Photoanode material, photoanode, preparation method of photoanode and application of photoanode in sewage treatment

Abstract

The invention relates to the technical field of sewage treatment, and particularly discloses a photoelectric anode material, a photoelectric anode, a preparation method of the photoelectric anode and application of the photoelectric anode in sewage treatment. The photoelectric anode material comprises a FeSe2 array layer and a layer containing Bi2O2WO4, wherein the layer containing Bi2O2WO4 is loaded on the FeSe2 array layer. FeSe2 has a narrow band gap, good light absorption performance and photo-generated charge separation capability, other semiconductors with wide band gaps can be sensitized to form heterojunctions, the photocurrent density and the electron quantum yield are promoted to be improved, and the photoelectric conversion efficiency of the catalytic material is enhanced. Bi2O2WO4 is formed by vertically alternating [Bi2O2] < 2 + > layers and [WO4] < 2-> layers, so that the separation of photo-induced electrons and holes is facilitated, and the catalytic oxidation reaction activity of the electrode is improved. Bi2O2WO4 and FeSe2 are compounded, so that respective sunlight response capability and photoelectrocatalytic performance can be improved, and the Bi2O2WO4 / FeSe2 composite photocatalyst has obvious application advantages in the field of environmental engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a photoelectric anode material, a photoelectric anode and a preparation method and application thereof. Background Art

[0002] Industrial wastewater has the characteristics of complex composition, difficult degradation, and large fluctuations in water quality and quantity. Industrial wastewater contains various organic and inorganic pollutants. For example, printing and dyeing wastewater contains a large amount of dyes and additives (such as alkali sulfide, hydrosulfite, etc.). These organic substances have complex components and diverse structures. Some of them are also biologically toxic, and it is difficult to completely remove them through a single treatment method; electroplating wastewater is rich in heavy metal ions, such as chromium, nickel, cadmium, copper, etc. These heavy metals cannot be biodegraded, will exist in the environment for a long time, and are easily enriched in organisms, causing serious harm to the ecosystem and human health. Different heavy metals require different treatment processes to be effectively removed, which increases the complexity of treatment.

[0003] At present, the commonly used methods for treating industrial wastewater include physical methods, chemical methods, biological methods and their corresponding combinations. The number of catalyst cycles in physical methods is limited, and traditional biochemical methods have many disadvantages such as large footprint, long treatment cycle, and poor treatment effect. Photoelectrocatalytic advanced oxidation wastewater treatment technology is that under the action of light or an external electric field, the photoelectrocatalytic material is excited to produce a large number of electrons and holes. After the separation of electrons and holes, they move in a directional manner, gather at the positive and negative poles and produce a large number of active free radicals. These active free radicals with strong oxidizing properties can react with pollutants in the water and be mineralized into carbon dioxide, water and inorganic salts, thereby achieving the purpose of water purification. In addition, these active free radicals can purify different types of water bodies, and can also enhance the biodegradability of the treated water body, thereby reducing the difficulty of its deep treatment.

[0004] However, due to the limitations of photoelectrocatalytic nanomaterials and other reasons, the existing photoelectrocatalytic advanced oxidation wastewater treatment technology has high energy consumption and its deep treatment efficiency for complex water quality is still not ideal. Therefore, it is urgent to develop a wastewater treatment material with obvious wastewater purification efficiency. Summary of the invention

[0005] In view of the above problems, the present invention provides a photoanode material, a photoanode and a preparation method and application thereof. By compounding the semiconductor Bi2O2WO4 and the n-type semiconductor FeSe2 array to form a heterojunction, which are used together as photoelectrocatalytic materials, the deep treatment efficiency of complex water bodies is improved, and at the same time, the rational use of energy is achieved.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: In a first aspect, the present invention provides a photoanode material, comprising a FeSe2 array layer and a Bi2O2WO4-containing layer supported on the FeSe2 array layer.

[0007] Compared with the prior art, the photoanode material provided by the present invention, the photocatalytic material FeSe2 has a narrower band gap, good light absorption performance and photogenerated charge separation ability, and is a typical power supply semiconductor (n-type semiconductor). It can sensitize other semiconductors with wider band gaps to form heterojunctions, promote the improvement of photocurrent density and electron quantum yield, and thus enhance the photoelectric conversion efficiency of the catalytic material. Bismuth metal semiconductors have low toxicity, high conductivity and an adjustable suitable band gap, and have excellent photocatalytic reaction activity and photoelectric conversion efficiency. [Bi2O2] 2+ Layer and salt acid radical [WO4] 2- In the stacked structure of Aurvillius photocatalytic material Bi2O2WO4, [Bi2O2] 2+ Layer and anion [WO4] 2- The layers are vertically alternating, and this structure is more conducive to promoting the separation of photogenerated electrons and holes, thereby improving the catalytic oxidation reaction activity of the electrode. The present invention selects a new type of Bi2O2WO4 and FeSe2 to form a heterojunction, which can improve their respective sunlight response capabilities and photoelectric catalytic performance, and has obvious application advantages in the fields of environmental engineering and sewage treatment.

[0008] Preferably, the thickness of the FeSe2 array layer is 3 μm to 5 μm.

[0009] It should be noted that the FeSe2 array layer in the present invention is arranged by a single layer of FeSe2 array, and the thickness of the FeSe2 array layer is the length of the FeSe2 array.

[0010] Preferably, the thickness of the Bi2O2WO4 layer is 80nm~200nm.

[0011] Preferably, the Bi2O2WO4-containing layer further comprises carbon nanofibers.

[0012] Carbon nanofibers have excellent toughness, mechanical strength, adhesion and conductivity. They can increase the adhesion between the active substances (FeSe2 array and Bi2O2WO4) in the photoanode material and the anode matrix, prevent the active substances from falling off the anode matrix, and improve the stability of the photoelectrode. At the same time, carbon nanofibers have good conductivity and will not reduce the electron transport performance of the photoanode, which is beneficial to improving the photoelectric catalytic activity of the electrode.

[0013] More preferably, the carbon nanofibers have a diameter of 150 nm to 200 nm and a length of 5 μm to 20 μm.

[0014] Preferably, the mass ratio of FeSe2 to Bi2O2WO4 in the photoanode material is 200:(10~50).

[0015] Further preferably, the mass ratio of FeSe2, Bi2O2WO4 and carbon nanofibers in the photoanode material is 200:(10~50):(0.8~1.6), more preferably 200:(20~40):(1~1.4).

[0016] The present invention can better exert the synergistic effect of the two by limiting the thickness of the FeSe2 array layer and the Bi2O2WO4-containing layer and the amount of FeSe2 and Bi2O2WO4 used, and has both good light response ability and good electrocatalytic performance.

[0017] Further preferably, the preparation method of FeSe2 comprises the following steps: S1-1, adding selenium powder to a reducing agent solution to perform a reduction reaction to obtain a divalent selenide solution; S1-2, adding a divalent iron salt, a chelating agent and a first dispersant into water, mixing with the divalent selenide solution, and performing a redox reaction to obtain FeSe2.

[0018] The present invention first reduces selenium powder to divalent selenide, and then undergoes redox reaction with divalent iron salt to obtain FeSe2; a chelating agent is used to coordinate ferrous ions to slowly release the ferrous ions, and a first dispersant is added to prevent powder agglomeration, which is conducive to the subsequent formation of uniform nano FeSe2 particles.

[0019] More preferably, in S1-1, the reducing agent solution comprises 18 wt% to 22 wt% of sodium borohydride solution.

[0020] More preferably, in S1-1, the mass ratio of the selenium powder to the reducing agent solution is 1:(2-15), and further preferably 1:(4-8).

[0021] More preferably, in S1-1, the temperature of the reduction reaction is 20°C to 30°C, and the reaction time is 30min to 50min.

[0022] More preferably, in S1-2, the divalent iron salt includes ferrous chloride.

[0023] More preferably, in S1-2, the chelating agent includes N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid.

[0024] More preferably, in S1-2, the first dispersant includes dodecyltrimethylammonium bromide.

[0025] More preferably, in S1-2, the mass ratio of the divalent iron salt, the chelating agent, the first dispersant, water and the divalent selenide solution is (2~10):(10~30):(0.01~0.05):(20~100):(6~30), and further preferably (4~8):(15~25):(0.01~0.05):(50~80):(10~25).

[0026] More preferably, in S1-2, the mixing temperature is 50°C to 70°C, the mixing speed is 100rpm to 200rpm, and the mixing time is 1h to 2h.

[0027] More preferably, in S1-2, the temperature of the redox reaction is 180°C to 200°C, and the reaction time is 3h to 6h.

[0028] The present invention first mixes at 50° C.-70° C., and then performs redox reaction at 180° C.-200° C., and adopts a gradient temperature increase method, which is beneficial to the generation of FeSe2 and avoids excessive reduction reaction to generate impurities such as FeSe and Fe2Se3.

[0029] For example, in S1-2, after the redox reaction is completed, the process further includes: cooling to room temperature, solid-liquid separation, washing and drying the solid to obtain FeSe2.

[0030] More preferably, in S1-2, the particle size of the FeSe2 is 10nm~180nm.

[0031] Further preferably, the preparation method of Bi2O2WO4 comprises the following steps: S2-1, adding tungstate, bismuth salt, a second dispersant and a pH adjuster into water, and performing a hydrolysis reaction under weak acid conditions to obtain a suspension; S2-2, subjecting the suspension to a first hydrothermal reaction to obtain Bi2O2WO4.

[0032] In the present invention, tungstate and bismuth salt are hydrolyzed in a weak acid to form a Bi(OH)WO4 white suspension, and the second dispersant reduces the number of agglomerated particles; then, through the first hydrothermal reaction, the layer axis lattice is continuously replaced and overlapped, and the bismuth salt and Bi(OH)WO4 continue to react, and finally nano-scale Bi2O2WO4 is generated.

[0033] More preferably, in S2-1, the tungstate comprises sodium tungstate.

[0034] More preferably, in S2-1, the bismuth salt comprises bismuth nitrate.

[0035] More preferably, in S2-1, the second dispersant includes polyethylene glycol.

[0036] More preferably, in S2-1, the pH adjuster comprises 1.7M~2.3M acetic acid solution and 1.7M~2.3M ammonium acetate solution; the mass ratio of the acetic acid solution to the ammonium acetate solution is (1.8~2.2):1.

[0037] More preferably, in S2-1, the mass ratio of the tungstate, bismuth salt, second dispersant and water is (2-8):(4-16):(0.5-1):(100-160), and further preferably (3-7):(8-12):(0.6-0.9):(120-150).

[0038] More preferably, in S2-1, the weakly acidic condition is pH=5~6.

[0039] More preferably, in S2-1, the temperature of the hydrolysis reaction is 20°C to 35°C, and the reaction time is 30min to 40min.

[0040] More preferably, in S2-2, the temperature of the first hydrothermal reaction is 160°C to 190°C, and the reaction time is 8h to 12h.

[0041] For example, in S2-1, after the first hydrothermal reaction is completed, the process further includes: cooling to room temperature, solid-liquid separation, washing and drying the solid to obtain Bi2O2WO4.

[0042] More preferably, in S2-2, the particle size of the Bi2O2WO4 is 10nm~150nm.

[0043] In a second aspect, the present invention provides a photoanode, comprising an anode substrate and the photoanode material loaded on the anode substrate.

[0044] The photoanode provided by the present invention improves the deep treatment efficiency of complex water bodies of industrial sewage by loading the photoanode material (including the FeSe2 array layer and the Bi2O2WO4-containing layer) on the anode substrate.

[0045] Preferably, the anode substrate comprises at least one of a stainless steel mesh, a titanium mesh, a copper mesh, an aluminum mesh, a molybdenum mesh, a nickel mesh, a stainless steel sheet, foamed nickel, foamed titanium or foamed aluminum.

[0046] In the present invention, the anode substrate is made of metal material, and the substrate is in the shape of a sheet, a mesh or a foam mesh. It has a unique porous structure, stable physical and chemical properties and good electrical conductivity, and is stable in different electrolytes. The porous structure can not only increase the surface area of ​​the anode, but also facilitate the reaction of ions in the electrolyte with the active material on the electrode, thereby improving the activity of the photoelectrocatalytic reaction, which is beneficial to the improvement of the photoelectrocatalytic advanced oxidation sewage treatment effect. Preferably, the anode substrate has a length of 50 mm to 100 mm, a width of 100 mm to 200 mm, and a thickness of 2 mm to 4 mm.

[0047] The present invention uses a non-toxic, low-cost, acid- and alkali-resistant nano-metal FeSe2 array and a Bi2O2WO4 semiconductor composite electrode. The electrode material has high adhesion and is not easy to fall off. It can be taken off for cleaning, soaking, regeneration and reuse, solving the problems of traditional suspended photocatalysts being difficult to recycle and easy to fall off. The present invention uses a cheap anode substrate with a large specific surface area and stable physical and chemical properties as a loading substrate for the photoelectric catalyst, effectively utilizing the photoelectric catalytic synergistic effect and saving sewage treatment costs.

[0048] In a third aspect, the present invention provides a method for preparing the photoanode, comprising the following steps: Sa, immersing the anode substrate in a mixture of FeSe2 and water to perform a second hydrothermal reaction to obtain a primary electrode; Sb, immersing the primary electrode in a mixed liquid of FeSe2, a silane coupling agent and a co-solvent, performing a third hydrothermal reaction to form a FeSe2 array layer, thereby obtaining a FeSe2 array electrode; Sc, coating a mixed solution of Bi2O2WO4, an adhesive and a solvent on the FeSe2 array electrode, and then calcining to form a Bi2O2WO4 layer to obtain a photoanode.

[0049] The preparation method of the photoanode provided by the present invention adopts the sol-gel method to load and grow the photoanode material on the anode substrate, and the photoanode is prepared by calcining and utilizing the annealing characteristics. The present invention first utilizes the second hydrothermal reaction to form and prepare the primary electrode; then, under the action of the cosolvent, the hydrothermal effect is utilized to make the nano-FeSe2 enter the surface of the primary electrode, and continuously nucleate and diffuse, and adsorb and couple under the action of the silane coupling agent, and deposit to form a FeSe2 array layer to obtain a FeSe2 array electrode; finally, the sol-gel method is used again to coat Bi2O2WO4 on the surface of the FeSe2 array electrode, and calcined to form a Bi2O2WO4-containing layer to obtain a photoanode.

[0050] For example, in Sa, before the immersion, the method further includes: placing the anode substrate in acetone and water in sequence, ultrasonicating for 10 minutes to 15 minutes respectively, and then drying.

[0051] The present invention pre-treats the anode substrate first, which can effectively remove impurities and oil stains on the surface of the anode substrate and increase the adhesion of subsequent photoelectric catalytic materials on the surface of the electrode substrate.

[0052] Preferably, in Sa, the mass ratio of FeSe2 to water is (1-4):(80-100).

[0053] Preferably, in Sa, the immersion time is 30 min to 60 min.

[0054] Preferably, in Sa, the temperature of the second hydrothermal reaction is 100° C. to 120° C., and the reaction time is 25 min to 40 min.

[0055] Under the specific second hydrothermal reaction conditions, the present invention enables FeSe2 to be evenly diffused and distributed on the surface of the anode substrate while ensuring that the crystal form of FeSe2 remains unchanged, while improving the cohesiveness and adhesion of FeSe2 on the anode substrate.

[0056] Preferably, in Sb, the silane coupling agent includes KH560.

[0057] Preferably, in Sb and Sc, the cosolvent comprises 40 wt % to 60 wt % of a polyvidone aqueous solution.

[0058] The polyvidone aqueous solution is an ionic liquid, which can increase the solubility of the system, reduce the interfacial tension, and is conducive to the full progress of the third hydrothermal reaction.

[0059] Preferably, in Sb, the mass ratio of FeSe2, silane coupling agent and solvent is (2~5):(1~4):(10~20).

[0060] Preferably, in Sb, the temperature of the third hydrothermal reaction is 80° C. to 120° C., and the reaction time is 4 h to 8 h.

[0061] It should be noted that the present invention does not limit the amount of the photoanode and the mixed liquid in Sa, as long as the mixed liquid can immerse the anode substrate; the present invention does not limit the amount of the primary electrode and the mixed liquid in Sb, as long as the mixed liquid can immerse the primary electrode.

[0062] Preferably, in Sc, the mixed liquid further includes carbon nanofibers.

[0063] Preferably, in Sc, the adhesive comprises polyamide.

[0064] Further preferably, in Sc, the molecular weight of the polyamide is 5000-12000, and the particle size is 200 mesh-300 mesh.

[0065] Preferably, in Sc, the mass ratio of Bi2O2WO4, adhesive and solvent is (6~32):(1~8):(10~80), more preferably (10~28):(2~7):(25~65), and more preferably (15~22):(3~6):(30~50).

[0066] Preferably, in Sc, the coating thickness is 80nm~200nm.

[0067] For example, in Sc, after coating and before calcining, the process further includes: natural drying for 4 min to 10 min.

[0068] Preferably, in Sc, the calcination temperature is 160° C. to 260° C. (more preferably 180° C. to 240° C.), and the calcination time is 60 min to 120 min.

[0069] In the present invention, under specific calcination conditions, the Bi2O2WO4 layer solidifies, the Bi2O2WO4 lattice gradually diffuses and tends to equilibrium, thereby increasing the cohesiveness and adhesion of the Bi2O2WO4 layer on the FeSe2 array electrode.

[0070] In the exemplary embodiment, Sc, after calcination, the step further comprises: cooling to room temperature.

[0071] In a fourth aspect, the present invention provides an application of the photoelectric anode material or the photoelectric anode in sewage treatment.

[0072] In a fifth aspect, the present invention provides a photoelectrocatalytic advanced oxidation wastewater treatment system, comprising the photoanode, photocathode, electrolytic cell, power supply and light source; The photoanode and the photocathode are located in the electrolytic cell, and the photoanode and the photocathode are connected to the power source via wires respectively; The light source is located outside the electrolytic cell and is used for irradiating light to the electrolytic cell.

[0073] The photoelectrocatalytic advanced oxidation sewage treatment system provided by the present invention combines photocatalytic technology with electrochemical catalytic technology to achieve deep treatment of sewage, improve the removal efficiency of organic pollutants, and reduce energy consumption. At the same time, the reaction conditions are mild, environmentally friendly, and easy to operate. It is suitable for water bodies with various water quality conditions, has a more effective purification effect in practical applications, and has a high market application value.

[0074] The present invention uses a photoanode loaded with a FeSe2 array / Bi2O2WO4 heterojunction in an electrolytic cell, which improves the deep treatment efficiency of complex water quality. The reaction conditions for sewage treatment are mild, green and low-carbon, and overcome the defects of high energy consumption and limited catalyst cycles of traditional advanced oxidation technology, and the treatment cycle is greatly shortened. The photoelectric catalytic system has extremely strong redox ability under the action of an external electric field and light radiation. The photoanode loses electrons and generates holes under the excitation of electric energy and light radiation. The holes are highly oxidizing and can directly react with pollutants, or react with water molecules to form hydroxyl radicals (·OH) to indirectly oxidize pollutants; and the electrons are directed to move to the cathode and aggregate under the action of an external electric field. The highly reducing electrons can not only directly catalyze the precipitation of heavy metal ions, but also react with water to generate superoxide radicals (·O 2- ), indirectly oxidize pollutants. The present invention improves the activity of photocatalytic and electrocatalytic oxidation reactions through photoelectrocatalytic advanced oxidation technology. The various components and materials have a synergistic effect, realizing deep treatment of sewage.

[0075] The photoelectrocatalytic advanced oxidation sewage treatment system provided by the present invention can be used to treat sewage with a COD of 600 mg / L to 10000 mg / L, an ammonia nitrogen value of 15 mg / L to 300 mg / L, and a heavy metal ion content of 5 mg / L to 120 mg / L.

[0076] Preferably, the photocathode includes at least one of a graphite electrode, a carbon rod electrode, a graphite fiber felt electrode or a plated metal electrode.

[0077] Further preferably, the photocathode includes at least one of carbon cloth, carbon fiber felt, titanium sheet, titanium mesh, platinum sheet or platinum mesh.

[0078] Preferably, the photoanode and the photocathode have the same size.

[0079] The present invention selects a sheet-shaped or mesh-shaped corrosion-resistant electrode as the photocathode, which has a small overpotential, a high hydrogen evolution potential, and is not prone to generating hydrogen and hydrogen embrittlement. The preferred photocathode of the present invention can fully utilize energy, reduce power consumption, and has the advantage of low carbon emission reduction.

[0080] Preferably, the volume of the electrolytic cell is 20L~150L.

[0081] Preferably, the water inlet and the water outlet of the electrolytic cell are respectively connected to peristaltic water pumps for controlling the water inlet flow rate and the water outlet flow rate, respectively.

[0082] The present invention can control the water inlet flow rate and the water outlet flow rate through a peristaltic water pump, thereby adjusting the treatment efficiency of pollutants in the water, shortening the time of photoelectrocatalytic advanced oxidation, and realizing the rational use of energy.

[0083] Preferably, a stirring device is provided in the electrolytic cell.

[0084] For example, the light source adopts a sunlight simulation system.

[0085] Preferably, the power supply is a DC power supply.

[0086] Preferably, the photoelectrocatalytic advanced oxidation wastewater treatment system also includes a water storage device, the water inlet of the water storage device is connected to the water outlet of the electrolytic cell through a pipe, and the water outlet of the water storage device is connected to the water inlet of the electrolytic cell through a pipe, so as to realize the circulation treatment of wastewater.

[0087] The present invention can repeatedly treat stubborn substances in the water body through the water storage device, so that the water quality is further purified until the water quality detection at the outlet meets the standard (COD is less than 60mg / L, ammonia nitrogen value is less than 15mg / L). It has the characteristics of simple operation and environmental friendliness, and is suitable for treating water bodies with different water qualities.

[0088] Since the photoelectrocatalytic advanced oxidation sewage treatment method has obvious efficiency, it is more suitable for short-term multiple operations. After multiple operations, the electrodes can be taken out, activated, cleaned, washed and recycled repeatedly, and have the characteristics of long-term stable operation and strong resistance to shock loads. The present invention can be controlled according to the actual situation of the inlet and outlet water, and buffered by a water storage device for secondary circulation treatment. Sewage treatment solutions can be formulated according to different water bodies, and the start-up time and power of the water pump operation in different links can be adjusted. The current of the power supply can be set according to a linear function with time as a variable, reducing degradation energy consumption and improving the current efficiency of the electrochemical system to meet the expected treatment conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 Schematic diagram of the structure of the photoelectrocatalytic advanced oxidation sewage treatment system in an embodiment of the present invention; wherein 1 represents a photoanode, 2 represents a photocathode, 3 represents an electrolytic cell, 301 represents a water inlet of the electrolytic cell, 302 represents a water outlet of the electrolytic cell, 303 represents a peristaltic water pump, 4 represents a power source, 5 represents a light source, and 6 represents a water storage device; Figure 2 is a SEM image of Bi2O2WO4 in Example 3 of the present invention; Figure 3 is a SEM image of the FeSe2 array in Example 3 of the present invention; Figures 4 and 5 This is a SEM image of the Bi2O2WO4 / FeSe2 array in Example 3 of the present invention; Figure 6 This is an element content analysis diagram of the Bi2O2WO4 / FeSe2 array in Example 3 of the present invention; Figure 7XRD patterns of Bi2O2WO4, Bi2O2WO4 / FeSe2 array and FeSe2-Bi2O2WO4 in Example 3 of the present invention; Figure 8 These are the Mott-Schottky curves of Bi2O2WO4, FeSe2 arrays and Bi2O2WO4 / FeSe2 arrays in Example 3 of the present invention; wherein, Figure a is the Mott-Schottky curve of Bi2O2WO4, Figure b is the Mott-Schottky curve of the FeSe2 array, and Figure c is the Mott-Schottky curve of the Bi2O2WO4 / FeSe2 array. DETAILED DESCRIPTION

[0090] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0091] See also Figure 1 The present invention provides a photoelectrocatalytic advanced oxidation sewage treatment system, comprising a photoanode 1, a photocathode 2, an electrolytic cell 3, a power source 4, a light source 5 and a water storage device 6; The photoanode 1 and the photocathode 2 are located in the electrolytic cell 3, and the photoanode 1 and the photocathode 2 are connected to the power source 4 via wires respectively; The light source 5 is located outside the electrolytic cell 3 and is used to irradiate the electrolytic cell 3 with light; The water inlet 301 and the water outlet 302 of the electrolytic cell 3 are respectively connected to a peristaltic water pump 303 for controlling the water inlet flow rate and the water outlet flow rate respectively; The water inlet of the water storage device 6 is connected to the water outlet 302 of the electrolytic cell 3 through a pipe, and the water outlet of the water storage device 6 is connected to the water inlet 301 of the electrolytic cell 3 through a pipe, so as to realize the circulation treatment of sewage.

[0092] In the present invention, the visible light radiation is provided by the light source of the HSX-F300 simulated sunlight system.

[0093] In the present invention, materials not specifically specified are all commercially available products. Water used in the present invention is all deionized water. The sewage used in the present invention is wastewater from an industrial park. After testing, the COD of the industrial park wastewater is 1026 mg / L, the ammonia nitrogen value is 68 mg / L, the BOD is 275 mg / L, the suspended matter content is 93 mg / L, the manganese ion content is 6.3 mg / L, the pH is 5.2, and the color index: the dilution multiple is 301.

[0094] Example 1 This embodiment provides a photoanode, including an anode substrate and a photoanode material loaded on the anode substrate; the photoanode material includes a FeSe2 array layer and a Bi2O2WO4 layer loaded on the FeSe2 array layer, and the Bi2O2WO4 layer also includes carbon nanofibers with a diameter of 150nm and a length of 5μm. The mass ratio of FeSe2, Bi2O2WO4 and carbon nanofibers in the photoanode material is 200:13:0.9.

[0095] The thickness of the FeSe2 array layer is 3 μm, and the thickness of the Bi2O2WO4 layer is 80 nm. The anode substrate is a molybdenum mesh with a length of 50 mm, a width of 200 mm, and a thickness of 2 mm.

[0096] The method for preparing the above-mentioned photoanode comprises the following steps: Preparation of S1, FeSe2: S1-1, add selenium powder to 18wt% NaBH4 solution, the mass ratio of selenium powder to NaBH4 solution is 1:10, mix well, and carry out reduction reaction at room temperature for 30 minutes, the reaction system becomes colorless, and a divalent selenide solution is obtained; S1-2, FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid and dodecyltrimethylammonium bromide (CTAB) were added to water and mixed evenly, and mixed with the divalent selenide solution at 50°C and 100rpm for 2h (the mass ratio of FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, CTAB, water and divalent selenide solution was 2:10:0.01:20:8), and then redox reaction was carried out in a reactor at 180°C for 5h, cooled to room temperature, solid-liquid separation was performed, the solid was taken and washed with deionized water 3 times, washed with anhydrous ethanol 3 times, and vacuum dried at 60°C for 5h to obtain FeSe2 with an average particle size of 13nm.

[0097] Preparation of S2, Bi2O2WO4: S2-1, dissolve Na2WO4·2H2O in water, add Bi(NO3)3·5H2O, polyethylene glycol 2000 and pH adjuster (2.3M acetic acid solution and 2.3M ammonium acetate solution), the mass ratio of Na2WO4·2H2O, Bi(NO3)3·5H2O, polyethylene glycol 2000, pH adjuster and water is 2:4:0.5:0.01:100, at which point the pH of the system is 5, and after a hydrolysis reaction at 20°C for 40 minutes, a suspension is obtained; S2-2, the suspension was subjected to the first hydrothermal reaction in a high-pressure reactor at 160°C. After keeping warm for 12 hours, it was cooled to room temperature, the solid and liquid were separated, and the solid was washed with deionized water 3 times, anhydrous ethanol 3 times, and vacuum dried at 60°C for 5 hours to obtain Bi2O2WO4 with an average particle size of 60 nm.

[0098] It should be noted that this embodiment does not limit the sequence of S1 and S2.

[0099] S3, placing the anode substrate in acetone and water in turn, ultrasonically treating each for 10 minutes, naturally drying, and then immersing it in a mixture of FeSe2 and water for 30 minutes, with a mass ratio of FeSe2 to water being 1:80. Then taking it out and placing it in a reactor at 100°C for a second hydrothermal reaction. After keeping warm for 35 minutes, a primary electrode was obtained.

[0100] S4, immersing the primary electrode in a mixture of FeSe2, KH560 and 50wt% polyvidone K30 aqueous solution, the mass ratio of FeSe2, KH560 and polyvidone K30 aqueous solution is 2:1:10, and performing a third hydrothermal reaction in a reactor at 80°C. After keeping warm for 8h, a FeSe2 array layer is formed, which is then cooled to room temperature, washed with water and dried to obtain a FeSe2 array electrode.

[0101] S5, using a coating machine, a mixed solution of Bi2O2WO4, carbon nanofibers, 200 mesh polyamide with a molecular weight of 5000 and 50wt% of polyvidone K30 aqueous solution (the mass ratio of Bi2O2WO4, polyamide and polyvidone K30 aqueous solution is 6:1:10) is coated on the FeSe2 array electrode. The coating is 80nm thick. After natural drying for 4min, it is calcined at 160℃ for 120min to form a Bi2O2WO4 layer. After cooling to room temperature, a photoanode containing Bi2O2WO4 / FeSe2 array is obtained.

[0102] Example 2 This embodiment provides a photoanode, including an anode substrate and a photoanode material loaded on the anode substrate; the photoanode material includes a FeSe2 array layer and a Bi2O2WO4-containing layer loaded on the FeSe2 array layer, and the Bi2O2WO4-containing layer also includes carbon nanofibers with a diameter of 180nm and a length of 10μm. The mass ratio of FeSe2, Bi2O2WO4 and carbon nanofibers in the photoanode material is 200:25:1.

[0103] The thickness of the FeSe2 array layer is 4 μm, and the thickness of the Bi2O2WO4 layer is 100 nm. The anode substrate is a titanium sheet with a length of 60 mm, a width of 120 mm, and a thickness of 3 mm.

[0104] The method for preparing the above-mentioned photoanode comprises the following steps: Preparation of S1, FeSe2: S1-1, add selenium powder to a 20wt% NaBH4 solution, the mass ratio of selenium powder to NaBH4 solution is 1:6, mix well, and carry out reduction reaction at room temperature for 40 minutes, the reaction system becomes colorless, and a divalent selenide solution is obtained; S1-2, FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid and CTAB were added to water, mixed evenly, and mixed with divalent selenide solution at 60°C and 120rpm for 1.5h (the mass ratio of FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, CTAB, water and divalent selenide solution was 3:15:0.02:40:15), and then redox reaction was carried out in a reactor at 185°C for 5h, cooled to room temperature, solid-liquid separation was performed, the solid was taken and washed with deionized water 3 times, washed with anhydrous ethanol 3 times, and vacuum dried at 70°C for 5h to obtain FeSe2 with an average particle size of 40nm.

[0105] Preparation of S2, Bi2O2WO4: S2-1, dissolve Na2WO4·2H2O in water, add Bi(NO3)3·5H2O, polyethylene glycol 2000 and pH adjuster (2.0M acetic acid solution and 2.1M ammonium acetate solution), the mass ratio of Na2WO4·2H2O, Bi(NO3)3·5H2O, polyethylene glycol 2000, pH adjuster and water is 4:8:0.7:0.02:120, at which time the pH of the system is 5.5, and after hydrolysis reaction at 25°C for 30 minutes, a suspension is obtained; S2-2, the suspension was subjected to the first hydrothermal reaction in a high-pressure reactor at 170°C. After keeping warm for 10 hours, it was cooled to room temperature, the solid and the liquid were separated, and the solid was washed with deionized water 4 times, anhydrous ethanol 4 times, and vacuum dried at 70°C for 5 hours to obtain Bi2O2WO4 with an average particle size of 80 nm.

[0106] It should be noted that this embodiment does not limit the sequence of S1 and S2.

[0107] S3, placing the anode substrate in acetone and water in turn, ultrasonically treating for 10 min and 15 min respectively, naturally drying, and then immersing it in a mixture of FeSe2 and water for 40 min, with a mass ratio of FeSe2 to water being 2:90. Then taking it out and placing it in a reactor at 110°C for a second hydrothermal reaction. After keeping warm for 30 min, a primary electrode was obtained.

[0108] S4, immersing the primary electrode in a mixture of FeSe2, KH560 and 40wt% polyvidone K30 aqueous solution, the mass ratio of FeSe2, KH560 and polyvidone K30 aqueous solution is 3:2:15, and performing a third hydrothermal reaction in a reactor at 90°C. After keeping warm for 7 hours, a FeSe2 array layer is formed, cooled to room temperature, washed with water and dried to obtain a FeSe2 array electrode.

[0109] S5, using a coating machine, a mixture of Bi2O2WO4, carbon nanofibers, 260 mesh polyamide with a molecular weight of 8000 and 60wt% of polyvidone K30 aqueous solution (the mass ratio of Bi2O2WO4, polyamide and polyvidone K30 aqueous solution is 16:4:30) is coated on the FeSe2 array electrode. The coating has a thickness of 100nm. After natural drying for 5 minutes, it is calcined at 180°C for 100 minutes to form a Bi2O2WO4 layer. After cooling to room temperature, a photoanode containing a Bi2O2WO4 / FeSe2 array is obtained.

[0110] Example 3 This embodiment provides a photoanode, including an anode substrate and a photoanode material loaded on the anode substrate; the photoanode material includes a FeSe2 array layer and a Bi2O2WO4 layer loaded on the FeSe2 array layer, and the Bi2O2WO4 layer also includes carbon nanofibers with a diameter of 200nm and a length of 15μm. The mass ratio of FeSe2, Bi2O2WO4 and carbon nanofibers in the photoanode material is 200:30:1.2.

[0111] The thickness of the FeSe2 array layer is 4 μm, and the thickness of the Bi2O2WO4 layer is 180 nm. The anode substrate is a nickel foam with a length of 800 mm, a width of 140 mm, and a thickness of 3.5 mm.

[0112] The method for preparing the above-mentioned photoanode comprises the following steps: Preparation of S1, FeSe2: S1-1, add selenium powder to 20wt% NaBH4 solution, the mass ratio of selenium powder to NaBH4 solution is 1:3.5, mix well, and carry out reduction reaction at room temperature for 40 minutes, the reaction system becomes colorless, and a divalent selenide solution is obtained; S1-2, FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid and CTAB were added to water, mixed evenly, and mixed with divalent selenide solution at 60°C and 180rpm for 1.5h (the mass ratio of FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, CTAB, water and divalent selenide solution was 8:20:0.04:80:20), and then redox reaction was carried out in a reactor at 190°C for 5h, cooled to room temperature, solid-liquid separation was performed, the solid was taken and washed with deionized water 4 times, washed with anhydrous ethanol 4 times, and vacuum dried at 80°C for 4h to obtain FeSe2 with an average particle size of 120nm.

[0113] Preparation of S2, Bi2O2WO4: S2-1, dissolve Na2WO4·2H2O in water, add Bi(NO3)3·5H2O, polyethylene glycol 2000 and pH adjuster (2M acetic acid solution and 2M ammonium acetate solution), the mass ratio of Na2WO4·2H2O, Bi(NO3)3·5H2O, polyethylene glycol 2000, pH adjuster and water is 7:12:0.8:0.04:150, at which time the pH of the system is 6, and the suspension is obtained after hydrolysis reaction at 30°C for 35 minutes; S2-2, the suspension was subjected to the first hydrothermal reaction in a high-pressure reactor at 180°C. After keeping warm for 10 hours, it was cooled to room temperature, the solid and liquid were separated, and the solid was washed with deionized water 4 times, anhydrous ethanol 4 times, and vacuum dried at 80°C for 5 hours to obtain Bi2O2WO4 with an average particle size of 120 nm.

[0114] The above-mentioned product was subjected to electron microscope scanning and X-ray diffraction test, and the results were as follows: Figure 2 and Figure 7 The above-mentioned product was subjected to a Mott-Schottky curve test, and the results were as follows: Figure 8 The results show that the slope of the Mott-Schottky curve of Bi2O2WO4 prepared in this embodiment is negative, and Bi2O2WO4 belongs to a p-type semiconductor.

[0115] It should be noted that this embodiment does not limit the sequence of S1 and S2.

[0116] S3, the anode substrate was placed in acetone and water in turn, ultrasonicated for 12 minutes respectively, naturally dried, and then immersed in a mixture of FeSe2 and water for 50 minutes, with a mass ratio of FeSe2 to water of 3:90. Then, the substrate was taken out and placed in a reactor at 110°C for a second hydrothermal reaction. After keeping warm for 30 minutes, a primary electrode was obtained.

[0117] S4, immersing the primary electrode in a mixture of FeSe2, KH560 and 50wt% polyvidone K30 aqueous solution, the mass ratio of FeSe2, KH560 and polyvidone K30 aqueous solution is 4:3:15, and performing a third hydrothermal reaction in a reactor at 110°C. After keeping warm for 6 hours, a FeSe2 array layer is formed, cooled to room temperature, washed with water and dried to obtain a FeSe2 array electrode.

[0118] The above-mentioned product was subjected to electron microscope scanning test, and the results were as follows: Figure 3 As shown; the FeSe2 array was tested for Mott-Schottky curve, and the results are as follows Figure 8 The results show that the slope of the Mott-Schottky curve of the FeSe2 array prepared in this embodiment is positive, and the FeSe2 array is an n-type semiconductor.

[0119] S5, using a coating machine, a mixed solution of Bi2O2WO4, carbon nanofibers, 300 mesh molecular weight 9870 polyamide and 50wt% polyvidone K30 aqueous solution (the mass ratio of Bi2O2WO4, polyamide and polyvidone K30 aqueous solution is 25:6:70) is coated on the FeSe2 array electrode. The coating has a thickness of 180nm. After natural drying for 8 minutes, it is calcined at 220°C for 90 minutes to form a Bi2O2WO4 layer. After cooling to room temperature, a photoanode containing a Bi2O2WO4 / FeSe2 array is obtained.

[0120] The surface of the obtained product was scanned by electron microscope and tested by X-ray diffraction. Figures 4 and 5 and Figure 7 As shown; the element content analysis of Bi2O2WO4 / FeSe2 array is performed, and the results are as follows Figure 6 To further verify the composition of the Bi2O2WO4 / FeSe2 array, a mixture of FeSe2 and Bi2O2WO4 (denoted as FeSe2-Bi2O2WO4) with a mass ratio of 200:30 was subjected to an X-ray diffraction test. The results are shown in Figure 7 As shown; and the Bi2O2WO4 / FeSe2 array was tested for Mott-Schottky curve, the results are as follows Figure 8 c. The results show that the Bi2O2WO4 / FeSe2 array prepared in this embodiment contains Bi2O2WO4 and FeSe2, and the Mott-Schottky curve is inverted V shape, forming a pn heterojunction.

[0121] Example 4 This embodiment provides a photoanode, including an anode substrate and a photoanode material loaded on the anode substrate; the photoanode material includes a FeSe2 array layer and a Bi2O2WO4-containing layer loaded on the FeSe2 array layer, and the Bi2O2WO4-containing layer also includes carbon nanofibers with a diameter of 200nm and a length of 20μm. The mass ratio of FeSe2, Bi2O2WO4 and carbon nanofibers in the photoanode material is 200:45:1.5.

[0122] The thickness of the FeSe2 array layer is 5 μm, and the thickness of the Bi2O2WO4 layer is 200 nm. The anode substrate is a titanium mesh with a length of 100 mm, a width of 200 mm, and a thickness of 4 mm.

[0123] The method for preparing the above-mentioned photoanode comprises the following steps: Preparation of S1, FeSe2: S1-1, add selenium powder to 22wt% NaBH4 solution, the mass ratio of selenium powder to NaBH4 solution is 1:3, mix well, and carry out reduction reaction at room temperature for 50min, the reaction system becomes colorless, and a divalent selenide solution is obtained; S1-2, FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid and CTAB were added to water, mixed evenly, and mixed with divalent selenide solution at 70°C and 200rpm for 1h (the mass ratio of FeCl2·4H2O, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, CTAB, water and divalent selenide solution was 10:30:0.05:100:28), and then redox reaction was carried out in a reactor at 200°C for 3h, cooled to room temperature, solid-liquid separation was performed, the solid was taken and washed with deionized water 4 times, washed with anhydrous ethanol 4 times, and vacuum dried at 90°C for 3h to obtain FeSe2 with an average particle size of 150nm.

[0124] Preparation of S2, Bi2O2WO4: S2-1, dissolve Na2WO4·2H2O in water, add Bi(NO3)3·5H2O, polyethylene glycol 2000 and pH adjuster (1.7M acetic acid solution and 1.7M ammonium acetate solution), the mass ratio of Na2WO4·2H2O, Bi(NO3)3·5H2O, polyethylene glycol 2000, pH adjuster and water is 8:16:1:0.05:160, at which time the pH of the system is 5.5, and the suspension is obtained after hydrolysis reaction at 35°C for 30 minutes; S2-2, the suspension was subjected to the first hydrothermal reaction in a high-pressure reactor at 190°C. After keeping warm for 8 hours, it was cooled to room temperature, the solid and liquid were separated, and the solid was washed with deionized water 5 times, anhydrous ethanol 5 times, and vacuum dried at 80°C for 5 hours to obtain Bi2O2WO4 with an average particle size of 145 nm.

[0125] It should be noted that this embodiment does not limit the sequence of S1 and S2.

[0126] S3, placing the anode substrate in acetone and water in turn, ultrasonically treating each for 10 minutes, drying naturally, and then immersing it in a mixture of FeSe2 and water for 60 minutes, with a mass ratio of FeSe2 to water being 4:100. Then, taking it out and placing it in a reactor at 120°C for a second hydrothermal reaction. After keeping warm for 25 minutes, a primary electrode was obtained.

[0127] S4, immersing the primary electrode in a mixture of FeSe2, KH560 and 40wt% polyvidone K30 aqueous solution, the mass ratio of FeSe2, KH560 and polyvidone K30 aqueous solution is 5:4:20, and performing a third hydrothermal reaction in a reactor at 120°C. After keeping warm for 4.5h, a FeSe2 array layer is formed, cooled to room temperature, washed with water and dried to obtain a FeSe2 array electrode.

[0128] S5, using a coating machine, a mixture of Bi2O2WO4, carbon nanofibers, 300 mesh polyamide with a molecular weight of 12000 and 50wt% of polyvidone K30 aqueous solution (the mass ratio of Bi2O2WO4, polyamide and polyvidone K30 aqueous solution is 32:8:80) is coated on the FeSe2 array electrode. The coating has a thickness of 200nm. After natural drying for 10min, it is calcined at 260℃ for 65min to form a Bi2O2WO4 layer. After cooling to room temperature, a photoanode containing Bi2O2WO4 / FeSe2 array is obtained.

[0129] Comparative Example 1 This comparative example provides a photoanode, which is similar to Example 3, except that the Bi2O2WO4 in the Bi2O2WO4 layer is replaced with ferrous tungstate. The remaining conditions are the same as those in Example 3 and will not be described in detail.

[0130] The preparation method of the photoanode is similar to that of Example 3, except that step S2 is deleted, and Bi2O2WO4 in S5 is replaced with ferrous tungstate of equal mass. The remaining conditions are the same as those of Example 3 and will not be described in detail.

[0131] Comparative Example 2 This comparative example provides a photoanode, which is similar to Example 3, except that Bi2O2WO4 in the Bi2O2WO4-containing layer is replaced with BiWO6. The remaining conditions are the same as those in Example 3 and will not be described in detail.

[0132] The preparation method of the photoanode is similar to that of Example 3, except that step S2 is deleted and Bi2O2WO4 in S5 is replaced with BiWO6 of equal mass. The remaining conditions are the same as those of Example 3 and will not be described in detail.

[0133] Comparative Example 3 This comparative example provides a photoanode, which is similar to Example 2, except that Bi2O2WO4 in the Bi2O2WO4-containing layer is replaced with BiVO4. The remaining conditions are the same as those in Example 2 and will not be described in detail.

[0134] The preparation method of the photoanode is similar to that of Example 2, except that step S2 is deleted and Bi2O2WO4 in S5 is replaced with BiVO4 of equal mass. The remaining conditions are the same as those of Example 2 and will not be described in detail.

[0135] Comparative Example 4 This comparative example provides a photoanode, which is similar to Example 3, except that the FeSe2 in the FeSe2 array layer is replaced by TiO2. The remaining conditions are the same as those in Example 3 and will not be described in detail.

[0136] The preparation method of the photoanode is similar to that of Example 3, except that step S1 is deleted, and FeSe2 in S3-S4 is replaced with an equal mass of TiO2. The remaining conditions are the same as those of Example 3 and will not be described in detail.

[0137] Comparative Example 5 This comparative example provides a photoanode, which is similar to Example 2, except that the FeSe2 in the FeSe2 array layer is replaced by ZnO. The remaining conditions are the same as those in Example 2 and will not be described in detail.

[0138] The preparation method of the above-mentioned photoanode is similar to that of Example 2, except that step S1 is deleted, and FeSe2 in S3-S4 is replaced with ZnO of the same mass. The remaining conditions are the same as those of Example 2 and will not be described in detail.

[0139] Comparative Example 6 This comparative example provides a photoanode, which is similar to Example 3, except that the Bi2O2WO4 in the Bi2O2WO4 layer is replaced by BiWO6, and the FeSe2 in the FeSe2 array layer is replaced by TiO2. The remaining conditions are the same as those in Example 3 and will not be repeated.

[0140] The preparation method of the above-mentioned photoanode is similar to that of Example 3, except that: Steps S1-S2 are deleted, FeSe2 in S3-S4 is replaced with an equal mass of TiO2, and Bi2O2WO4 in S5 is replaced with an equal mass of BiWO6. The remaining conditions are the same as those of Example 3 and will not be repeated here.

[0141] Application Example 1 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0142] The photoelectrocatalytic advanced oxidation wastewater treatment system comprises a photoanode 1, a photocathode 2, an electrolytic cell 3, a power source 4 (DC power source), a light source 5 and a water storage device 6; The photoanode 1 and the photocathode 2 are located in the electrolytic cell 3, and the photoanode 1 and the photocathode 2 are connected to the power source 4 through wires respectively; The light source 5 is located outside the electrolytic cell 3 and is used to irradiate the electrolytic cell 3 with light; The water inlet 301 and the water outlet 302 of the electrolytic cell 3 are respectively connected to a peristaltic water pump 303, which is used to control the water inlet flow rate and the water outlet flow rate respectively; a stirring device is provided in the electrolytic cell 3; The water inlet of the water storage device 6 is connected to the water outlet 302 of the electrolytic cell 3 through a pipe, and the water outlet of the water storage device 6 is connected to the water inlet 301 of the electrolytic cell 3 through a pipe, so as to realize the circulation treatment of sewage.

[0143] The photoanode 1 is the photoanode of Example 1, and the photocathode 2 is a plated tungsten electrode with the same size as the photoanode. The volume of the electrolytic cell is 100L.

[0144] The method of sewage treatment includes the following steps: SI, introduce the sewage to be treated into the electrolytic cell 3 of the photoelectrocatalytic advanced oxidation sewage treatment system, add 0.1wt% sodium hydroxide solution, adjust the pH of the sewage to be treated to 5.0, then add anhydrous sodium sulfate to adjust the conductivity of the sewage to be treated to 550μS / cm, and at the same time adjust the voltage of the power supply 4 to 80V, turn on the simulated solar light source 5 and the stirring device, and perform photoelectrocatalytic treatment on the sewage for 60min.

[0145] SII, the sewage that has undergone the photoelectrocatalytic treatment is discharged into the water storage device 6 through the peristaltic water pump 303, and the treatment effect of the photoelectrocatalytic advanced oxidation sewage treatment system on the sewage is evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0146] Application Example 2 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0147] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 1, except that the photoanode 1 is the photoanode of Example 2, and the photocathode 2 is a titanium mesh with the same size as the photoanode. The remaining devices and connection relationships are the same as those in Application Example 1 and will not be described in detail.

[0148] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0149] Application Example 3 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0150] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 1, except that the photoanode 1 is the photoanode of Example 3, and the photocathode 2 is a graphite felt electrode of the same size as the photoanode. The remaining devices and connection relationships are the same as those in Application Example 1 and will not be described in detail.

[0151] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0152] Application Example 4 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0153] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 1, except that the photoanode 1 is the photoanode of Example 4, and the photocathode 2 is a carbon rod electrode of the same size as the photoanode. The remaining devices and connection relationships are the same as those in Application Example 1 and will not be described in detail.

[0154] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0155] Application Comparative Example 1 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0156] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 3, except that the photoanode 1 is the photoanode of Comparative Example 1. The remaining devices and connection relationships are the same as those in Application Example 1 and will not be described in detail.

[0157] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0158] Application Comparative Example 2 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0159] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 3, except that the photoanode 1 uses the photoanode of Comparative Example 2. The remaining devices and connection relationships are the same as those in Application Example 3 and will not be described in detail.

[0160] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0161] Application Comparative Example 3 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0162] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 2, except that the photoanode 1 uses the photoanode of Comparative Example 3. The remaining devices and connection relationships are the same as those in Application Example 2 and will not be described in detail.

[0163] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0164] Application Comparative Example 4 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0165] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 3, except that the photoanode 1 uses the photoanode of Comparative Example 4. The remaining devices and connection relationships are the same as those in Application Example 3 and will not be described in detail.

[0166] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0167] Application Comparative Example 5 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0168] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 2, except that the photoanode 1 uses the photoanode of Comparative Example 5. The remaining devices and connection relationships are the same as those in Application Example 2 and will not be described in detail.

[0169] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0170] Application Comparative Example 6 This application example provides a method for treating sewage using a photoelectrocatalytic advanced oxidation sewage treatment system.

[0171] The photoelectrocatalytic advanced oxidation sewage treatment system is similar to that in Application Example 3, except that the photoanode 1 uses the photoanode of Comparative Example 6. The remaining devices and connection relationships are the same as those in Application Example 3 and will not be described in detail.

[0172] The method for sewage treatment is the same as that in Application Example 1 and will not be described in detail.

[0173] Table 1 Water performance indicators of application examples and comparative examples

[0174] Among them, the sewage was taken from the industrial park. After testing, the COD of the industrial park wastewater was 1026mg / L, the ammonia nitrogen value was 68mg / L, the BOD was 275mg / L, the suspended matter content was 93mg / L, the manganese ion content was 6.3mg / L, pH=5.2, and the color index: the dilution multiple was 301.

[0175] As can be seen from Table 1, after the sewage is treated by the photoelectrocatalytic advanced oxidation sewage treatment system of Application Examples 1 to 4, the COD, ammonia nitrogen, BOD, SS and chromaticity test results of the effluent performance indicators are better than the national primary standards, indicating that the photoelectrocatalytic advanced oxidation sewage treatment system provided by the present invention can effectively treat industrial sewage in depth.

[0176] Compared with Examples 2-3, Comparative Examples 1-3 and Comparative Example 6 use non-Bi2O2WO4 semiconductors as photoanode. After sewage treatment, the test results of effluent performance show that COD and ammonia nitrogen values ​​have increased significantly, and the effluent ammonia nitrogen value even reaches 66 mg / L, which is much higher than the national first-level standard. This shows that replacing the Bi2O2WO4 semiconductor nanomaterial in the photoanode reduces the efficiency of its photoelectrocatalytic oxidation reaction, and does not play the synergistic effect of photocatalysis and electrocatalytic oxidation of FeSe2 and Bi2O2WO4, which significantly reduces the water treatment performance of the entire system compared with the embodiment.

[0177] Compared with Examples 1 to 3, Comparative Examples 4 to 6 use non-nano FeSe2 arrays as photoanodes. After sewage treatment, the effluent performance test results show that the purification performance of the photoelectrocatalytic advanced oxidation sewage treatment system is significantly reduced. This further shows that the present invention uses nano FeSe2 and Bi2O2WO4 semiconductor composites to give full play to the synergistic effect of the composite material photoanode and cathode, and can generate a large number of electrons and holes under the excitation of light and external electric field. After the separation of electrons and holes, they move in a directional manner, gather at the positive and negative poles and generate a large number of active free radicals. After the active free radicals react with pollutants in water, the water purification efficiency can be significantly improved.

[0178] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A photoanode material, characterized in that: The invention comprises a FeSe2 array layer and a Bi2O2WO4-containing layer supported on the FeSe2 array layer.

2. The photoanode material according to claim 1, characterized in that The thickness of the FeSe2 array layer is 3 μm to 5 μm; and / or The thickness of the Bi2O2WO4 layer is 80nm~200nm.

3. The photoanode material according to claim 1 or 2, characterized in that: The Bi2O2WO4-containing layer also includes carbon nanofibers; The carbon nanofibers have a diameter of 150 nm to 200 nm and a length of 5 μm to 20 μm; The mass ratio of FeSe2, Bi2O2WO4 and carbon nanofibers in the photoanode material is 200:(10~50):(0.8~1.6).

4. The photoanode material according to claim 3, characterized in that The preparation method of FeSe2 comprises the following steps: S1-1, adding selenium powder to a reducing agent solution to perform a reduction reaction to obtain a divalent selenide solution; S1-2, adding a divalent iron salt, a chelating agent and a first dispersant into water, mixing with the divalent selenide solution, and performing an oxidation-reduction reaction to obtain FeSe2; The preparation method of Bi2O2WO4 comprises the following steps: S2-1, adding tungstate, bismuth salt, second dispersant and pH adjuster into water, and performing hydrolysis reaction under weak acid condition to obtain suspension; S2-2, subjecting the suspension to a first hydrothermal reaction to obtain Bi2O2WO4.

5. The photoanode material according to claim 4, characterized in that In S1-1, the reducing agent solution comprises 18wt% to 22wt% of sodium borohydride solution, and the mass ratio of the selenium powder to the reducing agent solution is 1:(2 to 15); and / or In S1-1, the reduction reaction temperature is 20°C to 30°C, and the reaction time is 30min to 50min; and / or In S1-2, the divalent iron salt includes ferrous chloride, the chelating agent includes N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, and the first dispersant includes dodecyltrimethylammonium bromide; and / or In S1-2, the mass ratio of the divalent iron salt, the chelating agent, the first dispersant, water and the divalent selenide solution is (2-10):(10-30):(0.01-0.05):(20-100):(6-30); and / or In S1-2, the temperature of the redox reaction is 180°C to 200°C, and the reaction time is 3h to 6h; and / or In S2-1, the tungstate includes sodium tungstate, the bismuth salt includes bismuth nitrate, the second dispersant includes polyethylene glycol, and the pH adjuster includes 1.7M~2.3M acetic acid solution and 1.7M~2.3M ammonium acetate solution; and / or In S2-1, the mass ratio of the tungstate, bismuth salt, second dispersant and water is (2-8):(4-16):(0.5-1):(100-160), and the weak acid condition is pH=5-6; and / or In S2-1, the temperature of the hydrolysis reaction is 20°C to 35°C, and the reaction time is 30min to 40min; and / or In S2-2, the temperature of the first hydrothermal reaction is 160°C to 190°C, and the reaction time is 8h to 12h.

6. A photoanode, characterized in that: The invention comprises an anode substrate and the photoanode material according to any one of claims 1 to 5 loaded on the anode substrate.

7. The method for preparing the photoanode according to claim 6, characterized in that: The following steps are involved: Sa, immersing the anode substrate in a mixture of FeSe2 and water to perform a second hydrothermal reaction to obtain a primary electrode; Sb, immersing the primary electrode in a mixed liquid of FeSe2, a silane coupling agent and a co-solvent, performing a third hydrothermal reaction to form a FeSe2 array layer, thereby obtaining a FeSe2 array electrode; Sc, coating a mixed solution of Bi2O2WO4, an adhesive and a solvent on the FeSe2 array electrode, and then calcining to form a Bi2O2WO4 layer to obtain a photoanode.

8. The method for preparing a photoanode according to claim 7, characterized in that: In Sa, the mass ratio of FeSe2 to water is (1-4):(80-100); and / or In Sa, the temperature of the second hydrothermal reaction is 100°C to 120°C, and the reaction time is 25min to 40min; and / or In Sb and Sc, the cosolvent comprises 40 wt % to 60 wt % of a polyvidone aqueous solution; and / or In Sb, the mass ratio of FeSe2, silane coupling agent and cosolvent is (2-5):(1-4):(10-20); and / or Sb, the temperature of the third hydrothermal reaction is 80°C to 120°C, and the reaction time is 4h to 8h; and / or In Sc, the mixed liquid further includes carbon nanofibers; and / or Sc, the adhesive comprises polyamide; and / or In Sc, the mass ratio of Bi2O2WO4, adhesive and solvent is (6-32):(1-8):(10-80); and / or In Sc, the calcination temperature is 160° C. to 260° C., and the calcination time is 60 min to 120 min.

9. Use of the photoanode material according to any one of claims 1 to 5 or the photoanode according to claim 6 in sewage treatment.

10. A photoelectrocatalytic advanced oxidation wastewater treatment system, characterized in that: The method comprises the photoanode, the photocathode, the electrolytic cell, the power supply and the light source as claimed in claim 6; The photoanode and the photocathode are located in the electrolytic cell, and the photoanode and the photocathode are connected to the power source via wires respectively; The light source is located outside the electrolytic cell and is used for irradiating light to the electrolytic cell.

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