of methyl orange by the Cu2O / SiC / g-C3N4 composite photocatalyst at different cycle numbers. Detailed Implementation

[0027] This invention provides a method for preparing a Cu2O / SiC / g-C3N4 ternary composite material, comprising the following steps:

[0028] SiC and carbon-nitrogen precursors were mixed, and the resulting mixture was calcined to obtain SiC / g-C3N4 powder.

[0029] The SiC / g-C3N4 powder, cationic surfactant, copper source and water are mixed. An alkali metal hydroxide solution is added to the resulting mixture to form a copper hydroxide flocculent precipitate. A reducing agent solution is added to the resulting precipitate solution to reduce the copper hydroxide to cuprous oxide, thus obtaining a solution containing cuprous oxide.

[0030] The cuprous oxide-containing liquid was subjected to a hydrothermal reaction, followed by solid-liquid separation, to obtain a Cu2O / SiC / g-C3N4 ternary composite material.

[0031] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.

[0032] This invention involves mixing SiC and carbon-nitrogen precursors, and then calcining the resulting mixture to obtain SiC / g-C3N4 powder.

[0033] In this invention, the carbon-nitrogen precursor preferably includes at least one selected from melamine, urea, cyanamide, dicyandiamide, and thiourea, more preferably melamine; the mass ratio of SiC to the carbon-nitrogen precursor is preferably 1:1 to 5, more preferably 1:2 to 4, and even more preferably 1:3. This invention does not impose any special requirements on the mixing; any method known in the art that can achieve uniform mixing is acceptable. In an embodiment of this invention, grinding and mixing are specifically employed.

[0034] In this invention, the calcination temperature is preferably 450–750°C, more preferably 500–650°C, and even more preferably 550–600°C; the calcination holding time is preferably 3–5 h, more preferably 3.5–4.5 h. In this invention, the calcination is preferably carried out in an air atmosphere. During the calcination process, the carbon-nitrogen precursor decomposes to form g-C3N4. This invention allows for the simultaneous preparation of SiC and g-C3N4 in a single step by mixing and calcining the SiC and carbon-nitrogen precursor, resulting in a simple process, inexpensive raw materials, and low preparation cost.

[0035] After the calcination is completed, the present invention preferably cools the furnace to room temperature to obtain SiC / g-C3N4 powder.

[0036] After obtaining SiC / g-C3N4 powder, the present invention mixes the SiC / g-C3N4 powder, cationic surfactant, copper source and water to obtain a mixed liquid.

[0037] In this invention, the cationic surfactant preferably comprises hexadecyltrimethylammonium bromide (CTAB); the molar ratio of copper ions to the cationic surfactant in the copper source is preferably 1:0.5–3, more preferably 1:1–2.5, and even more preferably 1:1.5–2. In this invention, the cationic surfactant accelerates the dispersion of cuprous oxide particles, making them smaller and more uniform, and allowing for easier mixing with other substances. Simultaneously, the cuprous oxide crystals grown with the addition of the cationic surfactant exhibit a unique polyhedral morphology, resulting in better photocatalytic performance.

[0038] In this invention, the copper source is preferably CuCl2·2H2O. In this invention, the mass ratio of copper ions to SiC / g-C3N4 powder in the copper source is preferably 1:3 to 18, more preferably 1:5 to 15, and even more preferably 1:8 to 12.

[0039] In this invention, the preferred method of mixing the SiC / g-C3N4 powder, cationic surfactant, copper source and water is as follows: adding SiC / g-C3N4 powder to water and stirring for 30 min, then adding cationic surfactant and stirring for 30 min, and finally adding copper source and stirring for 30 min.

[0040] After obtaining the mixed liquid, the present invention adds an alkali metal hydroxide solution to the mixed liquid to form a copper hydroxide flocculent precipitate, and adds a reducing agent solution to the obtained precipitate liquid to reduce the copper hydroxide to cuprous oxide, thereby obtaining a liquid containing cuprous oxide.

[0041] In this invention, the alkali metal hydroxide solution preferably includes NaOH solution or KOH solution, more preferably NaOH solution; the concentration of the alkali metal hydroxide solution is preferably 2.5 mol / L; the molar ratio of copper ions to alkali metal hydroxide in the copper source is preferably 1:5 to 10, more preferably 1:6 to 9, and even more preferably 1:7 to 8.

[0042] In this invention, the alkali metal hydroxide solution is preferably added dropwise. There are no special requirements for the dropwise addition rate; it can be added dropwise one at a time. During the dropwise addition of the alkali metal hydroxide, a blue flocculent substance, namely copper hydroxide precipitate, gradually appears.

[0043] After the alkali metal hydroxide solution has been added, the present invention preferably continues stirring for 30 minutes before adding the reducing agent solution to the resulting precipitate solution.

[0044] In this invention, the reducing agent solution is preferably an ascorbic acid solution or a glucose solution; the molar ratio of copper ions in the copper source to the reducing agent in the reducing agent solution is preferably 1:0.25-1, more preferably 1:0.4-0.8, and even more preferably 1:0.5-0.6. In this invention, the concentration of the reducing agent solution is preferably 0.1 mol / L. In this invention, the reducing agent solution is preferably added dropwise. This invention does not have special requirements for the rate of addition; dropwise addition is sufficient. This invention preferably involves dropwise addition under stirring conditions, and after addition, stirring is preferably continued for 30 minutes. During the addition of the reducing agent solution, the precipitate solution first turns green (basic copper carbonate), then yellow (partially oxidized Cu2O mixed with green basic copper carbonate), and finally red, indicating that copper hydroxide is reduced to cuprous oxide, resulting in a solution containing cuprous oxide.

[0045] After obtaining the cuprous oxide-containing liquid, the present invention performs a hydrothermal reaction on the cuprous oxide-containing liquid and separates the solid and liquid components to obtain a Cu2O / SiC / g-C3N4 ternary composite material.

[0046] In this invention, the hydrothermal reaction is preferably carried out in a polytetrafluoroethylene (PTFE) reactor. The temperature of the hydrothermal reaction is preferably 120–200°C, more preferably 130–180°C, and even more preferably 140–150°C; the reaction time is preferably 7–15 h, more preferably 9–13 h, and even more preferably 10–11 h. During the hydrothermal reaction, cuprous oxide crystals grow and deposit onto SiC and g-C3N4.

[0047] After the hydrothermal reaction is completed, the present invention preferably cools the obtained hydrothermal reaction product to room temperature before performing solid-liquid separation. The present invention does not have special requirements for the method of solid-liquid separation; any solid-liquid separation method well-known in the art can be used, such as centrifugation.

[0048] After completing the solid-liquid separation, the present invention preferably further includes washing, drying, and grinding the obtained solid with deionized water and anhydrous ethanol to obtain the Cu2O / SiC / g-C3N4 ternary composite material. The present invention does not have special requirements for the drying conditions; drying conditions well known in the art can be used. In the embodiments of the present invention, drying at 60°C for 3 hours is specifically employed.

[0049] This invention provides a Cu2O / SiC / g-C3N4 ternary composite material prepared by the method described above. In the Cu2O / SiC / g-C3N4 ternary composite material, a pn junction is formed between Cu2O and g-C3N4, while a Z-scheme heterojunction is constructed between Cu2O and SiC. The two mechanisms work synergistically to effectively promote the separation of electrons and holes from the Cu2O photocatalyst, inhibit the photo-self-decomposition of Cu2O, and form an equivalent wide bandgap. This fully utilizes the strong oxidizing property of the SiC valence band and the strong reducing property of the Cu2O conduction band, significantly improving the photocatalytic performance.

[0050] This invention provides the application of the Cu2O / SiC / g-C3N4 ternary composite material described above as a photocatalyst in the degradation of organic pollutants in water.

[0051] In this invention, the organic pollutant preferably includes organic dyes and / or antibiotics; the organic dye preferably includes one or more of methyl orange, orange-yellow G, methylene blue and rhodamine B; the antibiotic preferably includes tetracycline hydrochloride.

[0052] The present invention does not impose any special limitation on the application method described herein; any application method well known in the art may be used.

[0053] The following detailed description, in conjunction with embodiments, illustrates the Cu2O / SiC / g-C3N4 ternary composite material, its preparation method, and its applications provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] S1. Grind and mix 1g SiC and 4g melamine thoroughly to obtain a mixed powder. Place the mixed powder in a muffle furnace and calcine it at 550℃ for 4 hours. After cooling with the furnace, take it out to obtain SiC / g-C3N4 powder.

[0056] S2. Weigh 0.1g SiC / g-C3N4 powder into 10mL of deionized water and stir for 30min. Then add 1.822g CTAB and continue stirring for 30min. Next, add 0.85g CuCl2·2H2O and stir for 30min. Then, add 12mL of 2.5mol / L NaOH solution dropwise. Blue flocculent matter will gradually appear. Continue stirring for 30min. Then, add 25mL of 0.1mol / L ascorbic acid solution dropwise and stir thoroughly for 30min to obtain a mixed solution.

[0057] S3. Transfer the mixture to a polytetrafluoroethylene reactor and carry out a hydrothermal reaction at 150℃ for 12 hours. After natural cooling, remove the mixture and centrifuge at 6000 r / min for 10 minutes to separate the solid. Wash the solid three times with deionized water and three times with anhydrous ethanol, and then dry it in a forced-air drying oven at 60℃ for 3 hours. After grinding, the sample obtained is Cu2O / SiC / g-C3N4 (abbreviated as C-SCN) composite photocatalyst.

[0058] Comparative Example 1

[0059] Cu2O preparation process: 1.822g CTAB was dissolved in 10mL of deionized water and stirred for 30min. Then, 0.85g CuCl2·2H2O was added to the mixture, and stirring was continued for 30min. Subsequently, 12mL of 2.5mol / L NaOH solution was added dropwise, and blue flocculent matter gradually appeared. After stirring for 30min, 25mL of 0.1mol / L ascorbic acid solution was added dropwise, and stirring was carried out thoroughly for 1h. During this process, the solution changed from green to orange-yellow, and finally a brick-red suspension was obtained. The prepared solution was transferred to a polytetrafluoroethylene reactor and reacted at 150℃ for 12h. After natural cooling, the mixed solution was removed, centrifuged to obtain the solid, washed three times each with deionized water and anhydrous ethanol, and then dried in a forced-air drying oven at 60℃ for 3h. After grinding, the sample was obtained.

[0060] Comparative Example 2

[0061] g-C3N4 preparation process: Melamine was placed in a muffle furnace and calcined at 550℃ for 4 hours with a heating rate of 5℃ / min. After cooling in the furnace, it was ground to obtain a yellow powder.

[0062] Comparative Example 3

[0063] Preparation process of SiC / g-C3N4: 1g of SiC and 4g of melamine were thoroughly ground and mixed, placed in a muffle furnace, and calcined at 550℃ for 4h with a heating rate of 5℃ / min. After cooling in the furnace, the mixture was ground to obtain a light yellow powdery SiC / g-C3N4 binary composite material.

[0064] Comparative Example 4

[0065] Preparation process of Cu2O / g-C3N4: Dissolve 0.1g g-C3N4 in 10mL of deionized water, stir for 30min, and repeat the preparation method of Cu2O to obtain Cu2O / g-C3N4 binary composite material.

[0066] Comparative Example 5

[0067] Cu2O / SiC preparation process: Dissolve 0.1g of SiC in 10mL of deionized water, stir for 30min, and then repeat the preparation method of Cu2O to obtain Cu2O / SiC binary composite material.

[0068] Comparative Example 6

[0069] Preparation process of Cu2O-ZnO / g-C3N4: 1g ZnCO3 and 3g melamine were thoroughly ground and mixed to obtain a mixed powder. The mixed powder was placed in a muffle furnace and calcined at 550℃ for 4h. After cooling with the furnace, ZnO / g-C3N4 powder was obtained. 0.1g ZnO / g-C3N4 powder was weighed and stirred in 10mL deionized water for 30min. Then 1.822g CTAB was added and stirred for another 30min. Then 0.85g CuCl2·2H2O was added and stirred for another 30min. Then 12mL of 2.5mol / L NaOH solution was added dropwise, and blue flocculent matter gradually appeared. The mixture was stirred for another 30min. Then 25mL of 0.1mol / L ascorbic acid solution was added dropwise and stirred thoroughly for another 30min to obtain a mixed solution. The mixture was transferred to a polytetrafluoroethylene reactor and subjected to a hydrothermal reaction at 140°C for 9 hours. After natural cooling, the mixture was removed and centrifuged to obtain a solid. The solid was washed three times each with deionized water and anhydrous ethanol and then dried in a forced-air drying oven at 60°C for 4 hours. After grinding, the sample obtained was Cu2O-ZnO / g-C3N4.

[0070] Results and performance testing

[0071] The Cu2O / SiC / g-C3N4 composite photocatalyst prepared in Example 1 was characterized by SEM, and the results are as follows: Figure 1 As shown, from Figure 1 It can be seen that the Cu2O / SiC / g-C3N4 composite catalyst is a composite structure of Cu2O, SiC, and g-C3N4. The small spherical particles are SiC, the blocky particles are g-C3N4, and the octahedrons are Cu2O. The three are closely attached together, indicating that these three materials have been well combined.

[0072] The Cu2O / SiC / g-C3N4 composite photocatalyst prepared in Example 1 was characterized by TEM, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that Cu2O has a large, dark spherical morphology, g-C3N4 has an irregular, light-colored morphology, while SiC has small spherical particles.

[0073] Figure 3 Photomultiplicity (PL) plots of the Cu2O / SiC / g-C3N4 composite photocatalyst, Cu2O, g-C3N4, and SiC. From... Figure 3It can be seen that the photoluminescence intensity of the Cu2O / SiC / g-C3N4 composite photocatalyst is lower than that of the Cu2O, g-C3N4 and SiC samples, and its photoluminescence signal is suppressed, indicating that the recombination process is slower, the decay lifetime of photogenerated electrons is longer, and the recombination rate of electron-hole pairs is lower.

[0074] Figure 4 The graphs show the degradation rate curves of methyl orange for different catalysts, specifically the degradation rate curves of methyl orange for the Cu2O / SiC / g-C3N4 composite photocatalyst prepared in the examples, the Cu2O / SiC, Cu2O / g-C3N4, and SiC / g-C3N4 binary composite materials prepared in the comparative examples, and the degradation rate curves of methyl orange for the seven photocatalysts (pure Cu2O, SiC, and g-C3N4) in the presence of each alone. Figure 4 The specific data are shown in Table 1, and the degradation data for Cu2O-ZnO / g-C3N4 prepared in Comparative Example 6 are shown in Table 2. In the photocatalytic experiment, 10 mg of sample was dispersed in 50 mL of an initial 20 mg / L methyl orange solution. The mixed solution was filled into a glass reaction flask and placed in the photocatalytic instrument. Before illumination, the mixture was stirred in the dark for 20 min to reach adsorption-desorption equilibrium. Equal portions of the sample were taken at fixed time intervals, centrifuged to remove suspended solids, and measured using a UV-Vis spectrophotometer with an absorption peak of 464 nm. Figure 4 As shown in Table 1, under visible light (λ > 400 nm) conditions, the Cu2O / SiC / g-C3N4 (C-SCN) composite photocatalyst exhibited the highest degradation rate of methyl orange (93.70%) within 90 min, indicating that the prepared composite photocatalyst possesses strong photocatalytic performance.

[0075] Table 1. Degradation rate (%) of methyl orange by different photocatalysts

[0076]

[0077] Table 2. Degradation rate (%) of methyl orange by Cu2O-ZnO / g-C3N4

[0078]

[0079] Compared to Cu2O-ZnO / g-C3N4, under the same experimental conditions, the Cu2O / SiC / g-C3N4 composite photocatalyst of this invention exhibits significantly improved performance. As shown in Tables 1 and 2, the first-order reaction kinetic degradation coefficient k of the Cu2O / SiC / g-C3N4 composite photocatalyst is 0.028 min. -1 The comparative example Cu2O-ZnO / g-C3N4 had a min value of 0.0232 min. -1The improvement rate is approximately 20.8%. Furthermore, this invention uses SiC to replace ZnO, which eliminates the water ecological safety risks associated with Zn release during the use of composite materials in water treatment. This is because SiC, Si, and C are all non-toxic compounds or elements, while Zn poses a significant health hazard to humans in water (the Class III standard in the "Surface Water Environmental Quality Standard" (GB3838-2002) stipulates that the concentration of Zn should not exceed 1.0 mg / L, while no such standard applies to SiC, Si, and C).

[0080] Figure 5 The graph shows the degradation rate curves of methyl orange by the Cu2O / SiC / g-C3N4 composite photocatalyst under different cycle numbers. The specific steps of the cycle experiment were as follows: the material from the previous catalytic degradation experiment was collected, washed three times each with pure water and anhydrous ethanol by centrifugation, and finally dried in a forced-air drying oven at 60℃ for 3 hours. The concentration of the methyl orange solution in each cycle was 20 mg / L, and the experimental time was 110 min (90 min of light exposure). The degradation process was the same as in the photocatalytic experiment, and three cycles were performed. The photocatalytic stability of the Cu2O-SiC / g-C3N4 composite photocatalyst was investigated based on the changes in degradation rate. Figure 5 It can be seen that the degradation rates of methyl orange from the first cycle to the third cycle were 94.79%, 93.76%, and 88.89%, respectively. After three cycles, the composite photocatalyst still exhibits high photocatalytic stability.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of Cu2O / SiC / g-C3N4 ternary composite material as a photocatalyst in the degradation of organic pollutants in water, characterized in that, The preparation method of the Cu2O / SiC / g-C3N4 ternary composite material includes the following steps: SiC and carbon-nitrogen precursors were mixed, and the resulting mixture was calcined to obtain SiC / g-C3N4 powder. The SiC / g-C3N4 powder, cationic surfactant, copper source and water are mixed. An alkali metal hydroxide solution is added to the resulting mixture to form a copper hydroxide flocculent precipitate. A reducing agent solution is added to the resulting precipitate solution to reduce the copper hydroxide to cuprous oxide, thus obtaining a solution containing cuprous oxide. The cuprous oxide-containing liquid was subjected to a hydrothermal reaction, followed by solid-liquid separation, to obtain a Cu2O / SiC / g-C3N4 ternary composite material.

2. The application according to claim 1, characterized in that, The carbon-nitrogen precursor includes at least one of melamine, urea, cyanamide, dicyandiamide, and thiourea; the mass ratio of SiC to the carbon-nitrogen precursor is 1:1 to 5.

3. The application according to claim 1 or 2, characterized in that, The roasting temperature is 450~750℃, and the holding time is 3~5 h.

4. The application according to claim 1, characterized in that, The mass ratio of copper ions to SiC / g-C3N4 powder in the copper source is 1:3~18.

5. The application according to claim 1, characterized in that, The cationic surfactant includes hexadecyltrimethylammonium bromide; the molar ratio of copper ions to the cationic surfactant in the copper source is 1:0.5~3.

6. The application according to claim 1, characterized in that, The alkali metal hydroxide solution includes NaOH solution or KOH solution; the molar ratio of copper ions to alkali metal hydroxide in the copper source is 1:5~10.

7. The application according to claim 1, characterized in that, The reducing agent solution is an ascorbic acid solution or a glucose solution; the molar ratio of copper ions in the copper source to the reducing agent in the reducing agent solution is 1:0.25~1.

8. The application according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 120~200℃ for 7~15 h.

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