A photocatalyst based on g-c3n4 surface defect anchoring ni / mn janus diatomic site, and a preparation method and application thereof

Abstract

The application discloses a kind of photocatalyst based on g-C3N4 surface defect anchoring Ni / Mn Janus double atomic site and preparation method and application, the photocatalyst includes g-C3N4 with surface defect and Ni and Mn loaded on the g-C3N4, the Ni and Mn are anchored at g-C3N4 surface defect and form Janus structure.The application is in photocatalytic CO2 reduction coupling antibiotic oxidation reaction application.The photocatalyst of the application can realize the efficient coupling reaction of CO2 reduction and antibiotic oxidation, simultaneously realizes the efficient reduction of CO2 and the oxidation degradation of antibiotic in water body under visible light driving.By regulating catalyst surface electronic structure and active site distribution, the synergistic performance of two reaction paths is realized, and the catalytic effect of "one stone two birds" is achieved.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, and in particular to a photocatalyst based on g-C3N4 surface defects anchoring Ni / Mn Janus diatomic sites, its preparation method, and its application. Background Technology

[0002] In recent years, photocatalytic CO2 reduction technology has attracted widespread attention due to its potential in mitigating the energy crisis and the greenhouse effect. Meanwhile, antibiotics, as an emerging pollutant, are widely present in the aquatic environment, seriously threatening ecosystems and human health. Therefore, developing multifunctional photocatalysts capable of simultaneously achieving CO2 resource conversion and antibiotic degradation is of great significance.

[0003] g-C3N4, a polymer semiconductor material with visible light responsiveness, is widely used in photocatalysis research due to its good stability and simple preparation. However, its catalytic performance is limited by its high photogenerated carrier recombination rate and limited active sites. Although there are reports that introducing surface defects and anchoring single-atom metals can effectively improve its electronic structure regulation ability and catalytic activity, its functions remain relatively limited. Summary of the Invention

[0004] The main objective of this invention is to provide a photocatalyst based on g-C3N4 surface defect anchoring Ni / Mn Janus diatomic sites that can achieve a highly efficient coupling reaction of CO2 reduction and antibiotic oxidation under visible light, and has the functions of environmental remediation and resource recycling, as well as its preparation method and application.

[0005] To achieve the above objectives, the present invention provides a photocatalyst based on Ni / Mn Janus diatomic sites anchored by surface defects in g-C3N4, comprising g-C3N4 having surface defects and Ni and Mn loaded on the g-C3N4, wherein the Ni and Mn are anchored at the surface defects of the g-C3N4 and form a Janus structure.

[0006] Furthermore, the defect is a carbon vacancy.

[0007] Furthermore, both Ni and Mn exist in single-atom form.

[0008] The present invention also provides a method for preparing the above-mentioned photocatalyst, characterized by comprising the following steps:

[0009] (1) g-C3N4 was prepared by thermal polycondensation.

[0010] (2) Heat-treating g-C3N4 in an H2 atmosphere to introduce surface defects;

[0011] (3) Ni and Mn were loaded onto g-C3N4 by photodeposition.

[0012] Further, the operation process of step (1) is as follows: melamine and urea are mixed evenly, ground, and then calcined in air at 500-600°C.

[0013] Further, the operation process of step (2) is as follows: after grinding g-C3N4, it is calcined in H2 atmosphere at 500-600℃.

[0014] Further, the operation process of step (3) is as follows: Ni and Mn precursor salts are dispersed in methanol aqueous solution, g-C3N4 is added, mixed evenly, and then photodeposition reaction is carried out under full-arc ultraviolet light irradiation and 6℃. Finally, the product is collected by centrifugation and washing and then dried.

[0015] Further, in step (3), the precursor salt of Ni is NiCl2·6H2O, the precursor salt of Mn is MnCl2, and the mass ratio of g-C3N4 with surface defects to NiCl2·6H2O and MnCl2 is 200:20~100:20~100. This yields photocatalysts with different proportions.

[0016] The present invention also provides an application of the above-mentioned photocatalyst in the photocatalytic CO2 reduction coupled with antibiotic oxidation reaction.

[0017] Furthermore, the antibiotic is one or more of ciprofloxacin, tetracycline, sulfamethoxazole, and levofloxacin hydrochloride.

[0018] The design principle of this invention is as follows:

[0019] The asymmetric structure of Janus (dihedral) metal active sites provides diverse surface environments for catalytic reactions, allowing multiple different chemical reactions to occur simultaneously on a single particle. This not only modulates the kinetics of the support, controls the adsorption of reactants and intermediates, and lowers the activation barrier, but also improves catalytic efficiency and adjusts product selectivity, which is of great significance for refining catalytic theory and designing highly efficient catalysts.

[0020] Surface defects in g-C3N4 materials not only provide numerous coordination unsaturated sites for anchoring metal atoms, but also, under photoinduced conditions, form photoexcited defects. These defects represent a potential candidate for dynamically anchoring metal atoms, capturing atomically dispersed metal atoms and enabling the manipulation of the electronic structure of the active metal center, while also altering the atomic arrangement and electronic structure of the support. Therefore, constructing bifunctional dynamic defects on the surface of g-C3N4 materials can serve as an effective strategy for precisely anchoring and studying Janus metal active sites.

[0021] This invention achieves stable anchoring of Ni and Mn single atoms through surface defect engineering. Specifically, g-C3N4 is pretreated using an H2 atmosphere heat treatment method to create a controllable defect structure on its surface, thereby enhancing the interaction between metal atoms and the g-C3N4 matrix, preventing metal agglomeration, and achieving single-atom-level dispersion. Subsequent experiments using aberration-corrected transmission electron microscopy verified that Ni and Mn exist stably in single-atom form on the g-C3N4 surface.

[0022] In this invention, Ni and Mn form a Janus structure, enabling synergistic effects across multiple reaction pathways and improving catalytic efficiency and selectivity. Specifically, Ni and Mn are anchored to defect sites on the surface of g-C3N4, forming diatomic active centers with a Janus structure. This structure effectively promotes electron transfer and synergistic effects between the two metals, thereby significantly enhancing the activity and selectivity of the catalyst in photocatalytic reactions. Subsequent experimental results show that, compared with single Ni or Mn catalysts, the Ni / Mn Janus diatomic catalyst exhibits superior catalytic performance in CO2 reduction and antibiotic oxidation reactions.

[0023] The beneficial effects of this invention are reflected in:

[0024] Defects on the g-C3N4 surface possess strong coordination capabilities, enabling them to form stable coordination structures with metal atoms. By controlling the defect density and distribution, selective anchoring of Ni and Mn single atoms can be achieved, forming Janus-structured diatomic sites. In this Janus structure, Ni and Mn are located at different active sites on the g-C3N4 surface, forming a synergistic bimetallic active center. The Mn site is used for antibiotic oxidation, while the Ni site is used for CO2 reduction, thus achieving highly efficient photocatalytic CO2 reduction coupled with antibiotic oxidation. This structure offers the following catalytic advantages:

[0025] Spatially separated active centers: Ni sites mainly participate in CO2 reduction reactions, while Mn sites dominate antibiotic oxidation reactions, achieving spatial separation and functional division of the two reaction pathways.

[0026] Metal-metal synergistic effect: Electron transfer and regulation occur between Ni and Mn through the g-C3N4 matrix, optimizing the adsorption energy of reaction intermediates and improving overall catalytic efficiency.

[0027] Enhanced charge separation capability: The Janus structure facilitates the directional migration of photogenerated electrons and holes, reduces recombination probability, and improves quantum efficiency.

[0028] The coupled reaction mechanism of CO2 reduction and antibiotic oxidation: Under visible light irradiation, g-C3N4 generates electron-hole pairs. Subsequently, electrons migrate to Ni sites and combine with CO2 molecules, generating CO, CH4, and other products through a multi-electron reduction process. Simultaneously, holes migrate to Mn sites and participate in the oxidation of antibiotic molecules, further oxidizing them into smaller molecules, or even mineralizing them into CO2 and H2O. By controlling the electronic structure of the catalyst surface, the distribution of active sites, and reaction conditions, the two reaction pathways can be efficiently synergistically modified.

[0029] This invention's photocatalyst enables highly efficient coupling of CO2 reduction and antibiotic oxidation. Under visible light, it simultaneously achieves efficient CO2 reduction (e.g., to CO or CH4) and the oxidative degradation of antibiotics (e.g., tetracyclines, sulfonamides) in water. By controlling the electronic structure and active site distribution on the catalyst surface, the two reaction pathways are synergistically executed, achieving a "two birds with one stone" catalytic effect. Experimental data show that under simulated sunlight irradiation, the CO2 reduction yield is increased by more than 15 times, and the antibiotic degradation rate can reach over 90%. This provides a new approach to solving the coupling problem of CO2 reduction and water pollution control.

[0030] Furthermore, the photocatalyst preparation process of this invention is simple and highly reproducible, showing promising prospects for industrial application. The preparation method employs conventional steps such as g-C3N4 synthesis, defect introduction, metal precursor loading, and heat treatment. The process flow is simple, highly operable, and suitable for large-scale production. Simultaneously, the catalyst exhibits stable structure and good cycle performance, demonstrating excellent industrial application prospects and making it widely applicable in environmental remediation and energy conversion fields. Attached Figure Description

[0031] Figure 1 This is the EPR diagram of the catalyst of this invention;

[0032] Figure 2 This is an aberration-corrected electron microscope (A) structural image of the catalyst of this invention (in the image, image A is Ni / Mn@gC). 3-x N4 electron microscope image, image B is Ni / Mn@gC 3-x N4mapping diagram);

[0033] Figure 3 This is the result of the photocatalytic CO2 reduction coupled with CIP oxidation activity of a series of catalysts of the present invention;

[0034] Figure 4 The results are based on the photocatalytic CO2 reduction coupled with CIP oxidation activity of catalysts with different substrate materials;

[0035] Figure 5 These are the results of the photocatalytic activity of the catalyst of this invention in different reaction systems;

[0036] Figure 6 The results show the photocatalytic activity of the catalyst of this invention in different antibiotic solutions. Detailed Implementation

[0037] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0038] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0039] Example 1

[0040] Photocatalyst 0.05Ni / Mn@gC 3-x Preparation of N4

[0041] The preparation method includes the following steps:

[0042] (1) Preparation of g-C3N4

[0043] Mix 0.5g of melamine and 5g of urea evenly, grind in a mortar for 15 minutes, then place in a quartz boat and in air atmosphere at 2.5℃·min. -1 The temperature was increased to 550℃ and held for 4 hours to obtain g-C3N4.

[0044] (2) Introducing surface carbon defects during heat treatment in H2 atmosphere

[0045] Grind 0.5 g of g-C3N4 in a mortar for 15 min, then place it in a quartz boat and heat it at 2.5 °C·min in an H2 atmosphere. -1 Heating to 550℃ at a heating rate and holding for 4 hours yielded g-C3N4 with surface carbon vacancy defects, denoted as gC. 3-x N4.

[0046] (3) 0.05Ni / Mn@gC 3-x Preparation of N4

[0047] Add 10 mg of NiCl2·6H2O and 10 mg of MnCl2 to 80 mL of 10 wt% methanol aqueous solution, stir for 10 min, and then add 200 mg of gC. 3-xN4 was added, stirred for 10 min, and ultrasonically treated for 10 min. Then, photodeposition was performed under full-arc irradiation with a 500W mercury lamp. During the reaction, the solution temperature was maintained at 6℃ using a circulating water system. After 3 h of reaction, the powder was washed three times by centrifugation with deionized water. The collected powder was dried at 70℃ for 12 h to obtain a photocatalyst based on Ni / Mn Janus diatomic sites anchored by surface defects in g-C3N4, denoted as 0.05Ni / Mn@gC 3-x N4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.05:0.05:1).

[0048] Example 2

[0049] Photocatalyst 0.05Ni / Mn@gC 3-x Preparation of N4

[0050] The preparation method includes the following steps:

[0051] (1) Preparation of g-C3N4

[0052] Mix 0.5g of melamine and 5g of urea thoroughly, grind in a mortar for 15 minutes, then place in a quartz boat and incubate at 5°C in air. -1 The temperature was increased to 500℃ and held for 2 hours to obtain g-C3N4.

[0053] (2) Introducing surface carbon defects during heat treatment in H2 atmosphere

[0054] Grind 0.5 g of g-C3N4 in a mortar for 15 min, then place it in a quartz boat and incubate at 5 °C for 1 min in an H2 atmosphere. -1 Heating to 500℃ at a heating rate and holding for 2 hours yields g-C3N4 with surface carbon vacancy defects, denoted as gC. 3-x N4.

[0055] (3) 0.05Ni / Mn@gC 3-x Preparation of N4

[0056] Add 10 mg of NiCl2·6H2O and 10 mg of MnCl2 to 80 mL of 10 wt% methanol aqueous solution, stir for 5 min, and then add 200 mg of gC. 3-xN4 was added, stirred for 5 minutes, and ultrasonically treated for 5 minutes. Then, photodeposition was carried out under full-arc irradiation with a 500W mercury lamp. During the reaction, the solution temperature was maintained at 6℃ using a circulating water system. After 2 hours of reaction, the powder was washed three times by centrifugation with deionized water. The collected powder was dried at 70℃ for 12 hours to obtain a photocatalyst based on Ni / Mn Janus diatomic sites anchored by surface defects in g-C3N4, denoted as 0.05Ni / Mn@gC 3-x N4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.05:0.05:1).

[0057] Example 3

[0058] Photocatalyst 0.05Ni / Mn@gC 3-x Preparation of N4

[0059] The preparation method includes the following steps:

[0060] (1) Preparation of g-C3N4

[0061] Mix 0.5g of melamine and 5g of urea evenly, grind in a mortar for 15 minutes, then place in a quartz boat and incubate at 10°C in air. -1 The temperature was increased to 600℃ and held for 6 hours to obtain g-C3N4.

[0062] (2) Introducing surface carbon defects during heat treatment in H2 atmosphere

[0063] Grind 0.5 g of g-C3N4 in a mortar for 15 min, then place it in a quartz boat and incubate at 10 °C for 1 min in an H2 atmosphere. -1 Heating to 600℃ at a heating rate and holding for 6 hours yielded g-C3N4 with surface carbon vacancy defects, denoted as gC 3-x N4.

[0064] (3) 0.05Ni / Mn@gC 3-x Preparation of N4

[0065] Add 10 mg of NiCl2·6H2O and 10 mg of MnCl2 to 80 mL of 10 wt% methanol aqueous solution, stir for 15 min, and then add 200 mg of gC. 3-xN4 was added, stirred for 15 min, and ultrasonically treated for 15 min. Then, photodeposition was carried out under full-arc irradiation with a 500W mercury lamp. During the reaction, the solution temperature was maintained at 6℃ using a circulating water system. After 4 h of reaction, the powder was washed three times by centrifugation with deionized water. The collected powder was dried at 70℃ for 12 h to obtain a photocatalyst based on Ni / Mn Janus diatomic sites anchored by surface defects of g-C3N4, denoted as 0.05Ni / Mn@gC 3-x N4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.05:0.05:1).

[0066] Example 4

[0067] Photocatalyst 0.1Ni / Mn@gC 3-x Preparation of N4

[0068] The preparation method of this embodiment is basically the same as that of Example 1, except that in step (3), the amount of NiCl2·6H2O added is adjusted to 20mg, and the amount of MnCl2 added is also adjusted to 20mg. The resulting photocatalyst is denoted as 0.1Ni / Mn@gC. 3-x N4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.1:0.1:1).

[0069] Example 5

[0070] Photocatalyst 0.2Ni / Mn@gC 3-x Preparation of N4

[0071] The preparation method of this embodiment is basically the same as that of Example 1, except that in step (3), the amount of NiCl2·6H2O added is adjusted to 40mg, and the amount of MnCl2 added is also adjusted to 40mg. The resulting photocatalyst is denoted as 0.2Ni / Mn@gC. 3-x N4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.2:0.2:1).

[0072] Example 6

[0073] Photocatalyst 0.3Ni / Mn@gC 3-x Preparation of N4

[0074] The preparation method of this embodiment is basically the same as that of Example 1, except that in step (3), the amount of NiCl2·6H2O added is adjusted to 60mg, and the amount of MnCl2 added is also adjusted to 60mg. The resulting photocatalyst is denoted as 0.3Ni / Mn@gC. 3-xN4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.3:0.3:1).

[0075] Example 7

[0076] Photocatalyst 0.4Ni / Mn@gC 3-x Preparation of N4

[0077] The preparation method of this embodiment is basically the same as that of Example 1, except that in step (3), the amount of NiCl2·6H2O added is adjusted to 80mg, and the amount of MnCl2 added is also adjusted to 80mg. The resulting photocatalyst is denoted as 0.4Ni / Mn@gC. 3-x N4 (NiCl2·6H2O:MnCl2:gC) 3-x N4 mass ratio = 0.4:0.4:1).

[0078] Experimental Example 1

[0079] Surface defect analysis of photocatalysts

[0080] g-C3N4 and gC prepared in Example 1 3-x N4 and 0.2Ni / Mn@gC prepared in Example 5 3-x Taking N4 as an example, we analyze its surface defects. Figure 1 As shown, g-C3N4 calcined in air exhibits a weaker EPR signal; while g-C3N4 calcined in H2 atmosphere shows a weaker EPR signal. 3-x N4 exhibits a strong EPR signal, further indicating that carbon defects have been successfully introduced into the material structure. It is noteworthy that when Ni and Mn atoms are introduced into gC... 3-x After the N4 system, the EPR signal was significantly weakened, which further confirms that surface carbon defects can effectively promote the formation of Ni / Mn Janus diatomic site catalysts.

[0081] Experiment Example 2

[0082] Structural Feature Analysis of Photocatalysts

[0083] The photocatalyst 0.2Ni / Mn@gC prepared in Example 5 3-x Taking N4 as an example, observe its microstructure.

[0084] See Figure 2 In the figure, Figure A represents 0.2Ni / Mn@gC 3-x Aberration-corrected electron micrograph of N4, image B is for 0.2Ni / Mn@gC 3-x The element mapping diagram of N4. (From...) Figure 2It can be seen that Ni and Mn single atoms are uniformly dispersed in gC 3-x N4 matrix surface, further confirming gC 3-x The surface defects of N4 can effectively anchor Ni and Mn single atoms, forming Ni / Mn Janus diatomic site catalysts.

[0085] Experimental Example 3

[0086] Activity analysis of photocatalysts for CO2 reduction coupled with ciprofloxacin (CIP) oxidation

[0087] The photocatalysts prepared in the above embodiments, based on Ni / Mn Janus diatomic sites anchored by g-C3N4 surface defects, were used in a coupled reaction system of photocatalytic CO2 reduction coupled with CIP oxidation decomposition. The specific process is as follows:

[0088] After adding 50 mg of photocatalyst to the photocatalytic reactor, 50 mL of CIP aqueous solution (20 mg / L) was added and the mixture was ultrasonically dispersed for 5 min. The reactor was then vacuum-evacuated, and 50 mL of CO2 (99.999% purity) reaction gas was introduced into the reactor. The reaction was then carried out under 300 W xenon lamp irradiation. The gaseous products of the photocatalytic reaction (mainly CO and CH4) were measured using gas chromatography every 1 h. After 5 h of reaction, the reaction solution was collected, and the catalyst powder was removed by centrifugation. Finally, the absorbance of the CIP supernatant after the catalytic reaction was measured using a UV-Vis spectrophotometer.

[0089] Figure 3 This invention relates to a series of photocatalysts (Example 1: 0.05Ni / Mn@gC). 3-x N4, 0.1Ni / Mn@gC in Example 4 3-x N4, 0.2Ni / Mn@gC from Example 5 3-x N4, 0.3Ni / Mn@gC from Example 6 3-x N4, 0.4Ni / Mn@gC from Example 7 3-x The photocatalytic CO2 reduction coupled with CIP oxidation activity of g-C3N4 and gC N4 (using g-C3N4 and gC N4 ... 3-x N4 was used as a control). Figure 3 It can be seen that gC 3-x The photocatalytic performance of N4 is significantly superior to that of g-C3N4; after loading Ni and Mn single atoms, Ni / Mn@gC 3- x The photocatalytic performance of N4 was significantly improved, and the Ni / Mn@gC ratio increased with the increase of Ni and Mn single-atom deposition. 3-xThe photocatalytic CO2 reduction coupled with CIP oxidation activity of N4 increases until it reaches its maximum at 0.2 wt%. Afterward, with further increases in the amount of Ni and Mn single-atom deposition, the Ni / Mn@gC... 3-x The photocatalytic redox performance of N4 gradually decreased.

[0090] Experiment Example 4

[0091] Comparative analysis of the photocatalytic activity of different types of photocatalysts

[0092] Following the method in Example 5, a series of control photocatalysts 0.2Ni@gC were prepared. 3-x N4 (omitting the addition of MnCl2, the amount of NiCl2·6H2O remains unchanged), 0.2Mn@gC 3-x N4 (omitting the addition of NiCl2·6H2O, while keeping the amount of MnCl2 unchanged), 0.2Ni / Mn@g-C3N4 (omitting step 2, gC in step 3) 3-x N4 was replaced with g-C3N4 without surface defects prepared in step 1), and 0.2Ni / Mn@gC 3-x The photocatalytic CO2 reduction coupled CIP oxidation activity of N4 and each control photocatalyst was determined (the determination method is the same as in Experiment 2).

[0093] The results are as follows Figure 4 As shown. By Figure 4 It can be seen that 0.2Ni / Mn@gC 3-x N4 to 0.2Ni@gC 3-x N4, 0.2Mn@gC 3-x N4 and 0.2Ni / Mn@g-C3N4 exhibit excellent photocatalytic redox performance, mainly attributed to the fact that surface defects anchoring the Ni / Mn Janus diatomic sites are the primary factor enhancing photocatalytic redox performance. Meanwhile, 0.2Ni@gC... 3-x N4 and 0.2Mn@gC 3-x None of the N4 materials formed a Janus structure, and the 0.2Ni / Mn@g-C3N4 materials used a defect-free matrix material, so their performance could not achieve the effect of this application.

[0094] Experimental Example 5

[0095] Analysis of the Influence of Different Reaction Systems on the Catalytic Activity of the Photocatalyst of the Present Invention

[0096] Referring to the method in Experimental Example 2, different reaction systems were constructed (a single CIP oxidation system, a coupled reaction system of CO2 reduction coupled with CIP oxidation, and a single CO2 reduction system). The 0.2Ni / Mn@gC obtained in Example 5 was then compared with these systems.3-x The N4 catalyst was tested for catalytic activity in the above systems. The coupled reaction system corresponds to the coupled reaction system of photocatalytic CO2 reduction coupled with CIP oxidation in Experiment 2; the single CIP oxidation system is the same as Experiment 2 without the addition of CO2; and the single CO2 reduction system is the same as Experiment 2 without the addition of CIP aqueous solution.

[0097] Test results as follows Figure 5 As shown. By Figure 5 It can be seen that 0.2Ni / Mn@gC 3-x The N4 photocatalyst exhibits the best photocatalytic redox performance in the "coupled reaction system of photocatalytic CO2 reduction coupled with CIP oxidation," significantly outperforming other "single reaction systems." This confirms that the coupled reaction system achieves full utilization of charge carriers, thus demonstrating remarkable photocatalytic oxidation performance. Therefore, the photocatalyst prepared in this invention, based on Ni / Mn Janus diatomic sites anchored by surface defects in g-C3N4, has potential applications in synergistically alleviating the energy crisis and treating industrial wastewater.

[0098] Experimental Example 6

[0099] Analysis of the effects of different antibiotics on the catalytic activity of the photocatalyst of this invention

[0100] Referring to the method in Experimental Example 2, coupling reaction systems for different antibiotics were constructed respectively (a coupling reaction system of CO2 reduction coupled with metronidazole (MNZ) oxidation, a coupling reaction system of CO2 reduction coupled with CIP oxidation, a coupling reaction system of CO2 reduction coupled with tetracycline (TC) oxidation, and a coupling reaction system of CO2 reduction coupled with levofloxacin (LVX) oxidation, i.e., replacing different antibiotics based on Experimental Example 2), and the 0.2Ni / Mn@gC prepared in Example 5 was used. 3-x The activity of the N4 catalyst was tested in the above-mentioned coupled reaction systems.

[0101] Test results as follows Figure 6 As shown. By Figure 6 It can be seen that 0.2Ni / Mn@gC 3-x The N4 photocatalyst exhibited excellent photocatalytic redox performance in the "coupled reaction system of photocatalytic CO2 reduction coupled with the oxidation of different types of antibiotics", which further confirms that the photocatalyst based on the surface defect anchoring of Ni / Mn Janus diatomic sites prepared in this invention has broad applicability and shows good application potential in synergistically alleviating the energy crisis and industrial wastewater treatment.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Application of a photocatalyst based on g-C3N4 surface defect anchoring Ni / Mn Janus diatomic sites in photocatalytic CO2 reduction coupling antibiotic oxidation reaction, characterized in that, The photocatalyst comprises g-C3N4 with surface defects and Ni and Mn loaded on the g-C3N4, the Ni and Mn being anchored at the surface defects of the g-C3N4 and forming a Janus structure.

2. Use according to claim 1, wherein The defects are carbon vacancies.

3. The use according to claim 1, wherein The Ni and Mn are both in the form of single atoms.

4. The application or the preparation method of the photocatalyst according to any one of claims 1 to 3, comprising the following steps: (1) preparing g-C3N4 by a thermal condensation method; (2) introducing surface defects to the g-C3N4 by heat treatment in a H2 atmosphere; (3) loading Ni and Mn on the g-C3N4 by a photo-deposition method.

5. The use according to claim 4, wherein the compound is ###0002### The operation process of step (1) is as follows: melamine and urea are mixed uniformly, ground, and then calcined at 500-600 ℃ in an air atmosphere.

6. The use according to claim 4, wherein the compound is ###0002### The operation process of step (2) is as follows: the g-C3N4 is ground and then calcined at 500-600 ℃ in a H2 atmosphere.

7. The use according to claim 4, wherein the compound is ###0002### The operation process of step (3) is as follows: the precursor salts of Ni and Mn are dispersed in a methanol aqueous solution, g-C3N4 is added, mixed uniformly, then photo-deposition reaction is carried out under the condition of irradiation of a full arc of ultraviolet light at 6 ℃, finally centrifugal washing is carried out, the obtained product is collected and dried.

8. The use according to claim 4, wherein In step (3), the precursor salt of Ni is NiCl2·6H2O, the precursor salt of Mn is MnCl2, and the mass ratio of g-C3N4 with surface defects to NiCl2·6H2O and MnCl2 is 200:20-100:20-100.

9. Use according to any one of claims 1 to 3, wherein The antibiotic is one or more of ciprofloxacin, tetracycline, sulfamethoxazole, and levofloxacin hydrochloride.

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