Preparation method of catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, catalytic material and application

Abstract

The invention provides a preparation method of a catalytic material for selectively generating singlet oxygen by electrocatalytic activated water, the catalytic material and application, and belongs to the technical field of water treatment.The preparation method comprises the steps that Cr (NO3) 3.9 H2O, MnCl2. 4H2O and PVP are jointly dissolved in water and fully stirred, and a reaction solution is obtained; performing vacuum drying or freeze drying on the reaction liquid to obtain a mixture; calcining the mixture at 750 + / -5 DEG C for 1 + / -0.1 h in an inert atmosphere, and then calcining at 250 + / -5 DEG C for 2 + / -0.1 h to obtain a calcined product; and grinding the calcined product to obtain the catalytic material of 200 + / -5 meshes. The catalytic material prepared by the method can activate H2O in the presence of an external electric field to selectively generate < 1 > O2, so that efficient degradation of organic pollutants is realized, and the process does not cause excessive sulfate or residual organic matters to be introduced into water, so that the method is more environment-friendly and economical.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and particularly relates to a preparation method of a catalytic material for selectively generating singlet oxygen from electrocatalytically activated water, a catalytic material and an application thereof. Background Art

[0002] With the improvement of industrialization level, people's requirements for environmental quality are getting higher and higher. Most persistent organic matter in industrial wastewater is highly toxic and difficult to degrade, which has attracted widespread attention. Singlet oxygen ( 1 O2) is considered to be the most promising oxidizing species for degrading organic pollutants. 1 O2 is still mainly produced by the electro-Fenton process, in which it is mainly produced by activating oxidants / precursors [peroxymonosulfate (PMS), persulfate (PS) and peracetic acid (PAA)] 1 O2, but this activation process will introduce excess sulfate or residual organic matter into the water. Therefore, in an external electric field environment, it is spontaneously generated by H2O activation. 1 O2 is considered to be an environmentally friendly and economical advanced oxidation process.

[0003] The currently published related patents are as follows:

[0004] Public patent 1: A high-coordinated iron single-atom catalyst for highly selectively generating singlet oxygen in electro-Fenton, a preparation method and its application (CN202410036211.4). This patent proposes a high-coordinated iron single-atom catalyst for highly selectively generating singlet oxygen in the electro-Fenton process. The high-coordinated iron single-atom active sites in the high-coordinated iron single-atom catalyst are loaded on graphite phase carbon nitride in a hexacoordinated form, so that the iron presents a high spin state, so that the contribution rate to singlet oxygen in the electro-Fenton degradation process of pollutants is close to 100%. However, this process requires additional exposure to oxygen, which leads to additional energy consumption.

[0005] Public patent 2: A method for preparing an iron single-atom catalyst for activating persulfate to generate singlet oxygen and its application in degrading new pollutants in water bodies (CN202310604918.6). This patent uses iron salts, nitrogen-containing organic precursors and templates as raw materials, and obtains an iron single-atom catalyst through mixed reaction, pyrolysis, acid washing and drying. The iron single-atom catalyst can efficiently activate permonosulfate (PMS) to produce singlet oxygen, and effectively degrade organic pollutants in wastewater through a singlet oxygen non-radical pathway. However, the activation of PMS not only leads to the generation of other free radicals and a decrease in selectivity, but the introduction of sulfate can easily cause secondary pollution of environmental water bodies.

[0006] Public patent three: Fe-N-4 active site single atom catalyst for selectively generating singlet oxygen by activating peroxydisulfate and its preparation method and application (CN202210801967.4). The single atom catalyst described in this patent is prepared by high-temperature pyrolysis of two MOFs, NH-2-MI L-53 and ZIF-8, as precursors; the catalytic center structure of the single atom catalyst is Fe-N-4. The catalyst of the present invention acts as an electron transfer mediator to activate peroxydisulfate (PDS) to generate singlet oxygen ( 1 O2) as an active species for degrading pollutants. However, single-atom catalysts are prone to deactivation during long-term use, resulting in a decrease in the actual application effect.

[0007] Therefore, the activation of H2O selectively generates 1 O2, it is of great value to develop heterogeneous electrocatalytic materials with fast mass transfer, high activity, and the ability to be recycled multiple times. Summary of the invention

[0008] In order to solve the problem of selective generation of 1 The present invention provides a method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen. The catalytic material prepared by the method can activate H2O to selectively generate singlet oxygen in the presence of an external electric field. 1 O2, thereby achieving efficient degradation of organic pollutants, and this process will not cause excessive sulfate or residual organic matter to be introduced into the water, which is more environmentally friendly and economical.

[0009] The present invention also provides a catalytic material for selectively generating singlet oxygen by electrocatalytically activating water and its application.

[0010] The present invention is achieved through the following technical solutions:

[0011] The present invention provides a method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, the preparation method comprising:

[0012] Dissolve Cr(NO3)3·9H2O, MnCl2·4H2O and PVP (polyvinyl pyrrolidone) in water and stir well to obtain a reaction solution;

[0013] vacuum drying or freeze drying the reaction solution to obtain a mixture;

[0014] In an inert atmosphere, the mixture is calcined at 750±5° C. for 1±0.1 h, and then calcined at 250±5° C. for 2±0.1 h to obtain a calcined product;

[0015] The calcined product was ground to obtain a catalytic material of 200±5 mesh.

[0016] Further, the Cr(NO3)3·9H2O, MnCl2·4H2O and PVP are dissolved in water and stirred sufficiently to obtain a reaction solution, which specifically includes:

[0017] Dissolve Cr(NO3)3·9H2O, MnCl2·4H2O and PVP in water, stir at 25±5℃ for 1±0.1h to obtain a reaction solution;

[0018] Among them, the mass ratio of Cr(NO3)3·9H2O, MnCl2·4H2O and PVP is 1:0.4925:1;

[0019] The K value of the PVP is 30.

[0020] Further, the reaction solution is vacuum dried or freeze dried to obtain a mixture, specifically comprising:

[0021] The reaction solution is vacuum dried or freeze dried, the vacuum drying temperature is 60±5° C., and the vacuum drying time is 10±0.1 h.

[0022] Further, in an inert atmosphere, the mixture is calcined at 750±5°C for 1±0.1h, and then calcined at 250±5°C for 2±0.1h to obtain a calcined product, which specifically includes:

[0023] In an inert atmosphere, the mixture is calcined at 750±5°C for 1±0.1h with a heating rate of 10°C / min, and after the calcination, it is cooled to 30-50°C to obtain a primary product;

[0024] In an inert atmosphere, the primary product is calcined at 250±5° C. for 2±0.1 h at a heating rate of 5° C. / min to obtain a calcined product.

[0025] Further, the calcined product is ground to obtain a catalytic material of 200±5 mesh, which specifically includes:

[0026] The calcined product was ground for 10±5 min to obtain a catalytic material of 200±5 mesh.

[0027] Based on the same inventive concept, the present invention provides a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen. The catalytic material is prepared by the above-mentioned method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen.

[0028] Based on the same inventive concept, the present invention provides a catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen. The catalytic material is a core-shell structure. The core-shell structure has a chromium-manganese double transition metal oxide as a core and a loose amorphous carbon layer as a shell. The structural formula of the catalytic material is Cr x Mn y O z @C, where the atomic percentage of Cr is 8.65%, the atomic percentage of Mn is 16.92%, and the total effective magnetic moment (μ eff ) is 3.71μb, corresponding to e g =0.89, the catalytic material can activate H2O selectively to generate 1 O2.

[0029] Based on the same inventive concept, the present invention provides a catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen. 1 Application of O2 or degradation of organic pollutants.

[0030] Based on the same inventive concept, the present invention also provides a method for catalytic degradation of organic pollutants, the method comprising:

[0031] Dispersing the above-mentioned catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen in a naphthol-ethanol solution to obtain a mixed solution;

[0032] The mixed solution is evenly coated on the surface of carbon paper to obtain a working electrode;

[0033] The working electrode, the reference electrode and the counter electrode form a three-electrode system, which is placed in water containing electrolytes and organic pollutants, and a voltage is applied to degrade the organic pollutants in a constant current mode.

[0034] Further, the naphthol-ethanol solution is prepared by mixing anhydrous ethanol and naphthol;

[0035] The ratio of the mass of the catalytic material, the volume of the anhydrous ethanol and the volume of the naphthol is 20 mg: 1 mL: 0.05 mL;

[0036] The loading amount of the catalytic material in the working electrode is 1±0.1 mg / cm 2 .

[0037] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0038] 1. The present invention discloses a method for preparing a catalytic material for selectively generating singlet oxygen from electrocatalytically activated water. The method uses Cr(NO)3 and MnCl2 as metal sources and PVP as carbon source. The three are mixed and then calcined in two stages under an inert atmosphere to form a catalytic material with a core-shell structure. The prepared catalytic material has a double transition metal oxide as a core and a loose amorphous carbon layer as a shell. Due to the interaction between the double metals, the oxygen-containing intermediates in the active site (Mn(Mn 0.193 Cr 1.808 )O4), thereby inducing the accumulation of singlet oxygen precursors (*OO), thereby achieving efficient generation of singlet oxygen. At the same time, the presence of the carbon shell improves the stability of the catalytic material, avoids the leaching of internal transition metals, ensures the catalytic activity and avoids the generation of secondary pollution. The preparation process of this method is simple, and the prepared catalytic material has a high catalytic efficiency in the process of activating water to produce singlet oxygen, which provides a basis for efficient H2O activation and production under ambient conditions. 1 O2 offers a promising solution.

[0039] 2. The present invention discloses a catalytic material for selectively generating singlet oxygen from electrocatalytically activated water, which comprises metal particles grown on a loose porous carbon substrate and wrapped by an amorphous carbon layer. The catalytic material contains a large number of unpaired electrons, has a double transition metal oxide as a core, and a loose amorphous carbon layer as a shell, and has a structural formula of Cr x Mn y O z @C, according to the results of inductively coupled plasma, the atomic percentage of Cr is 8.65%, and the atomic percentage of Mn is 16.92%. According to the magnetic moment change curve, the Cr x Mn y O z The total effective magnetic moment (μ eff ) is 3.71μb, corresponding to e g =0.89, the catalytic material can activate the selective generation of H2O in the presence of an external electric field 1 O2, to achieve H2O 1 The selective conversion of O2 can achieve efficient degradation of organic pollutants, and this process will not cause excessive sulfate or residual organic matter to be introduced into the water, which is more environmentally friendly and economical.

[0040] 3. The present invention discloses a catalytic material for selectively generating singlet oxygen from electrocatalytically activated water. The catalytic material has a double transition metal oxide as a core and a loose amorphous carbon layer as a shell. Based on the difference in electronegativity between Cr and Mn, under the synergistic effect of the double transition metals, the number of unpaired electrons in the catalytic material can be increased, the adsorption capacity of the material for oxygen-containing intermediates can be optimized, the activation effect on H2O can be improved, and the activation effect on H2O can be promoted. 1The production of O2 can activate H2O to produce 1 O2, and based on the construction of core-shell morphology, the wrapping of loose carbon layer effectively avoids the leaching of internal active metals, thus ensuring Cr x Mn y O z @C has long-term catalytic activity and avoids secondary pollution caused by metal ion leaching. The catalytic material of the present invention constructs a catalyst produced by H2O activation. 1 The new O2 pathway does not require the addition of additional oxidants during the activation of H2O to produce ROS, thus avoiding secondary pollution. It also exhibits stability during the catalytic reaction, and the degradation efficiency of organic pollutants has hardly decreased after continuous reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 The Cr x Mn y O z @Scanning electron microscope and transmission electron microscope images of C.

[0043] Figure 2 The Cr x Mn y O z @C's MT map.

[0044] Figure 3 The Cr x Mn y O z XRD pattern of @C.

[0045] Figure 4 The Cr x Mn y O z EPR spectrum of @C.

[0046] Figure 5A This is the EPR signal diagram of ·OH in DMPO capture suspension.

[0047] Figure 5B Capturing O2 in Suspension by DMPO ·- EPR signal diagram.

[0048] Figure 5C For TEMP capture in suspension 1 EPR signal diagram of O2.

[0049] Figure 6 Cr x Mn y O z @C shows the degradation effect of bisphenol A (BPA) with an initial concentration of 10 ppm.

[0050] Figure 7 Cr x Mn y O z @CResults of free radical quenching experiment for electrocatalytic degradation of BPA.

[0051] Figure 8 shows the use of 1,3-diphenylisobenzofuran (DPBF) as 1 O2 probe, Cr x Mn y O z @C is the fluorescence spectrum of the reaction liquid in the catalytic reaction system of the catalyst, where Figure A is the comparison group and Figure B is the experimental group under inert gas.

[0052] Fig. 9 Cr under different reaction atmospheres x Mn y O z @C system TEMP capture suspension 1 EPR signal diagram of O2.

[0053] Fig.10 Cr x Mn y O z @CDiagram showing the influence of different ions on electrocatalytic degradation of BPA.

[0054] Fig.11 Cr x Mn y O z @C Graph showing the influence of different pH values ​​on electrocatalytic degradation of BPA.

[0055] Fig.12 Cr x Mn y O z @CDifferent actual water environmental impact diagrams during electrocatalytic degradation of BPA.

[0056] Fig.13 The Cr x Mn y O z @C Batch usage degradation chart. DETAILED DESCRIPTION

[0057] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0058] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0059] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0060] The technical principle of the present invention is as follows:

[0061] The present invention provides a method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, comprising:

[0062] S1. Dissolve Cr(NO3)3·9H2O, MnCl2·4H2O and PVP (polyvinyl pyrrolidone) in water and stir well to obtain a reaction solution;

[0063] S2. The reaction solution is vacuum dried or freeze-dried to obtain a mixture;

[0064] S3. In an inert atmosphere, the mixture is calcined at 750±5°C for 1±0.1h, and then calcined at 250±5°C for 2±0.1h to obtain a calcined product;

[0065] S4. Grind the calcined product to obtain a catalytic material of 200±5 mesh.

[0066] Step S1 specifically includes:

[0067] Dissolve Cr(NO3)3·9H2O, MnCl2·4H2O and PVP in water, stir at 25±5℃ for 1±0.1h to obtain a reaction solution;

[0068] Among them, the mass ratio of Cr(NO3)3·9H2O, MnCl2·4H2O and PVP is 1:0.4925:1; and the K value of the PVP is 30.

[0069] In the present invention, the advantages of using Cr(NO)3 and MnCl2 as metal sources are that the multivalent (+1 to +7) of Mn can optimize the adsorption of intermediates by adjusting the coordination structure of the manganese center. 2+ , Mn 3+ and Mn 4+ ) and the surface adsorption / desorption process of oxygen species. 4+ -O· has a very high unpaired spin density on oxygen, which can destroy the π bond of Mn=O, thus facilitating the formation of OO bond ( 1 In addition, optimizing the adsorption / desorption intermediates on Mn can promote the OO coupling reaction, while Cr 3+ Due to its special electronic configuration (t 3 2g e 0 g ) can promote charge / electron transfer during electrocatalytic reactions and change the electronic structure of the d band of the metal center, thereby significantly increasing the electron donor capacity of the adjacent metal center and increasing the conductivity. The advantage of using PVP as a carbon source is that PVP, as a polymer compound, contains a large number of pyrrolidone groups. These pyrrolidone groups contain nitrogen-containing five-membered ring structures. These nitrogen-containing structures can form coordination bonds with metal ions to form complexes. This complex reaction can react with many metal ions, enhance the stability of metal ions, and change their chemical properties.

[0070] In the present invention, Cr(NO3)3·9H2O, MnCl2·4H2O and PVP are dissolved in water and stirred thoroughly to make the metal ions (Mn 2+ and Cr 3+ ) can fully contact with PVP molecules and undergo complexation reaction.

[0071] In the present invention, the mass ratio of Cr(NO3)3·9H2O, MnCl2·4H2O and PVP is 1:0.4925:1, which has the advantage of enabling metal ions to fully react with PVP; the K value of the PVP is 30, and K30 indicates that the relative molecular weight of the PVP used is about 45,000 to 55,000, which is conducive to its full complexation with metal ions. Too large or too small a relative molecular weight is not conducive to the occurrence of the target reaction.

[0072] Step S2 specifically includes:

[0073] The reaction solution is vacuum dried or freeze dried, the vacuum drying temperature is 60±5° C., and the vacuum drying time is 10±0.1 h.

[0074] In the present invention, the advantage of vacuum drying the reaction solution is that it prevents a large amount of oxygen in the air from affecting the structure of the prepared catalyst.

[0075] Step S3 specifically includes:

[0076] In an inert atmosphere, the mixture is calcined at 750±5°C for 1±0.1h with a heating rate of 10°C / min, and after the calcination, it is cooled to 30-50°C to obtain a primary product;

[0077] In an inert atmosphere, the primary product is calcined at 250±5° C. for 2±0.1 h at a heating rate of 5° C. / min to obtain a calcined product.

[0078] In the present invention, the advantage of calcining the mixture at 750±5°C for 1±0.1h is that while forming the chromium-manganese bimetallic oxide core, the PVP molecules are fully carbonized to form a loose carbon layer substrate. Too high a calcination temperature is likely to cause the collapse of the structure, while too low a temperature is not conducive to the formation of the structure. Too long a calcination time is likely to cause the collapse of the structure, while too short a reaction time is likely to cause an insufficient reaction, hindering the formation of the expected structure. The purpose of cooling after the first stage of calcination is to allow the cooled reactants to better adapt to the second stage of calcination.

[0079] In the present invention, the advantage of calcining the primary product at 250±5°C for 2±0.1h is that an amorphous carbon layer is formed to wrap around the core surface. Too high a calcination temperature is likely to cause the disappearance of amorphous carbon, while too low a temperature is not conducive to the formation of the amorphous carbon layer. Too long a reaction time is likely to reduce the content of amorphous carbon, while too short a reaction time is not conducive to the formation of an amorphous carbon layer.

[0080] Step S4 specifically includes:

[0081] The calcined product was ground for 10±5 min to obtain a catalytic material of 200±5 mesh.

[0082] In the present invention, the particle size of the catalytic material is controlled at 200±5. The purpose is to make the catalyst powder more conducive to the configuration of uniform catalyst ink, thereby facilitating the preparation of electrode sheets.

[0083] Based on the same inventive concept, the present invention provides a catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen. The catalytic material is a core-shell structure, wherein the core-shell structure has a double transition metal oxide as a core and a loose amorphous carbon layer as a shell. The structural formula of the catalytic material is Cr x Mn y O z @C, where the atomic percentage of Cr is 8.65%, the atomic percentage of Mn is 16.92%, and the total effective magnetic moment (μ eff) is 3.71μb, corresponding to e g =0.89, the catalytic material can activate H2O selectively to generate 1 O2.

[0084] In the present invention, Cr x Mn y O z @C has an atomic percentage of Cr of 8.65%, an atomic percentage of Mn of 16.92%, and a total effective magnetic moment (μ eff ) is 3.71μb, corresponding to e g =0.89 are to optimize the electron occupancy of the manganese site, achieve the appropriate adsorption of oxygen intermediates, promote the occurrence of OO coupling, promote the accumulation of *OO, and promote 1 Production of O2.

[0085] Based on the same inventive concept, the present invention also provides a method for catalytic degradation of organic pollutants, comprising:

[0086] Dispersing the above-mentioned catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen in a naphthol-ethanol solution to obtain a mixed solution;

[0087] The mixed solution is evenly coated on the surface of carbon paper to obtain a working electrode;

[0088] The working electrode, the reference electrode and the counter electrode form a three-electrode system, which is placed in water containing electrolytes and organic pollutants, and a voltage is applied to degrade the organic pollutants in a constant current mode.

[0089] Further, the naphthol-ethanol solution is prepared by mixing anhydrous ethanol and naphthol;

[0090] The ratio of the mass of the catalytic material, the volume of the anhydrous ethanol and the volume of the naphthol is 20 mg: 1 mL: 0.05 mL;

[0091] The loading amount of the catalytic material in the working electrode is 1±0.1 mg / cm 2 .

[0092] In the present invention, the purpose of dispersing the catalytic material in the naphthol-ethanol solution is to fully disperse the catalyst powder. The advantage of using the above-mentioned amount ratio of the catalytic material, anhydrous ethanol and naphthol is that the catalyst can be fully adhered to the carbon paper while avoiding the aggregation of a large amount of naphthol resin to cause a decrease in conductivity. The loading amount of the catalytic material on the working electrode surface is 1±0.1 mg / cm 2 The advantage is that the catalytic activity is guaranteed while avoiding the use of a large amount of catalyst which leads to increased reaction energy consumption.

[0093] The following will describe in detail the preparation method, catalytic material and application of a catalytic material for selectively generating singlet oxygen from electrocatalytically activated water in the present application in combination with embodiments and experimental data.

[0094] Example 1

[0095] The present embodiment provides a method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, comprising the following steps:

[0096] (1) Cr(NO3)3·9H2O, MnCl2·4H2O, and PVP(K30) were dissolved in ultrapure water at a mass ratio of 1:0.4925:1, and stirred at a constant temperature of 25°C for 1 h to allow the mixture to fully react, thereby obtaining a reaction solution.

[0097] (2) The reaction solution obtained in step (1) is placed in a vacuum oven and dried at 60° C. for 10 h, and then the dried product is ground (to prevent agglomerated solids from affecting the calcination effect) to obtain a mixture with a particle size of 200±5 mesh.

[0098] (3) The mixture obtained in step (2) was placed in a tubular furnace and calcined at 750° C. for 1 h in an Ar atmosphere at a heating rate of 10° C. / min. After calcination, the mixture was cooled to 40° C. and then heated to 250° C. at a rate of 5° C. / min and calcined for 2 h.

[0099] (4) Grinding the black loose solid obtained by calcining in step (3) into powder with a mesh size of about 200±5 mesh to obtain a catalytic material.

[0100] The catalytic material prepared in this example was characterized by scanning electron microscopy and transmission electron microscopy: Figure 1 It can be seen that the catalytic material presents an obvious core-shell structure. The bimetallic oxide core shows obvious lattice stripes and is wrapped by an amorphous carbon layer, presenting a core-shell structure.

[0101] Example 2

[0102] This example is a catalyst material (Cr x Mn y O z @C) Temperature-dependent magnetization (MT) measurements were performed to detect Cr x Mn y O z @C electrode spin state, the results are as follows Figure 2 . It is calculated that Cr in a magnetic field of H = 1kOe x Mn y O z @C's magnetic susceptibility (χ=M / H) obeys the paramagnetic Curie-Weiss law, and its total effective magnetic moment (μ eff ) can be obtained according to the Langevin theory from χ-1 The linear fit of the -T data was derived and its value was 3.71μ b , corresponding to eg=0.89.

[0103] Example 3

[0104] This example is a catalyst material (Cr x Mn y O z @C) XRD characterization was performed, and the results were as follows Figure 3 , found that Cr x Mn y O z @C is mainly composed of cubic Mn (Mn 0.193 Cr 1.808 )O4(PDF#85-1560) and corundum phase Cr2O3(PDF#38-1479). In addition, no other obvious structures were observed.

[0105] Example 4

[0106] This example is a catalyst material (Cr x Mn y O z @C) for EPR characterization. Figure 4 It can be seen that Cr x Mn y O z There are a large number of unpaired electrons inside @C, and its spins / g value is determined to be 1.431×10 16 spins / g.

[0107] Example 5

[0108] This example measures the catalytic material (Cr x Mn y O z @C) The situation of generating free radicals when activating water:

[0109] 1. Hydroxyl radical (·OH) and superoxide radical (O2 ·- ) detection.

[0110] (1) Three parallel experiments were conducted: experimental group a, 70 mL 0.1 M Na2SO4 electrolyte solution, experimental group b, 70 mL 0.1 M Na2SO4 electrolyte solution and a three-electrode system (Cr x Mn y O z@C as anode, Pt as cathode, Ag / AgCl as reference electrode); Experimental group c, 10ppm BPA solution + 70mL 0.1M Na2SO4 electrolyte solution and construct a three-electrode system (Cr x Mn y O z @C is the anode, Pt is the cathode, and Ag / AgCl is the reference electrode). 700uL 1M 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was added to three parallel experimental groups, where experimental group a was not energized, and experimental groups b and c were applied with a 15mA constant current.

[0111] In this embodiment, Cr x Mn y O z The preparation method of @C anode is as follows:

[0112] The catalytic material (Cr x Mn y O z @C) dispersed in naphthol-ethanol solution and evenly dropped on the surface of carbon paper to obtain Cr x Mn y O z @C anode. Wherein, the naphthol-ethanol solution is prepared by mixing anhydrous ethanol and naphthol; Cr x Mn y O z The ratio of the mass of @C, the volume of anhydrous ethanol and the volume of naphthol is 20mg:1mL:0.05mL; the size of the carbon paper is 2cm x2cm, and the drop coating amount is 200μL to ensure that the catalytic material Cr on the carbon paper x Mn y O z @C loading is 1 mg / cm 2 .

[0113] (2) After 5 minutes of reaction, the liquid sample described in step (1) is quickly taken using a spotting capillary, and then the generation of free radicals in the solution is detected using an electron paramagnetic resonance spectrometer (EPR).

[0114] The results are as follows Figure 5A As shown in Figure 2, B, it can be seen that: the Cr prepared in Example 1 of the present invention x Mn y O z @C catalytic materials produce almost no hydroxyl radicals (·OH) and superoxide radicals (O2 ·- ).

[0115] 2. Singlet oxygen ( 1 O2) detection.

[0116] (1) Three parallel experiments were conducted: experimental group a, 70 mL 0.1 M Na2SO4 electrolyte solution, experimental group b, 70 mL 0.1 M Na2SO4 electrolyte solution and a three-electrode system (Cr x Mn y O z @C as anode, Pt as cathode, Ag / AgCl as reference electrode); Experimental group c, 10ppm BPA solution + 70mL 0.1M Na2SO4 electrolyte solution and construct a three-electrode system (Cr x Mn y O z @C is the anode, Pt is the cathode, and Ag / AgCl is the reference electrode). 700uL 1M 2,2,6,6-tetramethylpiperidine (TEMP) was added to three parallel experimental groups, where experimental group a was not energized, and experimental groups b and c were applied with a 15mA constant current.

[0117] (2) After 5 minutes of reaction, quickly take the liquid sample described in step (1) using a spotting capillary, and then use an electron paramagnetic resonance spectrometer (EPR) to detect the generation of free radicals in the solution.

[0118] The results are as follows Figure 5C As shown, it can be seen that: Cr prepared in Example 1 of the present invention x Mn y O z @C catalytic materials can generate a large amount of singlet oxygen when activating water ( 1 O2), and 1 The production of O2 is independent of the presence of pollutants (BPA).

[0119] Example 6

[0120] In this example, the catalytic material (Cr x Mn y O z @C) Catalytic performance in the degradation of organic pollutants.

[0121] The catalytic material (Cr x Mn y O z @C) is dispersed in a naphthol-ethanol solution in a certain proportion, and then evenly dripped on the surface of carbon paper as a working electrode, forming a three-electrode system with a reference electrode and a counter electrode. The electrolyte, water and persistent organic pollutants to be treated are mixed, and a voltage is applied to degrade them in a constant current mode. The naphthol-ethanol solution is prepared by mixing anhydrous ethanol and naphthol, and the ratio of each raw material is 20 mg catalyst: 1 mL anhydrous ethanol: 50 μL naphthol. The size of the carbon paper is 2 cm x 2 cm, and the amount of the coating solution is 200 μL to ensure that the catalyst loading on the carbon paper is 1 mg / cm2 .

[0122] The Cr x Mn y O z @C carbon paper was used as the working electrode, Pt as the counter electrode, and Ag / AgCl as the reference electrode to construct a three-electrode system. The electrolyte solution was 70mL (containing 10ppm BPA+0.1M Na2SO4), and a 15mA constant current was applied during the reaction. Samples were taken at 0min, 20min, 40min, 60min, 80min, 100min, and 120min, and 1mL of each sample was quickly filtered with a syringe filter. The concentration of BPA was determined by liquid chromatography, and Cr was calculated. x Mn y O z @CDegradation efficiency of BPA at different times.

[0123] The results are as follows Figure 6 As shown, it can be seen that: Cr prepared in Example 1 x Mn y O z @C The catalytic material almost completely degraded 10 ppm of BPA within 1 hour.

[0124] Example 7

[0125] In this example, Cr x Mn y O z @C Generation of active oxygen species in the electrocatalytic system with the catalytic material as the anode:

[0126] (1) Coating Cr x Mn y O z @C carbon paper was used as the working electrode (preparation method was the same as in Example 6), Pt was used as the counter electrode, and Ag / AgCl was used as the reference electrode to construct a three-electrode system. The electrolyte solution was 70 mL (containing 10 ppm BPA + 0.1 M Na2SO4), 10 mM tert-butyl alcohol (TBA) was added to the electrolyte solution as a scavenger for hydroxyl radicals (·OH), and 200 U superoxide dismutase (SOD) was added as a superoxide radical (O2 ·- ) capture agent, and 10 mM L-histidine (L-His) was added as a singlet oxygen ( 1 O2) capture agent, and 200U of superoxide dismutase (CAT) was added as a hydrogen peroxide (H2O2) capture agent.

[0127] (2) A constant current of 15 mA was applied to the electrolyte solution with various capture agents added, and samples were taken at 0 min, 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min, respectively. 1 mL of the sample was quickly filtered with a syringe filter each time, and the concentration of BPA was determined by liquid chromatography. The degradation efficiency of BPA in different reaction systems at different times was calculated.

[0128] The results are as follows Figure 7 As shown ( Figure 7 The control group is the group without any quencher added), it can be seen that: Cr x Mn y O z @C In the electrocatalytic system where the catalytic material is the anode, a large amount of 1 O2, almost no OH, O2 ·- and H2O2.

[0129] Example 8

[0130] In this example, Cr x Mn y O z @C In the electrocatalytic system where the catalytic material is the anode 1 O2 production sources:

[0131] (1) Coating Cr x Mn y O z @C carbon paper was used as the working electrode, Pt as the counter electrode, and Ag / AgCl as the reference electrode to construct a three-electrode system. The electrolyte solution was 70mL (containing 10ppm BPA+0.1M Na2SO4), and a 15mA constant current was applied during the reaction. The electrolyte solution was divided into a control group and an experimental group. The control group was not aerated and the electrocatalytic reaction was carried out under normal conditions; the experimental group was aerated with Ar gas for half an hour before the electrocatalytic reaction to remove dissolved oxygen in the solution and was continuously aerated with Ar gas during the reaction.

[0132] (2) Sampling was performed at 0 min, 1 min, 5 min, 10 min, 20 min, 40 min, and 60 min, respectively. 1 mL of each sample was quickly filtered using a syringe filter, and the concentration of DPBF was determined using an ultraviolet spectrophotometer. The degradation efficiency of DPBF in different reaction systems at different times was calculated.

[0133] The results are shown in FIG8 , and it can be seen that: x Mn y O z @C In the electrocatalytic system with the catalytic material as the anode, the DPBF absorbance decreases over time regardless of whether the dissolved oxygen is removed, indicating that 1The production of O2 has nothing to do with the dissolved oxygen in the solution.

[0134] Example 9

[0135] This example further determines that Cr x Mn y O z @C In the electrocatalytic system where the catalytic material is the anode 1 O2 production sources:

[0136] (1) Coating Cr x Mn y O z @C carbon paper was used as the working electrode, Pt as the counter electrode, and Ag / AgCl as the reference electrode to construct a three-electrode system. The electrolyte solution was 70mL 0.1M Na2SO4, and 700uL 1M 2,2,6,6-tetramethylpiperidine (TEMP) was added, and a 15mA constant current was applied during the reaction. Among them, the electrolyte solution was divided into control group A, experimental group B and experimental group C:

[0137] The control group A was not aerated and the electrocatalytic reaction was carried out under normal conditions; the experimental group B was exposed to Ar for half an hour before the electrocatalytic reaction to remove dissolved oxygen in the solution and was continuously exposed to Ar during the reaction; the experimental group C was exposed to O2 for half an hour before the electrocatalytic reaction and was continuously exposed to O2 during the reaction.

[0138] (2) After 5 minutes of reaction, quickly take the liquid sample described in step (1) using a spotting capillary, and then use an electron paramagnetic resonance spectrometer (EPR) to detect the generation of free radicals in the solution.

[0139] The results are as follows Fig. 9 As shown, it can be seen that: x Mn y O z In the electrocatalytic system with the catalytic material as the anode, the comparison group A, the Ar group (experimental group B), and the O2 group (experimental group C) all produced obvious TEMP- 1 O2, and the signal strength difference is not large, further indicating 1 The production of O2 has nothing to do with the dissolved oxygen in the solution.

[0140] Example 10

[0141] This example determines the effect of environmental ion interference on Cr x Mn y O z @C The influence of the electrocatalytic system with the catalytic material as the anode:

[0142] The Cr x Mn y O z@C carbon paper was used as the working electrode, Pt as the counter electrode, and Ag / AgCl as the reference electrode to construct a three-electrode system. The electrolyte solution was 70mL of 10ppm BPA solution, and a constant current of 15mA was applied during the reaction. Samples were taken at 0min, 20min, 40min, 60min, 80min, 100min, and 120min, and 1mL of each sample was quickly filtered with a syringe filter. The concentration of BPA was determined by liquid chromatography, and the degradation efficiency of BPA in different reaction systems at different times was calculated.

[0143] Among them, different ion interferences are achieved by adding different electrolyte types to the electrolyte solution: 0.1M NaCl is used to measure Cl － Interference; 0.1M NaNO3 determination of NO3 － Interference; 0.1M NaF determination of F － Interference; 0.1M MgSO4 determination of Mg 2+ Interference; 0.1M K2SO4 determination of K + Interference. Among them, 0.1M Na2SO4 is used as Fig.10 The comparison group in .

[0144] The results are as follows Fig.10 As shown, it can be seen that: x Mn y O z @CIn the electrocatalytic system where the catalytic material is the anode, different anions and cations have almost no effect on the catalytic effect.

[0145] Embodiment 11

[0146] In this embodiment, Cr x Mn y O z @C The ability of the electrocatalytic system with the catalytic material as the anode to resist environmental pH interference:

[0147] The Cr x Mn y O z @C carbon paper was used as the working electrode, Pt as the counter electrode, and Ag / AgCl as the reference electrode to construct a three-electrode system. The electrolyte solution was 70mL of 10ppm BPA solution, and a constant current of 15mA was applied during the reaction. Samples were taken at 0min, 20min, 40min, 60min, 80min, 100min, and 120min, and 1mL of each sample was quickly filtered with a syringe filter. The concentration of BPA was determined by liquid chromatography, and the degradation efficiency of BPA in different reaction systems at different times was calculated.

[0148] Among them, different pH environments of the electrolyte solution were adjusted by 1M H2SO4 and 1M NaOH respectively to obtain electrolyte solutions with pH of 3, 5, 7 and 9.

[0149] The results are as follows Fig.11 As shown, it can be seen that: x Mn y O z @CIn the electrocatalytic system where the catalytic material is the anode, pH has almost no effect on the catalytic effect.

[0150] Example 12

[0151] In this embodiment, Cr x Mn y O z @C The degradation capacity of the electrocatalytic system with catalytic material as anode for organic pollutants in different actual water bodies:

[0152] The Cr x Mn y O z @C carbon paper was used as the working electrode, Pt as the counter electrode, and Ag / AgCl as the reference electrode to construct a three-electrode system. An electrolyte solution containing 10ppm BPA was prepared using different actual water samples, and a 15mA constant current was applied during the reaction. Sampling was performed at 0min, 20min, 40min, 60min, 80min, 100min, and 120min, and 1mL of the sample was quickly filtered with a syringe filter each time. The concentration of BPA was determined by liquid chromatography, and the degradation efficiency of BPA in different reaction systems at different times was calculated.

[0153] Among them, the electrolyte solution was prepared by adding Na2SO4 and BPA to water samples of different actual water bodies (tap water, industrial sewage, domestic sewage, municipal effluent and control group (ordinary water body)). The final concentration of Na2SO4 was 0.1M and the final concentration of BPA was 10ppm. The degradation of BPA was used to evaluate the impact on the actual water environment.

[0154] The results are as follows Fig.12 As shown, it can be seen that: x Mn y O z @CThe electrocatalytic system with catalytic material as anode can adapt well to different environmental water bodies.

[0155] Example 13

[0156] In this example, Cr x Mn y O z @C Cycling stability of electrocatalytic system with catalytic material as anode:

[0157] (1) Coating Cr x Mn y O z @C carbon paper was used as the working electrode, Pt as the counter electrode, Ag / AgCl as the reference electrode, and a three-electrode system was constructed. The electrolyte solution was 70mL (containing 10ppm BPA+0.1M Na2SO4), and a 15mA constant current was applied during the reaction. Samples were taken at 0min, 20min, 40min, 60min, 80min, 100min, and 120min, and 1mL of each sample was quickly filtered with a syringe filter. The concentration of BPA was determined by liquid chromatography, and the degradation efficiency of BPA at different times was calculated.

[0158] (2) Rinse the electrode sheet in step (1) with ultrapure water and then dry it in vacuum at 60° C. Take the dried electrode sheet and repeat the operation in step (1) to obtain the degradation efficiency of one cycle.

[0159] (3) Rinse the electrode sheet in step (2) with ultrapure water and then dry it in vacuum at 60° C. Take the dried electrode sheet and repeat the operation in step (1) to obtain the degradation efficiency of the second cycle.

[0160] (4) Rinse the electrode sheet in step (3) with ultrapure water and then dry it in vacuum at 60° C. Take the dried electrode sheet and repeat the operation in step (1) to obtain the degradation efficiency after 3 cycles.

[0161] (5) Rinse the electrode sheet in step (4) with ultrapure water and then dry it in vacuum at 60° C. Take the dried electrode sheet and repeat the operation in step (1) to obtain the degradation efficiency of 4 cycles.

[0162] (6) After rinsing the electrode sheet in step (5) with ultrapure water, vacuum dry it at 60° C. Take the dried electrode sheet and repeat the operation in step (1) to obtain the degradation efficiency after 5 cycles.

[0163] The results are as follows Fig.13 As shown, it can be seen that: x Mn y O z @C catalytic materials in electrocatalytic activation of H2O production 1 In the process of using O2 to degrade organic pollutants, its degradation efficiency did not significantly weaken after five consecutive uses, and the material showed excellent stability.

[0164] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0165] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0166] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, characterized in that: The preparation method comprises: Dissolve Cr(NO3)3·9H2O, MnCl2·4H2O and PVP in water and stir well to obtain a reaction solution; vacuum drying or freeze drying the reaction solution to obtain a mixture; In an inert atmosphere, the mixture is calcined at 750±5° C. for 1±0.1 h, and then calcined at 250±5° C. for 2±0.1 h to obtain a calcined product; The calcined product was ground to obtain a catalytic material of 200±5 mesh.

2. The method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen according to claim 1, characterized in that: The step of dissolving Cr(NO3)3·9H2O, MnCl2·4H2O and PVP in water and stirring the mixture sufficiently to obtain a reaction solution specifically comprises: Dissolve Cr(NO3)3·9H2O, MnCl2·4H2O and PVP in water, stir at 25±5℃ for 1±0.1h to obtain a reaction solution; Among them, the mass ratio of Cr(NO3)3·9H2O, MnCl2·4H2O and PVP is 1:0.4925:1; The K value of the PVP is 30.

3. The method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen according to claim 1, characterized in that: The step of vacuum drying or freeze drying the reaction solution to obtain a mixture specifically comprises: The reaction solution is vacuum dried or freeze dried, the vacuum drying temperature is 60±5° C., and the vacuum drying time is 10±0.1 h.

4. The method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen according to claim 1, characterized in that: In an inert atmosphere, the mixture is calcined at 750±5°C for 1±0.1h, and then calcined at 250±5°C for 2±0.1h to obtain a calcined product, which specifically includes: In an inert atmosphere, the mixture is calcined at 750±5°C for 1±0.1h with a heating rate of 10°C / min, and after the calcination, it is cooled to 30-50°C to obtain a primary product; In an inert atmosphere, the primary product is calcined at 250±5° C. for 2±0.1 h at a heating rate of 5° C. / min to obtain a calcined product.

5. The method for preparing a catalytic material for electrocatalytically activating water to selectively generate singlet oxygen according to claim 1, characterized in that: The calcined product is ground to obtain a catalytic material of 200±5 mesh, which specifically comprises: The calcined product was ground for 10±5 min to obtain a catalytic material of 200±5 mesh.

6. A catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, characterized in that: The catalytic material is prepared by the method for preparing a catalytic material for selectively generating singlet oxygen by electrocatalytically activating water according to any one of claims 1 to 5.

7. A catalytic material for electrocatalytically activating water to selectively generate singlet oxygen, characterized in that: The catalytic material is a core-shell structure, wherein the core-shell structure has a chromium-manganese double transition metal oxide as a core and a loose amorphous carbon layer as a shell. The structural formula of the catalytic material is Cr x Mn y O z @C, where the atomic percentage of Cr is 8.65%, the atomic percentage of Mn is 16.92%, and the total effective magnetic moment (μ eff ) is 3.71μb, corresponding to e g =0.89, the catalytic material can activate H2O selectively to generate 1 O2.

8. A catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen as claimed in claim 6 or 7, wherein the catalytic material is used for electrocatalytic activation of H2O to selectively generate 1 Application of O2 or degradation of organic pollutants.

9. A method for catalytic degradation of organic pollutants, characterized in that: The method comprises: Dispersing the catalytic material for electrocatalytic activation of water to selectively generate singlet oxygen as claimed in claim 6 or 7 in a naphthol-ethanol solution to obtain a mixed solution; The mixed solution is evenly coated on the surface of carbon paper to obtain a working electrode; The working electrode, the reference electrode and the counter electrode form a three-electrode system, which is placed in water containing electrolytes and organic pollutants, and a voltage is applied to degrade the organic pollutants in a constant current mode.

10. A method for catalytic degradation of organic pollutants according to claim 9, characterized in that: The naphthol-ethanol solution is prepared by mixing anhydrous ethanol and naphthol; The ratio of the mass of the catalytic material, the volume of the anhydrous ethanol and the volume of the naphthol is 20 mg: 1 mL: 0.05 mL; The loading amount of the catalytic material in the working electrode is 1±0.1 mg / cm 2 .

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