A high-catalytic-activity Ti / TiO2 NT / ZIF-67@C electrode, a preparation method and application thereof

Abstract

This invention discloses a highly catalytically active Ti / TiO2NT / ZIF-67@C electrode, its preparation method, and its applications. The preparation method specifically includes: 1) preparation of the Ti / TiO2NT electrode; 2) electrochemical synthesis and deposition of ZIF-67 to form the Ti / TiO2NT / ZIF-67 electrode; and 3) electrode carbonization to form the Ti / TiO2NT / ZIF-67@C electrode. This invention uses the synthesized metal-organic framework ZIF-67 as a precursor, deposits ZIF-67 onto a substrate using direct current electrodeposition, and obtains ZIF-67@C nanoparticles through carbonization. MOF materials have a large specific surface area and numerous electrocatalytic active sites, which not only improves the catalytic performance of the electrode but also enhances its corrosion resistance. Compared with other titanium-based electrodes, it exhibits enhanced electrocatalytic activity, making it a highly active and efficient electrode.

Description

Technical Field

[0001] This invention belongs to the field of active electrode technology, specifically relating to a highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode, its preparation method, and its application. Background Technology

[0002] With the development of industrial technology, water pollution has become a serious global problem. Printing wastewater, due to its large discharge volume, complex composition, and poor natural degradation ability, has a significant impact on the aquatic environment. Among these, azo dyes are one of the most widely used dyes in printing and dyeing processes; for example, methyl orange (MO) is highly stable in nature and difficult to degrade naturally. Common degradation technologies for azo dyes include adsorption, biodegradation, and electrochemical oxidation. Adsorption requires specific solution conditions and has a limited applicability; biodegradation has a long treatment time and low efficiency; electrochemical oxidation, by generating oxidizing free radical ions, has a significant degradation effect on pollutants.

[0003] When using electrochemical oxidation for degradation, titanium-based coated electrodes are typically the main metal oxide electrodes, also known as "morphologically stable electrodes" (DSA), and are currently the most promising anode materials for practical industrial production. These DSA electrodes have low manufacturing costs, controllable electrochemical processes, and strong corrosion resistance. They are widely used as insoluble electrodes in the electrochemical industry and are the most promising electrodes for achieving the industrial application requirements of electrocatalytic oxidation. However, the electrocatalytic activity of these metal oxide electrodes is not good and there is still room for improvement. Therefore, developing a new type of electrode with high catalytic activity remains one of the main themes that researchers are currently working on. Summary of the Invention

[0004] In view of this, the main objective of the present invention is to provide a method for preparing a highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode, which solves the problems of poor electrocatalytic activity and corrosion resistance of existing titanium-based coated electrodes.

[0005] Another objective of this invention is to provide a highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode.

[0006] Another objective of this invention is to provide an application of a highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode in electrocatalytic degradation.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a method for preparing a highly catalytically active Ti / TiO2NT / ZIF-67@C electrode, the method specifically including the following steps:

[0008] S1. The pretreated titanium sheet is used as the anode and placed in the ethylene glycol electrolyte. A titanium foil of the same size as the titanium sheet is used as the cathode for anodic oxidation. After oxidation, the anode is cleaned and dried, and then annealed in air to obtain a Ti / TiO2 NT electrode.

[0009] S2. Co(NO3)2·6H2O and dimethylimidazole are added to ethanol and mixed and stirred evenly. The Ti / TiO2 NT electrode obtained in S1 is used as the working electrode and the carbon rod is used as the counter electrode. Using an electrochemical workstation, the synthesis and deposition are carried out first with a constant current and then with a constant voltage to obtain the Ti / TiO2 NT / ZIF-67 electrode.

[0010] S3. Carbonize the Ti / TiO2 NT / ZIF-67 electrode obtained in S2 to obtain a Ti / TiO2 NT / ZIF-67@C electrode.

[0011] Preferably, in step S1, the ethylene glycol electrolyte contains 0.1–0.5 wt% NH4F and 1–5 wt% H2O.

[0012] Preferably, in step S1, the oxidation voltage during the anodizing process is 30–70V.

[0013] Preferably, in step S1, the annealing temperature is between 450°C and 550°C; the annealing time is between 1 and 2 hours; and the heating and cooling rate of the annealing process is 5°C / min.

[0014] Preferably, in S2, the molar ratio of Co(NO3)2·6H2O to dimethylimidazole is 1:(4-5).

[0015] Preferably, in step S2, the current density of the constant current electroplating is 0.1–0.3 mA / cm². 2 The constant current electroplating time is 20 to 50 minutes; the constant voltage electroplating voltage is -3 to -7V; and the constant voltage electroplating time is 60 to 300 seconds.

[0016] Preferably, in step S3, the carbonization temperature is 550-650℃ and the carbonization time is 1.5-2.5h.

[0017] Preferably, in step S3, the heating and cooling rate of the carbonization process is 5°C / min.

[0018] Another technical solution of the present invention is as follows: a highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode is prepared by the above-described preparation method.

[0019] The third technical solution of the present invention is implemented as follows: the application of the above-mentioned highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode in electrocatalytic degradation, specifically the method is as follows:

[0020] A Ti / TiO2 NT / ZIF-67@C electrode was used as the anode, and a platinum electrode as the cathode. The electrode was placed in a degradation solution consisting of 60–120 mg / L methyl orange and 0.1 mol / L Na2SO4. A constant current / constant voltage power supply was used, with a current density of 80–140 mA / cm². 2 The degradation performance of Ti / TiO2 NT / ZIF-67@C electrode on methyl orange in wastewater was investigated at 25℃ under different current densities, initial concentrations and pH values.

[0021] Compared with the prior art, (1) the preparation method of the present invention uses anodizing to prepare TiO2 NT on a titanium substrate, which significantly increases the specific surface area and provides more deposition points compared with direct deposition on the titanium substrate; (2) the preparation method of the present invention uses Ti / TiO2 NT electrode as working electrode and carbon rod as counter electrode, and puts it into a mixed solution of cobalt nitrate hexahydrate and dimethylimidazole, and prepares Ti / TiO2NT / ZIF-67 electrode by constant current and then constant voltage. Compared with other methods that first synthesize ZIF-67 and then deposit it, the method of direct electrochemical synthesis and deposition of the present invention is not only simple to operate, but also improves the purity, density and uniformity of the deposited layer, and also reduces the porosity, thereby improving the stability and catalytic performance of the electrode; (3) the electrode preparation process of the present invention is simple, the equipment is readily available, the cost is low, the obtained electrode has good catalytic activity, strong corrosion resistance, stable degradation effect, and degradation efficiency can reach 98.1%. Attached Figure Description

[0022] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the surface morphology of the highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode obtained by the preparation method provided in Example 1 of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] This invention provides a method for preparing a highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode, which specifically includes the following steps:

[0026] S1. A pretreated titanium sheet is used as the anode and placed in an ethylene glycol electrolyte containing 0.1–0.5 wt% NH4F and 1–5% H2O. A titanium foil of the same size as the titanium sheet is used as the cathode. The oxidation voltage is adjusted to 30–70 V for anodic oxidation. After oxidation, the electrode is washed and dried with ethanol and deionized water, and then annealed in air to obtain a Ti / TiO2 NT electrode. The annealing temperature is 450°C–550°C, the annealing time is 1–2 h, and the heating and cooling rate is 5°C / min.

[0027] S2. Co(NO3)2·6H2O and dimethylimidazole were added to ethanol at a molar ratio of 1:(4-5) and mixed thoroughly. The Ti / TiO2 NT electrode obtained in S1 was used as the working electrode, and a carbon rod was used as the counter electrode. Using an electrochemical workstation, a constant current was first applied, followed by a constant voltage, to synthesize and deposit the Ti / TiO2 NT / ZIF-67 electrode. The current density for constant current electroplating was 0.1-0.3 mA / cm². 2 The time for constant current electroplating is 20–50 min; the voltage for constant voltage electroplating is -3 to -7 V; the time for constant voltage electroplating is 60–300 s.

[0028] S3. The Ti / TiO2NT / ZIF-67 electrode obtained in S2 is carbonized for 1.5 to 2.5 hours under the protection of an inert gas at a temperature of 550-650℃. The heating and cooling rates during the carbonization process are 5℃ / min, to obtain the Ti / TiO2NT / ZIF-67@C electrode.

[0029] The following are specific examples.

[0030] The pretreated titanium sheet in step S1 of each of the following embodiments is obtained by the following method:

[0031] Polish the surface of the titanium sheet sequentially with 300-grit, 500-grit, 800-grit, 1000-grit, 1200-grit, and 1500-grit sandpaper until the surface is smooth. Then, ultrasonically wash the polished titanium sheet sequentially in acetone, anhydrous ethanol, and deionized water for 10 minutes each. Next, immerse it in a chemical polishing solution for 10–30 seconds, rinse with deionized water, and dry at room temperature for later use.

[0032] Example 1

[0033] The highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode provided in Example 1 of this invention was obtained through the following steps:

[0034] Preparation of S1 and Ti / TiO2 NT electrodes:

[0035] Pretreated titanium sheets were used as the anode and immersed in an ethylene glycol electrolyte containing 0.25 wt% NH4F and 2% H2O. Titanium foil of the same size as the titanium sheet was used as the cathode, and anodizing was performed by adjusting the oxidation voltage to 60 V. After oxidation, the electrodes were sequentially cleaned with ethanol and deionized water and dried. Following cleaning, the electrodes were annealed in air at 450°C for 2 hours to obtain a Ti / TiO2 NT electrode.

[0036] S2. Electrochemical synthesis and deposition of ZIF-67 to form Ti / TiO2 NT / ZIF-67 electrodes:

[0037] Co(NO3)2·6H2O and dimethylimidazole were added to 60 ml of ethanol in a molar ratio of 1:4 and mixed thoroughly. Using the prepared electrode as the working electrode and a carbon rod as the counter electrode, a constant current density of 0.2 mA / cm² was first applied using an electrochemical workstation. 2 Electroplating was performed for 10 minutes; then, a constant voltage of -5V was applied for 120 seconds to perform synthesis deposition, resulting in a Ti / TiO2 NT / ZIF-67 electrode.

[0038] S3, Electrode carbonization to form Ti / TiO2 NT / ZIF-67@C electrode:

[0039] The Ti / TiO2 NT / ZIF-67 electrode was placed in a tube furnace and carbonized for 2 hours under nitrogen as the protective gas at a carbonization temperature of 600℃ to obtain the Ti / TiO2 NT / ZIF-67@C electrode.

[0040] The Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 1 was applied to electrocatalytic degradation. The specific method was as follows: the Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 1 was used as the anode, and a platinum electrode as the cathode. The electrode was placed in a degradation solution containing 100 mg / L methyl orange and 0.1 mol / L Na2SO4. A constant current and constant voltage power supply was used, with a current density of 100 mA / cm². 2 The degradation performance of Ti / TiO2 NT / ZIF-67@C electrode on methyl orange in wastewater was investigated at a temperature of 25℃.

[0041] The results showed that the degradation efficiency of methyl orange reached 94.1% during the electrocatalytic degradation process.

[0042] In addition, through observation and analysis Figure 1As can be seen, in the highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 1, ZIF-67@C is uniformly distributed on its surface, and some nanotubes are exposed, which improves conductivity and increases catalytic activity.

[0043] Example 2

[0044] The highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode provided in Example 2 of this invention was obtained through the following steps:

[0045] Preparation of S1 and Ti / TiO2 NT electrodes:

[0046] Pretreated titanium sheets were used as the anode and immersed in an ethylene glycol electrolyte containing 0.3 wt% NH4F and 2% H2O. Titanium foil of the same size as the titanium sheet was used as the cathode, and the oxidation voltage was adjusted to 50V for anodic oxidation. After oxidation, the electrodes were sequentially cleaned with ethanol and deionized water and dried. After cleaning, the electrodes were annealed in air at 450℃ for 1 hour to obtain a Ti / TiO2 NT electrode.

[0047] S2. Electrochemical synthesis and deposition of ZIF-67 to form Ti / TiO2 NT / ZIF-67 electrodes:

[0048] Co(NO3)2·6H2O and dimethylimidazole were added to 60 ml of ethanol in a molar ratio of 1:5 and mixed thoroughly. Using the prepared electrode as the working electrode and a carbon rod as the counter electrode, a constant current density of 0.2 mA / cm² was first applied using an electrochemical workstation. 2 Electroplating for 10 min; then electroplating for 120 s at a constant voltage of -5 V to perform synthesis deposition and obtain Ti / TiO2 NT / ZIF-67 electrode.

[0049] S3, Electrode carbonization to form Ti / TiO2 NT / ZIF-67@C electrode:

[0050] The Ti / TiO2 NT / ZIF-67 electrode was placed in a tube furnace and carbonized for 2 hours under nitrogen as the protective gas at a carbonization temperature of 600℃ to obtain the Ti / TiO2 NT / ZIF-67@C electrode.

[0051] The Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 2 was applied to electrocatalytic degradation. The specific method was as follows: the Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 1 was used as the anode, and a platinum electrode as the cathode. The electrode was placed in a degradation solution containing 100 mg / L methyl orange and 0.1 mol / L Na2SO4. A constant current and constant voltage power supply was used, with a current density of 100 mA / cm².2 The degradation performance of Ti / TiO2 NT / ZIF-67@C electrode on methyl orange in wastewater was investigated at a temperature of 25℃.

[0052] The results showed that the degradation efficiency of methyl orange reached 95.3% during the electrocatalytic degradation process.

[0053] Example 3

[0054] The highly catalytically active Ti / TiO2 NT / ZIF-67@C electrode provided in Example 3 of this invention was obtained through the following steps:

[0055] Preparation of S1 and Ti / TiO2 NT electrodes:

[0056] Pretreated titanium sheets were used as the anode and immersed in an ethylene glycol electrolyte containing 0.25 wt% NH4F and 2% H2O. Titanium foil of the same size as the titanium sheet was used as the cathode, and anodizing was performed by adjusting the oxidation voltage to 60V. After oxidation, the electrodes were sequentially cleaned with ethanol and deionized water and dried. Following cleaning, the electrodes were annealed in air at 450℃ for 2 hours to obtain a Ti / TiO2 NT electrode.

[0057] S2. Electrochemical synthesis and deposition of ZIF-67 to form Ti / TiO2 NT / ZIF-67 electrodes:

[0058] Co(NO3)2·6H2O and dimethylimidazole were added to 60 ml of ethanol in a molar ratio of 1:4 and mixed thoroughly. Using the prepared electrode as the working electrode and a carbon rod as the counter electrode, a constant current density of 0.2 mA / cm² was first applied using an electrochemical workstation. 2 Electroplating for 10 min; then electroplating for 180 s at a constant voltage of -4 V to obtain the synthetic deposition, forming a Ti / TiO2 NT / ZIF-67 electrode;

[0059] S3, Electrode carbonization to form Ti / TiO2 NT / ZIF-67@C electrode:

[0060] The Ti / TiO2 NT / ZIF-67 electrode was placed in a tube furnace and carbonized for 2 hours under nitrogen as the protective gas at a carbonization temperature of 600℃ to obtain the Ti / TiO2 NT / ZIF-67@C electrode.

[0061] The Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 3 was applied to electrocatalytic degradation. The specific method was as follows: the Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 1 was used as the anode, and a platinum electrode as the cathode. The electrode was placed in a degradation solution containing 100 mg / L methyl orange and 0.1 mol / L Na2SO4. A constant current and constant voltage power supply was used, with a current density of 100 mA / cm². 2 The degradation performance of Ti / TiO2 NT / ZIF-67@C electrode on methyl orange in wastewater was investigated at a temperature of 25℃.

[0062] The results showed that the degradation efficiency of methyl orange reached 95.9% during the electrocatalytic degradation process.

[0063] Example 4

[0064] Embodiment 4 of this invention is an application embodiment, in which the electrode used is the Ti / TiO2NT / ZIF-67@C electrode obtained in Embodiment 1, and the specific method of this application is as follows:

[0065] The Ti / TiO2 NT / ZIF-67@C electrode obtained in Example 1 was used as the anode, and the platinum electrode was used as the cathode. The electrode was placed in a degradation solution consisting of 100 mg / L methyl orange and 0.1 mol / L Na2SO4. A constant current and constant voltage power supply was used, with a current density of 140 mA / cm². 2 The degradation performance of Ti / TiO2 NT / ZIF-67@C electrode on methyl orange in wastewater was investigated at a temperature of 25℃.

[0066] The results showed that the degradation efficiency of methyl orange reached 98.1% during the electrocatalytic degradation process.

[0067] In summary, the electrocatalytic oxidation treatment of methyl orange in wastewater using the Ti / TiO2 NT / ZIF-67@C electrode obtained in Examples 1-4 of this invention has a reasonable process flow, low investment cost, stronger electrode corrosion resistance, better degradation process stability, and higher degradation efficiency than ordinary titanium-based electrodes. The degradation efficiency of methyl orange reaches over 98.1%, and energy consumption is significantly reduced with fewer degradation side reactions, ensuring high degradation efficiency.

[0068] Furthermore, in the preparation of the Ti / TiO2 NT / ZIF-67@C electrode, this invention uses the synthesized metal-organic framework ZIF-67 as a precursor, deposits ZIF-67 onto the substrate using DC electrodeposition, and obtains ZIF-67@C nanoparticles (i.e., metal-organic framework materials) through carbonization. This results in a Ti / TiO2 NT / ZIF-67@C electrode with a large specific surface area and numerous electrocatalytic active sites, which not only improves the catalytic performance of the electrode but also enhances its corrosion resistance. Compared with other titanium-based electrodes, the electrode of this invention exhibits enhanced electrocatalytic activity, making it a highly active and efficient electrode.

[0069] In addition, metal-organic frameworks (MOFs) have unique advantages such as high specific surface area, porosity and controllable pore size, and diverse composition. Carbonization under a protective gas can transform the organic phase into a highly porous carbon phase. At the same time, the metal ions are combined with the carbon phase, which not only improves the conductivity but also retains the catalytic effect of the metal ions. MOF-derived carbon composites have good affinity for adsorbing organic pollutants and are often used for the adsorption of organic pollutants. Due to the unique structural characteristics and excellent electrochemical performance of MOF-derived materials, they have good application prospects in the field of electrocatalysis.

[0070] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a high-catalytic-activity Ti / TiO2 NT / ZIF-67@C electrode, the method specifically comprising the following steps: S1, placing a pretreated titanium sheet as an anode into an ethylene glycol electrolyte, and placing a titanium foil with the same size as the titanium sheet as a cathode, and performing anodic oxidation, and then cleaning and drying, and then performing annealing treatment in air to obtain a Ti / TiO2 NT electrode; S2, adding Co (NO3) 2·6H2O and dimethyl imidazole into ethanol, mixing and stirring uniformly, taking the Ti / TiO2 NT electrode obtained in S1 as a working electrode, and taking a carbon rod as a counter electrode, and using an electrochemical workstation to perform synthesis deposition by constant current and then constant voltage to obtain a Ti / TiO2 NT / ZIF-67 electrode; S3, carbonizing the Ti / TiO2 NT / ZIF-67 electrode obtained in S2 to obtain a Ti / TiO2 NT / ZIF-67@C electrode.

2. The preparation method of a high-catalytic-activity Ti / TiO2 NT / ZIF-67@C electrode according to claim 1, characterized in that, In S1, the ethylene glycol electrolyte contains 0.1-0.5wt% of NH4F and 1-5% of H2O by volume fraction.

3. The preparation method of a high-catalytic-activity Ti / TiO2 NT / ZIF-67@C electrode according to claim 2, characterized in that, In S1, the oxidation voltage during the anodic oxidation is 30-70V.

4. The preparation method of the high-catalytic-activity Ti / TiO2 NT / ZIF-67@C electrode according to any one of claims 1-3, characterized in that, In S1, the annealing treatment temperature is 450-550℃, the annealing treatment time is 1-2h, and the heating and cooling rates of the annealing treatment are 5℃ / min.

5. The preparation method of a high catalytic activity Ti / TiO2 NT / ZIF-67@C electrode according to claim 1, characterized in that, In S2, the molar ratio of Co (NO3) 2·6H2O to dimethyl imidazole is 1:(4-5).

6. The preparation method of a high catalytic activity Ti / TiO2 NT / ZIF-67@C electrode according to claim 5, characterized in that, The current density of the constant current electroplating is 0.1-0.3 mA / cm 2 ; the time of the constant current electroplating is 20-50 min; the voltage of the constant voltage electroplating is -3--7 V; and the time of the constant voltage electroplating is 60-300 s.

7. The preparation method of a high catalytic activity Ti / TiO2 NT / ZIF-67@C electrode according to claim 1, characterized in that, In S3, the carbonization temperature is 550-650℃, and the carbonization time is 1.5-2.5h.

8. The preparation method of a high catalytic activity Ti / TiO2 NT / ZIF-67@C electrode according to claim 7, characterized in that, In S3, the heating and cooling rates of the carbonization treatment are 5℃ / min.

9. A high catalytic activity Ti / TiO2 NT / ZIF-67@C electrode, characterized in that, The preparation method is prepared by any one of claims 1-8.

10. Use of the high-catalytic-activity Ti / TiO2 NT / ZIF-67@C electrode of claim 9 in electrocatalytic degradation.

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