CN113755042A

CN113755042A - Titanium dioxide coating and preparation method and application thereof

Info

Publication number: CN113755042A
Application number: CN202111016924.7A
Authority: CN
Inventors: 刘艳; 潘国涛
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2021-12-07

Abstract

The invention discloses a titanium dioxide coating and a preparation method and application thereof, wherein the method comprises the following steps: s1, uniformly mixing titanium dioxide, a binder, a conductive agent and deionized water to obtain slurry with the solid content of 10% -20%; s2, drying the coating obtained by spin-coating the slurry in the S1, and carrying out a crosslinking reaction to obtain a titanium dioxide coating; the crosslinking reaction temperature is 100-200 ℃, the crosslinking reaction vacuum degree is 0.08-0.1 MPa, and the crosslinking reaction time is 1-3 h; the mass ratio of the titanium dioxide to the binder to the conductive agent is 90: (5-15): (0.2 to 1.0); the binder is a mixture of styrene butadiene rubber, sodium carboxymethylcellulose and polyacrylic acid; the mass ratio of the styrene-butadiene rubber to the sodium carboxymethyl cellulose to the polyacrylic acid is 5: (1-5): (1-5). The invention provides a coating with a high cross-linked network, which has excellent photoelectric cathode protection performance and can be used for metal corrosion protection, organic pollutant degradation and hydrogen production by photolysis of water.

Description

Titanium dioxide coating and preparation method and application thereof

Technical Field

The invention relates to the technical field of metal corrosion protection, in particular to a titanium dioxide coating and a preparation method and application thereof.

Background

Metal corrosion is a great challenge facing today's society, especially the marine corrosion phenomenon is particularly severe. In the marine environment, a large amount of chloride ions and dissolved oxygen come into contact with the metal, accelerating metal corrosion. Economic loss caused by metal corrosion accounts for 1.5-3% of the total domestic production value every year in China, and the influence caused by the metal corrosion is not small. Therefore, a plurality of antiseptic measures are proposed, wherein the antiseptic effect is the most direct, and the most widely applied technology is cathode protection technology. The cathodic protection technology is generally divided into two types, one is cathodic protection method of an external circuit, and the other is cathodic protection method of a sacrificial anode, but the methods usually cause environmental pollution and large energy consumption, and are not an economic protection method. Therefore, the development of a green and pollution-free protection technology beneficial to renewable energy sources is urgent.

Under the background of developing green and environment-friendly and renewable resources vigorously, the principle of the technology is that a coating containing a semiconductor is coated on the surface of a protected metal, and the solar energy is converted into electric energy by the semiconductor, so that a stable cathode polarization potential is provided for the protected metal, and the corrosion protection effect on the metal is achieved. At present, the commonly used semiconductor mainly comprises titanium dioxide, for example, a coating which takes titanium dioxide as a main component and contains a conductive agent, sodium carboxymethyl cellulose and styrene butadiene rubber as disclosed in chinese invention patent CN106229474A, but when the coating is used for photocathode protection, the photopotential is only reduced by 600mV, that is, the coating has weak cathode polarization metal capability under illumination, so that the effect of protecting metal is not good.

Disclosure of Invention

The invention aims to overcome the problem of poor performance of the existing coating when used for photocathode protection, and provides a preparation method of a titanium dioxide coating, and the titanium dioxide coating prepared by the method has excellent photocathode protection performance.

It is another object of the present invention to provide a titanium dioxide coating.

It is a further object of the present invention to provide the use of said titanium dioxide coating.

The above object of the present invention is achieved by the following technical solutions:

a preparation method of a titanium dioxide coating comprises the following steps:

s1, uniformly mixing titanium dioxide, a binder, a conductive agent and deionized water to obtain slurry with the solid content of 10% -20%;

s2, drying the coating obtained by spin-coating the slurry in the S1, and carrying out a crosslinking reaction to obtain the titanium dioxide coating;

the crosslinking reaction temperature is 100-200 ℃, the crosslinking reaction vacuum degree is 0.08-0.1 MPa, and the crosslinking reaction time is 1-3 h;

the mass ratio of the titanium dioxide to the binder to the conductive agent is 90: (5-15): (0.2 to 1.0);

the binder is a mixture of styrene butadiene rubber, sodium carboxymethylcellulose and polyacrylic acid;

the mass ratio of the styrene-butadiene rubber to the sodium carboxymethyl cellulose to the polyacrylic acid is 5: (1-5): (1-5).

In the invention, polyacrylic acid side chain carboxylic acid groups can react with hydroxyl parts of sodium carboxymethylcellulose under specific conditions to generate ester groups for interconnection, and meanwhile carboxyl groups on polyacrylic acid can perform condensation reaction with hydroxyl groups on the surfaces of titanium dioxide particles to generate ester groups between a binder and titanium dioxide, so that a coating with a three-dimensional cross-linking structure and pi-pi conjugated delocalized electrons is formed, the charge transfer efficiency of the coating is improved, and the cathode protection performance of the material is further improved. The styrene butadiene rubber in the binder can improve the binding force between the coating and the substrate, so that the coating is not easy to fall off when used for the protection of the photocathode.

Preferably, the mass ratio of the titanium dioxide to the binder to the conductive agent is 90: (8-10): (0.4-0.6).

More preferably, the mass ratio of the titanium dioxide, the binder and the conductive agent is 90: 9.5: 0.5.

preferably, the mass ratio of the styrene-butadiene rubber, the sodium carboxymethyl cellulose and the polyacrylic acid is 5: (2-3): (2-3).

More preferably, the mass ratio of the styrene-butadiene rubber, the sodium carboxymethyl cellulose and the polyacrylic acid is 5: 2.5: 2.5.

preferably, the crosslinking reaction temperature is 130-180 ℃.

Preferably, the vacuum degree of the crosslinking reaction is 0.09-0.1 MPa.

Conductive agents conventional in the art may be used in the present invention. Preferably, the conductive agent is selected from one or more of acetylene black, carbon nanotubes, ketjen black, conductive graphite and carbon black.

A titanium dioxide coating prepared by the method.

The titanium dioxide in the titanium dioxide coating can generate photoproduction electrons and photoproduction holes under the irradiation of sunlight, the generated photoproduction electrons can be applied to a photocathode polarization metal substrate material to achieve the effect of protecting a base metal, and in addition, the photoproduction electrons and the photoproduction holes can also be applied to degradation of organic pollutants and hydrogen production through water photolysis. Therefore, the application of the titanium dioxide coating in metal corrosion protection, organic pollutant degradation and hydrogen production by photolysis of water also should be within the protection scope of the invention.

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

the invention takes titanium dioxide, a binder and a conductive agent as raw materials, prepares a titanium dioxide coating by controlling reaction conditions, and the titanium dioxide coating can strengthen the original TiO in the process of protecting the light capacitance₂Photoelectrochemical stability of the particles. Meanwhile, pi-pi conjugated delocalized electrons exist in the titanium dioxide coating, so that the charge transfer efficiency of the material is improved, the cathodic protection performance of the material is further improved, and the titanium dioxide coating can be used for metal corrosion protection, organic pollutant degradation and hydrogen production by photolysis of water.

Drawings

Figure 1 is an XRD pattern of the titanium dioxide coating and titanium dioxide as described in example 1.

FIG. 2 is a TEM image of the titanium dioxide coating described in example 1.

FIG. 3 is a diagram of the photo-potential (left) and photo-current density of the titanium dioxide coatings described in example 1 and comparative example 1.

Fig. 4 is a graph of the electrochemical impedance of the titanium dioxide coatings described in example 1 and comparative example 1.

FIG. 5 is a graph of the UV-VIS absorption spectra of the titanium dioxide coatings described in example 1 and comparative example 1.

Fig. 6 is a visual (left) and cross-sectional (right) SEM image of the titanium dioxide coating described in example 1.

Fig. 7 is a visual (left) and cross-sectional (right) SEM image of the titanium dioxide coating described in comparative example 1.

FIG. 8 is a graph of the EPR test results for the titanium dioxide coating, polyacrylic acid, and titanium dioxide described in example 1.

FIG. 9 is a graphical representation of the flexibility of the titanium dioxide coating described in example 1 on a substrate.

Detailed Description

In order to more clearly and completely describe the technical scheme of the invention, the invention is further described in detail by the specific embodiments, and it should be understood that the specific embodiments described herein are only used for explaining the invention, and are not used for limiting the invention, and various changes can be made within the scope defined by the claims of the invention.

Example 1

s1, mixing the components in a mass ratio of 90: 9.5: 0.5 of titanium dioxide, a binder, acetylene black and deionized water are uniformly mixed to obtain slurry with the solid content of 15 percent; the binder is a mixture of styrene butadiene rubber, sodium carboxymethylcellulose and polyacrylic acid, and the mass ratio of the styrene butadiene rubber to the sodium carboxymethylcellulose to the polyacrylic acid in the mixture is 5: 2.5: 2.5;

s2, placing the coating obtained by spin-coating the slurry in the S1 under the conditions that the temperature is 150 ℃ and the vacuum degree is 0.1MPa for cross-linking reaction for 2h to obtain the titanium dioxide coating which is marked as T-SBR-CMC-PAA.

Example 2

The present embodiment provides a method for preparing a titanium dioxide coating, which is different from embodiment 1 in that the mass ratio of titanium dioxide, a binder and a conductive agent in step S1 is 90: 5: 0.2.

example 3

The present embodiment provides a method for preparing a titanium dioxide coating, which is different from embodiment 1 in that the mass ratio of titanium dioxide, a binder and a conductive agent in step S1 is 90: 15: 1.

example 4

The present embodiment provides a method for preparing a titanium dioxide coating, which is different from embodiment 1 in that the mass ratio of titanium dioxide, a binder and a conductive agent in step S1 is 90: 8: 0.4.

example 5

The present embodiment provides a method for preparing a titanium dioxide coating, which is different from embodiment 1 in that the mass ratio of titanium dioxide, a binder and a conductive agent in step S1 is 90: 10: 0.6.

example 6

The present embodiment provides a preparation method of a titanium dioxide coating, which is different from that in embodiment 1, in step S1, the mass ratio of styrene-butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid is 5: 5: 5.

example 7

The present embodiment provides a preparation method of a titanium dioxide coating, which is different from that in embodiment 1, in step S1, the mass ratio of styrene-butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid is 5: 2: 2.

example 8

The present embodiment provides a preparation method of a titanium dioxide coating, which is different from that in embodiment 1, in step S1, the mass ratio of styrene-butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid is 5: 1: 1.

example 9

The comparative example provides a method of preparing a titanium dioxide coating, comprising the steps of:

s1, mixing the components in a mass ratio of 90: 9.5: 0.5 of titanium dioxide, a binder, acetylene black and deionized water are uniformly mixed to obtain slurry with the solid content of 10 percent; the binder is a mixture of styrene butadiene rubber, sodium carboxymethylcellulose and polyacrylic acid, and the mass ratio of the styrene butadiene rubber to the sodium carboxymethylcellulose to the polyacrylic acid in the mixture is 5: 2.5: 2.5;

s2, placing the coating obtained by spin-coating the slurry in the S1 under the conditions that the temperature is 100 ℃ and the vacuum degree is 0.1MPa for a cross-linking reaction for 2h to obtain the titanium dioxide coating.

Example 10

s1, mixing the components in a mass ratio of 90: 9.5: 0.5 of titanium dioxide, a binder, acetylene black and deionized water are uniformly mixed to obtain slurry with the solid content of 20 percent; the binder is a mixture of styrene butadiene rubber, sodium carboxymethylcellulose and polyacrylic acid, and the mass ratio of the styrene butadiene rubber to the sodium carboxymethylcellulose to the polyacrylic acid in the mixture is 5: 2.5: 2.5;

s2, placing the coating obtained by spin-coating the slurry in the S1 under the conditions that the temperature is 180 ℃ and the vacuum degree is 0.09MPa for a cross-linking reaction for 2h to obtain the titanium dioxide coating.

Example 11

This example provides a method for preparing a titanium dioxide coating, which is different from example 1 in that, in step S2, the crosslinking reaction temperature is 200 ℃ and the crosslinking reaction vacuum degree is 0.08 MPa.

Example 12

This example provides a method for preparing a titanium dioxide coating, which is different from example 1 in that, in step S2, the crosslinking reaction temperature is 130 ℃ and the crosslinking reaction vacuum degree is 0.1 MPa.

Example 13

This example provides a method for preparing a titanium dioxide coating layer, which is different from example 1 in that ketjen black is used instead of acetylene black in step S1.

Example 14

This example provides a method for preparing a titanium dioxide coating, which is different from example 1 in that conductive graphite is used instead of acetylene black in step S1.

Comparative example 1

The present comparative example provides a method for preparing a titanium dioxide coating, which is different from example 1 in that the binder in step S1 is a mixture of styrene-butadiene rubber and sodium carboxymethyl cellulose, and the mass ratio of styrene-butadiene rubber to carboxymethyl cellulose is 5: and 5, marking the obtained titanium dioxide coating as T-SBR-CMC.

Characterization of the test

FIG. 1 is XRD patterns of titanium dioxide raw material in example 1 of the present invention and titanium dioxide coating T-SBR-CMC-PAA using styrene butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid as binder in example 1. As can be seen from the figure, the crosslinking does not affect the crystal structure of the raw material itself. The XRD patterns of the titanium dioxide coatings described in examples 2-14 are similar to those of FIG. 1.

FIG. 2 is a TEM image of the titania coating prepared in example 1. As can be seen from fig. 2, the binder tightly cross-links the different nano-sized titanium dioxide together. TEM images of the titanium dioxide coatings described in examples 2-14 are similar to FIG. 2.

The titanium dioxide coatings described in example 1 and comparative example 1 were tested for photocathode protection performance, which is mainly reflected in the cathodic polarization capability (photopotential), the photocurrent, and the electrochemical impedance properties of the material during light exposure. The test was performed using a three-electrode single cell system at an electrochemical workstation Gamry 1010E. The titanium dioxide coating-supported 304 stainless steel metal is used as a working electrode, a 1x2cm platinum sheet is used as a system counter electrode, and an Ag/AgCl standard reference electrode is used as a system reference electrode. The electrolyte in the electrolytic cell was a 3.65 wt% NaCl solution, aimed at simulating the marine environment. Placing the three electrodes in simulated seawater, and using xenon lamp light source filtered by AM1.5 simulated sunlight filter to simulate power of 100mW cm^-2The electrochemical workstation observes the photoinduced potential and the photoinduced current of the simulated sunlight. The electrochemical impedance test was connected in a manner consistent with the above-described photoinduced potential test. The test results are shown in fig. 3 and 4.

FIG. 3 is a diagram of the photo-potential (left) and photo-current density of the titanium dioxide coatings described in example 1 and comparative example 1. As can be seen from fig. 3, the titanium dioxide coating T-SBR-CMC-PAA using styrene-butadiene rubber, sodium carboxymethylcellulose, and polyacrylic acid as binders in example 1 has a good response, and has a more negative photovoltaic potential (reduced by 720mV) and a more negative photovoltaic current density than the titanium dioxide coating T-SBR-CMC using styrene-butadiene rubber and sodium carboxymethylcellulose as binders in comparative example 1, and it is known that the titanium dioxide coating using styrene-butadiene rubber, sodium carboxymethylcellulose, and polyacrylic acid as binders has more excellent photocathode protective properties and exhibits excellent marine metal corrosion protective properties. The zeta potential and the zeta current of the titanium dioxide coatings described in examples 2 to 14 are substantially identical to the zeta potential and the zeta current of the titanium dioxide coating described in example 1.

Fig. 4 is a graph of the electrochemical impedance of the titanium dioxide coatings described in example 1 and comparative example 1. As can be seen from fig. 4, the electrochemical impedance modulus value of the titanium dioxide coating (T-SBR-CMC-PAA) using styrene-butadiene rubber, sodium carboxymethylcellulose, and polyacrylic acid as binders is slightly smaller than that of the titanium dioxide coating T-SBR-CMC coating using styrene-butadiene rubber and sodium carboxymethylcellulose as binders in comparative example 2, which indicates that the T-SBR-CMC-PAA has lower charge transfer resistance under illumination, and is beneficial to lead out photo-generated electrons, thereby showing better photocathode protection performance. The electrochemical impedance plots of the titanium dioxide coatings described in examples 2-14 are substantially identical to the electrochemical impedance plot of the titanium dioxide coating described in example 1.

FIG. 5 is a graph of the UV-VIS absorption spectra of the titanium dioxide coatings described in example 1 and comparative example 1. As can be seen from FIG. 5, the absorption domain of the titanium dioxide coating (T-SBR-CMC-PAA) using styrene-butadiene rubber, sodium carboxymethylcellulose and polyacrylic acid as the binder is significantly red-shifted to the 400nm visible light region compared with the absorption domain (380nm) of the conventional titanium dioxide, and is larger than the absorption domain value (370nm) of the T-SBR-CMC coating using styrene-butadiene rubber and sodium carboxymethylcellulose as the binder in comparative example 1. The ultraviolet-visible light absorption spectrogram of the titanium dioxide coating in the embodiment 2-14 is basically consistent with the ultraviolet-visible light absorption spectrogram of the titanium dioxide coating in the embodiment 1.

Fig. 6 is a visual (left) and cross-sectional (right) SEM image of the titanium dioxide coating described in example 1. Fig. 7 is a visual (left) and cross-sectional (right) SEM image of the titanium dioxide coating described in comparative example 1. As can be seen from a comparison of fig. 6 and 7, the titanium dioxide coating materials described in example 1 have higher compactability between them than those described in comparative example 1. Visual and cross-sectional SEM images of the titanium dioxide coatings described in examples 2-14 are similar to those of the titanium dioxide coating described in example 1.

FIG. 8 is a graph of the EPR test results for the titanium dioxide coating, polyacrylic acid, and titanium dioxide described in example 1. As shown in fig. 8, the titanium dioxide coating T-SBR-CMC-PAA described in example 1 has a peak at a g value of about 2.00, which proves that pi-pi conjugated delocalized electrons exist in the material, and is helpful for improving the photocathode protection performance of the titanium dioxide coating. The EPR test result graphs of the titanium dioxide coatings described in examples 2-14 are substantially consistent with the EPR test result graph of the titanium dioxide coating described in example 1.

FIG. 9 is a graph showing the flexibility of the titanium dioxide coating on a substrate as described in example 1. As can be seen from fig. 9, the coating did not peel off or brittle fracture at a large angle of bending the metal sheet, indicating excellent flexibility of the coating. The titanium dioxide coatings of examples 2-14 all had excellent flexibility.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The preparation method of the titanium dioxide coating is characterized by comprising the following steps:

2. The method for preparing the titanium dioxide coating according to claim 1, wherein the mass ratio of the titanium dioxide, the binder and the conductive agent is 90: (8-10): (0.4-0.6).

3. The method for preparing the titanium dioxide coating according to claim 2, wherein the mass ratio of the titanium dioxide to the binder to the conductive agent is 90: 9.5: 0.5.

4. the method for preparing the titanium dioxide coating according to claim 1, wherein the mass ratio of the styrene-butadiene rubber, the sodium carboxymethyl cellulose and the polyacrylic acid is 5: (2-3): (2-3).

5. The method for preparing the titanium dioxide coating according to claim 4, wherein the mass ratio of the styrene-butadiene rubber, the sodium carboxymethyl cellulose and the polyacrylic acid is 5: 2.5: 2.5.

6. the method of preparing the titanium dioxide coating according to claim 1, wherein the crosslinking reaction temperature is 130 to 180 ℃.

7. The method for preparing the titanium dioxide coating according to claim 1, wherein the degree of vacuum of the crosslinking reaction is 0.09 to 0.1 MPa.

8. The method for preparing the titanium dioxide coating according to claim 1, wherein the conductive agent is one or more selected from acetylene black, carbon nanotubes, ketjen black, conductive graphite, and carbon black.

9. A titanium dioxide coating, characterized in that it is prepared by the method of any one of claims 1 to 8.

10. Use of the titanium dioxide coating according to claim 9 for metal corrosion protection, degradation of organic contaminants and hydrogen production by photolysis of water.