Ti4O7 anode for CV cyclic electro-deposition of Rh element and preparation method and application of Ti4O7 anode

Abstract

The invention relates to a Ti4O7 anode for CV cyclic electro-deposition of Rh element and a preparation method and application thereof. The preparation method comprises the following steps: preparing a Ti4O7 electrode in a dual-power plasma sintering mode; the method comprises the following steps: performing plasma surface treatment on a Ti4O7 electrode, etching the Ti4O7 electrode subjected to plasma surface treatment in an acid solution, and performing fluorination treatment; in an electrochemical workstation, the etched and fluorinated Ti4O7 electrode is used as a working electrode, a platinum sheet is used as a counter electrode, silver / silver chloride is used as a reference electrode, a sodium sulfate solution is used as an electrolyte solution, a rhodium chloride solution is added for CV cyclic electrodeposition, the scanning range is-0.3-0.3 V, the scanning rate is 0.1 V / s, and the electrode after electrodeposition is cleaned and dried. According to the invention, the titanium black electrode subjected to dual-power plasma sintering is used as a substrate, the interface transfer resistance of the electrode is reduced in a CV cyclic deposition mode, and the electrochemical performance of the electrode is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of water resource remediation, and particularly relates to a Ti4O7 anode with CV cycle electrodeposition of Rh element and a preparation method and application thereof. BACKGROUND

[0002] Compared with general industrial electrode materials, titanium suboxide (Ti4O7) electrode has high chemical stability and corrosion resistance. The titanium suboxide anode has high oxygen evolution potential, which is conducive to anodic oxidation, and can be used as an electrochemical anode and widely applied to electrocatalytic degradation of organic pollutants and treatment of environmental wastewater such as landfill leachate and printing and dyeing wastewater. Commercial titanium suboxide electrode R ct has a large value and the production of hydroxyl radicals needs to be further improved. Therefore, it is necessary to improve the existing preparation method of titanium suboxide (Ti4O7) electrode. SUMMARY

[0003] To solve the defects and deficiencies of the prior art, the primary purpose of the present application is to provide a preparation method of a Ti4O7 anode with CV cycle electrodeposition of Rh element.

[0004] Another purpose of the present application is to provide a Rh@Ti4O7 electrode prepared by the above method.

[0005] Still another purpose of the present application is to provide the application of the above Rh@Ti4O7 electrode.

[0006] The purposes of the present application are achieved by the following technical solutions.

[0007] A preparation method of a Ti4O7 anode with CV cycle electrodeposition of Rh element, comprising the following steps:

[0008] (1) preparing a Ti4O7 electrode in the form of SPS (double power plasma sintering);

[0009] (2) performing plasma surface treatment on the Ti4O7 electrode prepared in step (1), then etching the Ti4O7 electrode after plasma surface treatment in an acid solution, and then performing fluorination treatment;

[0010] (3) in an electrochemical workstation, taking the Ti4O7 electrode after etching and fluorination in step (2) as a working electrode, a platinum sheet as a counter electrode, silver / silver chloride as a reference electrode, and sodium sulfate solution as an electrolyte solution, adding rhodium chloride solution to perform CV cycle electrodeposition, the scanning range is-0.3-0.3V, the scanning rate is 0.1V / s, the electrode after electrodeposition is washed and dried, and the Ti4O7 anode with CV cycle electrodeposition of Rh element (Rh@Ti4O7 electrode) is obtained.

[0011] Preferably, the concentration of the sodium sulfate solution in step (3) is 50 mmol / L, and the concentration of the rhodium chloride solution is 10 mmol / L; the volume ratio of the sodium sulfate solution to the rhodium chloride solution is 29:1.

[0012] Preferably, the number of CV cycles in step (3) is 5-35.

[0013] Preferably, the process parameters of the plasma surface treatment in step (2) are as follows: the operation pressure is set to 0.2 Mbar, the time is 30 min, the argon gas percentage is 20% under an argon atmosphere, and the flow rate is 10 L / min.

[0014] Preferably, the etching in step (2) is performed by weighing 85 wt% of a phosphoric acid solution and 30 wt% of a hydrogen peroxide solution to prepare a mixed solution (the volume ratio of the phosphoric acid solution to the hydrogen peroxide solution is preferably 3:2), placing the Ti4O7 electrode after plasma surface treatment into the mixed solution, etching at 80℃ for 75 min, rinsing, and finally drying.

[0015] Preferably, the fluorination treatment in step (2) is performed by preparing a 10 mmol / L sodium fluoride solution and adjusting the pH to 4, placing the etched Ti4O7 electrode into the solution, soaking for 12 h, and then washing and drying.

[0016] Preferably, the specific steps of step (1) include placing Ti4O7 powder in a graphite mold, placing the mold in a double-power vacuum plasma sintering furnace (SPR) for sintering, vacuumizing the furnace, and setting the sintering pressure to 5 MPa.

[0017] The sintering procedure is as follows: 0-5 min, heating from room temperature to 600℃ at a rate of 114℃ / min; 5-13 min, heating from 600℃ to 1000℃ at a rate of 50℃ / min; 13-17 min, heating from 1000℃ to 1100℃ at a rate of 25℃ / min; 17-37 min, maintaining 1100℃; after sintering, stopping heating and cooling to room temperature under vacuum at 5 MPa, and then taking out the Ti4O7 electrode.

[0018] Further preferably, the Ti4O7 electrode is a cylindrical Ti4O7 electrode with a diameter of 20 mm and a thickness of 1.5 mm.

[0019] The application also provides a Rh@Ti4O7 electrode prepared by the above method.

[0020] The Rh@Ti4O7 electrode can be used for degrading thiamethoxam or thiamethoxam-containing environmental wastewater.

[0021] Compared with the prior art, the application has the following advantages and beneficial effects:

[0022] The application adopts a double-power plasma sintered titanium suboxide electrode as a substrate, reduces the interface transfer resistance of the electrode in a CV cycle deposition manner, and increases the electrochemical performance of the electrode. ct The value is small.

[0023] The Rh in the Rh@Ti4O7 electrode prepared by the application exists in the form of single atoms, which greatly improves the oxygen vacancies of the electrode. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 XRD patterns of Rh@Ti4O7 electrodes with different CV cycle times.

[0025] Figure 2 LSV (a) and EIS (b) patterns of Rh@Ti4O7 electrodes and Ti4O7 electrodes.

[0026] Figure 3 Thiamethoxam degradation comparison patterns of different metal deposition (a), different CV cycle Rh@Ti4O7 electrodes (b), and 15-Rh@Ti4O7 electrodes and Rh / Ti4O7 electrodes (c).

[0027] Figure 4 Linear sweep voltammograms of 15-Rh@Ti4O7 electrodes and Rh / Ti4O7 electrodes.

[0028] Figure 5 Electrochemical impedance patterns of 15-Rh@Ti4O7 electrodes and Rh / Ti4O7 electrodes. DETAILED DESCRIPTION

[0029] The application will be further described in detail below in combination with examples and drawings, but the embodiments of the application are not limited thereto. The raw materials involved in the application can be directly purchased from the market. For the process parameters not specifically mentioned, the conventional techniques can be referred to.

[0030] Example 1:

[0031] S1, sintering Ti4O7 electrode: Ti4O7 powder was placed in a graphite mold and put into a double power vacuum plasma sintering furnace (SPR). The furnace was vacuumized and the sintering pressure was 5 MPa. The sintering procedure was as follows: 0-5 min, the temperature was raised from room temperature to 600 °C at a rate of 114 °C / min; 5-13 min, the temperature was raised from 600 °C to 1000 °C at a rate of 50 °C / min; 13-17 min, the temperature was raised from 1000 °C to 1100 °C at a rate of 25 °C / min; 17-37 min, 1100 °C was maintained; after sintering, the heating was stopped and the vacuum sintering was cooled to room temperature under the condition of 5 MPa, and then the Ti4O7 electrode with a diameter of 20 mm and a thickness of 1.5 mm was obtained.

[0032] S2, plasma surface treatment of Ti4O7 electrode: the running pressure was set to 0.2 mbar, the time was 30 min, the argon atmosphere was 20%, the flow rate was 10 L / min, and both sides were treated for 30 min.

[0033] S3, etching fluorinated Ti4O7 electrode after S2 treatment:

[0034] Etching: 85wt% phosphoric acid solution and 30wt% hydrogen peroxide solution were weighed and mixed to prepare a 100g mixed solution (volume ratio of phosphoric acid solution to hydrogen peroxide solution was 3:2), the Ti4O7 electrode was placed in the mixed solution, etched at 80 °C for 75 min, then washed and dried in an oven;

[0035] Fluorination: a 10mmol / L sodium fluoride solution was prepared and the pH was adjusted to 4, the etched Ti4O7 electrode was immersed in the solution for 12h, then taken out, washed and dried.

[0036] S4, preparation of Rh@Ti4O7 electrode: in an electrochemical workstation, the Ti4O7 electrode etched and fluorinated in step S3 was used as the working electrode, platinum sheet was used as the counter electrode, silver / silver chloride was used as the reference electrode, 29 mL of 50mmol / L sodium sulfate solution was taken, 1 mL of 10mmol / L rhodium chloride solution was added, and CV cyclic electrodeposition was carried out in the scanning range of-0.3-0.3V at a scanning rate of 0.1V / s, the CV cycle number was 5 times, the deposited electrode was washed with distilled water and then dried in an oven at 120 °C, and the electrode was prepared and recorded as 5-Rh@Ti4O7 electrode.

[0037] Examples 2-4:

[0038] Example 2-4 5-Rh@Ti4O7 electrode was prepared according to Example 1, and steps S1-S3 were the same as Example 1; the difference was that the number of cycles in step S4 was changed, and the number of CV cycles for electrodeposition was 15, 25, and 35, respectively, and the other conditions were the same as Example 1. The Rh@Ti4O7 electrodes prepared were denoted as 15-Rh@Ti4O7, 25-Rh@Ti4O7, and 35-Rh@Ti4O7, respectively.

[0039] The XRD patterns of the Rh@Ti4O7 electrodes prepared in Examples 1-4 and the Ti4O7 electrode prepared in step S1 are shown in Figure Figure 1 It can be seen that all the characteristic diffraction peaks of the pure Ti4O7 electrode and the Rh@Ti4O7 electrode were observed.

[0040] The linear sweep voltammograms of the Rh@Ti4O7 electrodes prepared in Examples 1-4 and the Ti4O7 electrode prepared in step S1 are shown in Figure Figure 2 The oxygen evolution potential of Ti4O7 is 1.30 V, while the oxygen evolution potentials of the Rh@Ti4O7 electrodes with different cycle numbers are 2.43 V, 2.46 V, 2.15 V, and 2.51 V, respectively, from high to low. A high oxygen evolution potential is beneficial to the generation of hydroxyl radicals and the inhibition of the oxygen evolution side reaction on the electrode surface.

[0041] The electrochemical impedance spectrograms of the Rh@Ti4O7 electrodes prepared in Examples 1-4 and the Ti4O7 electrode prepared in step S1 are shown in Figure Figure 2 In the EIS diagram, it can be clearly seen that the interfacial charge transfer resistance is in the order of 5-Rh@Ti4O 7< 15-Rh@Ti4O7<25-Rh@Ti4O7<35-Rh@Ti4O7, the interfacial charge transfer resistance is lower, and the electrochemical performance is better.

[0042] Comparative Example 1:

[0043] Steps S1-S3 were the same as Example 1.

[0044] S4, Preparation of Pt@Ti4O7 electrode: In the electrochemical workstation, the Ti4O7 electrode etched in step S3 after fluorination was used as the working electrode, platinum sheet was used as the counter electrode, silver / silver chloride was used as the reference electrode, 50 mmol / L of sodium sulfate solution was used as the electrolyte solution, 29 mL of sodium sulfate solution was taken, 1 mL of 10 mmol / L platinum chloride solution was added for CV cyclic electrodeposition, electrodeposition was carried out in the scanning range of-0.3-0.3 V, the scanning rate was 0.1 V / s, the cycle number was 15 times, and the deposited electrode was washed with distilled water and then placed in an oven for drying at 120 DEG C to prepare the Pt@Ti4O7 electrode.

[0045] Comparative Example 2:

[0046] Steps S1-S3 were the same as in Example 1;

[0047] S4, Preparation of Ir@Ti4O7 electrode: In the electrochemical workstation, the Ti4O7 electrode etched in step S3 after fluorination was used as the working electrode, platinum sheet was used as the counter electrode, silver / silver chloride was used as the reference electrode, 50 mmol / L of sodium sulfate solution was used as the electrolyte solution, 29 mL of sodium sulfate solution was taken, 1 mL of 10 mmol / L iridium tetrachloride solution was added for CV cyclic electrodeposition, electrodeposition was carried out in the scanning range of-0.3-0.3 V, the scanning rate was 0.1 V / s, the cycle number was 15 times, and the deposited electrode was washed with distilled water and then placed in an oven for drying at 120 DEG C to prepare the Ir@Ti4O7 electrode.

[0048] Comparative Example 3:

[0049] Steps S1-S3 were the same as in Example 1;

[0050] S4, Preparation of Pd@Ti4O7 electrode: In the electrochemical workstation, the Ti4O7 electrode etched in step S3 after fluorination was used as the working electrode, platinum sheet was used as the counter electrode, silver / silver chloride was used as the reference electrode, 50 mmol / L of sodium sulfate solution was used as the electrolyte solution, 29 mL of sodium sulfate solution was taken, 1 mL of 10 mmol / L palladium chloride solution was added for CV cyclic electrodeposition, electrodeposition was carried out in the scanning range of-0.3-0.3 V, the scanning rate was 0.1 V / s, the cycle number was 15 times, and the deposited electrode was washed with distilled water and then placed in an oven for drying at 120 DEG C to prepare the Pd@Ti4O7 electrode.

[0051] Comparative Example 4:

[0052] S1, sintering Ti4O7 electrode: Ti4O7 powder was placed in a graphite mold and put into a double power vacuum plasma sintering furnace (SPR). The furnace was vacuumized and the sintering pressure was 5 MPa. The sintering procedure was as follows: 0-5 min, the temperature was raised from room temperature to 600 °C at a rate of 114 °C / min; 5-13 min, the temperature was raised from 600 °C to 1000 °C at a rate of 50 °C / min; 13-17 min, the temperature was raised from 1000 °C to 1100 °C at a rate of 25 °C / min; 17-37 min, 1100 °C was kept; after sintering, the heating was stopped and the vacuum sintering was cooled to room temperature under the condition of 5 MPa, and then the Ti4O7 electrode with a diameter of 20 mm and a thickness of 1.5 mm was obtained.

[0053] S2, the electrode of Ti4O7 was subjected to plasma surface treatment (the operation pressure was set to 0.2 mbar, the time was 30 min, the argon atmosphere was 20%, and the flow rate was 10 L / min).

[0054] S3, etching the Ti4O7 electrode treated by S2:

[0055] Etching: 85 wt% of phosphoric acid solution and 30 wt% of hydrogen peroxide solution were weighed and mixed to prepare a 100 g mixed solution (the volume ratio of phosphoric acid solution to hydrogen peroxide solution was 3:2). The Ti4O7 electrode was placed in the mixed solution and etched at 80 °C for 75 min, then washed and dried in an oven.

[0056] Fluorination: a 10 mmol / L sodium fluoride solution was prepared and the pH was adjusted to 4. The etched Ti4O7 electrode was immersed in the solution for 12 h, then taken out, washed and dried.

[0057] S4, preparation of Rh / Ti4O7 electrode: the Ti4O7 electrode treated by etching and fluorination in step S3 was deposited by cathode deposition. The solution used in the deposition was the same as that used in the CV cycle deposition. After deposition at a current density of 1 mA / cm 2 2 for 10 min, the electrode was washed with distilled water and dried in an oven at 120 °C to obtain the Rh / Ti4O7 electrode.

[0058] The electrodes 15-Rh@Ti4O7 prepared in Example 2 and the electrode Rh / Ti4O7 prepared in Comparative Example 4 were compared in terms of electrochemical performance, as shown in Table 1. Figure 4 , 5 As shown in Table 1, the oxygen evolution potential of the electrode 15-Rh@Ti4O7 can reach 2.41 eV, while the oxygen evolution potential of the electrode Rh / Ti4O7 is only 1.68 eV. In addition, the electrode 15-Rh@Ti4O7 also has a lower charge transfer resistance.

[0059] Application experiment: Ti4O7 electrodes prepared in steps S1 of the above Examples 1-4, Ti4O7 electrodes etched and fluorinated in step S3 (denoted as F@Ti4O7), Rh@Ti4O7 electrodes prepared in step S4 (5-Rh@Ti4O7, 15-Rh@Ti4O7, 25-Rh@Ti4O7, 35-Rh@Ti4O7) and Pt@Ti4O7, Ir@Ti4O7, Pd@Ti4O7, Rh / Ti4O7 electrodes prepared in Comparative Examples 1-4 were used as anodes for the degradation of thiamethoxam.

[0060] Experimental conditions: 100 mL of 10 mg / L thiamethoxam aqueous solution was measured, 1.4202 g of Na2SO4 electrolyte was added, and after mixing, it was poured into an electrolytic cell. Ti4O7 electrodes prepared in steps S1 of the above Examples 1-4, Ti4O7 electrodes etched and fluorinated in step S3 (denoted as F@Ti4O7), Rh@Ti4O7 electrodes prepared in step S4 and Pt@Ti4O7, Ir@Ti4O7, Pd@Ti4O7, Rh / Ti4O7 electrodes prepared in Comparative Examples 1-4 were used as anodes, and the same size of pre-treated pure titanium mesh was used as the cathode, and a customized penetrating device (outer square and inner circle, inner circle cylindrical diameter 2 cm, height 2 cm, on the basis of the inner circle, add a small cylinder with a diameter of 1.8 cm, shorter than the inner circle by 2 mm) was selected, with the anode at the bottom and the cathode at the top. A double electrode system with a constant current density of 30 mA / cm 2 , a magnetic stirring rate of 750 r / min and a room temperature condition was used for oxidation for 40 min.

[0061] The degradation of thiamethoxam using the electrodes 15-Rh@Ti4O7 and F@Ti4O7, Ti4O7, Pt@Ti4O7, Ir@Ti4O7, Pd@Ti4O7 prepared in the application is shown in (a) of Figure 3 , and the electrode 15-Rh@Ti4O7 has the best degradation effect, which can be completely degraded within 30 min, with a degradation rate of 99.89%;

[0062] As shown in (b) of Figure 3 , the Rh@Ti4O7 prepared by different CV cycle times, the adsorption stage shows that this electrode has no adsorption effect on thiamethoxam, and its degradation is due to electrochemical oxidation, and the degradation effect of 15-Rh@Ti4O7 is the best.

[0063] Thiamethoxam degradation experiments were conducted on the electrodes 15-Rh@Ti4O7 prepared in Example 2 and the electrodes Rh / Ti4O7 prepared in Comparative Example 4, as shown in Figure 3As shown in (c) in Table 2, the electrode 15-Rh@Ti4O7 prepared in Example 2 has a thiamethoxam degradation rate of 99.89% at 30 min, which is 27% higher than that of the electrode Rh / Ti4O7 prepared in Comparative Example 4 (degradation rate of 73.75%).

[0064] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing a Ti4O7 anode with Rh element by CV cyclic electrodeposition, characterized in that, Includes the following steps: (1) Ti4O7 electrode was prepared by dual-power plasma sintering; (2) The Ti4O7 electrode obtained in step (1) is subjected to plasma surface treatment, and then the plasma-treated Ti4O7 electrode is etched in an acid solution and then subjected to fluorination treatment. (3) In an electrochemical workstation, the Ti4O7 electrode etched and fluorinated in step (2) is used as the working electrode, a platinum sheet is used as the counter electrode, silver / silver chloride is used as the reference electrode, sodium sulfate solution is used as the electrolyte solution, and rhodium chloride solution is added to perform CV cyclic electrodeposition. The scanning range is -0.3 to 0.3 V and the scanning rate is 0.1 V / s. The electrode after electrodeposition is cleaned and dried to obtain the Ti4O7 anode with Rh element CV cyclic electrodeposition.

2. The method according to claim 1, characterized in that, The concentration of the sodium sulfate solution in step (3) is 50 mmol / L, and the concentration of the rhodium chloride solution is 10 mmol / L; the volume ratio of the sodium sulfate solution to the rhodium chloride solution is 29:

1.

3. The method according to claim 1, characterized in that, The number of CV cycles in step (3) is 5 to 35.

4. The method according to claim 1, characterized in that, The process parameters for plasma surface treatment in step (2) are as follows: the operating pressure is set to 0.2 Mbar, the time is 30 min, the argon gas content is 20%, and the flow rate is 10 L / min.

5. The method according to claim 1, characterized in that, The plasma surface treatment time for step (2) is 30 minutes.

6. The method according to claim 1, characterized in that, The specific steps of etching in step (2) are as follows: weigh 85wt% phosphoric acid solution and 30wt% hydrogen peroxide solution to prepare a mixed solution, put the plasma-treated Ti4O7 electrode into the mixed solution, etch at 80℃ for 75min, rinse clean, and finally dry.

7. The method according to claim 1, characterized in that, The specific steps of the fluorination treatment in step (2) include: preparing a 10 mmol / L sodium fluoride solution and adjusting the pH to 4, immersing the etched Ti4O7 electrode in the solution for 12 hours, and then taking it out, washing and drying it.

8. The method according to claim 1, characterized in that, The specific steps of step (1) include: placing Ti4O7 powder in a graphite mold, placing it in a dual-power vacuum plasma sintering furnace for sintering, drawing a vacuum inside the furnace, and sintering at a pressure of 5 MPa. The sintering procedure is as follows: from room temperature to 600℃ at a heating rate of 114℃ / min for 0–5 min; from 600℃ to 1000℃ at a heating rate of 50℃ / min for 5–13 min; from 1000℃ to 1100℃ at a heating rate of 25℃ / min for 13–17 min; and held at 1100℃ for 17–37 min. After sintering, heating is stopped, and the electrode is cooled to room temperature under a vacuum of 5 MPa. The electrode is then removed to obtain the Ti4O7 electrode.

9. A Rh@Ti4O7 electrode prepared by the method according to any one of claims 1 to 8.

10. The application of the Rh@Ti4O7 electrode of claim 9 in the degradation of thiamethoxam or environmental wastewater containing thiamethoxam.

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