AuAg-loaded bimetallic Ag2Mo2O7 / g-C3N5 composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of composite photocatalytic materials, in particular to an AuAg-loaded bimetallic Ag2Mo2O7 / g-C3N5 composite material as well as a preparation method and application thereof. According to the specific technical scheme, the preparation method comprises the following steps: firstly, obtaining an AuAg-loaded bimetal g-C3N5 (AuAg / g-C3N5) material in one step by using an in-situ reduction and roasting method; meanwhile, rod-shaped Ag2Mo2O7 is prepared by using a condensation reflux method; and finally, the mixture of the AuAg / g-C3N5 and the Ag2Mo2O7 is stirred and roasted, and the AuAg loaded bimetallic Ag2Mo2O7 / g-C3N5 (Ag2Mo2O7 / AuAg / g-C3N5) composite material is obtained. The preparation method has the characteristics of simplicity in operation, low cost, environment friendliness, no need of complicated post-treatment steps and the like. Meanwhile, the composite photocatalytic material disclosed by the invention has relatively high photocatalytic activity, has relatively high photocatalytic degradation efficiency on tetracycline hydrochloride and ciprofloxacin, and can be used for treating antibiotic pollution in wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of composite photocatalytic materials, and particularly relates to a AuAg bimetal-loaded Ag2Mo2O7 / g-C3N5 composite material, a preparation method thereof, and an application thereof. Background Art

[0002] As is well known, the extensive use of antibiotics will cause the residues of antibiotics in the environment. The residual antibiotics pose a great threat and damage to the organisms living in the water body. At the same time, the normal operation of the food chain is also deeply interfered. Therefore, it is necessary to treat these wastewaters in a timely and effective manner. However, conventional water treatment processes (such as flocculation, adsorption, membrane separation, biological oxidation, etc.) cannot effectively and thoroughly remove antibiotics in the water body, and have certain limitations. Therefore, it is urgent to develop new treatment technologies.

[0003] Semiconductor photocatalytic technology has become an effective way to remove antibiotics in water due to its characteristics of low energy consumption, no secondary pollution, and environmental friendliness. As an organic semiconductor non-metal material that can respond to visible light, graphitic carbon nitride has attracted much attention because of its good chemical stability, narrow band gap, and simple preparation method. It has been widely used in the fields of photocatalytic degradation of organic pollutants, water splitting for hydrogen production, bacterial inactivation, and CO2 reduction, etc. It mainly includes g-C3N4, g-C3N5, etc. Compared with g-C3N4, g-C3N5 has a higher diffusion-limited current density and a lower overpotential, making its photocatalytic performance better. However, there is also a problem that the catalytic effect is poor due to the easy recombination of photogenerated electrons and holes generated under light irradiation. To overcome this defect, noble metal nanoparticles can be used to modify the surface of g-C3N5 to form a plasmonic photocatalyst to enhance its visible light absorption and promote the separation of photogenerated electron-hole pairs, thereby improving the photocatalytic efficiency. For example, the Chinese patent with the publication number of CN119230855A discloses that Cu-doped g-C3N5 and citric acid are ground evenly, pyrolyzed in a tubular furnace under a N2 atmosphere to obtain Cu / g-C3N5. Then it is dispersed in a NaOH solution, and a Pt 4+ solution is added, and a NaBH4 solution is dropped, stirred, centrifuged, and washed. After vacuum drying, a PtCu / g-C3N5 catalyst is obtained.

[0004] To further improve the photocatalytic activity of g-C3N5, constructing composite materials with g-C3N5 heterostructures is also a feasible method. The Chinese patent with the publication number CN119327501A discloses the preparation of Bi2SiO5 / g-C3N5 composite materials by reacting bismuth salts, silicates, 3-amino-1,2,4-triazole, and cetyltrimethylammonium bromide. The degradation rate of rhodamine B can reach 98.82% within 120 minutes. The Bi2SiO5 / g-C3N5 heterojunction structure increases the range of light response, improves the photocatalytic reaction rate, and the formation of holes enables more stable electron transfer. The Chinese patent with the publication number CN114904547A provides a preparation method for a mixed crystal phase WO3@g-C3N5 composite photocatalyst. The degradation rate of the prepared composite catalyst for rhodamine B can reach up to 97% at most, which is 9.8 times and 2.5 times that of WO3 and g-C3N5 respectively.

[0005] In addition, as a visible-light-responsive semiconductor photocatalytic material, Ag2Mo2O7 forms a heterojunction structure with carbon nitride compounds and has been widely used in the photocatalytic degradation of organic pollutants. For example, Noor Izzati Md Rosli et al. (Materials Letters 294(2021)129791) synthesized a Z-type rod-like Ag2Mo2O7 / g-C3N4 (AMO / BCN) composite material by hydrothermal method. The degradation rate of phenol can reach up to 97% within 70 minutes. The enhanced photocatalytic performance is attributed to the effective charge transfer through the Z-type mechanism of rod-like AMO and BCN. Wang et al. (RSC Advances 4(2014)51008-51015) successfully prepared a g-C3N4 / m-Ag2Mo2O7 composite photocatalyst by a simple two-step method. The degradation rate of rhodamine B can reach up to 80% within 90 minutes. The enhancement of photocatalytic activity is due to the synergistic effect of the well-aligned energy band structure after the combination of g-C3N4 and m-Ag2Mo2O7.

[0006] However, so far, there has been no report on the materials, preparation methods, and applications related to in-situ loading of AuAg bimetallic particles on g-C3N5 and then compounding with Ag2Mo2O7 to construct AuAg bimetallic-loaded Ag2Mo2O7 / g-C3N5. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides a composite material of AuAg bimetal loaded on Ag2Mo2O7 / g-C3N5, its preparation method and application. The prepared Ag2Mo2O7 / AuAg / g-C3N5 composite material has strong stability, can effectively inhibit the recombination of photo-generated electrons and holes, thereby significantly improving the photocatalytic activity, and overcomes the defect of poor photocatalytic performance of single semiconductor.

[0008] To achieve the above object, the present invention is realized through the following technical solutions:

[0009] The present invention discloses a composite material of AuAg bimetal loaded on Ag2Mo2O7 / g-C3N5. AuAg particles are deposited on the g-C3N5 matrix to obtain AuAg / g-C3N5, and then it is compounded with Ag2Mo2O7 to obtain the Ag2Mo2O7 / AuAg / g-C3N5 composite material.

[0010] Correspondingly, a preparation method of a composite material of AuAg bimetal loaded on Ag2Mo2O7 / g-C3N5 includes the following steps:

[0011] (1) Dissolve 3-amino-1,2,4-triazole and bromide in deionized water, add HAuCl4·4H2O solution and AgNO3, stir for 0.2 - 0.5 h, then dropwise add NaBH4 solution under ice-water bath conditions, continue to stir for 0.5 - 1.5 h, heat to dryness at 60 - 80 °C, then carry out roasting. After naturally cooling to room temperature, wash, dry and grind to obtain AuAg / g-C3N5 nanosheets;

[0012] (2) Dissolve MoO3 and AgNO3 in deionized water, heat and reflux with condensation at 60 - 80 °C under vigorous stirring for 4 - 7 h until a light yellow suspension appears, then stop. After washing, drying and grinding, rod-shaped Ag2Mo2O7 is obtained;

[0013] (3) Disperse the Ag2Mo2O7 prepared in step (2) and the AuAg / g-C3N5 nanosheets prepared in step (1) in absolute ethanol, stir vigorously until the absolute ethanol volatilizes completely and stops. Dry at 60 - 80 °C for 8 - 10 h, then grind and roast to obtain the Ag2Mo2O7 / AuAg / g-C3N5 composite material.

[0014] Preferably, in step (1), the mass ratio of 3-amino-1,2,4-triazole, bromide to deionized water is 1:6.6-7.1:200, the addition amounts of the HAuCl4·4H2O solution and AgNO3 are both 1%-7% of the mass of 3-amino-1,2,4-triazole, and the addition amount of the NaBH4 solution is 28%-32% of the mass of 3-amino-1,2,4-triazole; the bromide is sodium bromide, ammonium bromide or potassium bromide.

[0015] Preferably, in step (1), the concentration of the HAuCl4·4H2O solution is 6-10 g / L, and the concentration of the NaBH4 solution is 0.4-0.8 g / L.

[0016] Preferably, in step (1), the stirring speed is 100-300 rpm; during the calcination process, the heating rate is 5-10 °C / min, the holding time is 2-4 h, and the calcination temperature is 450-550 °C.

[0017] Preferably, in step (2), the mass ratio of MoO3, AgNO3 and deionized water is 1:2.3-2.8:500.

[0018] Preferably, in step (2), the speed of vigorous stirring is 300-500 rpm.

[0019] Preferably, in step (3), the mass ratio of Ag2Mo2O7 to AuAg / g-C3N5 nanosheets is 1:0.5-2, and the mass ratio of the total mass of Ag2Mo2O7 and AuAg / g-C3N5 nanosheets to absolute ethanol is 1:50-80.

[0020] Preferably, in step (3), the speed of vigorous stirring is 300-500 rpm; during the calcination process, the heating rate is 5-10 °C / min, the holding time is 2-4 h, and the calcination temperature is 450-550 °C.

[0021] Correspondingly, an application of the Ag2Mo2O7 / AuAg / g-C3N5 composite material prepared by the preparation method as a photocatalytic material in treating wastewater containing antibiotics for photocatalytic degradation of antibiotics in the wastewater under visible light irradiation.

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention first obtains the supported AuAg bimetallic g-C3N5 (AuAg / g-C3N5) material by one-step in-situ reduction and calcination method; at the same time, rod-shaped Ag2Mo2O7 is prepared by the condensation reflux method; finally, the mixture of AuAg / g-C3N5 and Ag2Mo2O7 is obtained by stirring and calcination to obtain the supported AuAg bimetallic Ag2Mo2O7 / g-C3N5 (Ag2Mo2O7 / AuAg / g-C3N5) composite material. This preparation method has the characteristics of simple operation, low cost, environmental friendliness, and no need for complex post-treatment steps. At the same time, the composite photocatalytic material of the present invention has high photocatalytic activity and high photocatalytic degradation efficiency for both tetracycline hydrochloride and ciprofloxacin, and can be used for the treatment of antibiotic pollution in wastewater.

[0024] 2. The synthesized supported AuAg bimetallic Ag2Mo2O7 / g-C3N5 composite material of the present invention has strong stability and the preparation process is easy to control. Among them, AuAg / g-C3N5 is synthesized in-situ by one-step method, and the preparation process is simple. At the same time, AuAg particles are deposited on the surface of g-C3N5 in-situ, which can produce surface plasmon resonance effect, thereby effectively enhancing the visible light absorption and promoting the separation of photogenerated electron-hole pairs, and then improving the photocatalytic efficiency.

[0025] 3. Due to the difference in the energy band structure and energy level position between Ag2Mo2O7 and g-C3N5, the heterojunction interface formed after the combination significantly improves the separation efficiency of electrons and holes. Coupled with the synergistic effect with AuAg / g-C3N5, when it is applied to photocatalytic oxidation to remove antibiotics in wastewater, it can improve the photocatalytic activity and overcome the defect of poor photocatalytic performance of single semiconductor. Description of the Drawings

[0026] Figure 1 is the X-ray diffraction (XRD) pattern of each material in each example and comparative example;

[0027] Figure 2 is the scanning electron microscopy (SEM) photograph of each material in each example and comparative example;

[0028] Figure 3 is the transmission electron microscopy (TEM) photograph of the Ag2Mo2O7 / 5AuAg / g-C3N5 composite material prepared in Example 3;

[0029] Figure 4 is the SEM-EDS elemental analysis diagram of the Ag2Mo2O7 / 5AuAg / g-C3N5 composite material prepared in Example 3;

[0030] Figure 5 is the photocatalytic degradation effect diagram of antibiotics (tetracycline hydrochloride, ciprofloxacin) of each material in each example and comparative example;

[0031] Figure 6 Verification diagram of the photocatalytic stability (five-cycle experiment) of the Ag2Mo2O7 / 5AuAg / g-C3N5 composite material prepared in Example 3. Detailed implementation manners

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0034] The present invention discloses a AuAg bimetal-loaded Ag2Mo2O7 / g-C3N5 composite material. AuAg particles are deposited on the g-C3N5 matrix to obtain AuAg / g-C3N5, and then it is compounded with Ag2Mo2O7 to obtain the Ag2Mo2O7 / AuAg / g-C3N5 composite material.

[0035] The present invention also discloses a preparation method of a AuAg bimetal-loaded Ag2Mo2O7 / g-C3N5 composite material, including the following steps:

[0036] (1) One-step preparation of the in-situ reduction and calcination method of AuAg / g-C3N5: Dissolve 3-amino-1,2,4-triazole and bromide in deionized water, add HAuCl4·4H2O solution and AgNO3, stir for 0.2 - 0.5 h, then dropwise add NaBH4 solution under ice-water bath conditions for reduction reaction, continue to stir for 0.5 - 1.5 h, heat to dryness at 60 - 80 °C, spread the obtained sample on a magnetic boat, place it in a muffle furnace for calcination, take it out and naturally cool to room temperature after calcination to obtain a dark brown sample, centrifuge and wash it with deionized water 3 - 5 times, dry it at 60 - 80 °C for 8 - 10 h, and grind it to obtain AuAg / g-C3N5 nanosheets;

[0037] Among them, the mass ratio of the 3-amino-1,2,4-triazole, bromide and deionized water is 1:6.6-7.1:200. The addition amounts of the HAuCl4·4H2O solution and AgNO3 are both 1%-7% of the mass of the 3-amino-1,2,4-triazole. The addition amount of the NaBH4 solution is 28%-32% of the mass of the 3-amino-1,2,4-triazole. The bromide is sodium bromide, ammonium bromide or potassium bromide. The concentration of the HAuCl4·4H2O solution is 6-10 g / L, and the concentration of the NaBH4 solution is 0.4-0.8 g / L.

[0038] Furthermore, the stirring speed is 100-300 rpm. During the calcination process, the heating rate is 5-10 °C / min, the holding time is 2-4 h, and the calcination temperature is 450-550 °C.

[0039] (2) Preparation of rod-shaped Ag2Mo2O7: Dissolve MoO3 and AgNO3 in deionized water, heat and condense under reflux at 60-80 °C with vigorous stirring for 4-7 h until a light yellow suspension appears, then stop. Centrifuge and wash with deionized water 3-5 times, dry at 60-80 °C for 8-10 h, and grind into powder to obtain rod-shaped Ag2Mo2O7.

[0040] Among them, the mass ratio of the MoO3, AgNO3 and deionized water is 1:2.3-2.8:500. The speed of vigorous stirring is 300-500 rpm.

[0041] (3) Calcination preparation of Ag2Mo2O7 / AuAg / g-C3N5: Disperse the Ag2Mo2O7 prepared in step (2) and the AuAg / g-C3N5 nanosheets prepared in step (1) in absolute ethanol, stir vigorously until the absolute ethanol evaporates completely and then stop, dry at 60-80 °C for 8-10 h and then grind, and then place in a muffle furnace for calcination to obtain the Ag2Mo2O7 / AuAg / g-C3N5 composite material.

[0042] Among them, the mass ratio of the Ag2Mo2O7 to the AuAg / g-C3N5 nanosheets is 1:0.5-2, and the mass ratio of the total mass of the Ag2Mo2O7 and the AuAg / g-C3N5 nanosheets to the absolute ethanol is 1:50-80.

[0043] Furthermore, the speed of vigorous stirring is 300-500 rpm. During the calcination process, the heating rate is 5-10 °C / min, the holding time is 2-4 h, and the calcination temperature is 450-550 °C.

[0044] The present invention also discloses the application of the Ag2Mo2O7 / AuAg / g-C3N5 composite material prepared by the above preparation method as a photocatalytic material in treating wastewater containing antibiotics, that is, photocatalytic degradation of antibiotics in wastewater under visible light irradiation.

[0045] The present invention will be further described below in conjunction with specific embodiments.

[0046] Example 1

[0047] A composite material of Ag2Mo2O7 / g-C3N5 loaded with AuAg bimetals, with g-C3N5 in-situ deposited with AuAg particles as the matrix, and then compounded with Ag2Mo2O7. Among them, the mass fractions of Au and Ag in-situ deposited on g-C3N5 are both 1%, and the mass ratio of Ag2Mo2O7 to AuAg / g-C3N5 is 1:0.5.

[0048] The above Ag2Mo2O7 / 1AuAg / g-C3N5 composite material is synthesized according to the following steps:

[0049] (1) Preparation of 1AuAg / g-C3N5: Weigh 0.2 g of 3-amino-1,2,4-triazole and 1.32 g of sodium bromide and dissolve them in 40 mL of deionized water. Add 0.29 mL of 7 g / L HAuCl4·4H2O solution and 0.002 g of AgNO3. After stirring at a speed of 100 rpm for 0.5 h, dropwise add 140 mL of 0.4 g / L NaBH4 solution under ice-water bath conditions for reduction reaction, and then continue to stir at a speed of 100 rpm for 1.5 h. Heat to dryness at 70 °C. The obtained sample is spread flat in a magnetic boat and placed in a muffle furnace for roasting. After roasting, take it out and cool naturally to room temperature to obtain a dark brown sample. Centrifuge and wash it 3 times with deionized water, dry it at 70 °C for 9 h, and grind it to obtain 1AuAg / g-C3N5 nanosheets. Among them, the heating rate of the muffle furnace is 5 °C / min, the holding time is 2 h, and the roasting temperature is 450 °C.

[0050] (2) Preparation of Ag2Mo2O7: Weigh 0.4 g of MoO3 and 0.92 g of AgNO3 and dissolve them in 200 mL of deionized water. Heat and reflux with condensation at 70 °C under vigorous stirring at a speed of 300 rpm for 7 h, and stop until a light yellow suspension appears. Centrifuge and wash it 3 times with deionized water, dry it at 70 °C for 9 h, and grind it into a powder to obtain rod-shaped Ag2Mo2O7;

[0051] (3) Preparation of Ag2Mo2O7 / 1AuAg / g-C3N5: Weigh 0.4 g of Ag2Mo2O7 and 0.2 g of AuAg / g-C3N5 and disperse them in 38.6 mL of absolute ethanol. Stir vigorously at a speed of 300 rpm until the absolute ethanol has completely evaporated and then stop. Dry at 70 °C for 9 h and then grind. Subsequently, place it in a muffle furnace for roasting to obtain the Ag2Mo2O7 / 1AuAg / g-C3N5 composite material. Among them, the heating rate of the muffle furnace is 5 °C / min, the holding time is 2 h, and the roasting temperature is 450 °C.

[0052] The Ag2Mo2O7 / 1AuAg / g-C3N5 composite material prepared by the above method was used for photocatalytic oxidative degradation of tetracycline hydrochloride and ciprofloxacin for 90 min, and the removal rates were 80.5% and 77.5% respectively.

[0053] Example 2

[0054] A composite photocatalytic material of Ag2Mo2O7 / g-C3N5 loaded with AuAg bimetal uses g-C3N5 with in-situ deposited AuAg particles as the matrix and is then compounded with Ag2Mo2O7. Among them, the mass fractions of Au and Ag in-situ deposited on g-C3N5 are both 3%, and the mass ratio of Ag2Mo2O7 to AuAg / g-C3N5 is 1:1.

[0055] The above Ag2Mo2O7 / 3AuAg / g-C3N5 composite material was synthesized according to the following steps:

[0056] (1) Preparation of 3AuAg / g-C3N5: Weigh 0.2 g of 3-amino-1,2,4-triazole and 1.36 g of ammonium bromide and dissolve them in 40 mL of deionized water. Add 1 mL of 6 g / L HAuCl4·4H2O solution and 0.006 g of AgNO3. Stir at a speed of 150 rpm for 0.4 h, and then dropwise add 116 mL of 0.5 g / L NaBH4 solution under ice-water bath conditions for reduction reaction. Then continue to stir at a speed of 150 rpm for 1 h, heat to dryness at 60 °C, spread the obtained sample on a magnetic boat, place it in a muffle furnace for roasting, take it out and cool to room temperature naturally after roasting to obtain a dark brown sample. Centrifuge and wash it 4 times with deionized water, dry it at 60 °C for 10 h, and grind it to obtain 3AuAg / g-C3N5 nanosheets. Among them, the heating rate of the muffle furnace is 6 °C / min, the holding time is 3 h, and the roasting temperature is 500 °C.

[0057] (2) Preparation of Ag2Mo2O7: Weigh 0.2 g of MoO3 and 0.46 g of AgNO3 and dissolve them in 100 mL of deionized water. Heat and condense under reflux at 60 °C with vigorous stirring at a speed of 350 rpm for 6 h. Stop until a light yellow suspension appears. Centrifuge and wash 4 times with deionized water, dry at 60 °C for 10 h, and grind into a powder to obtain rod-shaped Ag2Mo2O7.

[0058] (3) Preparation of Ag2Mo2O7 / 3AuAg / g-C3N5: Weigh 0.2 g of Ag2Mo2O7 and 0.2 g of AuAg / g-C3N5 and disperse them in 25.7 mL of absolute ethanol. Stir vigorously at a speed of 350 rpm until the absolute ethanol evaporates completely and then stop. Dry at 60 °C for 10 h and then grind. Subsequently, place it in a muffle furnace for roasting to obtain the Ag2Mo2O7 / 3AuAg / g-C3N5 composite material. Among them, the heating rate of the muffle furnace is 6 °C / min, the holding time is 3 h, and the roasting temperature is 500 °C.

[0059] The Ag2Mo2O7 / 3AuAg / g-C3N5 composite material prepared by the above method is used for photocatalytic oxidation degradation of tetracycline hydrochloride and ciprofloxacin for 90 min, and the removal rates are 83.7% and 81.7% respectively.

[0060] Example 3

[0061] A composite material of Ag2Mo2O7 / g-C3N5 loaded with AuAg bimetal uses g-C3N5 with in-situ deposited AuAg particles as the matrix and is then compounded with Ag2Mo2O7. Among them, the mass fractions of Au and Ag in-situ deposited on g-C3N5 are both 5%, and the mass ratio of Ag2Mo2O7 to AuAg / g-C3N5 is 1:1.5.

[0062] The above Ag2Mo2O7 / 5AuAg / g-C3N5 composite material is synthesized according to the following steps:

[0063] (1) Preparation of 5AuAg / g-C3N5: Weigh 0.3 g of 3-amino-1,2,4-triazole and 2.4 g of potassium bromide, dissolve them in 60 mL of deionized water, add 1.9 mL of 8 g / L HAuCl4·4H2O solution and 0.015 g of AgNO3. After stirring at a speed of 250 rpm for 0.3 h, dropwise add 150 mL of 0.6 g / L NaBH4 solution under ice-water bath conditions for reduction reaction. Then continue to stir at a speed of 250 rpm for 0.5 h, heat to dryness at 70 °C. The obtained sample is spread on a magnetic boat, placed in a muffle furnace for roasting. After roasting, take it out and cool naturally to room temperature to obtain a dark brown sample. Centrifuge and wash it 4 times with deionized water, dry it at 70 °C for 8 h, and grind it to obtain 5AuAg / g-C3N5 nanosheets. Among them, the heating rate of the muffle furnace is 8 °C / min, the holding time is 3 h, and the roasting temperature is 500 °C.

[0064] (2) Preparation of Ag2Mo2O7: Weigh 0.2 g of MoO3 and 0.46 g of AgNO3, dissolve them in 100 mL of deionized water, heat and reflux with condensation at 70 °C under vigorous stirring at a speed of 400 rpm for 5 h, and stop until a light yellow suspension appears. Centrifuge and wash it 4 times with deionized water, dry it at 70 °C for 8 h, and grind it into a powder to obtain rod-shaped Ag2Mo2O7.

[0065] (3) Preparation of Ag2Mo2O7 / 5AuAg / g-C3N5: Weigh 0.2 g of Ag2Mo2O7 and 0.3 g of AuAg / g-C3N5, disperse them in 32.1 mL of absolute ethanol, stir vigorously at a speed of 400 rpm until the absolute ethanol evaporates completely and stops. Dry it at 70 °C for 8 h and then grind it. Subsequently, place it in a muffle furnace for roasting to obtain the Ag2Mo2O7 / 5AuAg / g-C3N5 composite material. Among them, the heating rate of the muffle furnace is 8 °C / min, the holding time is 3 h, and the roasting temperature is 500 °C.

[0066] The Ag2Mo2O7 / 5AuAg / g-C3N5 composite material prepared by the above method is used for photocatalytic oxidation degradation of tetracycline hydrochloride and ciprofloxacin for 90 min, and the removal rates are 93.4% and 91.2% respectively.

[0067] Example 4

[0068] A composite material of Ag2Mo2O7 / g-C3N5 loaded with AuAg bimetal uses g-C3N5 with in-situ deposited AuAg particles as the matrix and is then compounded with Ag2Mo2O7. Among them, the mass fractions of Au and Ag in-situ deposited on g-C3N5 are both 7%, and the mass ratio of Ag2Mo2O7 to AuAg / g-C3N5 is 1:2.

[0069] The above Ag2Mo2O7 / 7AuAg / g-C3N5 composite material is synthesized according to the following steps:

[0070] (1) Preparation of 7AuAg / g-C3N5: Weigh 0.4 g of 3-amino-1,2,4-triazole and 2.84 g of sodium bromide and dissolve them in 80 mL of deionized water. Add 2.8 mL of 10 g / L HAuCl4·4H2O solution and 0.028 g of AgNO3. After stirring at 300 rpm for 0.2 h, dropwise add 160 mL of 0.8 g / L NaBH4 solution under ice-water bath conditions for reduction reaction. Then continue to stir at 300 rpm for 0.5 h, heat to dryness at 80 °C. The obtained sample is spread on a magnetic boat and placed in a muffle furnace for roasting. After roasting, take it out and naturally cool to room temperature to obtain a dark brown sample. Centrifuge and wash it 5 times with deionized water, dry it at 80 °C for 8 h, and grind it to obtain 7AuAg / g-C3N5 nanosheets. Among them, the heating rate of the muffle furnace is 10 °C / min, the holding time is 2 h, and the roasting temperature is 550 °C.

[0071] (2) Preparation of Ag2Mo2O7: Weigh 0.2 g of MoO3 and 0.46 g of AgNO3 and dissolve them in 100 mL of deionized water. Heat and reflux with condensation at 80 °C under vigorous stirring at 400 rpm for 4 h, and stop until a light yellow suspension appears. Centrifuge and wash it 5 times with deionized water, dry it at 80 °C for 8 h, and grind it into a powder to obtain rod-shaped Ag2Mo2O7;

[0072] (3) Preparation of Ag2Mo2O7 / 7AuAg / g-C3N5: Weigh 0.2 g of Ag2Mo2O7 and 0.4 g of 7AuAg / g-C3N5 and disperse them in 38.6 mL of absolute ethanol. Stir vigorously at 400 rpm until the absolute ethanol evaporates completely and stops. Dry it at 80 °C for 8 h and then grind it. Subsequently, place it in a muffle furnace for roasting to obtain the Ag2Mo2O7 / 7AuAg / g-C3N5 composite material. Among them, the heating rate of the muffle furnace is 10 °C / min, the holding time is 2 h, and the roasting temperature is 550 °C.

[0073] The Ag2Mo2O7 / 7AuAg / g-C3N5 composite material prepared by the above method is used for photocatalytic oxidation degradation of tetracycline hydrochloride and ciprofloxacin for 90 min, and the removal rates are 88.1% and 85.7% respectively.

[0074] Comparative Example 1

[0075] Directly use g-C3N5 as the application material for comparison.

[0076] Comparative Example 2

[0077] Directly use Ag2Mo2O7 as the application material for comparison.

[0078] Comparative Example 3

[0079] Directly use 5AuAg / g-C3N5 as the application material for comparison.

[0080] Characterization method:

[0081] The photocatalytic experiment was carried out in a photoreactor, which mainly consisted of four parts: the light source system included a 500W Xe lamp, a λ>420nm cut-off filter, and a cooling accessory; the reactor (a quartz tube with a capacity of 50 mL); and a magnetic stirrer. Before irradiation, 50 mL of an aqueous solution containing 20 mg of photocatalyst and 50 mg / L of antibiotic (tetracycline hydrochloride or ciprofloxacin) was magnetically stirred in the dark for 1 h. During irradiation, about 3 mL of the suspension was taken out from the reactor every 10 min and centrifuged to separate the photocatalyst. A total organic carbon analyzer (Shimadzu TOC-L CPH, Japan) was used to measure the antibiotic content in the supernatant of the sampled samples. The antibiotic content measured at different irradiation times was converted into the removal rate of the antibiotic, which can be defined by the following expression:

[0082] Removal rate of antibiotic = (C0 - C t ) / C0 × 100%

[0083] where C0 and C t are the antibiotic contents measured at 0 min of irradiation (i.e., just after adsorption) and t min, respectively.

[0084] Characterization experiment:

[0085] Figure 1 XRD patterns of the materials of Comparative Examples 1, 2, 3 and Examples 1, 2, 3, 4. It can be seen that characteristic peaks belonging to Au, Ag, and g-C3N5 can be seen in the curves of the 5AuAg / g-C3N5 composite material. Characteristic peaks belonging to Ag2Mo2O7, Au, Ag, and g-C3N5 can also be seen in the curves of the Ag2Mo2O7 / AuAg / g-C3N5 composite materials with different Ag2Mo2O7 contents. Moreover, with the increase in the contents of Ag2Mo2O7, Au, and Ag, the characteristic peaks belonging to Ag2Mo2O7, Au, and Ag are significantly enhanced, indicating that Ag2Mo2O7, AuAg, and g-C3N5 form a composite material.

[0086] Figure 2Scanning electron microscope (SEM) photographs of the materials of Comparative Examples 1, 2, 3 and Examples 1, 2, 3, 4. As can be seen from Figure 2a, the synthesized Ag2Mo2O7 is rod-shaped; as can be seen from Figure 2b, g-C3N5 is a two-dimensional nanosheet. As can be seen from Figure 2c, 5AuAg / g-C3N5 is also a two-dimensional nanosheet, but there are obvious particulate matters on its surface, which is due to the loading of Au and Ag particles, and it also indirectly shows that Au and Ag particles are successfully deposited in situ on the surface of g-C3N5. As can be seen from Figures 2d (Example 1), 2e (Example 2), 2f (Example 3), and 2g (Example 4), the Ag2Mo2O7 / AuAg / g-C3N5 composite material uses g-C3N5 with in-situ deposited AuAg particles as the matrix, and Ag2Mo2O7 is also coated on the surface of g-C3N5 to form a heterojunction, enabling them to exert their respective advantages and produce a synergistic effect, so that the prepared Ag2Mo2O7 / AuAg / g-C3N5 composite material has more excellent photocatalytic performance.

[0087] Figure 3 Transmission electron microscope (TEM) photograph of the Ag2Mo2O7 / 5AuAg / g-C3N5 composite material prepared in Example 3. To further verify whether the composite material of the present invention is successfully synthesized, the composite material of Example 3 with the best photocatalytic performance was selected for TEM characterization. As can be clearly seen from Figure 3 it that AuAg particles are deposited on the surface of g-C3N5, and rod-shaped Ag2Mo2O7 is coated on the surface of g-C3N5, indicating that the composite material of the present invention is successfully synthesized.

[0088] Figure 4 SEM-EDS elemental analysis diagram of the Ag2Mo2O7 / 5AuAg / g-C3N5 composite material prepared in Example 3. As can be seen from Figure 4 it that the composite material of Example 3 contains elements Ag, Mo, O, Au, C, and N, which further confirms that the composite material of the present invention is successfully synthesized.

[0089] Figure 5Photocatalytic degradation effect diagrams of antibiotics (tetracycline hydrochloride, ciprofloxacin) for the materials of Comparative Examples 1, 2, 3 and Examples 1, 2, 3, 4. The antibiotic adsorption capacities of all materials in each example and comparative example are weak. However, when AuAg particles are in-situ deposited on g-C3N5 to form AuAg / g-C3N5 materials, the ability to remove antibiotics is significantly higher than that of g-C3N5. This is because the surface plasmon resonance effect generated by the loaded AuAg particles can effectively enhance the visible light absorption and promote the separation of photo-generated electron-hole pairs, thereby improving the photocatalytic efficiency. After Ag2Mo2O7 is combined with AuAg / g-C3N5, the ability to remove antibiotics is significantly higher than that of AuAg / g-C3N5. Among them, the composite material of Example 3 (Ag2Mo2O7 / 5AuAg / g-C3N5) has the best effect on the photocatalytic oxidation degradation of tetracycline hydrochloride and ciprofloxacin for 90 min, and the removal rates are as high as 93.4% and 91.2% respectively. This is because after Ag2Mo2O7 is combined with g-C3N5, a heterojunction interface is formed, which can quickly transfer photo-generated electrons and holes, greatly reducing the recombination probability of photo-generated electrons and holes, thus improving the photocatalytic activity of the composite material.

[0090] Figure 6 Figure for verifying the photocatalytic stability (five-cycle experiment) of the composite material of Example 3. As can be seen from Figure 6 it, after five-cycle experiments, the degradation effect of the composite material of Example 3 still maintains good stability. After the fifth-cycle use, compared with the first time, it only decreases by 4.6% (tetracycline hydrochloride) and 6.5% (ciprofloxacin) respectively, and still maintains a high removal efficiency, indicating that the composite material prepared by the present invention has strong stability.

[0091] The above-described examples are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A supported AuAg bimetallic Ag2Mo2O7 / g-C3N5 composite material, characterized in that: Deposit AuAg particles on the g-C3N5 substrate to obtain AuAg / g-C3N5, and then compound it with Ag2Mo2O7 to obtain the Ag2Mo2O7 / AuAg / g-C3N5 composite material.

2. The preparation method of the AuAg bimetallic Ag2Mo2O7 / g-C3N5 composite material according to claim 1, characterized in that: It includes the following steps: (1) Dissolve 3-amino-1,2,4-triazole and bromide in deionized water, add HAuCl4·4H2O solution and AgNO3, stir for 0.2 - 0.5 h, then dropwise add NaBH4 solution under ice-water bath conditions, continue to stir for 0.5 - 1.5 h, heat to dryness at 60 - 80 °C, then carry out roasting, naturally cool to room temperature, wash, dry, and grind to obtain AuAg / g-C3N5 nanosheets; (2) Dissolve MoO3 and AgNO3 in deionized water, heat and condense under reflux at 60 - 80 °C with vigorous stirring for 4 - 7 h until a light yellow suspension appears and then stop, wash, dry, and grind to obtain rod-shaped Ag2Mo2O7; (3) Disperse the Ag2Mo2O7 prepared in step (2) and the AuAg / g-C3N5 nanosheets prepared in step (1) in absolute ethanol, stir vigorously until the absolute ethanol evaporates completely and then stop, dry at 60 - 80 °C for 8 - 10 h and then grind, and obtain the Ag2Mo2O7 / AuAg / g-C3N5 composite material after roasting.

3. The preparation method according to claim 2, characterized in that: In step (1), the mass ratio of the 3-amino-1,2,4-triazole, bromide to deionized water is 1:6.6 - 7.1:200, the addition amounts of the HAuCl4·4H2O solution and AgNO3 are both 1% - 7% of the mass of 3-amino-1,2,4-triazole, and the addition amount of the NaBH4 solution is 28% - 32% of the mass of 3-amino-1,2,4-triazole; the bromide is sodium bromide, ammonium bromide or potassium bromide.

4. The preparation method according to claim 3, characterized in that: In step (1), the concentration of the HAuCl4·4H2O solution is 6 - 10 g / L, and the concentration of the NaBH4 solution is 0.4 - 0.8 g / L.

5. The preparation method according to claim 3 or 4, characterized in that: In step (1), the stirring speed is 100 - 300 rpm; during the roasting process, the heating rate is 5 - 10 °C / min, the holding time is 2 - 4 h, and the roasting temperature is 450 - 550 °C.

6. The preparation method according to claim 2, characterized in that: In step (2), the mass ratio of the MoO3, AgNO3 and deionized water is 1:2.3 - 2.8:

500.

7. The preparation method according to claim 2 or 6, characterized in that: In step (2), the speed of vigorous stirring is 300 - 500 rpm.

8. The preparation method according to claim 2, characterized in that: In step (3), the mass ratio of the Ag2Mo2O7 to the AuAg / g-C3N5 nanosheets is 1:0.5 - 2, and the mass ratio of the total mass of the Ag2Mo2O7 and the AuAg / g-C3N5 nanosheets to absolute ethanol is 1:50 - 80.

9. The preparation method according to claim 2 or 8, characterized in that: In step (3), the speed of vigorous stirring is 300 - 500 rpm; during the roasting process, the heating rate is 5 - 10 °C / min, the holding time is 2 - 4 h, and the roasting temperature is 450 - 550 °C.

10. Application of the Ag2Mo2O7 / AuAg / g-C3N5 composite material prepared by the preparation method according to any one of claims 1 to 9 as a photocatalytic material in treating wastewater containing antibiotics.

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