Cobalt vacancy regulation hollow multi-shell nickel cobalt oxide catalyst as well as preparation method and application thereof

Abstract

The invention discloses a cobalt vacancy regulation hollow multi-shell nickel-cobalt oxide catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: mixing glucose, zinc salt, cobalt salt, nickel salt and water, and carrying out hydrothermal reaction, calcination and etching to obtain the cobalt vacancy regulation hollow multi-shell nickel-cobalt oxide catalyst. According to the preparation method, zinc salt, cobalt salt, nickel salt and glucose are taken as raw materials, metal nickel, cobalt and zinc are crosslinked on polysaccharide through hydrothermal reaction to form a net-shaped structure, carbon and metal zinc on the surface are removed through calcination and etching, and the stable cobalt vacancy regulation hollow multi-shell nickel-cobalt oxide catalyst with the hollow multi-shell structure is formed. The preparation method disclosed by the invention has the advantages of simple process, safe raw materials, low cost, batch production and the like; the prepared cobalt vacancy regulation hollow multi-shell nickel cobalt oxide catalyst has the advantages of good catalytic activity, high degradation efficiency, good stability, strong anti-interference performance, low metal ion leaching rate and the like.

Description

Technical Field

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

[0002] Advanced oxidation technology based on persulfate shows broad application prospects in the remediation of organic pollution in water bodies, especially antibiotics, with peroxydisulfate (PDS) and peroxymonosulfate (PMS) being the most widely used. At present, various catalysts have been used to remediate organic pollution in water bodies, such as transition metal spinels, biochar, etc. Taking transition metal spinels as an example, they are considered to be ideal catalysts for activating persulfates, but their conductivity is poor, some transition metal spinels are prone to agglomeration, resulting in insufficient active sites, and their stability in water environments is poor, which limits the application of transition metal spinels in the field of advanced oxidation. Therefore, how to overcome the above problems and obtain a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with good catalytic activity, high degradation efficiency, good stability, strong anti-interference, and low metal ion leaching rate has become a top priority. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies 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 and low metal ion leaching rate, as well as a preparation method and application thereof.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions.

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

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

[0007] S2, subjecting the mixed solution obtained in step S1 to a hydrothermal reaction to obtain a precursor;

[0008] S3, calcining the precursor obtained in step S2 to obtain a mixture;

[0009] S4, immersing the mixture obtained in step S3 in an alkaline solution for etching to obtain a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies.

[0010] The above preparation method is further improved. In step S1, the ratio of the total molar amount of the zinc salt and the 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 ratio of the molar amount of glucose to the total molar amount of the zinc salt, the cobalt salt and the nickel salt is 0.5-2:1.

[0011] The above preparation method is further improved, in step S2, the temperature of the hydrothermal reaction is 160°C to 200°C, and the time of the hydrothermal reaction is 360min to 440min.

[0012] The above preparation method is further improved, in step S3, the calcination temperature is 300°C to 500°C, the calcination time is 0.5h to 1.5h, the heating rate during the calcination process is 0.5°C / min to 1.5°C / min, and the calcination is carried out in an air atmosphere.

[0013] The above preparation method is further improved, in step S1, the specific process of mixing is:

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

[0015] (2) Mixing zinc salt, cobalt salt, nickel salt and water, adding mixed solution A, and mixing again to obtain a mixed solution; the zinc salt is zinc acetate dihydrate, the cobalt salt is cobalt acetate tetrahydrate, and the nickel salt is nickel acetate tetrahydrate, the mixing is carried out under stirring conditions, and the re-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] The above preparation method is further improved, in step S2, the following treatment is further performed after the hydrothermal reaction: the reaction product is centrifuged, washed, and dried; the centrifugal speed is 6000rpm to 8000rpm, the centrifugal time is 5min to 7min, the washing is performed using ethanol and water, the drying is performed under vacuum conditions, the drying temperature is 50°C to 80°C, and the drying time is 10h to 14h;

[0017] In step S3, the following treatments are further performed after the calcination: washing and drying the calcined product;

[0018] In step S4, the etching time is 1h to 3h, the alkaline solution is at least one of a sodium hydroxide solution and a potassium hydroxide solution, the concentration of the alkaline solution is 2.5M to 3.5M, and the following treatments are performed after the etching: the etching product is washed and dried; the washing is performed by filtration with water, the filtration time is 8min to 15min, the drying is performed under vacuum conditions, the drying temperature is 50°C to 80°C, 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 preparation method of the 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 treating organic pollutant wastewater.

[0021] The above application is further improved, comprising the following steps: mixing the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies and water containing organic pollutants, adding persulfate to carry out degradation reaction, and realizing the degradation of organic pollutants in the water; the ratio of the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies to the water containing organic pollutants is 0.02g~0.10g:1L.

[0022] The above application is further improved, wherein the amount of persulfate added is 0.1 mmol to 2.0 mmol per liter of water containing organic pollutants, the persulfate is potassium hydrogen persulfate, the organic pollutants in the water containing organic pollutants include at least one of antibiotics and dyes, the antibiotic is at least one of carbamazepine, tetracycline hydrochloride and sulfamethoxazole, the dye is 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, and the degradation reaction time is ≥10 min.

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

[0024] (1) The present invention discloses a method for preparing a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies, wherein zinc salt, cobalt salt, nickel salt and glucose are used as raw materials, and metal nickel, cobalt and zinc are cross-linked on polysaccharides to form a network structure through a hydrothermal reaction, and then calcined and etched to remove carbon and metal zinc on the surface to form a stable hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies with a hollow multi-shell structure. The preparation method of the present invention has the advantages of simple process, safe raw materials, low cost, and batch production; the prepared hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies has the advantages of good catalytic activity, high degradation efficiency, good stability, strong anti-interference, and low metal ion leaching rate.

[0025] (2) The preparation method of the present invention can obtain a cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with an appropriate shell thickness by optimizing the ratio of the molar amount of glucose to the total molar amount of zinc salt, cobalt salt, and nickel salt to 0.5 to 2:1, thereby achieving efficient degradation of organic pollutants. When the molar ratio of glucose to metal salt (the total molar amount of zinc salt, cobalt salt, and nickel salt) is too high, the shell wall thickness of the catalyst will become thinner, and the thin shell wall is not easy to maintain the hollow multi-shell microsphere (HMs) structure, resulting in structural collapse; when the molar ratio of glucose to metal salt (the total molar amount of zinc salt, cobalt salt, and nickel salt) is too low, the shell wall thickness of the catalyst will become thicker, and the thick shell wall will affect the mass transfer efficiency of the catalyst. That is to say, the molar ratio of glucose to metal salt (the total molar amount of zinc salt, cobalt salt, and nickel salt) is too high or too low, which is not conducive to the degradation of organic pollutants by the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst.

[0026] (3) The preparation method of the present invention can obtain a hollow multi-shell nickel-cobalt oxide catalyst with an appropriate number of shell layers regulated by cobalt vacancies by optimizing the calcination temperature to 300°C to 500°C, 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 of ​​the catalyst and reduce the number of active sites. In other words, too many or too few shell layers are not conducive to the degradation of organic pollutants by the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies.

[0027] (4) The present invention also provides an application of a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies in treating wastewater with organic pollutants. By directly mixing the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies and water with organic pollutants, and then adding persulfate for degradation reaction, the organic pollutants in the water can be effectively degraded. The catalyst has the advantages of simple operation, good degradation effect, and low cost, and is suitable for various complex and changeable practical application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), the nickel cobalt oxide catalyst in Comparative Example 1 (NiCo2O4), and the hollow multi-shell nickel cobalt oxide catalyst in Comparative Example 2 (NiCo / HMs).

[0029] Figure 2 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs).

[0030] Figure 3 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), the nickel cobalt oxide catalyst in Comparative Example 1 (NiCo2O4), and the hollow multi-shell nickel cobalt oxide catalyst in Comparative Example 2 (NiCo / HMs).

[0031] Figure 4 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), 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 are shown in Figure 2.

[0032] Figure 5 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), the nickel cobalt oxide catalyst in Comparative Example 1 (NiCo2O4), and the hollow multi-shell nickel cobalt oxide catalyst in Comparative Example 2 (NiCo / HMs).

[0033] Figure 6 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), electron paramagnetic resonance spectrum of the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2.

[0034] Figure 7 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), hollow multi-shell nickel cobalt oxide catalyst (Al-NiCo vac / HMs) activated persulfate to degrade tetracycline hydrochloride.

[0035] Figure 8The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), nickel cobalt oxide catalyst (NiCo2O4), and hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) activated persulfate to degrade tetracycline hydrochloride.

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

[0037] Fig.10 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs, NiCo 0.5 / HMs、NiCo 1.0 / HMs、NiCo 2.0 / HMs) activated persulfate to degrade tetracycline hydrochloride.

[0038] Fig.11 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac / HMs) and hollow multi-shell nickel cobalt oxide catalysts (NiCo / HMs) to activate persulfate for the degradation of tetracycline hydrochloride.

[0039] Fig.12 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs) activated persulfate to degrade sulfamethoxazole, carbamazepine, rose bengal B, and methylene blue. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.

[0041] Embodiment 1:

[0042] A method for preparing a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies of the present invention comprises the following steps:

[0043] (1) 0.028 mol of glucose monohydrate was dissolved in 10 mL of deionized water, and the mixture was vigorously stirred at a stirring speed of 500 rpm for 30 min to be completely dissolved, thereby obtaining a mixed solution A; 0.013 mol of nickel acetate tetrahydrate, 0.025 mol of cobalt acetate tetrahydrate and 0.001 mol of zinc acetate dihydrate were dissolved in 40 mL of deionized water, and the mixture was stirred at a stirring speed of 400 rpm for 30 min to obtain a mixed solution B; the mixed solution A and the mixed solution B were transferred to a 100 mL polytetrafluoroethylene-lined autoclave, and the mixture was stirred at a stirring speed of 400 rpm for 30 min, and then ultrasonicated for 30 min to completely mix the mixture to obtain a mixed solution.

[0044] (2) The mixed solution obtained in step (1) was subjected to a hydrothermal reaction at 180° C. for 400 min. After the reaction was completed and naturally cooled, the reaction product was collected by centrifugation at a speed of 7000 rpm for 5 min, first washed with anhydrous ethanol for 3 times, then washed with deionized water for 3 times, and 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 quartz boat with a lid, placed in a tube furnace, and heated to 400°C at a heating rate of 1°C / min in a static air atmosphere for calcination, and kept at 400°C for 1 hour. After the tube furnace is cooled to room temperature, the calcined product is taken out and ground, and the ground product is washed three times with deionized water, collected by centrifugation at a speed of 7000 rpm for 6 minutes, and dried in a vacuum drying oven at 60°C for 12 hours to obtain a mixture.

[0046] (4) Immersing the mixture obtained in step (3) in a sodium hydroxide solution (the concentration of the solution is 3M) for 2 hours for etching; then, the etched product is passed through a vacuum filtration device, washed with deionized water for 15 minutes until the filtrate is 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 metal salt amounts were prepared, and the preparation method was the same as that of the cobalt vacancy regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac The preparation method of the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy is basically the same as that of the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy. The only difference is that 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 metal salt amounts were prepared, and the preparation method was similar to that of cobalt vacancy regulated hollow multi-shell nickel-cobalt oxide catalysts (NiCo vac The preparation method of the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy is basically the same as that of the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy. The only difference is that 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 the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac The preparation method of the catalyst is basically the same as that of the catalyst of the present invention, except 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 prepared 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 hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac The preparation method of the hollow multi-shell nickel-cobalt oxide catalyst is basically the same as that of the hollow multi-shell nickel-cobalt oxide catalyst NiCo / HMs, except 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 prepared 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 hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac The preparation methods of the hollow multi-shell nickel-cobalt oxide catalysts are basically the same as those of the hollow multi-shell nickel-cobalt oxide catalysts (Al-NiCo / HMs), except that: in step (1), aluminum acetate tetrahydrate is used to replace zinc acetate dihydrate, and the amount of aluminum acetate tetrahydrate used is 0.001 mol; the hollow multi-shell nickel-cobalt oxide catalysts prepared are denoted as Al-NiCo vac / HMs.

[0055] Figure 1 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), the nickel cobalt oxide catalyst in Comparative Example 1 (NiCo2O4), and the hollow multi-shell nickel cobalt oxide catalyst in Comparative Example 2 (NiCo / HMs). Figure 1Among them, (a) and (b) are NiCo2O4, (c) and (d) are NiCo / HMs, (e) and (f) are NiCo vac / HMs. Figure 1 It can be seen that due to the absence of glucose, the nickel cobalt oxide catalyst (NiCo2O4) presents an irregular shape and a rough surface; while the NiCo / HMs catalyst with glucose presents a porous surface and a relatively uniform spherical structure, and its formation process is: metal nickel and cobalt form a network structure on the polysaccharide through cross-linking. vac / HMs) contains a multi-shell hollow structure of nano-scale units, and its formation process is as follows: metal nickel, cobalt and zinc form a network structure on the polysaccharide through cross-linking, and then calcination and etching are performed to remove the carbon and metal zinc on the surface to form a stable cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst with a hollow multi-shell structure.

[0056] Figure 2 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs). Figure 2 Among them, (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-layer shell structure; from (c) to (f), it can be seen that the material has a disordered lattice staggered arrangement and no large continuous and uniform lattice plane; in (c) and (d), the lattice fringes of 0.224nm and 0.220nm correspond to the (222) plane of NiCo2O4, and the lattice fringes of 0.283nm and 0.1999nm correspond to the (220) and (400) planes of NiCo2O4, respectively, which is consistent with the results of the XRD spectrum. It can be seen that cobalt vacancies regulate the hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs) exhibit a porous, spherical structure with three shells.

[0057] Figure 3 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), the nickel cobalt oxide catalyst in Comparative Example 1 (NiCo2O4), and the hollow multi-shell nickel cobalt oxide catalyst in Comparative Example 2 (NiCo / HMs). Figure 3 It can be seen that NiCo2O4, NiCo / HMs, NiCo vacThe characteristic diffraction peaks of / HMs at 2θ of 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, which is consistent with the standard card JCPDS card number 73-1702, that is, NiCo2O4, NiCo / HMs, NiCo vac / HMs all have spinel nickel-cobalt oxide morphology, proving the successful synthesis of each catalyst. vac The peaks of the NiCo2O4 and NiCo / HMs samples are weaker than those of the NiCo2O4 and NiCo / HMs samples. This is 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 24.8, 33.2, 42.0 and 52.7° 2θ can be attributed to the (003), (004), (005) and (006) crystal planes of CoO2, respectively. vac The diffraction peak of / HMs at 21.1° represents the (002) plane reflection of the carbon material, which indicates that about 3% of the carbon sphere template has not been removed.

[0058] Figure 4 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), 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 are shown in Figure 2. Figure 4 In the figure, (a) is the isothermal adsorption-desorption curve, and (b) is the pore size distribution diagram. Figure 4 It can be seen that NiCo2O4, NiCo / HMs, NiCo vac The average pore size distribution of / HMs is relatively wide, concentrated at around 40.62nm, 10.76nm, and 13.18nm, respectively, which is consistent with the mesoporous characteristics (2-50nm); at the same time, the hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs) has the best number of mesopores and the largest BET surface area, which is not only beneficial to the adsorption and activation of PMS on the catalyst surface, but also to the oxidation and degradation of organic pollutants by active substances near the catalyst surface, showing excellent reaction kinetics, thereby achieving efficient and rapid removal of organic pollutants.

[0059] Figure 5 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo vacXPS graphs 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 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-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), the electron paramagnetic resonance spectrum 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 showed a stronger EPR signal (g = 2.005), namely NiCo vac / HMs have a higher vacancy concentration, which is attributed to the V centers caused by the increase of 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, the preparation method of which is basically the same as the preparation method of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, the only difference being that in step (3), the calcination temperature is 300° C.; the hollow multi-shell nickel-cobalt oxide catalyst prepared is recorded as NiCo / HMs-300.

[0063] Comparative Example 5:

[0064] A hollow multi-shell nickel-cobalt oxide catalyst, the preparation method of which is basically the same as the preparation method of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, the only difference being that in step (3), the calcination temperature is 500° C.; the hollow multi-shell nickel-cobalt oxide catalyst prepared is recorded as NiCo / HMs-500.

[0065] Comparative Example 6:

[0066] A hollow multi-shell nickel-cobalt oxide catalyst, the preparation method of which is basically the same as the preparation method of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, 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 hollow multi-shell nickel-cobalt oxide catalyst prepared is denoted as NiCo 0.5 / HMs.

[0067] Comparative Example 7:

[0068] A hollow multi-shell nickel-cobalt oxide catalyst, the preparation method of which is basically the same as the preparation method of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, 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 hollow multi-shell nickel-cobalt oxide catalyst prepared is denoted as NiCo 1.0 / HMs.

[0069] Comparative Example 8:

[0070] A hollow multi-shell nickel-cobalt oxide catalyst, the preparation method of which is basically the same as the preparation method of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, except 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 hollow multi-shell nickel-cobalt oxide catalyst prepared is recorded 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 treating organic pollutant wastewater, specifically using the cobalt vacancy regulated hollow multi-shell nickel-cobalt oxide catalyst to degrade tetracycline hydrochloride in water, comprising the following steps:

[0072] The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac / HMs), the nickel cobalt oxide catalyst (NiCo2O4) in Comparative Example 1, the hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) in Comparative Example 2, the hollow multi-shell nickel cobalt oxide catalyst (Al-NiCo vac / HMs), 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 0.5 / HMs), Comparative Example 7 Hollow Multi-shell Nickel Cobalt Oxide Catalyst (NiCo 1.0 / HMs), Comparative Example 8 Hollow Multi-shell Nickel Cobalt Oxide Catalyst (NiCo 2.0 / HMs), 5 mg each, were added into 100 mL of a tetracycline hydrochloride (TCH) solution with a concentration of 10 mg / L and a pH of 5.00, and then 1 mL of a 100 mM potassium persulfate solution was added and mixed evenly, so that the concentration of potassium persulfate in the reaction system was 1 mM, and the catalytic reaction was carried out at room temperature and a rotation speed of 350 rpm for 60 minutes to achieve the degradation of tetracycline hydrochloride.

[0073] Figure 7 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), hollow multi-shell nickel cobalt oxide catalyst (Al-NiCo vac / HMs) activated persulfate to degrade tetracycline hydrochloride. Figure 7 It can be seen that compared with the NiCo vac / HMs, Al-NiCo with addition of aluminum acetate tetrahydrate vac / HMs degradation activity is poor. In addition, we tested the metal ion concentrations of the two catalysts after the reaction, Al-NiCo vac / HMs reaction solution ion concentrations are: cobalt 1.69mg / L, nickel 7.78mg / L; and NiCo vac / HMs reaction solution ion concentrations are: cobalt 0.63mg / L, nickel 0.78mg / L, in line with the Chinese national standard (GB 8978-1996) nickel (1mg / L) and cobalt (1mg / L) allowable emission limits, while Al-NiCo vac / HMs causes more metal ion leaching, which is easy to cause secondary pollution. It can be seen that in Comparative Example 3, zinc acetate dihydrate is replaced by aluminum acetate tetrahydrate to obtain the hollow multi-shell nickel cobalt oxide catalyst (Al-NiCo vac / HMs) is not ideal, which makes Al-NiCo vac The degradation efficiency of tetracycline hydrochloride by / HMs decreased, and there was serious metal ion leaching.

[0074] Figure 8 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), nickel cobalt oxide catalyst (NiCo2O4), and hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) activated persulfate to degrade tetracycline hydrochloride. Figure 8 It can be seen that within 60 min, NiCo2O4, NiCo / HMs, NiCo vac / HMs for tetracycline hydrochloride removal rates were 67.23%, 84.65%, and 95.46%, respectively. It can be seen that the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs) have the best degradation efficiency and reaction kinetics, because: First, NiCo vac The nano-cavities between the shells of HMs form a special nano-enclosed microenvironment, which can promote the diffusion and adsorption of substances and induce a strong reaction. That is, through the nano-densification effect, the PMS molecules in the solution can not only be concentrated (enriched) to the NiCo vac / HMs catalyst cavity can also shorten the mass transfer distance of PMS, prolong the residence time, and promote the full exposure of active sites; secondly, NiCo vac The divalent cobalt and divalent nickel (≡Co(II) / ≡Ni(II)) on the surface of / HMs quickly contact the 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 conversion of Co, making the catalyst show high degradation efficiency; third, the introduction of Co vacancies will activate the adjacent Co sites to produce new active sites, thereby further improving the degradation efficiency of the catalyst.

[0075] Fig. 9 This is a diagram showing the effect of hollow multi-shell nickel cobalt oxide catalysts (NiCo / HMs, NiCo / HMs-300, NiCo / HMs-500) in Example 2 of the present invention on the degradation of tetracycline hydrochloride by activating persulfate. Fig.10 The hollow multi-shell nickel-cobalt oxide catalyst (NiCo / HMs, NiCo 0.5 / HMs、NiCo 1.0 / HMs、NiCo 2.0 / HMs) activated persulfate to degrade tetracycline hydrochloride. Fig. 9 It can be seen that compared with NiCo / HMs-300 and NiCo / HMs-500, NiCo / HMs has higher degradation activity, while NiCo / HMs-500 has the lowest degradation efficiency. This is because: when the calcination temperatures are 300℃, 400℃, and 500℃, the corresponding catalysts have 2, 3, and 4 shells, respectively, while NiCo / HMs-500 has a lower Co oh III-O covalent degree and higher charge transfer energy, and its very narrow micropores and thick shell (4 layers of shell) will limit the diffusion of NiCo / HMs-500 in the subsequent degradation reaction, making the degradation efficiency of NiCo / HMs-500 very poor. Fig.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, and the removal rate of tetracycline hydrochloride by the catalyst shows a trend of first decreasing, then increasing, and then decreasing. 1.0 The reaction rate constant of / HMs is 0.03468min -1 、NiCo 2.0 The reaction rate constant of / HMs is 0.02053min -1 Specifically, NiCo 0.5 / HMs has the highest removal rate for tetracycline hydrochloride, because: NiCo 0.5 The penetration depth of metal ions in / HMs is too high, resulting in unstable coordination between some metal ions and carbon spheres; NiCo 2.0 / HMs has the lowest removal rate for tetracycline hydrochloride, which is because: NiCo 2.0 The shell thickness of / HMs is very thin, and the hollow multi-shell microsphere (HMs) structure cannot be well maintained. It can be seen that the calcination temperature affects the number of shell layers of the hollow multi-shell structure of the hollow multi-shell nickel cobalt oxide catalyst, and the ratio of glucose to metal salt affects the shell thickness of the hollow multi-shell structure of the hollow multi-shell nickel cobalt oxide catalyst. Too many or too few shell layers, too high or too low shell thickness are not conducive to the degradation of tetracycline hydrochloride, and 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 less transmission restrictions of NiCo / HMs.

[0076] Fig.11 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac / HMs), hollow multi-shell nickel cobalt oxide catalyst (NiCo / HMs) activated persulfate to degrade tetracycline hydrochloride. Fig.11 It can be seen that NiCo vac / HMs, 0.0005-NiCo vac / HMs, 0.003-NiCo vac / HMs all exhibited excellent catalytic activity, indicating that cobalt vacancy defects had a very positive effect on the catalytic performance of the catalyst, which could significantly improve the degradation efficiency of the cobalt vacancy-regulated hollow multi-shelled nickel-cobalt oxide catalyst.

[0077] Embodiment 3:

[0078] An application of the cobalt vacancy regulation hollow multi-shell nickel-cobalt oxide catalyst in treating organic pollutants, specifically using the cobalt vacancy regulation hollow multi-shell nickel-cobalt oxide catalyst to degrade sulfamethoxazole (SMX), carbamazepine (CBZ), rose bengal B (RhB) and methylene blue (MB) in water, comprising the following steps:

[0079] Take 4 portions of the hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs), 5 mg each, were added to 100 mL of sulfamethoxazole solution, carbamazepine solution, rose bengal B solution and methylene blue solution with a volume of 100 mL and a concentration of 10 mg / L, and then 1 mL of potassium persulfate solution with a concentration of 100 mM was added and mixed evenly, so that the concentration of potassium persulfate in the reaction system was 1 mM, and the catalytic reaction was carried out at room temperature and a rotation speed of 350 rpm for 60 min to achieve the degradation of sulfamethoxazole, carbamazepine, rose bengal B and methylene blue.

[0080] Fig.12 The cobalt vacancy-controlled hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs) activated persulfate to degrade sulfamethoxazole, carbamazepine, rose bengal B, and methylene blue. Fig.12 It can be seen that within 10 min, the cobalt vacancies regulated the hollow multi-shell nickel cobalt oxide catalyst (NiCo vac / HMs) can completely degrade ciprofloxacin and Rose Bengal B with excellent degradation efficiency. This is because: Rose Bengal B and the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst have stronger electrostatic attraction, which can achieve rapid removal of Rose Bengal B; within 20 min, NiCo vac / HMs can completely degrade sulfamethoxazole; within 30 min, NiCo vac / HMs can completely degrade methylene blue. It can be seen that the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst (NiCo vac / HMs) have excellent ability to activate PMS to degrade organic pollutants, showing wide applicability and certain practical application potential.

[0081] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies, characterized in that: The following steps are involved: S1, mixing glucose, zinc salt, cobalt salt, nickel salt and water to obtain a mixed solution; S2, subjecting the mixed solution obtained in step S1 to a hydrothermal reaction to obtain a precursor; S3, calcining the precursor obtained in step S2 to obtain a mixture; S4, immersing the mixture obtained in step S3 in an alkaline solution for etching to obtain a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancies.

2. The method for preparing the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy according to claim 1, characterized in that: In step S1, the ratio of the total molar amount of the zinc salt and the 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 ratio of the molar amount of glucose to the total molar amount of the zinc salt, the cobalt salt and the nickel salt is 0.5-2:

1.

3. The method for preparing the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy according to claim 2, characterized in that: In step S2, the temperature of the hydrothermal reaction is 160°C to 200°C, and the time of the hydrothermal reaction is 360min to 440min.

4. The method for preparing the hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy according to claim 3, characterized in that: In step S3, the calcination temperature is 300°C to 500°C, the calcination time is 0.5h to 1.5h, the heating rate during the calcination process is 0.5°C / min to 1.5°C / min, and the calcination is carried out in an air atmosphere.

5. The method for preparing a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy according to any one of claims 1 to 4, characterized in that: In step S1, the specific process of the mixing is: (1) Mixing glucose and water to obtain a mixed solution A; the glucose is glucose monohydrate, the mixing is performed under stirring conditions, the stirring speed is 400 rpm to 500 rpm, and the stirring time is 20 min to 40 min; (2) Mixing zinc salt, cobalt salt, nickel salt and water, adding mixed solution A, and mixing again to obtain a mixed solution; the zinc salt is zinc acetate dihydrate, the cobalt salt is cobalt acetate tetrahydrate, and the nickel salt is nickel acetate tetrahydrate, the mixing is carried out under stirring conditions, and the re-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.

6. The method for preparing a hollow multi-shell nickel-cobalt oxide catalyst regulated by cobalt vacancy according to any one of claims 1 to 4, characterized in that: In step S2, the following treatments are further performed after the hydrothermal reaction: the reaction product is centrifuged, washed, and dried; the centrifugal speed is 6000 rpm to 8000 rpm, the centrifugal time is 5 min to 7 min, the washing is performed using ethanol and water, the drying is performed under vacuum conditions, the drying temperature is 50° C. to 80° C., and the drying time is 10 h to 14 h; In step S3, the following treatments are further performed after the calcination: washing and drying the calcined product; In step S4, the etching time is 1h to 3h, the alkaline solution is at least one of a sodium hydroxide solution and a potassium hydroxide solution, the concentration of the alkaline solution is 2.5M to 3.5M, and the following treatments are performed after the etching: the etching product is washed and dried; the washing is performed by filtration with water, the filtration time is 8min to 15min, the drying is performed under vacuum conditions, the drying temperature is 50°C to 80°C, and the drying time is 10h to 14h.

7. A cobalt vacancy regulated hollow multi-shell nickel-cobalt oxide catalyst prepared by the method for preparing a cobalt vacancy regulated hollow multi-shell nickel-cobalt oxide catalyst according to any one of claims 1 to 6.

8. Use of the cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst as claimed in claim 7 in treating organic pollutant wastewater.

9. The use according to claim 8, characterized in that: The following steps are involved: The cobalt vacancy-regulated hollow multi-shell nickel-cobalt oxide catalyst and water containing organic pollutants are mixed, 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.

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

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