A novel cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic anode material and its preparation method

Abstract

The present invention discloses a novel photoelectrocatalytic material and preparation method for forming a heterojunction between cobalt-nickel doped tungsten trioxide and zinc ferrite. The experiment prepared a photoelectrocatalyst forming a heterojunction between cobalt-nickel doped tungsten trioxide and zinc ferrite through precise three-step hydrothermal and passivation treatment. The heterojunction preparation method is as follows: first, deionized water, sodium tungstate dihydrate, potassium oxalate, cobalt nitrate hexahydrate, and nickel chloride hexahydrate are mixed and stirred to obtain a precursor through a hydrothermal method; then, the precursor is dried and sintered to obtain cobalt-nickel doped tungsten trioxide; then, a zinc ferrite film is prepared by mixing ferric chloride hexahydrate, sodium nitrate, and zinc nitrate hexahydrate through a secondary hydrothermal method, sintering, and soaking in sodium hydroxide; finally, a nickel-iron oxide passivation layer is loaded through a hydrothermal method. Compared with ordinary zinc ferrite, the heterojunction formed by the cobalt-nickel doped tungsten trioxide loaded with the zinc ferrite film has significant advantages such as excellent performance, excellent photocorrosion resistance, and stable performance.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectrocatalytic material chemistry, and specifically relates to a novel photoelectrocatalyst material of a novel cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction and a preparation method thereof. Background Art

[0002] Traditional fossil energy has led to resource shortages due to large-scale and uncontrolled exploitation. At the same time, it is non-renewable and easily causes corresponding environmental pollution. Hydrogen energy is a high-quality new energy source that is clean, pollution-free, has abundant reserves, and has high energy density. Research on hydrogen energy is divided into hydrogen evolution reaction and oxygen evolution reaction. Among them, oxygen evolution reaction is widely used in the preparation and research of pure oxygen, hydrogen energy intermediates, photoelectric materials for sterilization and disinfection equipment, and pollutant degradation materials. The photocatalytic oxygen evolution reaction occurs on the surface of the material, and the catalytic efficiency is often not high. It needs to overcome resistance such as solution and external circuit resistance, and requires a large overpotential. Photocatalysis can effectively separate electrons and holes by applying a bias voltage, thereby improving the photoelectric conversion efficiency. Therefore, the development of new photoelectric catalytic photoanode materials with visible light activity has become an important research topic.

[0003] Patent publication number CN114602486A discloses a method for nickel-ion doping tungsten trioxide photocatalyst, its products, and applications. The experiment first involves stirring and reacting tungstate with a strong acid solution, followed by centrifugal washing to obtain tungsten trioxide. The process then proceeds to mixing with a weak base solution, adding a nickel salt, stirring and reacting, and centrifuging to obtain nickel-ion doped tungsten trioxide. The difference between this invention and patent publication number CN114602486A lies in that the experiment first involves mixing tungstate dihydrate, nickel chloride hexahydrate, cobalt nitrate hexahydrate, and potassium oxalate, and then adjusting the pH of the solution to create an optimal reaction environment, representing bimetallic doping. The preparation method of this invention is a hydrothermal method, unlike the stirring reaction method disclosed in patent publication number CN114602486A, and the order in which the doping ions are added is also different.

[0004] Patent publication number CN103007950A discloses a nickel-ion-doped tungsten trioxide catalyst, its preparation method, and application. The experiment first involves heating and stirring hydrogen peroxide and tungsten powder, with nickel acetate as the source of nickel ions. The catalyst is then heated, stirred, aged, and finally heated and calcined to obtain the nickel-ion-doped tungsten trioxide catalyst. The difference between this patent and patent publication number CN103007950A lies in that the experiment first involves mixing and stirring tungstate dihydrate, nickel chloride hexahydrate, cobalt nitrate hexahydrate, and potassium oxalate, and then adjusting the pH of the solution to create an optimal reaction environment, representing bimetallic doping. Furthermore, the preparation method of this patent is a hydrothermal method, which differs from the heating and stirring reaction method described in patent publication number CN103007950A.

[0005] Patent publication number CN110970607A discloses a method for preparing cobalt-doped tungsten trioxide / CNTs anode materials for nano-ion batteries. In the experiment, cobalt-doped tungsten trioxide was prepared via a hydrothermal method, and then carbon nanotubes were grown on the surface for use as the anode material for sodium-ion batteries. This patent differs from patent publication number CN110970607A in that the experiment first involves mixing tungstate dihydrate, nickel chloride hexahydrate, cobalt nitrate hexahydrate, and potassium oxalate, and then adjusting the solution's pH to create an optimal reaction environment, representing a bimetallic doping method. Furthermore, this patent's application is primarily in the photoelectrocatalytic oxygen evolution reaction industry, unlike the lithium-ion battery anode material industry described in patent publication number CN110970607A.

[0006] The document "Wang Yingjie, Shen Yu, Liu Shuhong, Shi Jinru, et al. Construction and Antibiotic Degradation Performance of WO3 / ZnFe2O4 Nanomaterials. Journal of Dalian Jiaotong University, October 2019, Vol. 40, No. 5" published a process for preparing tungsten trioxide and zinc ferrite composite materials by solid phase grinding. The patent of this invention performs cobalt-nickel doping treatment on the substrate tungsten trioxide, and on this basis, prepares the zinc ferrite heterojunction by hydrothermal method, and finally adds a passivation layer treatment to prepare a high-performance cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic photoanode material.

[0007] The present invention prepares a cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic photoanode material through a precise and orderly three-step hydrothermal method. The photoanode catalytic material has significant advantages such as excellent performance, excellent photocorrosion resistance and excellent performance stability. Summary of the Invention

[0008] The main purpose of the present invention is to provide a photoelectric catalyst with high performance and excellent corrosion resistance.

[0009] In order to achieve the above-mentioned purpose, the present invention provides a novel cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectric catalyst material.

[0010] The preparation method of the present invention is simple and inexpensive. The prepared novel cobalt-nickel-doped tungsten trioxide and zinc ferrite heterojunction novel photoelectrocatalyst has excellent photoelectrochemical performance. Its performance under reversible hydrogen potential is 2.395 mA / square centimeter. After 8000 seconds of stability testing, the photocurrent performance still maintains a high performance of 1.843 mA / square centimeter.

[0011] The technical solution of the present invention:

[0012] The present invention proposes a novel cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic material, characterized in that the photoelectrocatalytic photoanode material is prepared by a precise and orderly three-step hydrothermal method to prepare the cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic photoanode material, and finally loaded with a nickel-iron oxide passivation layer, so that the photocurrent performance of the photoanode material is greatly improved, while the anti-photocorrosion performance and performance stability are maintained excellent.

[0013] The present invention proposes a novel photoelectric catalyst material of a cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction, characterized by comprising the following steps:

[0014] Step (1): deionized water, sodium tungstate dihydrate, potassium oxalate, cobalt nitrate hexahydrate, and nickel chloride hexahydrate are mixed and stirred evenly, and placed on conductive glass for hydrothermal reaction to prepare a cobalt-nickel doped tungsten trioxide precursor; the sample is taken out, washed with ethanol and deionized water for more than three times, and vacuum dried; the precursor sample is sintered to obtain a cobalt-nickel doped tungsten trioxide sample, and the sample is sealed and stored;

[0015] Step (2): ferric chloride hexahydrate, sodium nitrate, zinc nitrate hexahydrate, and deionized water are mixed and stirred uniformly, and a conductive glass sample doped with cobalt-nickel tungsten trioxide is placed thereon for hydrothermal reaction to obtain a heterojunction precursor, which is then dried, sintered, and soaked in sodium hydroxide to obtain a heterojunction, which is then washed with deionized water and ethanol for more than three times, vacuum-dried, and sintered at high temperature;

[0016] Step (3): Finally, place a heterojunction conductive glass sample, load a nickel-iron oxide passivation layer by a hydrothermal method, wash it with deionized water and ethanol for more than three times and vacuum dry it to obtain a new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0017] A preferred solution is that in step (1), 2.5-4.5 mmol of sodium tungstate dihydrate, 0.4-0.6 mmol of potassium oxalate, 0.04-0.1 mmol of cobalt nitrate hexahydrate, 0.05-0.1 mmol of nickel chloride hexahydrate and 40-45 ml of deionized water are weighed and placed in a beaker for stirring. The pH value of the solution is adjusted with a 2 mol / L hydrochloric acid solution, and the pH value of the solution is adjusted to 0.8-1.2. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is preferably turbid light green. The conductive glass is placed in the beaker for hydrothermal reaction. The deposited surface of the conductive glass should be placed downward. The transfer volume of the hydrothermal reaction solution needs to be checked so that the conductive glass is not completely immersed. A 2 mm × 10 mm unimmersed portion is reserved. The hydrothermal temperature should be set to 170-190 degrees Celsius, and the hydrothermal reaction time should be set to 20-30 hours.

[0018] A preferred solution is that in step (2), 4 to 8 mmoles of zinc nitrate hexahydrate, 5 to 10 mmoles of sodium nitrate, and 5 to 10 mmoles of ferric chloride hexahydrate are weighed and mixed with 50 ml of deionized water, stirred and dissolved, and stirred for 30 minutes to prepare a uniform hydrothermal reaction solution, into which a carbon-doped tungsten trioxide conductive glass sample is placed for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing downward, leaving a 4 mm × 10 mm unsubmerged portion. The temperature of the hydrothermal reaction should be set to 90 to 115 degrees Celsius, and the time of the hydrothermal reaction should be set to 5 to 8 hours.

[0019] A preferred solution is that in step (3), 20-30 mmol of ferric chloride hexahydrate and 20-30 mmol of nickel chloride hexahydrate are weighed, mixed, stirred and dissolved, and placed in conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing downward, leaving a 6 mm × 10 mm unsubmerged part. The hydrothermal temperature should be set to 96-100 degrees Celsius, and the hydrothermal reaction time should be set to 30-45 minutes. After taking out the sample, vacuum drying is performed to prepare a nickel-iron oxide passivation layer.

[0020] A preferred solution is that in steps (1) to (3), the drying temperature is 60 degrees Celsius and the vacuum drying time is 2 hours.

[0021] A preferred solution is that in steps (1) to (3), the electrolyte solutions used in all sample tests need to be slowly bubbled with nitrogen for 20 to 30 minutes to remove the oxygen component in the electrolyte solution; ice bags need to be placed next to the electrolyte solution or intermittent testing needs to be performed to prevent the electrolyte solution from being exposed to light for more than 40 minutes, which may cause the temperature to rise and thus avoid inaccurate test results; before testing, the test distance needs to be calculated and specified accurately to ensure the standard sunlight intensity of AM 1.5; the light intensity should be checked regularly every week to avoid the light intensity being weakened due to the long-term use of the xenon lamp, thereby affecting the standard sunlight intensity.

[0022] The beneficial effects of the above scheme are as follows: (1) The present invention uses deionized water, sodium nitrate, ferric chloride hexahydrate, potassium oxalate, cobalt nitrate hexahydrate, nickel chloride hexahydrate, hydrochloric acid and other raw materials to prepare a heterojunction, which is low in cost and has excellent performance; (2) The present invention first modifies the tungsten trioxide substrate by cobalt-nickel doping, and then loads a zinc ferrite film by a hydrothermal method to form a heterojunction, which greatly improves the photocurrent catalytic performance and has excellent photoelectrocatalytic stability. (3) The present invention makes the heterojunction have excellent anti-photocorrosion performance by loading and treating the nickel-iron oxide passivation layer. After 8000 seconds of stability testing, the photocurrent still maintains a high performance of 1.843 mA / cm2.

[0023] In summary, the novel cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction novel photoelectric catalyst material proposed in the present invention has the advantages of excellent photoelectric performance and excellent corrosion resistance; it has great scientific research and industrial application value in the pure oxygen industry, hydrogen energy intermediate preparation and research, sterilization equipment material industrialization and pollutant degradation industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the linear sweep voltammetry (LSV) comparison diagram of the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0025] Figure 2 This is the X-ray photoelectron spectroscopy (XPS) of a new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0026] Figure 3 This is a comparison chart of transient photocurrent tests of a new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0027] Figure 4 This is a stability test comparison chart of a new photoelectric catalyst material with a heterojunction of cobalt-nickel doped tungsten trioxide and zinc ferrite.

[0028] Figure 5This is a 300-second open circuit voltage test comparison chart (OCPT) of a new photoelectric catalyst material with a cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0029] Figure 6 This is a 2000-second open circuit voltage test comparison chart (OCPT) of a new photoelectric catalyst material with a cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0030] Figure 7 This is the X-ray high-resolution photoelectron spectrum of the 4f orbital of tungsten element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0031] Figure 8 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of the cobalt element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0032] Figure 9 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of the iron element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0033] Figure 10 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of zinc element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0034] Figure 11 This is the X-ray high-resolution photoelectron spectrum of the 1s orbital of oxygen element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0035] Figure 12 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of the nickel element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

[0036] Figure 13 This is a comparison diagram of the mechanism of the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. DETAILED DESCRIPTION

[0037] The present invention will be described in detail with reference to the following examples.

[0038] Example 1

[0039] First, weigh 2.5 mmol of sodium tungstate dihydrate, 0.4 mmol of potassium oxalate, 0.04 mmol of cobalt nitrate hexahydrate, 0.05 mmol of nickel chloride hexahydrate and 40 ml of deionized water, put them into a beaker and stir, adjust the pH value of the solution with 2 mol / L hydrochloric acid solution, and the pH value of the solution is adjusted to 0.8. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is best when it is turbid light green. Put it into conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing down. The transfer volume of the hydrothermal reaction solution needs to be detected so that the conductive glass is not completely immersed. Reserve a 2 mm × 10 mm unimmersed part. The hydrothermal temperature should be set to 170 degrees Celsius, and the hydrothermal reaction time should be set to 20 hours. Next, 4 mmol of zinc nitrate, 5 mmol of sodium nitrate, and 5 mmol of ferric chloride were weighed and mixed with 50 ml of deionized water, stirred and dissolved. After stirring for 30 minutes, a uniform hydrothermal reaction solution was prepared. A carbon-doped tungsten trioxide conductive glass sample was placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should be placed downward, leaving a 4 mm x 10 mm unsubmerged area. The hydrothermal reaction temperature should be set to 90 degrees Celsius, and the reaction time should be set to 5 hours. Finally, 20 mmol of ferric chloride hexahydrate and 20 mmol of nickel chloride hexahydrate were weighed and mixed, stirred and dissolved, and then placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should be placed downward, leaving a 6 mm x 10 mm unsubmerged area. The hydrothermal temperature should be set to 96 degrees Celsius, and the reaction time should be set to 30 minutes. After removing the sample, vacuum drying and passivation treatment were performed to prepare a nickel-iron oxide passivation layer. Figure 1 This is a linear sweep voltammetry (LSV) comparison diagram of a new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The photocurrent in this embodiment can be as high as 2.218 mA / cm2. Figure 2This is the X-ray photoelectron spectrum (XPS) of a new photoelectrocatalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. Tungsten, oxygen, zinc, iron, cobalt and carbon elements can be clearly distinguished from the spectrum, which is consistent with "Yayao Lan, Zhifeng Liu, Zhengang Guo, Mengnan Ruan and Xifei Li, A promising p-type Co-ZnFe2O4 nanorod film as a photocathode for photoelectrochemical watersplitting, Chem. Commun., 2020, 56, 5279" and "Zhichao Hao, Mengnan Ruan, Zhengang Guo, Weiguo Yan, Xiangfeng Wu and Zhifeng Liu, The synergistic role of the photosensitivity effect and extended space charge region in an inorganic–organic WO3 / PANI photoanode for efficient PEC water splitting, SustainableEnergyFuels, 2021, 5, 2893" and other standard peaks are consistent. In this implementation case, the characteristic peak of the cobalt element is not obvious in the full spectrum of XPS, which indirectly proves that the cobalt element here is the cobalt element in tungsten trioxide doping; the characteristic peak of the iron element is strong, and the characteristic peak intensity and fitting accuracy of the nickel element are both medium. Part of the characteristic peak signal of the nickel element comes from the nickel element in tungsten trioxide doping, and part comes from the nickel element in the passivation layer. In this implementation case, in the nickel-iron oxide passivation layer formed by the catalytic material, the nickel-iron ratio content after coordination is low, but the photocurrent performance is good.

[0040] Example 2

[0041] First, weigh 4.5 mmol of sodium tungstate dihydrate, 0.6 mmol of potassium oxalate, 0.1 mmol of cobalt nitrate hexahydrate, 0.1 mmol of nickel chloride hexahydrate and 45 ml of deionized water, put them into a beaker and stir, adjust the pH value of the solution with 2 mol / L hydrochloric acid solution, and the pH value of the solution is adjusted to 1.2. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is best when it is turbid light green. Put it into conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing down. The transfer volume of the hydrothermal reaction solution needs to be detected so that the conductive glass is not completely immersed. Reserve a 2 mm × 10 mm unimmersed part. The hydrothermal temperature should be set to 190 degrees Celsius, and the hydrothermal reaction time should be set to 30 hours. Next, 8 mmol of zinc nitrate hexahydrate, 10 mmol of sodium nitrate, and 10 mmol of ferric chloride hexahydrate were weighed and mixed with 50 ml of deionized water, stirred and dissolved. After stirring for 30 minutes, a uniform hydrothermal reaction solution was prepared. A carbon-doped tungsten trioxide conductive glass sample was placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should face downward, leaving a 4 mm x 10 mm unsubmerged area. The hydrothermal reaction temperature should be set to 115 degrees Celsius, and the reaction time should be set to 8 hours. Finally, 30 mmol of ferric chloride hexahydrate and 30 mmol of nickel chloride hexahydrate were weighed and mixed, stirred and dissolved, and then placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should face downward, leaving a 6 mm x 10 mm unsubmerged area. The hydrothermal temperature should be set to 100 degrees Celsius, and the reaction time should be set to 45 minutes. The sample was removed and vacuum dried to prepare a nickel-iron oxide passivation layer. Figure 3 This is a comparison chart of transient photocurrent tests of a new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The light response signal of this implementation case is very excellent, and the best photocurrent performance can reach 2.29 mA / cm2. Figure 4 This is a stability test comparison chart of the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The photocurrent stability of this implementation case is excellent, especially the photocurrent performance stability after forming the heterojunction and adding the passivation layer; after 8000 seconds of photocurrent stability test, the photocurrent only dropped by about 10%.

[0042] Example 3

[0043] First, weigh 3.5 mmol of sodium tungstate dihydrate, 0.5 mmol of potassium oxalate, 0.07 mmol of cobalt nitrate hexahydrate, 0.075 mmol of nickel chloride hexahydrate and 42 ml of deionized water, put them into a beaker and stir, adjust the pH value of the solution with 2 mol / L hydrochloric acid solution, and the pH value of the solution is adjusted to 1.0. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is best when it is turbid light green. Put it into conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing down. The transfer volume of the hydrothermal reaction solution needs to be detected so that the conductive glass is not completely immersed. Reserve a 2 mm × 10 mm unimmersed part. The hydrothermal temperature should be set to 180 degrees Celsius, and the hydrothermal reaction time should be set to 25 hours. Next, 6 mmol of zinc nitrate hexahydrate, 7.5 mmol of sodium nitrate, and 7.5 mmol of ferric chloride hexahydrate were weighed and mixed with 50 ml of deionized water, stirred and dissolved. After stirring for 30 minutes, a uniform hydrothermal reaction solution was prepared. A carbon-doped tungsten trioxide conductive glass sample was placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should face downward, leaving a 4 mm x 10 mm unsubmerged area. The hydrothermal reaction temperature should be set to 112 degrees Celsius, and the reaction time should be set to 6.5 hours. Finally, 25 mmol of ferric chloride hexahydrate and 25 mmol of nickel chloride hexahydrate were weighed and mixed and dissolved. The solution was then placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should face downward, leaving a 6 mm x 10 mm unsubmerged area. The hydrothermal temperature should be set to 98 degrees Celsius, and the reaction time should be set to 38 minutes. The sample was removed and vacuum dried to prepare a nickel-iron oxide passivation layer. Figure 5 This is a 300-second open circuit voltage test comparison chart (OCPT) of a new photoelectric catalyst material with a cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. In this implementation case, the open circuit voltage of the catalyst material after loading the nickel-iron oxide passivation layer is at the lowest state, and the chopping performance of the OCPT is very excellent. Figure 6 This is a 2000-second open circuit voltage test comparison chart (OCPT) of a new photoelectric catalyst material with a heterojunction of cobalt-nickel doped tungsten trioxide and zinc ferrite. The slope of the curve of the photoelectric catalyst material after forming a heterojunction and loading a passivation layer is smaller, proving that the carrier lifetime is longer, which is consistent with the strength of the photocurrent performance shown in the patent of this invention.

[0044] Example 4

[0045] First, weigh 2.8 mmol of sodium tungstate dihydrate, 0.45 mmol of potassium oxalate, 0.05 mmol of cobalt nitrate hexahydrate, 0.06 mmol of nickel chloride hexahydrate and 41 ml of deionized water, put them into a beaker and stir, adjust the pH value of the solution with 2 mol / L hydrochloric acid solution, and the pH value of the solution is adjusted to 0.9. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is best when it is turbid light green. Put it into conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing down. The transfer volume of the hydrothermal reaction solution needs to be detected so that the conductive glass is not completely immersed. Reserve a 2 mm × 10 mm unimmersed part. The hydrothermal temperature should be set to 175 degrees Celsius, and the hydrothermal reaction time should be set to 21 hours. Then, 5 mmol of zinc nitrate hexahydrate, 6 mmol of sodium nitrate, and 6 mmol of ferric chloride hexahydrate were weighed and mixed with 50 ml of deionized water, stirred and dissolved. After stirring for 30 minutes, a uniform hydrothermal reaction solution was prepared. A carbon-doped tungsten trioxide conductive glass sample was placed for hydrothermal reaction. The deposited surface of the conductive glass should be placed downward, leaving a 4 mm × 10 mm unsubmerged area. The hydrothermal reaction temperature should be set to 95 degrees Celsius and the hydrothermal reaction time should be set to 6 hours. Finally, 22 mmol of ferric chloride hexahydrate and 22 mmol of nickel chloride hexahydrate were weighed and mixed, stirred and dissolved, and placed in the conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed downward, leaving a 6 mm × 10 mm unsubmerged area. The hydrothermal temperature should be set to 98 degrees Celsius and the hydrothermal reaction time should be set to 32 minutes. After removing the sample, vacuum drying was performed to prepare a nickel-iron oxide passivation layer. Figure 7 This is an X-ray high-resolution photoelectron spectrum of the 4f orbital of tungsten element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. In this embodiment, the characteristic peaks of tungsten element at 34.9 electron volts and 37.1 electron volts are very obvious, proving that the substrate in this embodiment is a tungsten trioxide doped catalytic material. Figure 8 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of the cobalt element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The characteristic peak of the cobalt element at 782.5 electron volts is relatively obvious, but the satellite peak is not obvious, which indirectly confirms that the position of the cobalt element is located in the cobalt-nickel doped tungsten trioxide substrate. Figure 9 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of the iron element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The two characteristic peaks of the iron element at 724.3 electron volts and 710.8 electron volts are very obvious, and the satellite peaks accompanying the two characteristic peaks are also relatively obvious. Figure 10This is a high-resolution X-ray photoelectron spectrum of the 2p orbital of zinc in a novel photoelectrocatalyst material of a cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The two characteristic peaks of zinc at 1045.1 electron volts and 1021.3 electron volts are more obvious. The appearance of the characteristic peaks and satellite peaks of zinc and iron elements is consistent with the positions of the characteristic peaks and satellite peaks of zinc ferrite in many literatures such as "Jianhua Han, Yayao Lan, Qinggong Song, Huiyu Yan, Jianhai Kang, Yanrui Guo and Zhifeng Liu, Zincferrite-based pn homojunction with multi-effect forefficient photoelectrochemical water splitting, Chem. Commun., 2020, 56, 13205", proving that the zinc ferrite film was synthesized in this embodiment. Figure 11 This is the X-ray high-resolution photoelectron spectrum of the 1s orbital of oxygen element in the new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. Figure 12 This is the X-ray high-resolution photoelectron spectrum of the 2p orbital of the nickel element in the new photoelectric catalyst material of the cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The characteristic peak intensity and fitting accuracy of the nickel element are medium. The main reason is that the nickel element at the cobalt-nickel doped tungsten trioxide substrate becomes blurred and weak due to the multi-layer loading and coordination effect, just like the cobalt element; however, since there is still a small amount of nickel element signal in the nickel-iron oxide passivation layer on the surface, although the proportion of nickel-iron content after the coordination effect is low, overall, the nickel element signal is at a medium level, which is consistent with the facts of this implementation case.

[0046] Example 5

[0047] First, weigh 4.4 mmol of sodium tungstate dihydrate, 0.5 mmol of potassium oxalate, 0.08 mmol of cobalt nitrate hexahydrate, 0.08 mmol of nickel chloride hexahydrate and 44 ml of deionized water, put them into a beaker and stir, adjust the pH value of the solution with 2 mol / L hydrochloric acid solution, and the pH value of the solution is adjusted to 1.1. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is best when it is turbid light green. Put it into conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing down. The transfer volume of the hydrothermal reaction solution needs to be detected so that the conductive glass is not completely immersed. Reserve a 2 mm × 10 mm unimmersed part. The hydrothermal temperature should be set to 178 degrees Celsius, and the hydrothermal reaction time should be set to 28 hours. Next, 6 mmol of zinc nitrate hexahydrate, 8 mmol of sodium nitrate, and 8 mmol of ferric chloride hexahydrate were weighed and mixed with 50 ml of deionized water, stirred and dissolved. After stirring for 30 minutes, a uniform hydrothermal reaction solution was prepared. A carbon-doped tungsten trioxide conductive glass sample was placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should face downward, leaving a 4 mm x 10 mm unsubmerged area. The hydrothermal reaction temperature was set to 110 degrees Celsius, and the reaction time was set to 7 hours. Finally, 28 mmol of ferric chloride hexahydrate and 28 mmol of nickel chloride hexahydrate were weighed and mixed and dissolved. The solution was then placed in the solution for a hydrothermal reaction. The deposited surface of the conductive glass should face downward, leaving a 6 mm x 10 mm unsubmerged area. The hydrothermal temperature was set to 98 degrees Celsius, and the reaction time was set to 42 minutes. The sample was removed and vacuum dried to produce a nickel-iron oxide passivation layer. Figure 13 This is a mechanism comparison diagram of a new photoelectric catalyst material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction. The carrier distribution state in the mechanism diagram is consistent with the actual photocurrent catalytic performance in the patent of this invention.

[0048] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic anode material, characterized in that: The photoelectrocatalytic anode material is prepared through three precise and orderly hydrothermal reactions, and is finally passivated, which greatly improves the photocurrent performance of the photoelectrocatalytic anode material. At the same time, the catalyst has excellent photocorrosion resistance and photocurrent stability. The method for manufacturing the cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction photoelectrocatalytic anode material comprises the following steps: Step (1): deionized water, sodium tungstate dihydrate, potassium oxalate, cobalt nitrate hexahydrate, and nickel chloride hexahydrate are mixed and stirred evenly, and placed on conductive glass for hydrothermal reaction to prepare a cobalt-nickel doped tungsten trioxide precursor; the sample is taken out, washed with ethanol and deionized water for more than three times, and vacuum dried; the precursor sample is sintered to obtain a cobalt-nickel doped tungsten trioxide sample, and then sealed and stored; Step (2): ferric chloride hexahydrate, sodium nitrate, zinc nitrate hexahydrate, and deionized water are mixed and stirred uniformly, and a cobalt-nickel-doped tungsten trioxide conductive glass sample is placed thereon for hydrothermal reaction to obtain a heterojunction precursor, which is then dried, sintered, and soaked in sodium hydroxide to obtain a heterojunction, which is then washed with deionized water and ethanol for more than three times, vacuum-dried, and sintered at high temperature; Step (3): Finally, place a heterojunction conductive glass sample, load a nickel-iron oxide passivation layer by a hydrothermal method, wash it with deionized water and ethanol for more than three times and vacuum dry it to obtain a new photoelectrocatalytic anode material of cobalt-nickel doped tungsten trioxide and zinc ferrite heterojunction.

2. The manufacturing method according to claim 1, characterized in that In the step (1), 2.5 to 4.5 mmol of sodium tungstate dihydrate, 0.4 to 0.6 mmol of potassium oxalate, 0.04 to 0.1 mmol of cobalt nitrate hexahydrate, 0.05 to 0.1 mmol of nickel chloride hexahydrate and 40 to 45 ml of deionized water are weighed and placed in a beaker for stirring. The pH value of the solution is adjusted with a 2 mol / L hydrochloric acid solution to a pH value adjustment range of 0.8 to 1.

2. After stirring for 6 hours, a uniform hydrothermal reaction solution is obtained. The solution is turbid light green and is placed in a conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed downward, leaving a 2 mm × 10 mm unsubmerged portion. The hydrothermal temperature should be set to 170 to 190 degrees Celsius, and the hydrothermal reaction time should be set to 20 to 30 hours.

3. The manufacturing method according to claim 1, characterized in that In the step (2), 4 to 8 millimoles of zinc nitrate hexahydrate, 5 to 10 millimoles of sodium nitrate, and 5 to 10 millimoles of ferric chloride hexahydrate are weighed and mixed with 50 milliliters of deionized water, stirred and dissolved. After stirring for 30 minutes, a uniform hydrothermal reaction solution is prepared, and a cobalt-nickel-doped tungsten trioxide-doped conductive glass sample is placed therein for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing downward, leaving a 4 mm × 10 mm unsubmerged portion. The temperature of the hydrothermal reaction should be set to 90 to 115 degrees Celsius, and the time of the hydrothermal reaction should be set to 5 to 8 hours.

4. The manufacturing method according to claim 1, characterized in that In the step (3), 20 to 30 millimoles of ferric chloride hexahydrate and 20 to 30 millimoles of nickel chloride hexahydrate are weighed, stirred and dissolved, and placed in a conductive glass for hydrothermal reaction. The deposited surface of the conductive glass should be placed facing downward, leaving a 6 mm × 10 mm unsubmerged part. The hydrothermal temperature should be set to 96 to 100 degrees Celsius, and the hydrothermal reaction time should be set to 30 to 45 minutes. After taking out the sample, vacuum drying treatment is performed to prepare a nickel-iron oxide passivation layer.

5. The manufacturing method according to claim 1, characterized in that In the steps (1) to (3), the drying temperature is 60 degrees Celsius and the vacuum drying time is 2 hours.

6. The manufacturing method according to claim 2, claim 3 or claim 4, characterized in that: The electrolyte solutions used in all sample tests need to be slowly bubbled with nitrogen for 20 to 30 minutes to remove the oxygen content in the electrolyte solution; ice packs need to be placed next to the electrolyte solution or intermittent testing should be performed to prevent the electrolyte solution from being exposed to light for more than 40 minutes, which would cause the temperature to rise and thus avoid inaccurate test results; before testing, the accurate test distance needs to be calculated to ensure the standard sunlight intensity of AM 1.5; the light intensity should be checked regularly every week to prevent the light intensity from being weakened due to the long-term use of the xenon lamp, which would affect the standard sunlight intensity.

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