A CV-cycle electrodeposition method for Rh-element Ti4O7 anode, its preparation method, and its application.

Abstract

This invention relates to a cyclic electrodeposition (CV) of Rh element in Ti4O7 anode, its preparation method, and its application. The preparation method includes the following steps: preparing a Ti4O7 electrode by dual-power plasma sintering; subjecting the Ti4O7 electrode to plasma surface treatment, then etching the plasma-treated Ti4O7 electrode in an acid solution, followed by fluorination; in an electrochemical workstation, using the etched and fluorinated Ti4O7 electrode as the working electrode, a platinum sheet as the counter electrode, silver / silver chloride as the reference electrode, and sodium sulfate solution as the electrolyte solution, with rhodium chloride solution added, performing CV cyclic electrodeposition with a scan range of -0.3 to 0.3 V and a scan rate of 0.1 V / s; the electrode after electrodeposition is cleaned and dried. This invention uses a sub-titanium oxide electrode sintered by dual-power plasma as the substrate, and the CV cyclic deposition method reduces the interfacial transfer resistance of the electrode, thereby increasing its electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of water resource remediation, specifically relating to a Ti4O7 anode for CV cyclic electrodeposition of Rh elements, its preparation method, and its application. Background Technology

[0002] Compared to general industrial electrode materials, titanium suboxide (Ti4O7) electrodes exhibit high chemical stability and corrosion resistance. Titanium suboxide has a high oxygen evolution potential at the anode, which is beneficial for anodic oxidation. It can be widely used as an electrochemical anode in the electrocatalytic degradation of organic pollutants and the treatment of environmental wastewater such as landfill leachate and dyeing wastewater. Commercial titanium suboxide electrodes R ct The hydroxyl radical yield is relatively high, and further improvement is needed. Therefore, it is necessary to improve the existing methods for preparing titanium suboxide (Ti4O7) electrodes. Summary of the Invention

[0003] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing a Ti4O7 anode with Rh element through CV cyclic electrodeposition.

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

[0005] Another object of the present invention is to provide applications of the above-described Rh@Ti4O7 electrode.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a Ti4O7 anode with Rh element by CV cyclic electrodeposition includes the following steps:

[0008] (1) Ti4O7 electrode was prepared by SPS (dual power plasma sintering);

[0009] (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.

[0010] (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 (Rh@Ti4O7 electrode) with Rh element CV cyclic electrodeposition.

[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 to 35.

[0013] Preferably, the process parameters for plasma surface treatment in step (2) are: 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.

[0014] Preferably, 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 (the volume ratio of phosphoric acid solution and hydrogen peroxide solution is preferably 3:2), put the plasma-treated Ti4O7 electrode into the mixed solution, etch at 80℃ for 75min, rinse clean, and finally dry.

[0015] Preferably, 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.

[0016] Preferably, the specific steps of step (1) include: placing Ti4O7 powder in a graphite mold and sintering it in a dual-power vacuum plasma sintering furnace (SPR), with the furnace being evacuated and the sintering pressure being 5MPa;

[0017] 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.

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

[0019] The present invention also provides an Rh@Ti4O7 electrode prepared by the above method.

[0020] The Rh@Ti4O7 electrode described above can be used to degrade thiamethoxam or environmental wastewater containing thiamethoxam.

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

[0022] This invention employs a sub-titanium oxide electrode sintered by dual-power plasma as the substrate, and uses CV cyclic deposition to reduce the interfacial transfer resistance of the electrode, thereby increasing its electrochemical performance. The Rh@Ti4O7 electrode prepared by this invention has a high oxygen evolution potential, and R... ct The value is relatively small.

[0023] In the Rh@Ti4O7 electrode prepared by this invention, Rh exists in the form of single atoms, which greatly increases the number of oxygen vacancies in the electrode. Attached Figure Description

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

[0025] Figure 2 LSV (a) and EIS (b) plots of the Rh@Ti4O7 electrode and the Ti4O7 electrode.

[0026] Figure 3 Comparative graphs of thiamethoxam degradation for different metal depositions (a), different CV cycles of Rh@Ti4O7 electrodes (b), and 15-Rh@Ti4O7 and Rh / Ti4O7 electrodes (c).

[0027] Figure 4 Linear scan voltammetry for 15-Rh@Ti4O7 electrode and Rh / Ti4O7 electrode.

[0028] Figure 5 Electrochemical impedance spectroscopy for 15-Rh@Ti4O7 and Rh / Ti4O7 electrodes. Detailed Implementation

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

[0030] Example 1:

[0031] S1. Sintering Ti4O7 Electrode: Ti4O7 powder was placed in a graphite mold and placed in a dual-power vacuum plasma sintering furnace (SPR). The furnace was evacuated, and the sintering pressure was 5 MPa. The sintering procedure was as follows: 0–5 min, heating from room temperature to 600℃ at a heating rate of 114℃ / min; 5–13 min, heating from 600℃ to 1000℃ at a heating rate of 50℃ / min; 13–17 min, heating from 1000℃ to 1100℃ at a heating rate of 25℃ / min; 17–37 min, holding at 1100℃. After sintering, heating was stopped, and the electrode was cooled to room temperature under a vacuum of 5 MPa. The electrode was then removed, yielding a cylindrical Ti4O7 electrode with a diameter of 20 mm and a thickness of 1.5 mm.

[0032] S2. Perform plasma surface treatment on the Ti4O7 electrode (set the operating pressure to 0.2 mbar, time to 30 min, under an argon atmosphere with an argon percentage of 20%), with a flow rate of 10 L / min, and treat both sides for 30 min each.

[0033] S3, Etching the Ti4O7 electrode after fluorination S2 treatment:

[0034] Etching: Weigh 85wt% phosphoric acid solution and 30wt% hydrogen peroxide solution to prepare a 100g mixed solution (the volume ratio of phosphoric acid solution to hydrogen peroxide solution is 3:2). Place the Ti4O7 electrode into the mixed solution, etch at 80℃ for 75min, rinse clean, and place in an oven to dry.

[0035] Fluorination: Prepare a 10 mmol / L sodium fluoride solution and adjust the pH to 4. Immerse the etched Ti4O7 electrode in the solution for 12 hours, then remove it, wash and dry it.

[0036] Preparation of S4 and Rh@Ti4O7 electrodes: In an electrochemical workstation, the Ti4O7 electrode etched and fluorinated in step S3 was used as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. A 50 mmol / L sodium sulfate solution was used as the electrolyte solution. 29 mL of sodium sulfate solution was taken and 1 mL of a 10 mmol / L rhodium chloride solution was added for CV cyclic electrodeposition. Electrodeposition was performed in a scan range of -0.3 to 0.3 V, with a scan rate of 0.1 V / s and 5 CV cycles. After deposition, the electrode was rinsed with distilled water and dried in an oven at 120 °C to obtain the electrode, which was denoted as 5-Rh@Ti4O7 electrode.

[0037] Examples 2-4:

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

[0039] The XRD patterns of Rh@Ti4O7 electrodes and Ti4O7 electrodes (prepared in step S1) prepared in Examples 1-4 with different cycle numbers are shown below. Figure 1 As shown, both the pure Ti4O7 electrode and the Rh@Ti4O7 electrode exhibited all the characteristic diffraction peaks.

[0040] Linear scan voltammetry diagrams of Rh@Ti4O7 electrodes and Ti4O7 electrodes (prepared in step S1) prepared in Examples 1-4 with different cycle numbers are shown below. Figure 2 As shown in (a), the oxygen evolution potential of Ti4O7 is 1.30V, while the oxygen evolution potential of Rh@Ti4O7 electrodes with different cycles is 2.43V, 2.46V, 2.15V and 2.51V from high to low CV cycle number. The high oxygen evolution potential is conducive to the generation of hydroxyl radicals and inhibits the oxygen evolution side reaction on the electrode surface.

[0041] The electrochemical impedance spectroscopy spectra of Rh@Ti4O7 electrodes and Ti4O7 electrodes (prepared in step S1) prepared in Examples 1-4 with different cycle numbers are shown below. Figure 2 As shown in (b) of the diagram, it can be clearly seen in the EIS plot that the interfacial charge transfer resistances are ordered as 5-Rh@Ti4O 7< The 15-Rh@Ti4O7 < 25-Rh@Ti4O7 < 35-Rh@Ti4O7 exhibits lower interfacial charge transfer resistance and better electrochemical performance.

[0042] Comparative Example 1:

[0043] Steps S1 to S3 are the same as in Example 1;

[0044] S4. Preparation of Pt@Ti4O7 electrode: In an electrochemical workstation, the Ti4O7 electrode etched and fluorinated in step S3 was used as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. A 50 mmol / L sodium sulfate solution was used as the electrolyte solution. 29 mL of sodium sulfate solution was taken and 1 mL of 10 mmol / L platinum chloride solution was added for CV cyclic electrodeposition. Electrodeposition was performed in a scan range of -0.3 to 0.3 V, with a scan rate of 0.1 V / s and 15 cycles. After deposition, the electrode was rinsed with distilled water and dried in an oven at 120 °C to obtain the Pt@Ti4O7 electrode.

[0045] Comparative Example 2:

[0046] Steps S1 to S3 are the same as in Example 1;

[0047] Preparation of S4 and Ir@Ti4O7 electrodes: In an electrochemical workstation, the Ti4O7 electrode etched and fluorinated in step S3 was used as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. 50 mmol / L sodium sulfate solution was used as the electrolyte solution. 29 mL of sodium sulfate solution was taken and 1 mL of 10 mmol / L iridium tetrachloride solution was added for CV cyclic electrodeposition. Electrodeposition was performed in the scan range of -0.3 to 0.3 V, the scan rate was 0.1 V / s, and the number of cycles was 15. After deposition, the electrode was rinsed with distilled water and dried in an oven at 120 °C to obtain the Ir@Ti4O7 electrode.

[0048] Comparative Example 3:

[0049] Steps S1 to S3 are the same as in Example 1;

[0050] Preparation of S4 and Pd@Ti4O7 electrodes: In an electrochemical workstation, the Ti4O7 electrode etched and fluorinated in step S3 was used as the working electrode, a platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode. A 50 mmol / L sodium sulfate solution was used as the electrolyte solution. 29 mL of sodium sulfate solution was taken and 1 mL of 10 mmol / L palladium chloride solution was added for CV cyclic electrodeposition. Electrodeposition was performed in a scan range of -0.3 to 0.3 V, with a scan rate of 0.1 V / s and 15 cycles. After deposition, the electrode was rinsed with distilled water and dried in an oven at 120 °C to obtain the Pd@Ti4O7 electrode.

[0051] Comparative Example 4:

[0052] S1. Sintering Ti4O7 Electrode: Ti4O7 powder was placed in a graphite mold and placed in a dual-power vacuum plasma sintering furnace (SPR). The furnace was evacuated, and the sintering pressure was 5 MPa. The sintering procedure was as follows: 0–5 min, heating from room temperature to 600℃ at a heating rate of 114℃ / min; 5–13 min, heating from 600℃ to 1000℃ at a heating rate of 50℃ / min; 13–17 min, heating from 1000℃ to 1100℃ at a heating rate of 25℃ / min; 17–37 min, holding at 1100℃. After sintering, heating was stopped, and the electrode was cooled to room temperature under a vacuum of 5 MPa. The electrode was then removed, yielding a cylindrical Ti4O7 electrode with a diameter of 20 mm and a thickness of 1.5 mm.

[0053] S2. Perform plasma surface treatment on the Ti4O7 electrode (set the operating pressure to 0.2 mbar, time to 30 min, under an argon atmosphere, with argon accounting for 20% and a flow rate of 10 L / min), treating both sides for 30 min each.

[0054] S3, Etching the Ti4O7 electrode after fluorination S2 treatment:

[0055] Etching: Weigh 85wt% phosphoric acid solution and 30wt% hydrogen peroxide solution to prepare a 100g mixed solution (the volume ratio of phosphoric acid solution to hydrogen peroxide solution is 3:2). Place the Ti4O7 electrode into the mixed solution, etch at 80℃ for 75min, rinse clean, and place in an oven to dry.

[0056] Fluorination: Prepare a 10 mmol / L sodium fluoride solution and adjust the pH to 4. Immerse the etched Ti4O7 electrode in the solution for 12 hours, then remove it, wash and dry it.

[0057] S4. Preparation of Rh / Ti4O7 electrode: The fluorinated Ti4O7 electrode etched in step S3 was deposited as a cathode using the same solution as that used in CV cycle deposition, at a current density of 1 mA / cm². 2 After deposition for 10 minutes, the electrode is washed with distilled water and dried in an oven at 120°C to obtain the Rh / Ti4O7 electrode.

[0058] The electrochemical performance of the electrode 15-Rh@Ti4O7 prepared in Example 2 was compared with that of the electrode Rh / Ti4O7 prepared in Comparative Example 4. Figure 4 , 5 As shown, the oxygen evolution potential of electrode 15-Rh@Ti4O7 can reach 2.41 eV, while the oxygen evolution potential of electrode Rh / Ti4O7 is only 1.68 eV; in addition, electrode 15-Rh@Ti4O7 also has a lower charge transfer resistance.

[0059] Application Experiments: The Ti4O7 electrodes prepared in step S1 of Examples 1-4 above, the fluorinated Ti4O7 electrodes etched in step S3 (denoted as F@Ti4O7), the Rh@Ti4O7 electrodes (5-Rh@Ti4O7, 15-Rh@Ti4O7, 25-Rh@Ti4O7, 35-Rh@Ti4O7) prepared in step S4, and the Pt@Ti4O7, Ir@Ti4O7, Pd@Ti4O7, and 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, and 1.4202 g of Na2SO4 electrolyte was added. After mixing, the mixture was poured into an electrolytic cell. The Ti4O7 electrode prepared in step S1 of Examples 1-4, the fluorinated Ti4O7 electrode etched in step S3 (denoted as F@Ti4O7), the Rh@Ti4O7 electrode prepared in step S4, and the Pt@Ti4O7, Ir@Ti4O7, Pd@Ti4O7, and Rh / Ti4O7 electrodes prepared in Comparative Examples 1-4 were used as anodes. A pretreated pure titanium mesh of the same size was used as the cathode. A custom-designed through-hole device (square outer cylinder, circular inner cylinder with a diameter of 2 cm and a height of 2 cm, plus a small cylinder with a diameter of 1.8 cm, 2 mm shorter vertically than the inner cylinder) was used, with the anode at the bottom and the cathode at the top. A constant current density of 30 mA / cm² was used in a dual-electrode system. 2 Magnetic stirring speed 750 r / min, oxidation at room temperature for 40 min.

[0061] The electrodes 15-Rh@Ti4O7 and F@Ti4O7, Ti4O7, Pt@Ti4O7, Ir@Ti4O7, and Pd@Ti4O7 prepared in this invention were used to degrade thiamethoxam as follows: Figure 3 As shown in (a), electrode 15-Rh@Ti4O7 exhibits the best degradation effect, achieving complete degradation within 30 minutes with a degradation rate of 99.89%.

[0062] like Figure 3 Figure (b) shows Rh@Ti4O7 prepared with different CV cycles. The adsorption stage indicates that this electrode does not adsorb thiamethoxam, and its degradation is due to electrochemical oxidation. Among them, 15-Rh@Ti4O7 has the best degradation effect.

[0063] The electrode 15-Rh@Ti4O7 prepared in Example 2 and the electrode Rh / Ti4O7 prepared in Comparative Example 4 were subjected to thiamethoxam degradation experiments. Figure 3As shown in (c), the electrode 15-Rh@Ti4O7 prepared in Example 2 showed a degradation rate of 99.89% for thiamethoxam in 30 min, which was 27% higher than that of the electrode Rh / Ti4O7 prepared in Comparative Example 4 (degradation rate of 73.75%).

[0064] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

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 min.

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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