CN115478277A

CN115478277A - Solvent-regulated photo-anode material and preparation method and application thereof

Info

Publication number: CN115478277A
Application number: CN202211048962.5A
Authority: CN
Inventors: 李伟华; 魏立诚
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2022-08-30
Filing date: 2022-08-30
Publication date: 2022-12-16

Abstract

The invention discloses a preparation method of a photo-anode material regulated and controlled by a solvent. Adding a titanium source or a zinc source into an alcohol solvent to dissolve to form a mixed solution, soaking a cleaned conductive substrate in the mixed solution, heating at 160-200 ℃, taking out the conductive substrate after heating, cleaning, drying, heating at 450-550 ℃, and cooling to obtain the photo-anode material; the alcohol solvent is monohydric alcohol. The photo-anode material has a specific spherical morphology, not only has more negative conduction band potential and photoinduced open-circuit potential, but also has higher current density and high photoelectric conversion efficiency, and can effectively realize the photo-cathode protection of metal in a marine environment when being coupled with protective metal, thereby obviously improving the durability of the metal.

Description

Solvent-regulated photo-anode material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of ocean photoelectric cathode protection, and particularly relates to a solvent-regulated photo-anode material and a preparation method and application thereof.

Background

Corrosion is a process in which a metal in a high-energy state spontaneously reacts with an electrolyte to form a metal compound, resulting in a system that becomes low in energy. Because of the wide use of metals, corrosion of metals occurs in the atmosphere, in soils, and in bodies of water. With the development of scientific technology, people acquire marine resources increasingly frequently and cause marine equipment to be inevitably in contact with seawater and corrode. Thus, for an ocean-going environment, repair and replacement of equipment requires a great deal of effort and economic cost. In view of the above, the research on how to fundamentally slow down or suppress corrosion of the anticorrosion technique is urgent.

Cathodic protection is a common and effective corrosion protection technique, which is divided into sacrificial anode cathodic protection and impressed current cathodic protection. The sacrificial anode cathodic protection method adopts a method of coupling metal with more negative self-corrosion potential with protected metal, and the principle is that the corrosion of active metal continuously transfers electrons to the protected metal to generate protection. The principle of the impressed current cathodic protection method is that the cathode of a power supply is connected with metal, and the anode is connected with a refractory electrode to form a loop so as to achieve the protection effect. However, the two methods have the problem of periodically replacing the active metal or the power supply, and limit the further popularization of the two methods.

In recent years, a new cathodic protection method, namely a photocathode protection method attracts people's eyes. Compared with the traditional cathodic protection method, the method has the following advantages: (1) environmental protection: no reaction product is generated, and the pollution is reduced; (2) the cost is low: the metal can be continuously protected by only coupling a semiconductor element. Some common semiconductor materials are tin dioxide, tungsten oxide, zinc sulfide, indium sulfide and the like, but the protection effect of corrosion prevention is unsatisfactory due to the fact that a conduction band of the materials is not negative enough and is difficult to protect relatively active steel (tin dioxide, tungsten oxide, cuprous oxide and the like), or some materials are oxidized by water to cause failure and deterioration (cadmium sulfide, zinc sulfide, nickel sulfide and the like).

However, there are also some metal oxides (such as titanium dioxide, zinc oxide, etc.), which have a relatively negative conduction band and excellent resistance to light corrosion, theoretically provide a more negative protective potential than the protective body, and maintain protection for a long time. However, some of the metal oxides have poor photogenerated electron-hole separation efficiency, which results in low photoactivity of the semiconductor.

Thus, metal oxides are typically modified to increase their photoactivity, and morphology control has proven to be an effective performance improvement among many modification methods. Controlling BiVO by controlling the pH of the reaction system ₄ Grow into different shapes, thereby achieving the improvement of performance. But existing goldThe oxide modification method is usually synthesized in a hydrochloric acid aqueous solution by a hydrothermal method, the conventional hydrothermal method is generally to add raw materials into the hydrochloric acid aqueous solution, stir and dissolve the raw materials, heat the mixture in a reaction kettle and cool the mixture to obtain the metal oxide, however, the shape of the metal oxide modified by the hydrothermal method is difficult to control, and the application of the photoelectric property of the metal oxide is limited.

In addition, the common application of photocathode protection is the use of hole-trapping systems, e.g. with Na ₂ S solution system, na ₂ SO ₃ +Na ₂ S solution system or NaOH + Na ₂ The S solution system acts as a photovoltaic cell. Although the method can achieve good protection, the application environment is far from the real marine environment. If metal protection for marine environments is required, a hole scavenger free system, i.e. application in a sodium chloride solution system, must be required.

Disclosure of Invention

In view of the above-mentioned prior art problems, an object of the present invention is to provide a method for preparing a photoanode material regulated by a solvent, which synthesizes a photoanode material with a specific spherical morphology in a specific alcohol solvent system, and has a more negative conduction band potential and a photo-induced open circuit potential, a higher current density, a high photoelectric conversion efficiency, and realizes efficient photocathode protection of metals in a marine environment, and significantly improves durability of metals.

The second purpose of the invention is to provide a photo-anode material prepared by the preparation method.

The third purpose of the invention is to provide the application of the photoanode material in photoelectrochemical cathodic protection.

In order to realize the purpose, the invention is realized by the following technical scheme:

a preparation method of a solvent-regulated photo-anode material comprises the steps of adding a titanium source or a zinc source into an alcohol solvent to be dissolved to form a mixed solution, soaking a cleaned conductive substrate into the mixed solution, heating at 160-200 ℃, taking out the conductive substrate after heating is finished, cleaning, drying, heating at 450-550 ℃, and cooling to obtain the photo-anode material; the alcohol solvent is monohydric alcohol.

The optical activity of the metal oxide can be improved by modifying the metal oxide, and the shape regulation and control is proved to be an effective performance improvement method in a plurality of modification methods. The inventor finds that a titanium source or a zinc source can be hydrolyzed under a specific alcohol solvent system to obtain titanium dioxide or zinc oxide with a specific spherical morphology, and the titanium dioxide or the zinc oxide with the morphology not only has more negative conduction band potential and photoinduced open-circuit potential, but also has higher current density and high photoelectric conversion efficiency. The high-efficiency photoelectric cathode protection of metal in the marine environment can be realized, and the durability of the metal is obviously improved.

Preferably, the titanium source is selected from one or both of isopropyl titanate or tetrabutyl titanate.

Further preferably, the titanium source is selected from isopropyl titanate.

Preferably, the zinc source is selected from one or more of zinc acetate, zinc chloride or zinc sulphate.

Further preferably, the zinc source is selected from zinc acetate.

Preferably, the alcoholic solvent is selected from one or more of methanol, ethanol, propanol, isopropanol or butanol.

Further preferably, the alcohol solvent is ethanol.

Preferably, the concentration of the titanium source or the zinc source dissolved in the alcohol solvent is 0.03-0.09 mol/L. At this concentration range, higher yields of the product titanium dioxide or zinc oxide can be obtained.

Preferably, the conductive substrate is heated at 180 ℃ for 8-12 h.

Preferably, the conductive substrate is heated at 500 ℃ for 0.5 to 1 hour.

Preferably, the conductive substrate is FTO conductive glass (fluorine-doped tin oxide conductive glass), and the conductive substrate is immersed in the mixed solution with the conductive surface facing downward.

Preferably, the conductive substrate is placed in acetone for ultrasonic cleaning, and is taken out and dried at room temperature after the cleaning.

Further preferably, the time of ultrasonic cleaning is more than or equal to 10min.

Preferably, the drying temperature is 60-90 ℃.

In addition, the invention also protects the photoanode material prepared by the preparation method.

Furthermore, the invention also protects the application of the photoanode material in photoelectrochemical cathodic protection.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a solvent-regulated modification method of a photoanode material, which preferably prepares titanium dioxide or zinc oxide with a specific spherical morphology structure in an alcohol solvent system, and as the photoanode material, overcomes the defects of difficult control of morphology and poor photoelectric performance of modified metal oxides prepared by a traditional hydrothermal method; therefore, the high-efficiency photocathode protection of the metal in the marine environment can be realized, and the durability of the metal is obviously improved.

Drawings

Fig. 1 is an X-ray diffraction analysis diagram of the photoanode materials prepared in example 1, example 2 and comparative example 1.

Fig. 2 is an X-ray diffraction analysis diagram of the photoanode materials obtained in example 3, example 4 and comparative example 2.

Fig. 3 is a scanning electron micrograph of the photoanode material obtained by the preparation of example 1, example 2 and comparative example 1, wherein (a) is a scanning electron micrograph of comparative example 1, (b) is a scanning electron micrograph of example 1, and (c) is a scanning electron micrograph of example 2.

Fig. 4 is a scanning electron micrograph of the photoanode materials obtained in example 3, example 4, and comparative example 2, wherein (a) is a scanning electron micrograph of comparative example 2, (b) is a scanning electron micrograph of example 3, and (c) is a scanning electron micrograph of example 4.

Fig. 5 is a graph of photo-induced current density versus time for photo-anode materials prepared in example 1, example 2 and comparative example 1.

Fig. 6 is a graph of photo-induced current density versus time for the photo-anode materials prepared in example 3, example 4 and comparative example 2.

Fig. 7 is an open circuit potential versus time plot of photo-anode materials prepared in example 1, example 2, and comparative example 1 coupled to 304 stainless steel.

Fig. 8 is an open circuit potential versus time curve of photoanode materials prepared in example 3, example 4, and comparative example 2 coupled to 304 stainless steel.

Detailed Description

The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Example 1

A preparation method of a solvent-regulated photo-anode material comprises the following preparation steps:

(1) Placing FTO conductive glass (fluorine-doped tin oxide conductive glass) in acetone, ultrasonically cleaning for 10min, taking out, and airing at room temperature;

(2) Adding 60ml of ethanol into a reaction kettle, adding 0.005mol of isopropyl titanate to dissolve the isopropyl titanate into the ethanol, placing the cleaned FTO conductive glass in the reaction kettle with the conductive surface facing downwards, heating at 180 ℃ for 10 hours, and cooling to room temperature;

(3) Cleaning the FTO glass cooled to room temperature in the step (2) by using deionized water, and drying in an oven at 80 ℃;

(4) And (4) placing the dried FTO conductive glass in the step (3) in a muffle furnace, heating for 0.5h at 500 ℃, and cooling to room temperature to obtain the photoanode material.

Example 2

(2) Adding 60ml of isopropanol into a reaction kettle, adding 0.005mol of isopropyl titanate to dissolve the isopropyl titanate into the isopropanol, placing the cleaned FTO conductive glass into the reaction kettle with the conductive surface facing downwards, heating for 10 hours at 180 ℃, and cooling to room temperature;

Example 3

(2) Adding 60ml of ethanol into a reaction kettle, adding 0.005mol of zinc acetate to dissolve the zinc acetate into the ethanol, placing the cleaned FTO conductive glass in the reaction kettle with the conductive surface facing downwards, heating at 180 ℃ for 10 hours, and cooling to room temperature;

Example 4

(2) Adding 60ml of isopropanol into a reaction kettle, adding 0.005mol of zinc acetate to dissolve the zinc acetate into ethanol, placing the cleaned FTO conductive glass in the reaction kettle with the conductive surface facing downwards, heating at 180 ℃ for 10 hours, and cooling to room temperature;

Example 5

This example differs from example 1 in that: in the step (2), heating for 12h at 160 ℃; in step (4), heating is carried out at 450 ℃ for 1h.

Example 6

This example differs from example 1 in that: in the step (2), heating for 8h at 200 ℃; in step (4), the mixture is heated at 550 ℃ for 0.5h.

Comparative example 1

Comparative example 1 differs from example 1 in that: in the step (2), 0.005mol of isopropyl titanate and 60ml of an aqueous hydrochloric acid solution (18.5% by weight) were added to a reaction vessel to dissolve isopropyl titanate in the aqueous hydrochloric acid solution, the FTO glass was placed in the reaction vessel with the conductive surface facing downward, heated at 180 ℃ for 10 hours, and cooled to room temperature.

Comparative example 2

Comparative example 2 differs from example 1 in that: in the step (2), 0.005mol of zinc acetate and 60ml of hexamethylenetetramine aqueous solution (0.55 mol/L) are added into a reaction kettle, so that the zinc acetate is dissolved in the hexamethylenetetramine aqueous solution, the FTO glass conductive surface is placed downwards in the reaction kettle, heated at 180 ℃ for 10 hours, and cooled to room temperature.

Test example 1

The photoanode materials prepared in examples 1 to 4 and comparative examples 1 to 2 were subjected to X-ray diffraction analysis under the following test conditions: the scanning speed is 10 deg./min, and the results are shown in FIGS. 1 and 2; wherein, FIG. 1 is an X-ray diffraction analysis chart of example 1, example 2 and comparative example 1; FIG. 2 is an X-ray diffraction analysis chart of example 3, example 4 and comparative example 2. As can be seen from fig. 1, the diffraction peaks of the crystal planes of

titanium dioxide

101, 004, 220, 211, 204 appear at 25.1 °,37.5 °,47.8 °,54.8 ° and 62.6 °, which indicates that all three materials prepared in example 1, example 2 and comparative example 1 are titanium dioxide. As can be seen from fig. 2, the

zinc oxide

100, 002, 101, 102, 110, 103 crystal plane diffraction peaks appear at 32.1 °, 34.9 °, 36.7 °, 48.0 °, 56.7 ° and 63.3 °, indicating that example 3, example 4 and comparative example 2 are zinc oxide.

Test example 2

The photoanode materials prepared in examples 1 to 2 and comparative example 1 were subjected to scanning electron microscopy analysis under the following test conditions: the acceleration voltage is 20kv; the photoanode materials prepared in examples 3 to 4 and comparative example 2 were subjected to scanning electron microscopy analysis under the following test conditions: the acceleration voltage was 20kv.

The results are shown in FIGS. 3 and 4, in which FIG. 3 (a) is a SEM image of comparative example 1, (b) is a SEM image of example 1, and (c) is a SEM image of example 2; FIG. 4 (a) is a SEM image of comparative example 2, (b) is a SEM image of example 3, and (c) is a SEM image of example 4. As can be seen from fig. 3, the titanium dioxide in comparative example 1 has a plate-like structure, whereas example 1 forms a nano-spherical structure and example 2 forms a nano-spherical structure. As can be seen from fig. 4, the zinc oxide in comparative example 2 has a hexagonal prism structure, whereas example 3 forms a nano spherical structure, and example 4 forms a nano spherical structure.

Test example 3

The photo-generated current density analysis was performed on the photo-anode materials prepared in examples 1 to 2 and comparative example 1, using titanium dioxide as a working electrode, a platinum sheet as a counter electrode, and Ag/AgCl as a reference electrode, under the following test conditions: 3.5% sodium chloride in water, 0V bias, 350 seconds long; the results are shown in FIG. 5. The photo-generated current density analysis was performed on the photo-anode materials prepared in examples 3 to 4 and comparative example 2, using zinc oxide as a working electrode, a platinum sheet as a counter electrode, and Ag/AgCl as a reference electrode, under the following test conditions: 3.5% sodium chloride aqueous solution, 0V bias, 350 seconds duration; the results are shown in FIG. 6.

As can be seen from FIG. 5, the current density of the system of example 1 reached 105. Mu.A·cm ^-2 And, the current density is larger than that of the system of example 2 and that of the system of comparative example 1, indicating that the photoelectric conversion efficiency of the system of example 1 is the highest. As can be seen from FIG. 6, the current density of the system of example 3 reached 220. Mu.A. Cm ^-2 The current density is larger than that of the system of example 4 and the system of comparative example 2, which shows that the photoelectric conversion efficiency of the system of example 3 is the highest.

Test example 4

The photo-anode materials prepared in examples 1-2 and comparative example 1 were subjected to open circuit potential analysis, using titanium dioxide as a working electrode, a platinum sheet as a counter electrode, and Ag/AgCl as a reference electrode, under the following test conditions: 3.5% aqueous sodium chloride, 0V bias, 350 seconds long, coupling 304 stainless steel; the results are shown in FIG. 7. The photo-anode materials prepared in examples 3 to 4 and comparative example 2 were subjected to open-circuit potential analysis using zinc oxide as a working electrode, a platinum sheet as a counter electrode, and Ag/AgCl as a reference electrode under the following test conditions: 3.5% aqueous sodium chloride, 0V bias, 350 seconds long, coupling 304 stainless steel; the results are shown in FIG. 8.

As can be seen from FIG. 7, the open circuit potential of the photo-induced voltage of the system of example 1 is most negative (-0.45V), which indicates that the protection of 304 stainless steel is the best, and also matches the photo-generated current density result. As can be seen from FIG. 8, the open circuit potential of the photo-induced voltage in the system of example 3 is most negative (-0.19V), which indicates that it is best for protecting 304 stainless steel, and also matches the above photo-generated current density results.

The foregoing examples are merely illustrative and serve to explain some of the features of the method of the present invention. The appended claims are intended to claim as broad a scope as is conceivable, and the examples presented herein demonstrate the results of applicants' actual experiments. Accordingly, it is applicants' intention that the appended claims are not to be limited by the choice of examples illustrating features of the invention. Also, where numerical ranges are used in the claims, subranges therein are included, and variations in these ranges are also to be construed as possible being covered by the appended claims.

Claims

1. A preparation method of a solvent-regulated photo-anode material is characterized in that a titanium source or a zinc source is added into an alcohol solvent to be dissolved to form a mixed solution, a cleaned conductive substrate is soaked in the mixed solution and is heated at 160-200 ℃, the conductive substrate is taken out after the heating is finished to be cleaned, dried, heated at 450-550 ℃, and cooled to obtain the photo-anode material; the alcohol solvent is monohydric alcohol.

2. The method according to claim 1, wherein the titanium source is one or two selected from isopropyl titanate and tetrabutyl titanate.

3. The method of claim 1, wherein the zinc source is selected from one or more of zinc acetate, zinc chloride, or zinc sulfate.

4. The preparation method according to claim 1, wherein the alcohol solvent is selected from one or more of methanol, ethanol, propanol, isopropanol or butanol.

5. The process according to claim 1, wherein the alcoholic solvent is selected from ethanol.

6. The preparation method according to claim 1, wherein the concentration of the titanium source or the zinc source dissolved in the alcohol solvent is 0.03 to 0.09mol/L.

7. The method of claim 1, wherein the conductive substrate is heated at 180 ℃ for 8 to 12 hours.

8. The method according to claim 1, wherein the conductive substrate is FTO conductive glass, and the conductive substrate is immersed in the mixed solution with the conductive surface facing downward.

9. The photoanode material prepared by the preparation method of any one of claims 1 to 8.

10. Use of the photoanode material of claim 9 in photoelectrochemical cathodic protection.