A method for evaluating the photoinduced cathodic protection performance of semiconductor materials

Abstract

The present invention relates to the technical field of photoelectrochemical cathode protection, and in particular to a method for evaluating the photocathodic protection performance of semiconductor materials. A method for evaluating the photocathodic protection performance of semiconductor materials, comprising the following steps: step A, preparing semiconductor electrodes from semiconductor materials; step B, dark state anodic polarization curve test of the metal to be protected: testing the anodic polarization curve of the metal to be protected in a desired solution environment and in a dark state; step C, photocathodic polarization curve test of the semiconductor electrode: testing the cathode polarization curve of the semiconductor electrode in a desired solution environment and under illumination. The method for evaluating the photocathodic protection performance of semiconductor materials can preliminarily judge the photocathodic protection performance of semiconductor electrodes for specific metals without coupling metal electrodes, has a fast characterization speed, and a high accuracy, and solves the problems of poor stability and low test efficiency of existing characterization methods for the photocathodic protection performance of semiconductor materials.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectrochemical cathode protection, and in particular to a method for evaluating the photoinduced cathode protection performance of semiconductor materials. Background Art

[0002] Photoelectrochemical cathodic protection is an emerging metal corrosion protection technology. It uses the photoelectric conversion effect of semiconductor materials and solar energy to effectively inhibit metal corrosion. It is economical, efficient, green and energy-saving, and has great application potential. However, the characterization method of the photoinduced cathodic protection performance of semiconductor materials has the problems of insufficient stability and low efficiency. This is mainly because in the traditional photoinduced cathodic protection performance test process, the semiconductor material electrode needs to be coupled with the metal electrode to test the changes in coupling potential and current density under light; before the next repeated test, the metal electrode must be re-grinded and polished to remove the surface polarization layer, and it needs to be stable in the solution for a long time, which greatly limits the test efficiency of the photoinduced cathodic protection performance. Therefore, it is of great practical significance to study a new method that can quickly evaluate the photoinduced cathodic protection performance of semiconductor materials. Summary of the invention

[0003] In response to the problems raised by the background technology, the purpose of the present invention is to propose a method for evaluating the photocathodic protection performance of semiconductor materials. The method can preliminarily judge the photocathodic protection performance of semiconductor electrodes to specific metals without coupling metal electrodes. The characterization speed is fast and the accuracy is high. The photocathodic protection performance of semiconductor materials can be evaluated quickly and accurately, which solves the problems of poor stability and low test efficiency of existing characterization methods for the photocathodic protection performance of semiconductor materials.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A method for evaluating the photocathodic protection performance of a semiconductor material comprises the following steps:

[0006] Step A, preparing a semiconductor electrode from a semiconductor material;

[0007] Step B, dark state anodic polarization curve test of the metal to be protected: testing the anodic polarization curve of the metal to be protected in a desired solution environment and in a dark state;

[0008] Step C, photoinduced cathode polarization curve test of semiconductor electrode: testing the cathode polarization curve of semiconductor electrode under the required solution environment and illumination, wherein the required solution environment in step C is the same as the required solution environment in step B;

[0009] Step D, plotting the cathode polarization curve of the semiconductor electrode and the anode polarization curve of the metal to be protected into the same graph, intersecting the cathode polarization curve with the anode polarization curve to obtain an intersection, and evaluating the photocathodic protection performance of the semiconductor material for the metal to be protected under the required solution environment and light according to the potential value and current density value corresponding to the intersection.

[0010] Further, in step A, after preparing a semiconductor electrode from a semiconductor material, the photoinduced open circuit potential of the semiconductor electrode is tested in a three-electrode system under a desired solution environment and light.

[0011] In the step B, the self-corrosion potential of the metal to be protected in the desired solution environment is tested, and then the anodic polarization curve of the metal to be protected is tested in the desired solution environment and in a dark state;

[0012] When testing the anodic polarization curve of the metal to be protected, the test potential range is from the self-corrosion potential of the metal to be protected to the negative scanning to the photoinduced open circuit potential of the semiconductor electrode;

[0013] In the step C, when testing the cathode polarization curve of the semiconductor electrode, the test potential range is from the photoinduced open circuit potential of the semiconductor electrode to the self-corrosion potential of the metal to be protected.

[0014] Further, in step B, the scanning speed when testing the anodic polarization curve of the metal to be protected is 1.666 mV / s;

[0015] In the step C, the scanning speed when testing the cathode polarization curve of the semiconductor electrode is 1.666 mV / s.

[0016] Further, in step A, after preparing a semiconductor electrode from a semiconductor material, the photoinduced open circuit potential of the semiconductor electrode is tested in a three-electrode system in a 3.5wt% NaCl solution environment and under the illumination of AM1.5G simulated sunlight;

[0017] In the step B, the self-corrosion potential of the metal to be protected in a 3.5wt% NaCl solution environment is tested, and then the anodic polarization curve of the metal to be protected is tested in a 3.5wt% NaCl solution environment and in a dark state;

[0018] In the step C, the cathode polarization curve of the semiconductor electrode is tested in a 3.5 wt % NaCl solution environment and under the illumination of AM1.5G simulated sunlight.

[0019] Further, in step B, an electrochemical workstation is used to test the self-corrosion potential of the metal to be protected in a desired solution environment, and then an electrochemical workstation is used to test the anodic polarization curve of the metal to be protected in the desired solution environment and in a dark state;

[0020] In the step C, an electrochemical workstation is used to test the cathode polarization curve of the semiconductor electrode under the desired solution environment and illumination.

[0021] To further illustrate, the semiconductor material is selected from any one or more of ZnO, ZnO / PEDOT:PSS and ZnO / CdS, and the metal to be protected is selected from any one or more of 316L stainless steel and pure copper.

[0022] To further illustrate, in step A, the method for preparing a semiconductor electrode from a semiconductor material is as follows: 2 mg of semiconductor material, 80 μL of deionized water, 15 μL of isopropanol and 5 μL of Nafion buffer solution are mixed and ground for 30 minutes to obtain a uniform dispersion, the dispersion is applied to the surface of a FTO conductive glass substrate, and naturally dried to obtain a semiconductor electrode.

[0023] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0024] By testing the anodic polarization curve of the metal electrode to be protected in the desired solution environment and in the dark state (without light), and testing the cathodic polarization curve of the semiconductor electrode under light under the same solution environment, the potential value and current density value corresponding to the intersection of the cathodic polarization curve and the anodic polarization curve are the photocathodic protection performance of the semiconductor material to the metal to be protected under the solution environment and light. Since the photocathodic protection requires the photoinduced potential to be as negative as possible, the more the intersection is offset in the negative potential direction, the better the photocathodic protection performance is, which is used as the basis for judging the photocathodic protection performance of the semiconductor material of the semiconductor electrode to the metal to be protected. The method does not need to directly couple the semiconductor electrode with the metal electrode, but only needs to test the polarization curves of the two separately. The photocathodic protection performance of the semiconductor electrode to a specific metal can be preliminarily judged without coupling the metal electrode. The characterization speed is fast and the accuracy is high. It can realize the rapid and accurate evaluation of the photocathodic protection performance of the semiconductor material, and solves the problems of poor stability and low test efficiency of the characterization method of the photocathodic protection performance of the existing semiconductor material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic flow chart of a method for evaluating the photocathodic protection performance of a semiconductor material according to an embodiment of the present invention;

[0026] Figure 2 is a comparison diagram of light-irradiation / dark-state Tafel curves of three semiconductor materials, ZnO, ZnO / PEDOT:PSS and ZnO / CdS, in 3.5wt% NaCl solution according to Example 1 of the present invention;

[0027] Figure 3It is a schematic diagram (actual potential) of the photocathodic protection performance of three semiconductor materials, ZnO, ZnO / PEDOT:PSS and ZnO / CdS, on 316LSS in a 3.5wt% NaCl solution, which is actually tested in Example 1 of the present invention;

[0028] Figure 4 It is a schematic diagram of the photocathodic protection performance of three semiconductor materials, namely, ZnO, ZnO / PEDOT:PSS and ZnO / CdS, on 316LSS in a 3.5wt% NaCl solution, which is actually tested in Example 1 of the present invention (actual current density);

[0029] Figure 5 It is a schematic diagram (actual potential) of the photocathodic protection performance of three semiconductor materials, ZnO, ZnO / PEDOT:PSS and ZnO / CdS, to Cu in a 3.5wt% NaCl solution, which is actually tested in Example 1 of the present invention;

[0030] Figure 6 It is a schematic diagram of the photocathodic protection performance of three semiconductor materials, ZnO, ZnO / PEDOT:PSS and ZnO / CdS, to Cu in a 3.5wt% NaCl solution actually tested in Example 1 of the present invention (actual current density). DETAILED DESCRIPTION

[0031] like Figure 1 As shown, a method for evaluating the photocathodic protection performance of a semiconductor material comprises the following steps:

[0032] Step A, preparing a semiconductor electrode from a semiconductor material;

[0033] Step B, dark state anodic polarization curve test of the metal to be protected: testing the anodic polarization curve of the metal to be protected in a desired solution environment and in a dark state;

[0034] Step C, photoinduced cathode polarization curve test of semiconductor electrode: testing the cathode polarization curve of semiconductor electrode under the required solution environment and illumination, wherein the required solution environment in step C is the same as the required solution environment in step B;

[0035] Step D, plotting the cathode polarization curve of the semiconductor electrode and the anode polarization curve of the metal to be protected into the same graph, intersecting the cathode polarization curve with the anode polarization curve to obtain an intersection, and evaluating the photocathodic protection performance of the semiconductor material for the metal to be protected under the required solution environment and light according to the potential value and current density value corresponding to the intersection.

[0036] The present invention proposes a method for accurately judging the photocathodic protection performance of semiconductor materials. The method is a comparison method of the dark-state Tafel anode polarization curve of the metal to be protected and the photocathodic polarization curve of the semiconductor electrode. By testing the anode polarization curve of the metal electrode to be protected in the desired solution environment and the dark state (without light), and testing the cathode polarization curve of the semiconductor electrode under light under the same solution environment, the potential value and current density value corresponding to the intersection of the cathode polarization curve and the anode polarization curve are the photocathodic protection performance of the semiconductor material to the metal to be protected under the solution environment and light. Since the photocathodic protection requires the photoinduced potential to be as negative as possible, the more the intersection is offset in the negative potential direction, the better the photocathodic protection performance is, which is used as the basis for judging the photocathodic protection performance of the semiconductor material of the semiconductor electrode to the metal to be protected.

[0037] This method does not require direct coupling of the semiconductor electrode and the metal electrode, and only requires testing of the separate polarization curves of the two. The photocathodic protection performance of the semiconductor electrode to a specific metal can be preliminarily determined without coupling the metal electrode. The characterization speed is fast and the accuracy is high. The photocathodic protection performance of semiconductor materials can be evaluated quickly and accurately, and the problems of poor stability and low test efficiency of existing characterization methods for the photocathodic protection performance of semiconductor materials are solved.

[0038] Further, in step A, after preparing a semiconductor electrode from a semiconductor material, the photoinduced open circuit potential of the semiconductor electrode is tested in a three-electrode system under a desired solution environment and light.

[0039] In the step B, the self-corrosion potential of the metal to be protected in the desired solution environment is tested, and then the anodic polarization curve of the metal to be protected is tested in the desired solution environment and in a dark state;

[0040] When testing the anodic polarization curve of the metal to be protected, the test potential range is from the self-corrosion potential of the metal to be protected to the negative scanning to the photoinduced open circuit potential of the semiconductor electrode;

[0041] In the step C, when testing the cathode polarization curve of the semiconductor electrode, the test potential range is from the photoinduced open circuit potential of the semiconductor electrode to the self-corrosion potential of the metal to be protected.

[0042] In order to minimize the influence of polarization on the electrode of the metal to be protected, when testing the anodic polarization curve of the metal to be protected, the test potential range is from the self-corrosion potential of the metal to be protected to the negative scan to the photoinduced open circuit potential (OCP) of the semiconductor electrode; in order to minimize the influence of polarization on the semiconductor electrode, when testing the cathodic polarization curve of the semiconductor electrode, the test potential range is from the photoinduced open circuit potential (OCP) of the semiconductor electrode to the positive scan to the self-corrosion potential of the metal to be protected.

[0043] Preferably, in step B, the scanning speed when testing the anodic polarization curve of the metal to be protected is 1.666 mV / s;

[0044] In the step C, the scanning speed when testing the cathode polarization curve of the semiconductor electrode is 1.666 mV / s.

[0045] If the test speed is too fast or too slow when testing the anodic polarization curve and the cathodic polarization curve, it may affect the stability of the test results. Therefore, by optimizing the scanning speed when testing the anodic polarization curve of the metal to be protected, and optimizing the scanning speed when testing the cathodic polarization curve of the semiconductor electrode, the stability of the method for evaluating the photocathodic protection performance of the semiconductor material is guaranteed, and the accuracy of the characterization is improved.

[0046] Further, in step A, after preparing a semiconductor electrode from a semiconductor material, the photoinduced open circuit potential of the semiconductor electrode is tested in a three-electrode system in a 3.5wt% NaCl solution environment and under the illumination of AM1.5G simulated sunlight;

[0047] In the step B, the self-corrosion potential of the metal to be protected in a 3.5wt% NaCl solution environment is tested, and then the anodic polarization curve of the metal to be protected is tested in a 3.5wt% NaCl solution environment and in a dark state;

[0048] In the step C, the cathode polarization curve of the semiconductor electrode is tested in a 3.5 wt % NaCl solution environment and under the illumination of AM1.5G simulated sunlight.

[0049] In this embodiment, the required solution environment is a 3.5wt% NaCl solution environment, and the required lighting conditions are AM1.5G simulated sunlight. It should be noted that the cathode polarization curve of the semiconductor electrode and the anode polarization curve of the metal electrode to be protected must be tested in the same solution environment.

[0050] Specifically, in step B, an electrochemical workstation is used to test the self-corrosion potential of the metal to be protected in a desired solution environment, and then an electrochemical workstation is used to test the anodic polarization curve of the metal to be protected in the desired solution environment and in a dark state;

[0051] In the step C, an electrochemical workstation is used to test the cathode polarization curve of the semiconductor electrode under the desired solution environment and illumination.

[0052] The electrochemical workstation is used to test the self-corrosion potential of the metal to be protected, the anodic polarization curve of the metal to be protected, and the cathodic polarization curve of the semiconductor electrode. The operation is convenient. When the electrochemical workstation is used to test the anodic polarization curve and the cathodic polarization curve, the metal electrode to be protected is connected to the working electrode port of the electrochemical workstation, and a suitable reference electrode and counter electrode are selected for testing. Among them, when testing the anodic polarization curve, the potential scanning direction is from the open circuit potential to the negative potential direction; when testing the anodic polarization curve, the potential scanning direction is from the open circuit potential to the positive potential direction.

[0053] To further illustrate, the semiconductor material is selected from any one or more of ZnO, ZnO / PEDOT:PSS and ZnO / CdS, and the metal to be protected is selected from any one or more of 316L stainless steel and pure copper.

[0054] The semiconductor material can be selected from any one of zinc oxide (ZnO), zinc oxide / poly(3,4-ethylenedioxythiophene):polystyrene sulfonate composite material (ZnO / PEDOT:PSS) and zinc oxide / cadmium sulfide composite material (ZnO / CdS), and the metal to be protected is selected from any one of 316L stainless steel (316LSS) and pure copper (Cu). It is further explained that when multiple semiconductor materials are selected, semiconductor electrodes are prepared from different semiconductor materials respectively, and then the cathode polarization curves of different semiconductor electrodes are tested. When multiple metals to be protected are selected, the anodic polarization curves of different metals to be protected are tested, and the cathode polarization curves of semiconductor electrodes made of different semiconductor materials and the anodic polarization curves of different metals to be protected are plotted in the same figure, so that the photocathodic protection performance of different semiconductor materials on different metals to be protected can be evaluated, and the protection performance can be compared.

[0055] To further illustrate, in step A, the method for preparing a semiconductor electrode from a semiconductor material is as follows: 2 mg of semiconductor material, 80 μL of deionized water, 15 μL of isopropanol and 5 μL of Nafion buffer solution are mixed and ground for 30 minutes to obtain a uniform dispersion, the dispersion is applied to the surface of a FTO conductive glass substrate, and naturally dried to obtain a semiconductor electrode.

[0056] By preparing the semiconductor material into a stable photoelectrode, it is convenient to test the Tafel cathode polarization curve of the semiconductor electrode in the required solution environment and light. It is further explained that the semiconductor electrode is disposable and must be replaced with a new semiconductor electrode for testing after the test is completed.

[0057] In order to facilitate the understanding of the present invention, the present invention is described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0058] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0059] Example 1

[0060] Step A, preparing semiconductor electrodes from semiconductor materials: using ZnO, ZnO / PEDOT:PSS and ZnO / CdS powders as semiconductor materials, respectively preparing different semiconductor electrodes, and the method for preparing semiconductor electrodes from semiconductor materials is as follows: mixing 2 mg of semiconductor material, 80 μL of deionized water, 15 μL of isopropanol and 5 μL of Nafion buffer solution, and grinding for 30 minutes to obtain a uniform dispersion, applying the dispersion to the surface of a FTO conductive glass substrate, and drying naturally to obtain a semiconductor electrode;

[0061] The photoinduced open circuit potential of each semiconductor electrode was tested in a three-electrode system under the illumination of 3.5wt% NaCl solution and AM1.5G simulated sunlight.

[0062] Step B, dark state anodic polarization curve test of the metal to be protected: 316L stainless steel (316LSS) and pure copper (Cu) are used as the metals to be protected, and the self-corrosion potential of the two metals to be protected in a 3.5wt% NaCl solution environment is tested by an electrochemical workstation, and then the anodic polarization curves of the two metals to be protected are tested in a 3.5wt% NaCl solution environment and in a dark state by an electrochemical workstation;

[0063] When testing the anodic polarization curve of the metal to be protected, the test potential range is from the self-corrosion potential of the metal to be protected to the photoinduced open circuit potential of the semiconductor electrode, and the scanning speed is 1.666mV / s;

[0064] Step C, photoinduced cathode polarization curve test of semiconductor electrode: in a 3.5wt% NaCl solution environment and under the illumination of AM1.5G simulated sunlight, the cathode polarization curve of each semiconductor electrode is tested using an electrochemical workstation, and the required solution environment in step C is the same as the required solution environment in step B;

[0065] When testing the cathode polarization curve of the semiconductor electrode, the test potential range is from the photoinduced open circuit potential of the semiconductor electrode to the self-corrosion potential of the metal to be protected, and the scanning speed is 1.666mV / s;

[0066] Step D: Plot the cathode polarization curve of the semiconductor electrode obtained by the test and the anode polarization curve of the metal to be protected obtained by the test into the same graph (e.g. Figure 2 As shown), the cathode polarization curve intersects with the anode polarization curve to obtain an intersection (the square frame in the figure is the intersection of different cathode polarization curves and different anode polarization curves), and the photocathodic protection performance of the semiconductor material to be protected under the required solution environment and light is evaluated according to the potential value and current density value corresponding to the intersection. Since the photocathodic protection requires that the photoinduced potential is as negative as possible, the more the intersection is shifted towards the negative potential direction, the better the photocathodic protection performance is, which is used as a basis for judging the photocathodic protection performance of the semiconductor material of the semiconductor electrode for the metal to be protected.

[0067] As can be seen from the figure, ZnO / CdS has the best photocathodic protection performance for the protected metals (316L stainless steel and pure copper); for 316L stainless steel, the photocathodic protection performance of ZnO is better than that of ZnO / PEDOT:PSS; for pure copper, the photocathodic protection performance of ZnO / PEDOT:PSS is better than that of ZnO.

[0068] In order to prove the accuracy of the method for evaluating the photocathodic protection performance of semiconductor materials, the actual photocathodic protection performance of semiconductor materials was tested and compared with the evaluation results of Example 1:

[0069] Step 1: connect three different semiconductor electrodes (the same as the three semiconductor electrodes prepared in Example 1) to the metal electrodes to be protected (the same as the two metal electrodes to be protected in Example 1) and immerse them in a 3.5wt% NaCl solution environment at the same time, and test the photoinduced open circuit potential (OCP) under the illumination of the interval dark state and AM1.5G simulated sunlight (such as Figure 3 and Figure 5 ) and the current density-time curve (as shown Figure 4 and Figure 6 The photocathodic protection performance of the three semiconductor electrodes is directly characterized by the more negative the potential and the greater the current density under light irradiation, which indicates that the photocathodic protection performance is better (as shown in the attached figure). Figure 3 , 4 shown).

[0070] Step 2, result comparison: read the polarization curve (attached Figure 2 ) corresponds to the current density and potential value (simulated value) and the actual measured photocathodic protection diagram (Appendix Figure 3 , 4, 5, 6), and the two groups of results are compared, as shown in Table 1. It can be found that the simulated values ​​obtained by the light / dark state Tafel curve comparison method are very consistent with the actual photocathodic protection performance, and can accurately reflect the advantages and disadvantages of the photocathodic protection performance of different materials to different metals.

[0071] Table 1 Comparison of light / dark Tafel curves Comparison of simulated photocathodic protection performance and actual performance

[0072]

[0073] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for evaluating the photocathodic protection performance of a semiconductor material, characterized in that: The following steps are involved: Step A, preparing a semiconductor electrode from a semiconductor material; Step B, dark state anodic polarization curve test of the metal to be protected: testing the anodic polarization curve of the metal to be protected in a desired solution environment and in a dark state; Step C, photoinduced cathode polarization curve test of semiconductor electrode: testing the cathode polarization curve of semiconductor electrode under the required solution environment and illumination, wherein the required solution environment in step C is the same as the required solution environment in step B; Step D, plotting the cathode polarization curve of the semiconductor electrode and the anode polarization curve of the metal to be protected into the same graph, intersecting the cathode polarization curve with the anode polarization curve to obtain an intersection, and evaluating the photocathodic protection performance of the semiconductor material for the metal to be protected under the required solution environment and light according to the potential value and current density value corresponding to the intersection.

2. The method for evaluating the photocathodic protection performance of a semiconductor material according to claim 1, characterized in that: In the step A, after preparing a semiconductor electrode from a semiconductor material, the photoinduced open circuit potential of the semiconductor electrode is tested in a three-electrode system under a desired solution environment and light; In the step B, the self-corrosion potential of the metal to be protected in the desired solution environment is tested, and then the anodic polarization curve of the metal to be protected is tested in the desired solution environment and in a dark state; When testing the anodic polarization curve of the metal to be protected, the test potential range is from the self-corrosion potential of the metal to be protected to the negative scanning to the photoinduced open circuit potential of the semiconductor electrode; In the step C, when testing the cathode polarization curve of the semiconductor electrode, the test potential range is from the photoinduced open circuit potential of the semiconductor electrode to the self-corrosion potential of the metal to be protected.

3. The method for evaluating the photocathodic protection performance of a semiconductor material according to claim 2, characterized in that: In the step B, the scanning speed when testing the anodic polarization curve of the metal to be protected is 1.666 mV / s; In the step C, the scanning speed when testing the cathode polarization curve of the semiconductor electrode is 1.666 mV / s.

4. The method for evaluating the photocathodic protection performance of a semiconductor material according to claim 2, characterized in that: In the step A, after preparing a semiconductor electrode from a semiconductor material, the photoinduced open circuit potential of the semiconductor electrode is tested in a three-electrode system in a 3.5wt% NaCl solution environment and under the illumination of AM1.5G simulated sunlight; In the step B, the self-corrosion potential of the metal to be protected in a 3.5wt% NaCl solution environment is tested, and then the anodic polarization curve of the metal to be protected is tested in a 3.5wt% NaCl solution environment and in a dark state; In the step C, the cathode polarization curve of the semiconductor electrode is tested in a 3.5 wt % NaCl solution environment and under the illumination of AM1.5G simulated sunlight.

5. The method for evaluating the photocathodic protection performance of a semiconductor material according to claim 2, characterized in that: In the step B, the self-corrosion potential of the metal to be protected in the desired solution environment is tested using an electrochemical workstation, and then the anodic polarization curve of the metal to be protected is tested using an electrochemical workstation in the desired solution environment and in a dark state; In the step C, an electrochemical workstation is used to test the cathode polarization curve of the semiconductor electrode under the desired solution environment and illumination.

6. The method for evaluating the photocathodic protection performance of a semiconductor material according to claim 1, characterized in that: The semiconductor material is selected from any one or more of ZnO, ZnO / PEDOT:PSS and ZnO / CdS, and the metal to be protected is selected from any one or more of 316L stainless steel and pure copper.

7. The method for evaluating the photocathodic protection performance of a semiconductor material according to claim 6, characterized in that: In step A, the method for preparing a semiconductor electrode from a semiconductor material is as follows: 2 mg of semiconductor material, 80 μL of deionized water, 15 μL of isopropanol and 5 μL of Nafion buffer solution are mixed and ground for 30 minutes to obtain a uniform dispersion, the dispersion is applied to the surface of a FTO conductive glass substrate, and naturally dried to obtain a semiconductor electrode.

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