Cobalt vacancy regulated hollow multi-shell nickel cobalt oxide catalyst, preparation method and application thereof

Abstract

The application discloses a cobalt vacancy regulated hollow multi-shell nickel cobalt oxide catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: mixing glucose, a zinc salt, a cobalt salt, a nickel salt and water, and obtaining the cobalt vacancy regulated hollow multi-shell nickel cobalt oxide catalyst through a hydrothermal reaction, calcination and etching. According to the preparation method, the zinc salt, the cobalt salt, the nickel salt and the glucose are used as raw materials, the metal nickel, cobalt and zinc are cross-linked on polysaccharide to form a network structure through the hydrothermal reaction, and then the surface carbon and metal zinc are removed through the calcination and the etching, so that the cobalt vacancy regulated hollow multi-shell nickel cobalt oxide catalyst with a stable hollow multi-shell structure is formed. The preparation method has the advantages of simple process, safe raw materials, low cost and batch production. The cobalt vacancy regulated hollow multi-shell nickel cobalt oxide catalyst prepared by the method has the advantages of good catalytic activity, high degradation efficiency, good stability, strong anti-interference property and low metal ion leaching rate.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation water treatment, specifically relating to a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst, its preparation method, and its application. Background Technology

[0002] Advanced oxidation technologies based on persulfate have shown broad application prospects in the remediation of organic pollution in water bodies, particularly antibiotics, with persulfate (PDS) and permonsulfate (PMS) being the most widely used. Currently, various catalysts have been used to remediate organic pollution in water bodies, such as transition metal spinels and biochar. Transition metal spinels, for example, are considered ideal catalysts for activating persulfate; however, their poor conductivity, tendency for some to aggregate leading to insufficient active sites, and poor stability in aquatic environments limit their application in advanced oxidation. Therefore, overcoming these problems and obtaining a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with good catalytic activity, high degradation efficiency, good stability, strong anti-interference ability, and low metal ion leaching rate has become an urgent task. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with good catalytic activity, high degradation efficiency, good stability, strong anti-interference ability, and low metal ion leaching rate, as well as its preparation method and application.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0005] A method for preparing a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst includes the following steps:

[0006] S1. Mix glucose, zinc salt, cobalt salt, nickel salt and water to obtain a mixed solution;

[0007] S2. The mixed solution obtained in step S1 is subjected to a hydrothermal reaction to obtain the precursor;

[0008] S3. Calcine the precursor obtained in step S2 to obtain a mixture;

[0009] S4. Immerse the mixture obtained in step S3 in an alkaline solution and etch it to obtain a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst.

[0010] In a further improvement to the above preparation method, in step S1, the ratio of the total molar amount of the zinc salt and cobalt salt to the molar amount of the nickel salt is 2:1, the molar ratio of the zinc salt to the cobalt salt is 0.05-0.3:2.3-2.55, and the molar amount of the glucose to the total molar amount of the zinc salt, cobalt salt, and nickel salt is 0.5-2:1.

[0011] In a further improvement to the above preparation method, in step S2, the temperature of the hydrothermal reaction is 160℃~200℃, and the time of the hydrothermal reaction is 360min~440min.

[0012] In a further improvement to the above preparation method, in step S3, the calcination temperature is 300℃~500℃, the calcination time is 0.5h~1.5h, the heating rate during calcination is 0.5℃ / min~1.5℃ / min, and the calcination is carried out in an air atmosphere.

[0013] In a further improvement to the above preparation method, the mixing process in step S1 is as follows:

[0014] (1) Glucose and water are mixed to obtain mixed solution A; the glucose is glucose monohydrate, the mixing is carried out under stirring conditions, the stirring speed is 400 rpm to 500 rpm, and the stirring time is 20 min to 40 min;

[0015] (2) Mix zinc salt, cobalt salt, nickel salt and water, add mixed solution A, and mix again to obtain a mixed solution; the zinc salt is zinc acetate dihydrate, the cobalt salt is cobalt acetate tetrahydrate, the nickel salt is nickel acetate tetrahydrate, the mixing is carried out under stirring conditions, the second mixing is carried out under stirring and ultrasonic conditions, the stirring speed is 400 rpm to 500 rpm, the stirring time is 20 min to 40 min, and the ultrasonic time is 0.5 h to 1 h.

[0016] In a further improvement to the above preparation method, step S2 includes the following treatment after the hydrothermal reaction: centrifuging, washing, and drying the reaction product; the centrifugation speed is 6000 rpm to 8000 rpm, the centrifugation time is 5 min to 7 min, the washing is performed with ethanol and water, the drying is carried out under vacuum conditions, the drying temperature is 50℃ to 80℃, and the drying time is 10 h to 14 h;

[0017] In step S3, the following treatment is performed after calcination: the calcined product is washed and dried;

[0018] In step S4, the etching time is 1h to 3h, the alkaline solution is at least one of sodium hydroxide solution and potassium hydroxide solution, and the concentration of the alkaline solution is 2.5M to 3.5M. After etching, the following treatment is performed: the etched product is washed and dried; the washing is performed by water filtration, the filtration time is 8min to 15min, the drying is performed under vacuum conditions, the drying temperature is 50℃ to 80℃, and the drying time is 10h to 14h.

[0019] As a general technical concept, the present invention also provides a cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst prepared by the above-mentioned method for preparing cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst.

[0020] As a general technical concept, the present invention also provides an application of the above-mentioned cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst in the treatment of organic pollutant wastewater.

[0021] Further improvements to the above application include the following steps: mixing a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with water containing organic pollutants, adding persulfate to carry out a degradation reaction, thereby achieving the degradation of organic pollutants in the water; the ratio of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst to the water containing organic pollutants is 0.02g~0.10g∶1L.

[0022] In a further improvement to the above application, the amount of persulfate added is 0.1 mmol to 2.0 mmol per liter of water containing organic pollutants. The persulfate is potassium persulfate. The organic pollutants in the water containing organic pollutants include at least one of antibiotics and dyes. The antibiotics are at least one of carbamazepine, tetracycline hydrochloride, and sulfamethoxazole. The dyes are at least one of rose red B and methylene blue. The concentration of organic pollutants in the water containing organic pollutants is ≤10 mg / L. The degradation reaction time is ≥10 min.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] (1) This invention discloses a method for preparing a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst. Using zinc salt, cobalt salt, nickel salt, and glucose as raw materials, a hydrothermal reaction is used to crosslink metallic nickel, cobalt, and zinc onto the polysaccharide to form a network structure. After calcination and etching, surface carbon and metallic zinc are removed, resulting in a stable cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with a hollow multi-shell structure. The preparation method of this invention has advantages such as simple process, safe raw materials, low cost, and mass production capability. The resulting cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst has advantages such as good catalytic activity, high degradation efficiency, good stability, strong anti-interference ability, and low metal ion leaching rate.

[0025] (2) The preparation method of the present invention optimizes the molar ratio of glucose to the total molar ratio of zinc salt, cobalt salt, and nickel salt to 0.5 to 2:1, thereby obtaining a cobalt vacancy-controlled hollow multi-shell nickel cobalt oxide catalyst with suitable shell thickness, thus achieving efficient degradation of organic pollutants. When the molar ratio of glucose to metal salt (total molar ratio of zinc salt, cobalt salt, and nickel salt) is too high, the thickness of the outer shell wall of the catalyst will become thinner. If the shell wall is too thin, it will be difficult to maintain the hollow multi-shell microsphere (HMs) structure, resulting in structural collapse. When the molar ratio of glucose to metal salt (total molar ratio of zinc salt, cobalt salt, and nickel salt) is too low, the thickness of the outer shell wall of the catalyst will become thicker. If the shell wall is too thick, it will affect the mass transfer efficiency of the catalyst. In other words, both excessively high and excessively low molar ratios of glucose to metal salt (total molar ratio of zinc salt, cobalt salt, and nickel salt) are not conducive to the degradation of organic pollutants by the cobalt vacancy-controlled hollow multi-shell nickel cobalt oxide catalyst.

[0026] (3) The preparation method of the present invention, by optimizing the calcination temperature to 300℃~500℃, can obtain a cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst with a suitable number of shell layers, thereby achieving efficient degradation of organic pollutants. When the calcination temperature is too high, the number of shell layers of the catalyst will be too many, and too many shell layers will affect the charge transfer ability of the catalyst; when the calcination temperature is too low, the number of shell layers of the catalyst will be too few, and too few shell layers will reduce the specific surface area and active sites of the catalyst. In other words, too many or too few shell layers are not conducive to the degradation of organic pollutants by the cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst.

[0027] (4) The present invention also provides an application of cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst in the treatment of organic pollutant wastewater. By directly mixing cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst and organic pollutant water, and then adding persulfate for degradation reaction, organic pollutants in water can be effectively degraded. It has the advantages of simple operation, good degradation effect and low cost, and is suitable for various complex and variable practical application scenarios. Attached Figure Description

[0028] Figure 1 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac SEM images of the nickel-cobalt oxide catalyst (NiCo2O4) in Comparative Example 1 and the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2.

[0029] Figure 2 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac TEM image of / HMs).

[0030] Figure 3 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac XRD patterns of nickel cobalt oxide catalyst (NiCo2O4) in Comparative Example 1 and hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2.

[0031] Figure 4 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac Isothermal adsorption-desorption curves and pore size distribution diagrams of the nickel cobalt oxide catalyst (NiCo2O4) in Comparative Example 1 and the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2.

[0032] Figure 5 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac XPS plots of nickel cobalt oxide catalyst (NiCo2O4) in Comparative Example 1 and hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2.

[0033] Figure 6 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac Electron paramagnetic resonance spectra of the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2.

[0034] Figure 7 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 2 of this invention vac / HMs), hollow multi-shell nickel-cobalt oxide catalyst (Al-NiCo) vac The effect of / HMs) activating persulfate to degrade tetracycline hydrochloride.

[0035] Figure 8The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 2 of this invention vac The effect of activation of persulfate to degrade tetracycline hydrochloride by nickel cobalt oxide catalyst (NiCo2O4) and hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs).

[0036] Figure 9 This is a diagram showing the effect of hollow multi-shell nickel-cobalt oxide catalysts (NiCo / HMs, NiCo / HMs-300, NiCo / HMs-500) activating persulfate to degrade tetracycline hydrochloride in Example 2 of the present invention.

[0037] Figure 10 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs, NiCo) in Example 2 of this invention 0.5 / HMs、NiCo 1.0 / HMs、NiCo 2.0 The effect of / HMs) activating persulfate to degrade tetracycline hydrochloride.

[0038] Figure 11 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 2 of this invention vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac The effect of using hollow multi-shell nickel-cobalt oxide catalysts (NiCo / HMs) to activate persulfate for the degradation of tetracycline hydrochloride.

[0039] Figure 12 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 3 of this invention vac Comparison of the removal effects of activated persulfate on sulfamethoxazole, carbamazepine, rose red B, and methylene blue (HMs). Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0041] Example 1:

[0042] A method for preparing a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst according to the present invention includes the following steps:

[0043] (1) Dissolve 0.028 mol glucose monohydrate in 10 mL of deionized water and stir vigorously at 500 rpm for 30 min until completely dissolved to obtain mixed solution A; dissolve 0.013 mol nickel acetate tetrahydrate, 0.025 mol cobalt acetate tetrahydrate and 0.001 mol zinc acetate dihydrate in 40 mL of deionized water and stir at 400 rpm for 30 min to obtain mixed solution B; transfer mixed solution A and mixed solution B to a 100 mL high-pressure reactor lined with polytetrafluoroethylene and stir at 400 rpm for 30 min, then sonicate for 30 min to completely mix to obtain mixed solution.

[0044] (2) The mixed solution obtained in step (1) was subjected to hydrothermal reaction at 180°C for 400 min. After the reaction was completed and the mixture was naturally cooled, the reaction product was collected by centrifugation at 7000 rpm for 5 min. It was washed three times with anhydrous ethanol and then three times with deionized water. After centrifugation in the same manner, it was dried in a vacuum drying oven at 60°C for 12 h to obtain a dark brown precursor.

[0045] (3) The precursor powder obtained in step (2) is loaded into a covered quartz boat and placed in a tube furnace. Under static air atmosphere, it is heated to 400°C at a heating rate of 1°C / min for calcination. The temperature is maintained at 400°C for 1 hour. After the tube furnace cools to room temperature, the calcined product is taken out and ground. The ground product is washed three times with deionized water, centrifuged at 7000 rpm for 6 minutes and collected. It is then dried in a vacuum drying oven at 60°C for 12 hours to obtain a mixture.

[0046] (4) The mixture obtained in step (3) was immersed in a sodium hydroxide solution (3M concentration) for 2 hours for etching; then, the etched product was passed through a vacuum filtration device, washed with deionized water for 15 minutes until the filtrate was neutral, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain a cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst, denoted as NiCo. vac / HMs.

[0047] In this embodiment, cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalysts with different amounts of metal salts were also prepared. The preparation method is the same as that for cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalysts (NiCo). vac The preparation methods of / HMs) are basically the same, the only difference being: in step (1), the amount of zinc acetate dihydrate is 0.0005 mol, and the amount of cobalt acetate tetrahydrate is 0.0255 mol; the cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst obtained is denoted as 0.0005-NiCo vac / HMs.

[0048] In this embodiment, cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalysts with different amounts of metal salts were also prepared. The preparation method is the same as that for cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalysts (NiCo). vac The preparation methods of / HMs) are basically the same, the only difference being: in step (1), the amount of zinc acetate dihydrate is 0.003 mol, and the amount of cobalt acetate tetrahydrate is 0.023 mol; the cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst obtained is denoted as 0.003-NiCo vac / HMs.

[0049] Comparative Example 1:

[0050] A nickel-cobalt oxide catalyst, the preparation method of which is the same as that of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1. vac The preparation methods of / HMs) are basically the same, the only difference is that in step (1), glucose monohydrate and zinc acetate dihydrate are not added, and the amount of cobalt acetate tetrahydrate is 0.026 mol; the nickel cobalt oxide catalyst obtained is denoted as NiCo2O4.

[0051] Comparative Example 2:

[0052] A hollow multi-shell nickel-cobalt oxide catalyst, the preparation method of which is the same as the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1. vac The preparation methods of / HMs are basically the same, the only difference is that in step (1), zinc acetate dihydrate is not added, and the amount of cobalt acetate tetrahydrate is 0.026 mol; the hollow multi-shell nickel cobalt oxide catalyst obtained is denoted as NiCo / HMs.

[0053] Comparative Example 3:

[0054] A hollow multi-shell nickel-cobalt oxide catalyst, the preparation method of which is the same as the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1. vac The preparation methods of / HMs) are basically the same, the only difference being: in step (1), aluminum acetate tetrahydrate is used instead of zinc acetate dihydrate, and the amount of aluminum acetate tetrahydrate is 0.001 mol; the hollow multi-shell nickel cobalt oxide catalyst obtained is denoted as Al-NiCo vac / HMs.

[0055] Figure 1 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac SEM images of the nickel-cobalt oxide catalyst (NiCo2O4) in Comparative Example 1 and the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2. Figure 1In the diagram, (a) and (b) are NiCo2O4, (c) and (d) are NiCo / HMs, and (e) and (f) are NiCo. vac / HMs. From Figure 1 It can be seen that, without glucose, the nickel-cobalt oxide catalyst (NiCo2O4) exhibits an irregular morphology and a rough surface; while the NiCo / HMs catalyst with added glucose exhibits a porous surface and a more uniform spherical structure. Its formation process involves metallic nickel and cobalt forming a network structure on the polysaccharide through cross-linking. This invention provides a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo... vac / HMs) contains a multi-shell hollow structure with nanoscale units. Its formation process is as follows: metallic nickel, cobalt, and zinc form a network structure on polysaccharide through cross-linking. Then, through calcination and etching, carbon and metallic zinc on the surface are removed to form a stable cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with a hollow multi-shell structure.

[0056] Figure 2 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac TEM image of / HMs). Figure 2 In the images, (a) and (b) are conventional TEM images, and (c) to (f) are high-resolution TEM images. Figure 2 (a) and (b) clearly show that NiCo vac / HMs are regular spheres with a three-shell structure; from (c) to (f), it can be seen that the material has a disordered lattice arrangement and no large continuous uniform lattice planes; in (c) and (d), lattice fringes of 0.224 nm and 0.220 nm correspond to the (222) plane of NiCo2O4, while lattice fringes of 0.283 nm and 0.1999 nm correspond to the (220) and (400) planes of NiCo2O4, respectively, which is consistent with the results of the XRD pattern. It can be seen that cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst (NiCo vac / HMs) exhibit a porous, spherical structure with a three-layered shell.

[0057] Figure 3 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac XRD patterns of the nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 1 (NiCo2O4) and the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2. Figure 3 It can be seen that NiCo2O4, NiCo / HMs, and NiCo vacThe characteristic diffraction peaks of / HMs at 2θ (18.9°, 31.1°, 36.7°, 44.6°, 59.1°, and 64.9°) can be attributed to the (111), (220), (311), (400), (511), and (440) crystal planes of NiCo2O4, respectively. This is consistent with standard card JCPDS number 73-1702, i.e., NiCo2O4, NiCo / HMs, and NiCo vac All / HMs exhibited a spinel nickel-cobalt oxide crystalline morphology, confirming the successful synthesis of each catalyst. Additionally, NiCo... vac The peak values ​​of the / HMs sample are weaker than those of NiCo2O4 and NiCo / HMs because the introduction of Co vacancies reduces the crystallinity of the material. In addition to the characteristic peaks of NiCo2O4, the characteristic diffraction peaks of the nickel-cobalt oxide catalyst (NiCo2O4) at 2θ (24.8, 33.2, 42.0, and 52.7°) can be attributed to the (003), (004), (005), and (006) crystal planes of CoO2, respectively. NiCo / HMs, NiCo... vac The diffraction peak at 21.1° of / HMs indicates reflection from the (002) surface of the carbon material, suggesting that approximately 3% of the carbon sphere template was not removed.

[0058] Figure 4 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac Isothermal adsorption-desorption curves and pore size distribution diagrams of the nickel cobalt oxide catalyst (NiCo2O4) in Comparative Example 1 and the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2. Figure 4 In the diagram, (a) shows the isothermal adsorption-desorption curve, and (b) shows the pore size distribution. Figure 4 It can be seen that NiCo2O4, NiCo / HMs, and NiCo vac The average pore size distribution of / HMs is relatively wide, concentrated at approximately 40.62 nm, 10.76 nm, and 13.18 nm, respectively, which conforms to mesoporous characteristics (2-50 nm); Meanwhile, the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) of this invention... vac PMS has the optimal number of mesopores and the largest BET surface area, which not only facilitates the adsorption and activation of PMS on the catalyst surface, but also facilitates the oxidation and degradation of organic pollutants near the catalyst surface by active substances. It exhibits excellent reaction kinetics, thereby achieving efficient and rapid removal of organic pollutants.

[0059] Figure 5 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vacXPS plots of the nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 1 (NiCo2O4) and the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2. Figure 5 It can be seen that NiCo vac / HMs, NiCo2O4, and NiCo / HMs are all composed of Ni2p, Co2p, O1s, and C1s, which indicates the successful preparation of each catalyst.

[0060] Figure 6 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac Electron paramagnetic resonance spectra of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2. Figure 6 It can be seen that, compared with the EPR signal of NiCo / HMs (g = 2.004), NiCo... vac / HMs exhibits a stronger EPR signal (g = 2.005), i.e., NiCo vac / HMs have a higher vacancy concentration, which is attributed to the increased V centers caused by the increase in cation vacancies, indicating that NiCo vac / HMs successfully introduced cation vacancies (cobalt vacancies).

[0061] Comparative Example 4:

[0062] A hollow multi-shell nickel cobalt oxide catalyst is prepared in a manner that is basically the same as that of the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, except that the calcination temperature in step (3) is 300℃ and the hollow multi-shell nickel cobalt oxide catalyst obtained is denoted as NiCo / HMs-300.

[0063] Comparative Example 5:

[0064] A hollow multi-shell nickel cobalt oxide catalyst is prepared in a manner that is basically the same as that of the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, except that the calcination temperature in step (3) is 500℃ and the hollow multi-shell nickel cobalt oxide catalyst obtained is denoted as NiCo / HMs-500.

[0065] Comparative Example 6:

[0066] A hollow multi-shell nickel-cobalt oxide catalyst is prepared using a method that is essentially the same as that used in Comparative Example 2 for preparing the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs), with the only difference being that in step (1), the amount of nickel acetate tetrahydrate is 0.0185 mol and the amount of cobalt acetate tetrahydrate is 0.037 mol; the resulting hollow multi-shell nickel-cobalt oxide catalyst is denoted as NiCo. 0.5 / HMs.

[0067] Comparative Example 7:

[0068] A hollow multi-shell nickel-cobalt oxide catalyst is prepared using a method that is essentially the same as that used in Comparative Example 2 for preparing the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs), with the only difference being that in step (1), the amount of nickel acetate tetrahydrate is 0.009 mol and the amount of cobalt acetate tetrahydrate is 0.018 mol; the resulting hollow multi-shell nickel-cobalt oxide catalyst is denoted as NiCo. 1.0 / HMs.

[0069] Comparative Example 8:

[0070] A hollow multi-shell nickel-cobalt oxide catalyst is prepared using a method that is essentially the same as that used in Comparative Example 2 for preparing the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs), with the only difference being that in step (1), the amount of nickel acetate tetrahydrate is 0.0045 mol and the amount of cobalt acetate tetrahydrate is 0.009 mol; the resulting hollow multi-shell nickel-cobalt oxide catalyst is denoted as NiCo. 2.0 / HMs Example 2:

[0071] An application of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst of the present invention in the treatment of organic pollutant wastewater specifically involves using the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst to degrade tetracycline hydrochloride in water, including the following steps:

[0072] Take the cobalt vacancy-regulated hollow multi-shell nickel cobalt oxide catalyst (NiCo) from Example 1 respectively vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac Comparative Example 1: Nickel-cobalt oxide catalyst (NiCo2O4); Comparative Example 2: Hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs); Comparative Example 3: Hollow multi-shell nickel-cobalt oxide catalyst (Al-NiCo). vac Comparative Example 4: Hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs-300); Comparative Example 5: Hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs-500); Comparative Example 6: Hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs-300). 0.5 / HMs), Comparative Example 7 Hollow Multishell Nickel Cobalt Oxide Catalyst (NiCo) 1.0 / HMs), Comparative Example 8 Hollow Multishell Nickel Cobalt Oxide Catalyst (NiCo) 2.05 mg of each of the following ingredients (e.g., potassium persulfate) were added to 100 mL of a 10 mg / L solution of tetracycline hydrochloride (TCH) with a pH of 5.00. Then, 1 mL of a 100 mM potassium persulfate solution was added and mixed thoroughly to achieve a potassium persulfate concentration of 1 mM in the reaction system. The reaction was carried out at room temperature and 350 rpm for 60 min to achieve the degradation of tetracycline hydrochloride.

[0073] Figure 7 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 1 of this invention vac / HMs), hollow multi-shell nickel-cobalt oxide catalyst (Al-NiCo) vac The effect of / HMs) activation of persulfate on the degradation of tetracycline hydrochloride. From Figure 7 It can be seen that, compared to NiCo with the addition of zinc acetate dihydrate, vac / HMs, Al-NiCo with added aluminum acetate tetrahydrate vac The degradation activity of / HMs was poor. Furthermore, we tested the metal ion concentrations after the reaction of the two catalysts, Al-NiCo. vac The ion concentrations in the solution after the / HMs reaction were: cobalt 1.69 mg / L, nickel 7.78 mg / L; and NiCo vac The ion concentrations in the solution after the / HMs reaction were: cobalt 0.63 mg / L and nickel 0.78 mg / L, which meet the allowable emission limits for nickel (1 mg / L) and cobalt (1 mg / L) specified in the Chinese national standard (GB 8978-1996). The Al-NiCo... vac / HMs cause more metal ion leaching, easily leading to secondary pollution. It is evident that replacing zinc acetate dihydrate with aluminum acetate tetrahydrate in Comparative Example 3 results in a hollow multi-shell nickel-cobalt oxide catalyst (Al-NiCo). vac The introduction of cobalt vacancies in Al-NiCo ( / HMs) is not ideal, making the Al-NiCo vac / HMs exhibit decreased degradation efficiency for tetracycline hydrochloride and severe metal ion leaching.

[0074] Figure 8 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 2 of this invention vac The effect of activation of persulfate for tetracycline hydrochloride degradation by nickel cobalt oxide catalysts (NiCo / HMs), nickel cobalt oxide catalysts (NiCo2O4), and hollow multi-shell nickel cobalt oxide catalysts (NiCo / HMs). Figure 8 It can be seen that within 60 minutes, NiCo2O4, NiCo / HMs, and NiCo... vacThe removal rates of tetracycline hydrochloride by / HMs were 67.23%, 84.65%, and 95.46%, respectively. This demonstrates that the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) of this invention... vac / HMs) exhibits optimal degradation efficiency and reaction kinetics because: firstly, NiCo vac The nanocavities between the shells of / HMs form a unique nano-enclosed microenvironment that promotes material diffusion and adsorption, and triggers a strong reaction. Specifically, through the nano-densification effect, PMS molecules in solution can not only be concentrated (enriched) into NiCo... vac In the cavity of the / HMs catalyst, the mass transfer distance of PMS can be shortened, the residence time can be prolonged, and the active sites can be fully exposed; secondly, NiCo vac Divalent cobalt and divalent nickel (≡Co(II) / ≡Ni(II)) on the surface of / HMs rapidly come into contact with PMS molecules adsorbed on the catalyst surface. Since the redox potential of Ni(III) / Ni(II) (≤0.86V vs. NHE) is lower than that of Co(III) / Co(II) (~1.80V vs. NHE), the presence of Ni will accelerate the valence state transformation of Co, resulting in high degradation efficiency of the catalyst. Thirdly, the introduction of Co vacancies will activate adjacent Co sites to generate new active sites, thereby further improving the degradation efficiency of the catalyst.

[0075] Figure 9 This is a diagram showing the effect of hollow multi-shell nickel-cobalt oxide catalysts (NiCo / HMs, NiCo / HMs-300, NiCo / HMs-500) activating persulfate to degrade tetracycline hydrochloride in Example 2 of the present invention. Figure 10 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs, NiCo) in Example 2 of this invention 0.5 / HMs、NiCo 1.0 / HMs、NiCo 2.0 The effect of / HMs) activation of persulfate on the degradation of tetracycline hydrochloride. From Figure 9 It can be seen that compared with NiCo / HMs-300 and NiCo / HMs-500, NiCo / HMs exhibits higher degradation activity, while NiCo / HMs-500 has the lowest degradation efficiency. This is because when calcined at 300℃, 400℃, and 500℃, the corresponding catalysts formed have 2, 3, and 4 shells, respectively, while NiCo / HMs-500 has a lower Co content. oh IIIThe -O covalent degree and higher charge transfer energy, coupled with its very narrow micropores and thick outer shell (4 layers), restrict the diffusion of NiCo / HMs-500 during subsequent degradation reactions, resulting in very poor degradation efficiency. Figure 10 It can be seen that as the molar ratio of glucose to metal salt increases from 0.5 to 2.0, the thickness of the catalyst shell decreases, while the removal rate of tetracycline hydrochloride by the catalyst shows a trend of first decreasing, then increasing, and then decreasing again, as seen in NiCo. 1.0 The reaction rate constant of / HMs is 0.03468 min. -1 NiCo 2.0 The reaction rate constant of / HMs is 0.02053 min. -1 Specifically, NiCo 0.5 / HMs showed the highest removal rate of tetracycline hydrochloride because: NiCo 0.5 The excessively high penetration depth of metal ions within / HMs leads to unstable coordination between some metal ions and carbon spheres; NiCo 2.0 / HMs showed the lowest removal rate of tetracycline hydrochloride because: NiCo 2.0 The shell thickness of / HMs is very thin, which cannot well maintain the hollow multi-shell microsphere (HMs) structure. It can be seen that the calcination temperature affects the number of shell layers in the hollow multi-shell structure of the nickel cobalt oxide catalyst, and the ratio of glucose to metal salt affects the shell thickness. Too many or too few shell layers, or too high or too low shell thickness, are all detrimental to the degradation of tetracycline hydrochloride. In contrast, the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) prepared in Comparative Example 2 has a reasonable number of shell layers and shell thickness, high NiCo dispersibility, and fewer transport restrictions.

[0076] Figure 11 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 2 of this invention vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac The effect of using hollow multi-shell nickel-cobalt oxide catalysts (NiCo / HMs) to activate the degradation of tetracycline hydrochloride by persulfate is illustrated in the figure. Figure 11 It can be seen that NiCo vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vacBoth / HMs exhibited excellent catalytic activity, indicating that cobalt vacancy defects have a very positive impact on the catalytic performance of the catalyst, and can significantly improve the degradation efficiency of cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalysts.

[0077] Example 3:

[0078] An application of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst of the present invention in the treatment of organic pollutants, specifically, utilizing the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst to degrade sulfamethoxazole (SMX), carbamazepine (CBZ), rose red B (RhB), and methylene blue (MB) in water, includes the following steps:

[0079] Take 4 portions of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) from Example 1 vac 5 mg of each of the following solutions (Sulfamethoxazole, Carbamazepine, Rose Red B, and Methylene Blue) were added to 100 mL of each solution (10 mg / L): Sulfamethoxazole, Carbamazepine, Rose Red B, and Methylene Blue. Then, 1 mL of 100 mM potassium persulfate solution was added and mixed thoroughly to achieve a potassium persulfate concentration of 1 mM in the reaction system. The reaction was carried out at room temperature and 350 rpm for 60 min to achieve the degradation of Sulfamethoxazole, Carbamazepine, Rose Red B, and Methylene Blue.

[0080] Figure 12 The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) in Example 3 of this invention vac Comparison of the removal effects of / HMs) activated persulfate degradation on sulfamethoxazole, carbamazepine, rose red B, and methylene blue. From Figure 12 It can be seen that within 10 minutes, the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) exhibits significant performance. vac / HMs) can completely degrade ciprofloxacin and rose red B with excellent degradation efficiency. This is because: there is a stronger electrostatic attraction between rose red B and the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst, which enables rapid removal of rose red B; within 20 min, NiCo vac / HMs can completely degrade sulfamethoxazole; within 30 min, NiCo vac / HMs can completely degrade methylene blue. Therefore, the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo) of this invention... vac / HMs) have excellent ability to activate PMS to degrade organic pollutants, showing broad applicability and certain practical application potential.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst, characterized in that, Includes the following steps: S1. Glucose, zinc salt, cobalt salt, nickel salt and water are mixed to obtain a mixed solution; the ratio of the total molar amount of zinc salt and cobalt salt to the molar amount of nickel salt is 2:1, the molar ratio of zinc salt to cobalt salt is 0.05-0.3:2.3-2.55, and the ratio of the molar amount of glucose to the total molar amount of zinc salt, cobalt salt and nickel salt is 0.5-2:

1. S2. The mixed solution obtained in step S1 is subjected to a hydrothermal reaction to obtain the precursor; S3. Calcine the precursor obtained in step S2 to obtain a mixture; S4. Immerse the mixture obtained in step S3 in an alkaline solution and etch it to obtain a cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst; the etching time is 1h to 3h, the alkaline solution is at least one of sodium hydroxide solution and potassium hydroxide solution, and the concentration of the alkaline solution is 2.5M to 3.5M.

2. The preparation method of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst according to claim 1, characterized in that, In step S2, the temperature of the hydrothermal reaction is 160℃~200℃, and the time of the hydrothermal reaction is 360min~440min.

3. The preparation method of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst according to claim 2, characterized in that, In step S3, the calcination temperature is 300℃~500℃, the calcination time is 0.5h~1.5h, the heating rate during the calcination process is 0.5℃ / min~1.5℃ / min, and the calcination is carried out in an air atmosphere.

4. The method for preparing the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst according to any one of claims 1 to 3, characterized in that, In step S1, the specific process of mixing is as follows: (1) Glucose and water are mixed to obtain mixed solution A; the glucose is glucose monohydrate, the mixing is carried out under stirring conditions, the stirring speed is 400 rpm to 500 rpm, and the stirring time is 20 min to 40 min; (2) Mix zinc salt, cobalt salt, nickel salt and water, add mixed solution A, mix again to obtain mixed solution; the zinc salt is zinc acetate dihydrate, the cobalt salt is cobalt acetate tetrahydrate, the nickel salt is nickel acetate tetrahydrate, the mixing is carried out under stirring conditions, the second mixing is carried out under stirring and ultrasonic conditions, the stirring speed is 400 rpm to 500 rpm, the stirring time is 20 min to 40 min, and the ultrasonic time is 0.5 h to 1 h.

5. The method for preparing a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst according to any one of claims 1 to 3, characterized in that, In step S2, after the hydrothermal reaction, the following treatment is performed: the reaction product is centrifuged, washed, and dried; the centrifugation speed is 6000 rpm to 8000 rpm, the centrifugation time is 5 min to 7 min, the washing is performed with ethanol and water, the drying is carried out under vacuum conditions, the drying temperature is 50℃ to 80℃, and the drying time is 10 h to 14 h. In step S3, the following treatment is performed after calcination: the calcined product is washed and dried; In step S4, after etching, the following processing is performed: the etched product is washed and dried; the washing is carried out by water filtration for 8 min to 15 min; the drying is carried out under vacuum conditions at a temperature of 50°C to 80°C for 10 h to 14 h.

6. A cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst prepared by any one of the methods described in claims 1 to 5.

7. The application of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst as described in claim 6 in the treatment of organic pollutant wastewater.

8. The application according to claim 7, characterized in that, Includes the following steps: A cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst is mixed with water containing organic pollutants, and persulfate is added to carry out a degradation reaction to achieve the degradation of organic pollutants in the water. The ratio of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst to the water containing organic pollutants is 0.02g~0.10g∶1L.

9. The application according to claim 8, characterized in that, The amount of persulfate added is 0.1 mmol to 2.0 mmol per liter of water containing organic pollutants. The persulfate is potassium persulfate. The organic pollutants in the water containing organic pollutants include at least one of antibiotics and dyes. The antibiotics are at least one of carbamazepine, tetracycline hydrochloride, and sulfamethoxazole. The dyes are at least one of rose red B and methylene blue. The concentration of organic pollutants in the water containing organic pollutants is ≤10 mg / L. The degradation reaction time is ≥10 min.

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