Boron-doped carbon nitride-based cobalt single-atom catalyst and preparation method and application thereof

Abstract

The present invention provides a boron-doped carbon nitride-based cobalt single-atom catalyst and a preparation method and application thereof, comprising a boron-doped carbon nitride material with a lamellar structure, wherein a cobalt single atom forms a unique coordination with the lamellar boron carbon nitride to construct a boron-cobalt electron-poor and electron-rich dual site, drive persulfate to undergo simultaneous reduction and oxidation reactions, and construct an efficient free radical and non-free radical synergistic system. The above-mentioned boron carbon nitride-based single-atom catalyst has excellent performance in degrading carbamazepine and various organic pollutants.

Description

Technical Field

[0001] The present invention belongs to the field of Fenton-like reaction carbon nitride-based catalysts, and in particular relates to a boron-doped carbon nitride-based cobalt single-atom catalyst and a preparation method and application thereof. Background Art

[0002] The Fenton-like process of persulfate has been widely studied and applied in the degradation of organic pollutants due to its advantages such as economy, high efficiency, environmental friendliness, safety and stability. There are many ways to activate persulfate. Persulfate activated by metal ions is widely used because it does not require additional energy input, but there are problems such as metal ions are not easy to recover and are prone to secondary pollution. Single-atom catalysts make up for the above shortcomings. They have stronger reactivity, higher catalytic efficiency and less metal ion leaching. Therefore, the research on the degradation of organic pollutants by activating persulfate with single-atom catalysts is becoming more and more extensive.

[0003] In the persulfate Fenton process, there are two processes, free radical and non-radical, each with its own advantages: free radicals have strong oxidation ability, while non-radical oxidation has strong selectivity; free radical oxidation and non-radical oxidation in the reaction correspond to the reduction and oxidation reactions of persulfate, respectively, and the reduction and oxidation of persulfate are closely related to the electronic structure of the catalyst. At present, with the help of high-resolution characterization technology, the research on single-atom catalysts can adjust the coordination environment of the central metal atom and change the electronic structure at the atomic level, making it easier to construct a dual site of rich and poor electrons, drive the oxidation and reduction reactions of persulfate at the same time, and construct an efficient free radical and non-radical synergistic system, providing a theoretical basis for the treatment of actual complex wastewater.

[0004] Therefore, it is urgent to develop a single-atom catalyst that can simultaneously redox persulfate for efficient and selective wastewater treatment. Summary of the invention

[0005] The present invention aims to provide a boron-doped carbon nitride-based cobalt single-atom catalyst, which has a lamellar structure boron-doped carbon nitride material, wherein the cobalt single atom and the nitrogen in the lamellar boron carbon nitride form a B-Co-N 3 Coordination, the cobalt atom exists in the material as a single atom, which greatly improves the atomic utilization efficiency and catalyst performance. At the same time, the cobalt single atom is also a clear reaction site, which is convenient for constructing a boron-cobalt electron-poor and rich dual site, driving the reduction and oxidation reactions of persulfate at the same time, and constructing an efficient free radical and non-free radical synergistic system. The boron nitride carbon-based single atom catalyst has excellent performance in degrading carbamazepine and a variety of organic pollutants.

[0006] Another object of the present invention is to provide a method for preparing the boron-doped carbon nitride-based cobalt single-atom catalyst, comprising the following steps:

[0007] Step 1: Mix melamine and boron oxide in anhydrous ethanol and heat in a water bath at 60°C-80°C to obtain a carbon boron nitride base material precursor;

[0008] Step 2: grind the carbon boron nitride substrate material precursor, calcine at 450-550° C. for 2 h, heat it up at a rate of 20° C. / min, cool it to room temperature, wash it alternately with ethanol and water, and then dry it to obtain the carbon boron nitride substrate material;

[0009] Step 3: Add the dry boron carbon nitride base material to the cobalt ion solution and stir, then heat in a water bath at 160-200°C for reaction for 24 hours, and obtain the boron-doped carbon nitride-based cobalt single-atom catalyst after washing, drying and grinding.

[0010] As a more preferred technical solution of the present invention, in step 1, the mass ratio of melamine to boron oxide is 1:0.01-0.5.

[0011] As a more optimal technical solution of the present invention, the water bath heating temperature in step 1 is 80°C.

[0012] As a more preferred technical solution of the present invention, the mass ratio of melamine to boron in step 1 is 1:0.1.

[0013] As a more optimal technical solution of the present invention, the calcination temperature of melamine in step 2 is 550°C.

[0014] As a more preferred technical solution of the present invention, the cobalt ion solution in step 3 is obtained by adding 0.01-0.06 g of cobalt chloride hexahydrate to 60 ml of n-octanol solution and stirring.

[0015] As a more optimal technical solution of the present invention, the mass ratio of the carbon boron nitride base material to the cobalt chloride hexahydrate described in step three is 1:0.1-0.6.

[0016] As a more optimal technical solution of the present invention, in step three, the mass ratio of the carbon boron nitride base material to the cobalt chloride hexahydrate is 1:0.4.

[0017] As a more optimal technical solution of the present invention, the water bath heating temperature in step three is 200°C.

[0018] Another object of the present invention is to provide the above-mentioned boron-doped carbon nitride-based cobalt single-atom catalyst for Fenton-like removal of organic pollutants in water.

[0019] As a more preferred technical solution of the present invention, the organic pollutant is carbamazepine (CBZ).

[0020] Beneficial effects:

[0021] The boron-doped carbon nitride-based cobalt single-atom catalyst prepared by the present invention is a highly efficient Fenton-like pollutant degradation catalyst in a free radical / non-free radical coexistence system, which achieves the simultaneous enhancement of the free radical and non-free radical concentrations, and exhibits an excellent carbamazepine degradation effect, which is improved by 30% compared with the cobalt single-atom catalyst and the boron-doped carbon nitride material.

[0022] The boron-doped carbon nitride-based single-atom catalyst material of the present invention has an anion (SO 4 2− ,NO 3 − and Cl − It has good anti-interference performance in water matrix (tap water and secondary effluent, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the morphological characterization of 4%CoCN-B10% (200°C) of Example 4. Wherein a is the spherical aberration correction-high angle annular dark field scanning transmission electron microscope (AC-STEM) image of 4%CoCN-B10% (200°C) of Example 1, and b is the mapping image of 4%CoCN-B10% (200°C) of Example 1;

[0024] Figure 2 The X-ray diffraction patterns (XRD) of 4%CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2, and 4%CoCN (200°C) of Example 3;

[0025] Figure 3 It is the Fourier transform infrared (FT-IR) spectra of 4%CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2, and 4%CoCN (200°C) of Example 3;

[0026] Figure 4 is the X-ray photoelectron spectroscopy (XPS) of 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3;

[0027] Figure 5 The electrochemical impedance spectroscopy (EIS) of 4%CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2, and 4%CoCN (200°C) of Example 3;

[0028] Figure 6It is the instantaneous photocurrent response spectra (It) of 4%CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 6, and 4%CoCN (200°C) of Example 3;

[0029] Figure 7 This is the quenching experiment of CBZ active species degradation by 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3;

[0030] Figure 8 Electron spin resonance spectra (ESR) of sulfate radicals in CBZ degraded by 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3;

[0031] Fig. 9 is the singlet oxygen electron spin resonance spectra (ESR) of 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3 in degrading CBZ;

[0032] Fig.10 The efficiencies of CBZ removal by Fenton-like methods are 4% CoCN-B10% (200°C) of Example 4, 1% CoCN-B10% (200°C) of Example 10, 2% CoCN-B10% (200°C) of Example 11, and 6% CoCN-B10% (200°C) of Example 12;

[0033] Fig.11 It is the Fenton-like removal efficiency of CBZ by 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3 under the influence of different inorganic salts and humic acid;

[0034] Fig.12 It is the Fenton-like removal efficiency of different pollutants by 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0036] The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are conventional products that can be obtained commercially without specifying the manufacturer. If not otherwise specified, the embodiments are all based on conventional experimental conditions.

[0037] Example 1

[0038] 4 g of melamine was mixed with 20 ml of anhydrous ethanol and heated in a water bath at 80°C to prepare a carbon nitride base material precursor; the carbon nitride base material precursor was ground and calcined at 550°C for 2 h at a heating rate of 20°C / min. After cooling to room temperature, it was washed alternately with ethanol and water for 3 times and then dried to obtain a carbon nitride base material, recorded as CN.

[0039] Example 2

[0040] 4 g of melamine and 0.4 g of boron oxide were mixed in 20 ml of anhydrous ethanol, heated in a water bath at 80°C, and the ethanol was evaporated and then ground to obtain a white powdery boron nitride base material precursor; the boron nitride base material precursor was added to a 100 ml crucible, calcined at 550°C in a muffle furnace for 2 h with a heating rate of 20°C / min, cooled to room temperature, and washed alternately with ethanol and ultrapure water for 3 times after grinding, and vacuum dried at 60°C for 12 h to obtain a yellow granular prepared carbon nitride base material, recorded as CN-B10% (550°C).

[0041] Example 3

[0042] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN prepared in Example 1 was added to the cobalt ion solution, stirred for 30 min, and reacted at 200° C. for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60° C. for 10 h, and then ground to obtain a graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN (200° C.).

[0043] Example 4

[0044] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B10% (550°C) prepared in Example 2 was added to the cobalt ion solution, stirred for 30 min, and reacted at 200°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, recorded as 4% CoCN-B10% (200°C), and the morphology was characterized as follows: Figure 1 As shown in the figure, a is the spherical aberration correction-high angle annular dark field scanning transmission electron microscope (AC-STEM) image of 4%CoCN-B10% (200°C) in Example 1, and b is the mapping image of 4%CoCN-B10% (200°C) in Example 1; it indicates that the B element in the 4%CoCN-B10% (200°C) in Example 4 is successfully doped into the carbon nitride base material and the Co element is successfully in a single atomic form in the material.

[0045] The X-ray diffraction patterns (XRD) of 4% CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2, and 4% CoCN (200°C) of Example 3 are as follows: Figure 2 As shown; the CN-B10% (550°C) boron nitride carbon precursor of Example 2 was successfully synthesized and met the XRD peak shape of the CN (550°C) substrate material of Example 1; the 4%CoCN (200°C) cobalt single atom material of Example 3 was successfully synthesized and met the XRD peak shape of the CN (550°C) substrate material of Example 1; the 4%CoCN-B10% (200°C) of Example 4 was successfully synthesized, and the B element and the Co element were successfully introduced into the substrate material and the configuration of the substrate material was retained.

[0046] The Fourier transform infrared (FT-IR) spectra of 4% CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2 and 4% CoCN (200°C) of Example 3 are as follows: Figure 3 As shown; the CN-B10% (550°C) boron nitride carbon precursor of Example 2 was successfully synthesized and the Fourier infrared (FT-IR) peak shape of the CN (550°C) substrate material of Example 1 was consistent with that of the 4%CoCN (200°C) cobalt single atom material of Example 3 was successfully synthesized and the Fourier infrared (FT-IR) peak shape of the CN (550°C) substrate material of Example 1 was consistent with that of the 4%CoCN-B10% (200°C) of Example 4 was successfully synthesized, the B element and the Co element were successfully introduced into the substrate material and the configuration of the substrate material was retained.

[0047] The X-ray photoelectron spectroscopy (XPS) of 4%CoCN-B10% (200°C) of Example 4 and 4%CoCN (200°C) of Example 3 is as follows: Figure 4 As shown; the Co element peak of 4%CoCN-B10% (200°C) in Example 4 and the Co element peak of 4%CoCN (200°C) in Example 3 have an obvious red shift, indicating that the reduction performance of Co atoms in 4%CoCN-B10% (200°C) in Example 4 is improved after B element doping.

[0048] The electrochemical impedance spectroscopy (EIS) of 4% CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2 and 4% CoCN (200°C) of Example 3 are as follows: Figure 5 As shown, the electrochemical impedance of 4%CoCN-B10% (200°C) in Example 4 is the smallest and the material reaction performance is the best.

[0049] The instantaneous photocurrent response spectra (It) of 4%CoCN-B10% (200°C) of Example 4, CN (550°C) of Example 1, CN-B10% (550°C) of Example 2 and 4%CoCN (200°C) of Example 3 are as follows: Figure 6 As shown; the 4%CoCN-B10% (200°C) of Example 4 has the strongest instantaneous photocurrent response capability and the highest performance.

[0050] The results of the active species quenching experiment of 4%CoCN-B10% (200°C) degrading CBZ in Example 4 are as follows: Figure 7 As shown; the main active species in the degradation of CBZ by 4% CoCN-B10% (200°C) in Example 4 are sulfate radicals and non-radical singlet oxygen

[0051] The electron spin resonance spectra (ESR) of sulfate radicals in CBZ degraded by 4% CoCN-B10% (200°C) of Example 4 and 4% CoCN (200°C) of Example 3 are as follows: Figure 8 As shown; in the experiment of degrading CBZ, the main active species sulfate radical of 4% CoCN-B10% (200°C) of Example 4 was successfully detected and the signal intensity was higher than that of 4% CoCN (200°C) of Example 3.

[0052] The singlet oxygen electron spin resonance spectra (ESR) of 4% CoCN-B10% (200°C) of Example 4 and 4% CoCN (200°C) of Example 3 in the degradation of CBZ are shown in Figure 2. Fig. 9As shown; in the experiment of degrading CBZ, the main active species singlet oxygen of 4% CoCN-B10% (200°C) of Example 4 was successfully detected and the signal intensity was higher than that of 4% CoCN (200°C) of Example 3.

[0053] Example 5

[0054] 4 g of melamine and 0.4 g of boron oxide were mixed in 20 ml of anhydrous ethanol and heated in a water bath at 80°C to prepare a boron nitride base material precursor; the boron nitride base material precursor was ground and calcined at 450°C for 2 h at a heating rate of 20°C / min. After cooling to room temperature, it was washed alternately with ethanol and water for 3 times and then dried to obtain a yellow granular carbon nitride base material, recorded as CN-B10% (450°C).

[0055] Example 6

[0056] 4 g of melamine and 0.4 g of boron oxide were mixed in 20 ml of anhydrous ethanol and heated in a water bath at 80°C to prepare a boron nitride base material precursor; the boron nitride base material precursor was ground and calcined at 500°C for 2 h with a heating rate of 20°C / min. After cooling to room temperature, it was washed alternately with ethanol and water for 3 times and then dried to obtain a yellow granular carbon nitride base material, recorded as CN-B10% (500°C).

[0057] Example 7

[0058] 4 g of melamine and 0.2 g of boron oxide were mixed in 20 ml of anhydrous ethanol and heated in a water bath at 80°C to prepare a boron nitride base material precursor; the boron nitride base material precursor was ground and calcined at 550°C for 2 h at a heating rate of 20°C / min. After cooling to room temperature, it was washed alternately with ethanol and water for 3 times and then dried to obtain a yellow granular carbon nitride base material, recorded as CN-B5% (550°C).

[0059] Example 8

[0060] 4 g of melamine and 0.8 g of boron oxide were mixed in 20 ml of anhydrous ethanol and heated in a water bath at 80°C to prepare a white powdery boron nitride base material precursor; the boron nitride base material precursor was ground and calcined at 550°C for 2 h at a heating rate of 20°C / min. After cooling to room temperature, it was washed alternately with ethanol and water for 3 times and then dried to obtain a yellow granular carbon nitride base material, recorded as CN-B20% (550°C).

[0061] Example 9

[0062] 4 g of melamine and 2 g of boron oxide were mixed in 20 ml of anhydrous ethanol and heated in a water bath at 80°C to prepare a white powdery boron nitride base material precursor; the boron nitride base material precursor was ground and calcined at 550°C for 2 h at a heating rate of 20°C / min. After cooling to room temperature, it was washed alternately with ethanol and water for 3 times and then dried to obtain a yellow granular carbon nitride base material, recorded as CN-B50% (550°C).

[0063] Example 10

[0064] 0.01 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B10% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 200°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 1% CoCN-B10% (200°C).

[0065] Embodiment 11

[0066] 0.02 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B10% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 200°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 2% CoCN-B10% (200°C).

[0067] Example 12

[0068] 0.06 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B (1:0.1 550°C) was added to the cobalt ion solution and stirred for 30 min, then reacted at 200°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 6%CoCN-B10% (200°C).

[0069] Example 13

[0070] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B10% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 160°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B10% (160°C).

[0071] Embodiment 14

[0072] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B10% (550°C) was added to the cobalt ion solution, stirred for 30 min and reacted at 180°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B10% (180°C).

[0073] Embodiment 15

[0074] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution, stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B20% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 160°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B20% (160°C).

[0075] Example 16

[0076] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution, stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B20% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 180°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B20% (180°C).

[0077] Embodiment 17

[0078] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B20% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 200°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B20% (200°C).

[0079] Embodiment 18

[0080] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B50% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 160°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B50% (160°C).

[0081] Embodiment 19

[0082] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B50% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 180°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B50% (180°C).

[0083] Embodiment 20

[0084] 0.04 g of cobalt chloride hexahydrate was added to 60 ml of n-octanol solution and stirred for 30 min until completely dissolved to prepare a cobalt ion solution; 100 mg of CN-B50% (550°C) was added to the cobalt ion solution, stirred for 30 min, and reacted at 200°C for 24 h to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst, which was washed alternately with ethanol and water for 3 times, dried in a vacuum drying oven at 60°C for 10 h, and then ground to obtain a boron-doped graphite phase carbon nitride-based cobalt single-atom catalyst recorded as 4% CoCN-B50% (200°C).

[0085] Embodiment 21

[0086] The boron-doped graphite-phase carbon nitride-based cobalt single-atom catalyst in the above embodiment is used to remove different organic pollutants in a photo-Fenton manner.

[0087] First, 2 mg of boron-doped graphite-phase carbon nitride-based cobalt single-atom catalyst was placed in 20 mL of 0.04 mM CBZ, sulfamethoxazole (SMX, 0.04 mM), bisphenol A (BPA, 0.04 mM), 4-chlorophenol (4-CP, 0.04 mM), and atrazine (ATZ, 0.04 mM) aqueous solution and stirred for 30 min in the dark to reach adsorption-desorption equilibrium. Then, 0.0034 g of PMS and visible light were used to excite the reaction. Visible light was provided by a 300.100 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a wavelength filter less than 420 nm. The light intensity was 122.9 mW / cm 2 (Illuminated area = 3.34 cm 2 During the reaction, 2.0 mL of sample was collected every 1 minute and filtered through a 0.22 μm filter membrane, and then 1 mM Na2S2O3 was added. The concentration of each organic pollutant was determined using a Thermo Fisher liquid chromatograph. The results are shown in Fig.12 shown.

[0088] Experimental Example 3

[0089] The boron-doped graphite-phase carbon nitride-based cobalt single-atom catalyst in the above embodiment is used to remove different organic pollutants in a photo-Fenton manner.

[0090] First, 2 mg of boron-doped graphite-phase carbon nitride-based cobalt single-atom catalyst was placed in 20 mL of 0.04 mM CBZ and stirred for 30 min in the dark to reach adsorption-desorption equilibrium. Then, 0.0034 g of PMS and visible light were used to excite the reaction. The visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a wavelength filter less than 420 nm. The light intensity was 122.9 mW / cm 2 (Illuminated area = 3.34 cm 2 During the reaction, 2.0 mL of sample was collected every 1 min and filtered through a 0.22 μm filter membrane, and then 1 mM Na 2 S 2 O 3 After 5 min of reaction, the sample was centrifuged and dried for the next removal. This step was repeated 6 times. The CBZ concentration was determined using a Thermo Fisher liquid chromatograph.

[0091] The efficiencies of CBZ removal by Fenton-like methods for 4% CoCN-B10% (200°C) of Example 4, 1% CoCN-B10% (200°C) of Example 10, 2% CoCN-B10% (200°C) of Example 11, and 6% CoCN-B10% (200°C) of Example 12 are as follows: Fig.10 As shown; the efficiency and rate constant of Example 4 in the CBZ degradation experiment are 99% and 0.822, which are higher than 1%CoCN-B10% (200°C) of Example 10, 2%CoCN-B10% (200°C) of Example 11, and 6%CoCN-B10% (200°C) of Example 12.

[0092] The Fenton-like removal efficiency of CBZ by 4% CoCN-B10% (200°C) in Example 4 under the influence of different inorganic salts and humic acid is as follows: Fig.11 As shown in the figure, the material has a strong ability to resist the interference of inorganic salts. Except for bicarbonate, other inorganic salts have no effect on the degradation performance of the material.

[0093] The efficiency of 4%CoCN-B10% (200°C) in removing different pollutants by Fenton-like method in Example 4 is as follows: Fig.12 As shown in the figure, the material has good effects in the degradation of different pollutants, including 98% efficiency in the degradation of ATZ (atrazine), 84% efficiency in the degradation of BPA (bisphenol A), 87% efficiency in the degradation of SMX (sulfamethoxazole), and 62% efficiency in the degradation of 4-CP.

[0094] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

[0095] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a boron-doped carbon nitride-based cobalt single-atom catalyst, characterized in that: The method comprises the following steps: step 1, mixing melamine and boron oxide in anhydrous ethanol, heating in a water bath at 60-80°C to obtain a boron nitride carbon base material precursor; step 2, grinding the boron nitride carbon base material precursor, calcining at a high temperature of 450-550°C, cooling to room temperature, washing and drying to obtain a boron nitride carbon base material; step 3, adding the boron nitride carbon base material to a cobalt ion solution, stirring, then heating in a water bath at 160-200°C for reaction, washing and drying to obtain a boron-doped carbon nitride-based cobalt single-atom catalyst; The cobalt ion solution is obtained by adding cobalt chloride hexahydrate into n-octanol solution; The mass ratio of the carbon boron nitride base material to the cobalt chloride hexahydrate is 1:0.1-0.

6.

2. The method for preparing a boron-doped carbon nitride-based cobalt single-atom catalyst according to claim 1, characterized in that: In step 1, the mass ratio of melamine to boron oxide is 1:0.01-0.

5.

3. The method for preparing the boron-doped carbon nitride-based cobalt single-atom catalyst according to claim 1, characterized in that: In step 1, the mass ratio of melamine to boron is 1:0.

1.

4. The method for preparing a boron-doped carbon nitride-based cobalt single-atom catalyst according to claim 1, characterized in that: In step 2, the melamine calcination temperature is 550°C.

5. The method for preparing a boron-doped carbon nitride-based cobalt single-atom catalyst according to claim 1, characterized in that: In step 3, the mass ratio of the carbon boron nitride base material to the cobalt chloride hexahydrate is 1:0.4.

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