Reduced graphene / carbon nitride / molybdenum cobalt oxide composite material and preparation method and application thereof

Abstract

The invention discloses a reduced graphene / carbon nitride / molybdenum cobalt oxide composite material and a preparation method and application thereof, and belongs to the technical field of environment restoration functional materials. The preparation method comprises the following steps: synthesizing a solid molybdenum-cobalt oxide by taking nano silicon dioxide as a template, loading the solid molybdenum-cobalt oxide on reduced graphene, fully mixing the loaded material with a nitrogen-containing organic precursor, roasting, and finally removing the nano silicon dioxide template to obtain the reduced graphene / carbon nitride / molybdenum-cobalt oxide composite material. The preparation method of the composite material is mild, toxic and harmful raw materials are not involved, and the prepared reduced graphene / carbon nitride / molybdenum cobalt oxide composite material has relatively strong anti-interference capability and good cycle stability while the structural integrity of the material is maintained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental remediation functional materials, and particularly relates to a reduced graphene / carbon nitride / molybdenum cobalt oxide composite material, a preparation method and application thereof. BACKGROUND

[0002] Bisphenol A (BPA) is widely used in plastic and resin production. Due to its strong lipophilicity and bioaccumulation, it is easy to exist in the environment for a long time. BPA is difficult to be naturally degraded and poses a threat to the ecosystem and human health, especially the interference with the endocrine system, especially affecting children and pregnant women. Effective removal of BPA has become an important environmental protection issue. SUMMARY

[0003] The present application aims to provide a reduced graphene / carbon nitride / molybdenum cobalt oxide composite material, a preparation method and application thereof. By using nano-silicon dioxide as a template, a solid molybdenum cobalt oxide is synthesized, which is then loaded on reduced graphene. The loaded material is fully mixed with a nitrogen-containing organic precursor and calcined. Finally, the nano-silicon dioxide template is removed to obtain the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material. The preparation method of the composite material is mild and does not involve toxic and harmful raw materials. The prepared reduced graphene / carbon nitride / molybdenum cobalt oxide composite material maintains the integrity of the material structure while having strong anti-interference ability and good cycle stability.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] One of the technical schemes of the present application provides a preparation method of a reduced graphene / carbon nitride / molybdenum cobalt oxide composite material, comprising the following steps:

[0006] Nano-silicon dioxide, cobalt salt, molybdenum salt and dispersant are mixed uniformly in water, a solution containing sodium hydroxide is added, and a solid molybdenum cobalt oxide precursor is obtained after reaction. The solid molybdenum cobalt oxide precursor is calcined to obtain a solid molybdenum cobalt oxide. The solid molybdenum cobalt oxide and reduced graphene are dispersed in water together, and reduced graphene / solid molybdenum cobalt oxide is obtained after precipitation. A nitrogen-containing organic precursor is uniformly mixed with the reduced graphene / solid molybdenum cobalt oxide, and reduced graphene / carbon nitride / solid molybdenum cobalt oxide is obtained after calcination. The reduced graphene / carbon nitride / solid molybdenum cobalt oxide is mixed with a solution containing sodium hydroxide to remove nano-silicon dioxide, and the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material is obtained.

[0007] The reduced graphene (rGO) in the application has high specific surface area and conductivity, can effectively provide electrons, and promote the progress of catalytic reaction. The carbon nitride (g-C3N4) provides active sites for catalytic reaction through its rich nitrogen groups, and plays a bridge role in the process of electron transfer, improving the stability and reaction efficiency of the catalyst. The molybdenum cobalt oxide (CoMoO4, CM) has good catalytic performance, and the cobalt ions and molybdenum ions can synergistically activate the persulfate (PMS) to generate sulfate radicals (SO4 •− ) and hydroxyl radicals (•OH) with strong oxidizing ability, which can effectively attack the benzene ring structure in the BPA molecule and break its chemical bonds, thereby realizing the degradation of BPA. The reduced graphene / carbon nitride / molybdenum cobalt oxide composite material can not only enhance the activation ability of PMS through reasonable design of the structure, but also increase the number of active sites of the material through the synergistic effect of rGO and g-C3N4, thereby improving its BPA removal capacity. The cobalt ions in the molybdenum cobalt oxide play an important role in the degradation reaction, and improve the activation effect of PMS and accelerate the reaction rate.

[0008] Preferably, the cobalt salt is CoSO4•6H2O; the molybdenum salt is (NH4)6Mo7O 24 ·4H2O; and the dispersant is hexadecyl trimethyl ammonium bromide.

[0009] More preferably, in the preparation step of the solid molybdenum cobalt oxide precursor, the mass ratio of the nanosilica, sodium hydroxide, cobalt salt, molybdenum salt and dispersant is (0.5~0.6):(0.3~0.6):(0.5~0.6):(0.7~0.8):(0.05~0.06).

[0010] Preferably, in the preparation step of the solid molybdenum cobalt oxide precursor, the temperature of the reaction is 160~180℃, and the time is 8~15h.

[0011] Preferably, the temperature for calcining the solid molybdenum cobalt oxide precursor is 500~550℃, the time is 2~3h, and the heating rate is 5~10℃.

[0012] The calcination process can remove organic impurities in the material, enhance the thermal stability and mechanical strength of the material. At the same time, appropriate calcination temperature can optimize the crystal structure of the material, increase the number of active sites, and improve the activation ability of PMS.

[0013] Preferably, the mass ratio of the reduced graphene to the solid molybdenum cobalt oxide is (0.3~0.4):(1.0~1.2).

[0014] Preferably, when the solid molybdenum cobalt oxide and the reduced graphene are co-dispersed in water, the solid molybdenum cobalt oxide and the reduced graphene are dispersed in water respectively at 20-25 DEG C, a stirring rate of 450-600 rpm, and for 0.5-1 h, and then the obtained dispersions are mixed and stirred at 20-25 DEG C at a stirring rate of 450-600 rpm for 6-10 h.

[0015] During the stirring, by controlling the amount of the reduced graphene and the solid molybdenum cobalt oxide, the stirring temperature and rate, and other parameters, the solid molybdenum cobalt oxide can be uniformly dispersed on the surface of the reduced graphene, thereby realizing effective preparation of the material.

[0016] Preferably, the nitrogen-containing organic precursor is melamine.

[0017] More preferably, the mass ratio of the nitrogen-containing organic precursor to the reduced graphene / solid molybdenum cobalt oxide is (0.3-0.4):(0.3-0.4).

[0018] Preferably, when the mixture of the nitrogen-containing organic precursor and the reduced graphene / solid molybdenum cobalt oxide is calcined, the temperature program is first increased to 550-570 DEG C at a rate of 5-10 DEG C, held for 2-3 h, decreased to 23-25 DEG C, and then increased to 520-550 DEG C at a rate of 5-10 DEG C, and held for 2-3 h.

[0019] Preferably, in the step of removing the nanosilica, the mass ratio of the sodium hydroxide to the reduced graphene / carbon nitride / solid molybdenum cobalt oxide is (2-4):(4-5).

[0020] The second technical scheme of the present application provides a reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared by the above method.

[0021] The third technical scheme of the present application provides an application of the above reduced graphene / carbon nitride / molybdenum cobalt oxide composite material in activating persulfate.

[0022] The fourth technical scheme of the present application provides an application of the above reduced graphene / carbon nitride / molybdenum cobalt oxide composite material in degrading bisphenol A by activating persulfate.

[0023] The present application has the following beneficial technical effects:

[0024] The present application synthesizes the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material by a multi-step method, the reaction conditions are mild, no toxic and harmful raw materials are involved, and the prepared material is efficient, stable, and environmentally friendly.

[0025] The reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared by the method has rich active sites on the surface, and thus can realize efficient activation of peroxymonosulfate and efficient degradation of organic pollutants.

[0026] Through the structural design and the optimization of the preparation method, the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared by the method has extremely high efficiency in degrading BPA. In experiments, the degradation rate of BPA within 60 min is as high as 96.5%, which is much higher than that of molybdenum cobalt oxide, reduced graphene / molybdenum cobalt oxide composite material and carbon nitride / molybdenum cobalt oxide composite material. Moreover, the material has good stability during the reaction process and does not have obvious structural changes or activity decline, and can be repeatedly used, and has high practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0028] Figure 1 The scanning electron microscope image of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in Example 1.

[0029] Figure 2 The X-ray diffraction pattern (A) of reduced graphene and carbon nitride, and the X-ray diffraction pattern (B) of the composite materials prepared in Example 1 and Comparative Examples 2-3.

[0030] Figure 3 The X-ray photoelectron spectrogram of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in Example 1.

[0031] Figure 4 The ability of each catalyst prepared in Example 1 and Comparative Examples 1-3 to activate PMS to degrade BPA.

[0032] Figure 5 The anti-interference ability of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in Example 1 when activating PMS to degrade BPA.

[0033] Figure 6 The cycle stability of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in Example 1 when activating PMS to degrade BPA. DETAILED DESCRIPTION

[0034] The following detailed description of various exemplary embodiments of the application should not be considered to be limiting of the application, but merely illustrative in nature. It is understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] It should be noted that the present application does not describe in detail the conventional operation means in the art, and is not the focus of the present application.

[0036] In addition, for the numerical range in the present application, it is understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intermediate value in the stated range, is also encompassed within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.

[0038] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps.

[0039] As used herein, the term "room temperature" means 23-25°C, unless otherwise specified.

[0040] The raw materials used in the present application are commercially available.

[0041] Example 1

[0042] A method for preparing a graphene / carbon nitride / molybdenum cobalt oxide composite material, the steps are as follows:

[0043] (1) 50 mL of water and 0.5 g of nano-silica were stirred at 25°C and 600 rpm for 30 min to obtain a nano-silica dispersion;

[0044] (2) 0.3 g of sodium hydroxide was dissolved in 5 mL of ultrapure water at 25°C to obtain a sodium hydroxide solution;

[0045] (3) 0.5 g of CoSO4•6H2O, 0.7 g of (NH4)6Mo7O 24 24H2O, and 0.05 g of cetyltrimethylammonium bromide were dissolved in 50 mL of ultrapure water at 25°C to obtain a mixed solution;

[0046] (4) uniformly mixing the nano-silica dispersion liquid in step (1) with the mixed solution in step (3) to obtain a mixed solution;

[0047] (5) slowly adding the sodium hydroxide solution in step (2) to the mixed solution in step (4) at a speed of 5 drops / min at 25℃ to obtain a mixture;

[0048] (6) transferring the mixture in step (4) to a reaction kettle, heating and reacting at 160℃ for 8h in a blast drying oven, and after cooling to 25℃, filtering to obtain a precipitate;

[0049] (7) washing the precipitate obtained in step (6) with deionized water and anhydrous ethanol for 3 times respectively, and then vacuum drying at 60℃ for 12h, and grinding through a 200 mesh sieve to obtain a solid molybdenum cobalt oxide precursor;

[0050] (8) heating the precursor material in step (7) to 500℃ at a rate of 5℃ / min, and calcining at this temperature for 2h, and then reducing to room temperature to obtain a solid molybdenum cobalt oxide;

[0051] (9) adding 0.3g of reduced graphene into 50mL of ultrapure water, and stirring at 25℃ and 600rpm for 0.5h to uniformly disperse the reduced graphene;

[0052] (10) adding 1.0g of the solid molybdenum cobalt oxide prepared in step (8) into the dispersion liquid in step (9), and stirring at 25℃ and 600rpm for 6h, and then filtering to obtain a precipitate;

[0053] (11) washing the precipitate obtained in step (10) with deionized water and anhydrous ethanol for 3 times respectively, and then vacuum drying at 60℃ for 12h, and grinding through a 200 mesh sieve to obtain reduced graphene / solid molybdenum cobalt oxide;

[0054] (12) placing 0.3g of melamine and 0.3g of the reduced graphene / solid molybdenum cobalt oxide in step (11) in a mortar, and manually grinding the mixed powder with a pestle, and ensuring that the powder is fully contacted and rubbed during the grinding process by rotating and pressing the pestle, and the grinding time is 20min;

[0055] (13) heating the mixed powder after grinding in step (12) to 550℃ at a rate of 5℃ / min, and keeping the temperature for 2h, and then reducing to room temperature, and then heating to 520℃ at a rate of 5℃ / min, and keeping the temperature for 2h to prepare reduced graphene / carbon nitride / solid molybdenum cobalt oxide;

[0056] (14) dissolving 2g of sodium hydroxide in 50mL of ultrapure water at 25℃ to obtain a sodium hydroxide solution;

[0057] (15) 4 g of the reduced graphene / carbon nitride / solid molybdenum cobalt oxide obtained in step (13) was added into the sodium hydroxide solution in step (14), and stirred at 25℃ and 600 rpm for 8 h;

[0058] (16) The precipitate obtained in step (15) was washed with deionized water and anhydrous ethanol for 3 times respectively, and then vacuum dried at 60℃ for 12 h, and ground through a 200 mesh sieve to obtain the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material (GR-CM).

[0059] The material prepared in Example 1 was characterized and tested by a scanning electron microscope, an X-ray diffraction pattern, and an X-ray photoelectron spectrum, and the results are shown in Figures 1-3 .

[0060] Figure 1 The scanning electron microscope image of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in Example 1 of the present application is shown in Figure 1 , which shows that the microstructure of the prepared reduced graphene / carbon nitride / molybdenum cobalt oxide composite material presents a sheet structure, and the surface and interlayer are attached with molybdenum cobalt oxide nanoparticles, indicating that the material has been successfully synthesized.

[0061] Figure 2 The X-ray diffraction pattern (A) of the reduced graphene and carbon nitride, and the X-ray diffraction pattern (B) of the composite material prepared in Example 1 and Comparative Examples 2-3 are shown in Figure 2 , which shows that the structure of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in the present application not only contains the characteristic peaks of the reduced graphene and carbon nitride, but also contains the characteristic peaks of the molybdenum cobalt oxide nanoparticles, indicating that the material has been successfully synthesized.

[0062] Figure 3 The X-ray photoelectron spectrum of the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared in Example 1 of the present application is shown in Figure 3 , which shows that the characteristic elements of the prepared reduced graphene / carbon nitride / molybdenum cobalt oxide composite material not only contain the C and N elements of the reduced graphene and carbon nitride, but also contain the Co, Mo, and O elements of the molybdenum cobalt oxide nanoparticles, indicating that the material has been successfully synthesized.

[0063] Application Example 1

[0064] A method for degrading bisphenol A (BPA) in water by activated persulfate:

[0065] Experimental group one:

[0066] In the conical flask was added 100 mL of BPA solution with a concentration of 10 mg / L, and 0.01 g of GR-CM prepared in Example 1 and 0.01 g of persulfate (PMS) were added to the system to start the reaction. At a set time (60 min), 1.0 mL of the reaction solution was collected, filtered with a nylon needle filter, and then 0.5 mL of the reaction solution was quickly added to a brown vial containing 0.5 mL of methanol. The test results are shown in Table 1. Figure 4

[0067] Experiment Group Two:

[0068] In the conical flask was added 100 mL of BPA solution with a concentration of 10 mg / L, and 0.01 g of GR-CM prepared in Example 1 was added to the system to start the reaction. At a set time (60 min), 1.0 mL of the reaction solution was collected, filtered with a nylon needle filter, and then 0.5 mL of the reaction solution was quickly added to a brown vial containing 0.5 mL of methanol. The test results are shown in Table 2. Figure 4 GR-CM / PMS and GR-CM.

[0069] Figure 4 The effect verification chart of degrading bisphenol A in Experiment Group One and Experiment Group Two is shown in Figure 1. Figure 4 The test results show that the GR-CM prepared in Example 1 can efficiently activate persulfate to degrade bisphenol A in water, and the degradation rate of bisphenol A within 60 min is as high as 96.5%. The adsorption rate of bisphenol A by the prepared GR-CM within 60 min is only 11.76%, indicating that GR-CM cannot quickly enrich BPA on the surface of the catalyst.

[0070] Experiment Group Three:

[0071] In the conical flask was added 100 mL of BPA solution with a concentration of 10 mg / L, and different concentrations of coexisting ions were added to the system (the coexisting ions added and their concentrations in the system are shown in Table 3). Figure 5 Then, 0.01 g of GR-CM prepared in Example 1 and 0.01 g of persulfate (PMS) were added to start the reaction. At a set time (60 min), 1.0 mL of the reaction solution was collected, filtered with a nylon needle filter, and then 0.5 mL of the reaction solution was quickly added to a brown vial containing 0.5 mL of methanol. The test results are shown in Table 4. The experimental results show that the presence of coexisting ions does not have a significant impact on the catalytic performance of GR-CM, indicating that it has strong anti-interference ability. Figure 5

[0072] Experiment Group Four:

[0073] After the GR-CM from Experiment Group One was washed with methanol and ultrapure water alternately and vacuum dried at 60°C, five rounds of experiments on degrading BPA by activating PMS were continuously conducted, and the test results are shown in Table 5. Figure 6 ​​The experimental results show that the removal rate of BPA in the GR-CM / PMS system remains above 90% after five consecutive experiments, and the GR-CM has good stability.

[0074] Comparative Example 1

[0075] A preparation method of a molybdenum cobalt oxide material, the steps are as follows:

[0076] The same as Example 1, except that the solid molybdenum cobalt oxide obtained in step (8) is subjected to the treatment of step (15) and step (16), to prepare a molybdenum cobalt oxide (CoMoO4, CM).

[0077] The same test method as Experimental Group One in Application Example 1 is used, and the test results are shown in Table 1. Figure 4 The results show that the degradation rate of bisphenol A is 53.21% within 60 min.

[0078] Comparative Example 2

[0079] A preparation method of a reduced graphene / molybdenum cobalt oxide composite material, the steps are as follows:

[0080] The same as Example 1, except that the reduced graphene / solid molybdenum cobalt oxide in step (11) is subjected to the treatment of step (15) and step (16), to prepare a reduced graphene / molybdenum cobalt oxide composite material (rGO / CoMoO4, R-CM).

[0081] The same test method as Experimental Group One in Application Example 1 is used, and the test results are shown in Table 1. Figure 4 The results show that the degradation rate of bisphenol A is 54.89% within 60 min.

[0082] Comparative Example 3

[0083] A preparation method of a carbon nitride / molybdenum cobalt oxide composite material, the steps are as follows:

[0084] The same as Example 1, except that after step (8) is completed, steps (12)-(16) are directly performed, to prepare a carbon nitride / molybdenum cobalt oxide composite material (g-C3N4 / CoMoO4, G-CM).

[0085] The same test method as Experimental Group One in Application Example 1 is used, and the test results are shown in Table 1. Figure 4 The results show that the degradation rate of bisphenol A is 51.99% within 60 min.

[0086] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. A method for preparing a reduced graphene / carbon nitride / molybdenum cobalt oxide composite material, characterized by, The method comprises the following steps: The nanometer silicon dioxide, the cobalt salt, the molybdenum salt and the dispersing agent are mixed uniformly in water, a solution containing sodium hydroxide is added, and a solid molybdenum cobalt oxide precursor is obtained after reaction; the solid molybdenum cobalt oxide precursor is calcined to obtain a solid molybdenum cobalt oxide; the solid molybdenum cobalt oxide and reduced graphene are dispersed in water, and reduced graphene / solid molybdenum cobalt oxide is obtained after precipitation; a nitrogen-containing organic precursor is mixed uniformly with the reduced graphene / solid molybdenum cobalt oxide, and reduced graphene / carbon nitride / solid molybdenum cobalt oxide is obtained after calcination; the reduced graphene / carbon nitride / solid molybdenum cobalt oxide is mixed with a solution containing sodium hydroxide to remove nanometer silicon dioxide, and the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material is obtained.

2. The method for preparing the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material according to claim 1, characterized in that, The cobalt salt is CoSO4•6H2O; the molybdenum salt is (NH4)6Mo7O 24 4H2O; the dispersant is cetyl trimethyl ammonium bromide; in the preparation step of the solid molybdenum cobalt oxide precursor, the mass ratio of the nanosilica, sodium hydroxide, cobalt salt, molybdenum salt and dispersant is (0.5~0.6):(0.3~0.6):(0.5~0.6):(0.7~0.8):(0.05~0.06).

3. The method of claim 1, wherein the reduced graphene / carbon nitride / molybdenum cobalt oxide composite is prepared by the following steps of: In the preparation step of the solid molybdenum cobalt oxide precursor, the reaction temperature is 160-180°C, and the reaction time is 8-15h. ​ 4. The method of claim 1, wherein the reduced graphene / carbon nitride / molybdenum cobalt oxide composite is prepared by the following steps of: The temperature for calcining the solid molybdenum cobalt oxide precursor is 500-550°C, the time is 2-3h, and the temperature rising rate is 5-10°C; and / or, the mass ratio of the reduced graphene to the solid molybdenum cobalt oxide is (0.3-0.4):(1.0-1.2). ​ 5. The method of claim 1, wherein the reduced graphene / carbon nitride / molybdenum cobalt oxide composite is prepared by the following steps of: When the solid molybdenum cobalt oxide and the reduced graphene are dispersed in water, the solid molybdenum cobalt oxide and the reduced graphene are first dispersed in water respectively under the conditions of 20-25°C, a stirring rate of 450-600rpm, and a time of 0.5-1h, then the obtained dispersions are mixed, and the mixture is stirred at a temperature of 20-25°C and a stirring rate of 450-600rpm for 6-10h. ​ 6. The method of claim 1, wherein the reduced graphene / carbon nitride / molybdenum cobalt oxide composite is prepared by the following steps of: The nitrogen-containing organic precursor is melamine; and the mass ratio of the nitrogen-containing organic precursor to the reduced graphene / solid molybdenum cobalt oxide is (0.3-0.4):(0.3-0.4). ​ 7. The method for preparing the reduced graphene / carbon nitride / molybdenum cobalt oxide composite material according to claim 1, characterized in that, The temperature program for calcining the mixture of the nitrogen-containing organic precursor and the reduced graphene / solid molybdenum cobalt oxide is first rising to 550-570°C at a temperature rising rate of 5-10°C, holding for 2-3h, then lowering to 23-25°C, and then rising to 520-550°C at a temperature rising rate of 5-10°C, holding for 2-3h; and / or, in the step of removing nanometer silicon dioxide, the mass ratio of sodium hydroxide to the reduced graphene / carbon nitride / solid molybdenum cobalt oxide is (2-4):(4-5). 8.A reduced graphene / carbon nitride / molybdenum cobalt oxide composite material prepared by the method according to any one of claims 1-7. 9.The reduced graphene / carbon nitride / molybdenum cobalt oxide composite material of claim 8 is used for activating persulfate. 10.The reduced graphene / carbon nitride / molybdenum cobalt oxide composite material of claim 8 is used for degrading bisphenol A by activating persulfate.

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