A photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide, its preparation method and application

Abstract

This invention discloses a photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide, its preparation method, and its application, belonging to the field of advanced oxidation treatment technology. The method includes pretreatment, substrate material preparation, precursor solution preparation, hydrothermal reaction, and post-treatment steps. The photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide is prepared according to the method of this invention. The application is the degradation of sulfamethoxazole using the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide. The photoelectrocatalytic material prepared by this invention exhibits highly efficient degradation performance of sulfamethoxazole under visible light conditions. Furthermore, the preparation method is safe, simple, and efficient, showing potential for environmental remediation applications.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation treatment technology, specifically relating to a photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide, its preparation method and application. Background Technology

[0002] The problem of continuous input and accumulation of antibiotic-derived recalcitrant organic pollutants into the aquatic environment is becoming increasingly serious. Among them, sulfonamide antibiotics, represented by sulfamethoxazole (SMX), are frequently detected in natural water bodies due to their stable benzene and isoxazole ring structures, widespread use, and persistent environmental residues, and are difficult to remove effectively through conventional biochemical processes.

[0003] Photoelectrocatalytic oxidation technology utilizes semiconductor materials to generate photogenerated electron-hole pairs under illumination and achieves efficient separation under an applied bias voltage, thereby generating highly oxidizing reactive species to deeply degrade pollutants. It boasts advantages such as mild reaction conditions, high energy efficiency, and minimal risk of secondary pollution. However, the core bottleneck of this technology lies in the development of high-performance electrode materials. Among numerous semiconductor materials, highly ordered titanium dioxide nanotube arrays are considered ideal photoelectrocatalytic substrate materials due to their unique tubular structure perpendicular to the substrate, large specific surface area, excellent chemical stability, and ease of recycling. However, their response range is mainly in the ultraviolet region, with low absorption efficiency for visible light, and the rapid recombination of photogenerated carriers severely affects their photoelectric conversion efficiency.

[0004] Existing research has attempted to improve the performance of TiO2 nanotubes by loading them with multi-metal oxides. For example, some studies have used cathodic electrodeposition to prepare TiO2 nanotube arrays modified with Fe2O3, CuO, and NiO nanoparticles, which showed a significant improvement in phenol removal rate compared to unmodified samples. However, this technique still has significant limitations. For pollutants with more complex structures and greater resistance to degradation, such as sulfonamide antibiotics, the catalytic efficiency, selectivity, and long-term operational stability of existing modified materials still need further improvement. Therefore, it is essential to develop a highly efficient and stable photoelectrocatalytic material based on multi-metal oxide-supported TiO2 nanotube arrays. Summary of the Invention

[0005] To address the technical problems in existing technologies where TiO2 nanotube arrays modified with multi-metal oxides exhibit uneven metal oxide distribution, limited photogenerated carrier separation and transport efficiency, and insufficient catalytic degradation efficiency and long-term operational stability for sulfonamide antibiotics, the primary objective of this invention is to provide a method for preparing photoelectrocatalytic materials of TiO2 nanotubes supported by multi-metal oxides. By precisely controlling the band structure, interfacial charge transport characteristics, and surface active site distribution of the heterojunction, this method effectively assists in the application of external electrical energy under visible light.

[0006] The second objective of this invention is to provide a method for preparing a photoelectrocatalytic material using TiO2 nanotubes supported by a multi-metal oxide.

[0007] A third objective of this invention is to provide applications of the aforementioned photoelectrocatalytic material.

[0008] The first objective of this invention is achieved by the following steps: S1. First, wash the titanium foil, then perform chemical polishing; S2. The titanium foil treated in step S1 is placed in an electrolyte as an anode, and a DC voltage is applied for anodic oxidation. After that, the oxidized titanium foil is washed and then annealed to obtain anatase TiO2 nanotube substrate material. S3. Dissolve manganese nitrate tetrahydrate, calcium nitrate tetrahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, and citric acid in ultrapure water, and add ethylene glycol during stirring to obtain a precursor solution of multi-metal oxides. S4. The precursor solution of the multi-metal oxide is subjected to a hydrothermal reaction with the anatase TiO2 nanotube substrate material to obtain the reaction product, and then the reaction product is washed. S5. Anneal the washed reaction product to obtain a photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide.

[0009] Preferably, step S1 involves ultrasonically washing the titanium foil sequentially with acetone, anhydrous ethanol, and ultrapure water for 10 to 20 minutes each time.

[0010] Preferably, in step S1, the titanium foil has a Ti content of ≥99.99%, a thickness of 0.3 mm, and a size of 3.0 cm × 4.0 cm. The polishing solution for chemical polishing in step S1 is prepared by mixing hydrofluoric acid, nitric acid, and water in a volume ratio of 1:4:5, and the polishing time is 35 s to 60 s.

[0011] Preferably, the electrolyte preparation method in step S2 is to mix water and ethylene glycol at a volume ratio of 1:50 to obtain a solvent, and then add ammonium fluoride to the solvent at a mass ratio of ammonium fluoride to solvent of 1:400 to obtain the electrolyte.

[0012] Preferably, the electrolytic oxidation voltage in step S2 is 30V, and the electrolytic oxidation time is 1.5h to 3h.

[0013] Preferably, the annealing temperature in step S2 is 450℃~550℃, the heating rate is 3℃ / min~6℃ / min, and the holding time is 1.5h~3h.

[0014] Preferably, in step S3, the amounts of manganese nitrate tetrahydrate, calcium nitrate tetrahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and ferric nitrate nonahydrate are equal, each ranging from 0.01 mmol to 0.15 mmol; the amount of citric acid is 0.10 mmol to 1.50 mmol; the amount of ultrapure water is 20 ml; the amount of ethylene glycol is 30 ml; the stirring time of the precursor solution is 0.5 h to 2 h; and the stirring speed is 550 r / min to 650 r / min.

[0015] Preferably, the hydrothermal reaction temperature in step S4 is 150℃~200℃, and the reaction time is 10h~12h.

[0016] Preferably, the annealing temperature in step S5 is 350℃~500℃, the heating rate is 5℃ / min, and the holding time is 1.5h~3h.

[0017] The second objective of this invention is achieved by preparing the photoelectrocatalytic material of TiO2 nanotubes supported by the multi-metal oxide according to the aforementioned preparation method.

[0018] The third objective of this invention is achieved by applying the aforementioned multi-metal oxide-supported TiO2 nanotube photocatalytic material to the degradation of sulfamethoxazole, thereby achieving efficient removal of sulfamethoxazole.

[0019] The beneficial effects of this invention are: 1. This invention effectively modulates the band structure and improves the separation and migration efficiency of photogenerated carriers by loading multi-metal oxides onto TiO2 nanotubes. Through the synergistic effect of the above factors, the photoelectrocatalytic degradation activity driven by visible light is significantly enhanced. 2. Loading with oxides of transition metal elements Mn, Zn, Fe, and Co can effectively modulate the TiO2 band structure and improve photoelectrocatalytic efficiency. CaO doping can also increase the amount of active species generated. Compared with loading with a single metal oxide, multi-metal oxides (Mn, Ca, Zn, Co, Fe)O2... x Increased the number of reactive sites; 3. The photoelectrocatalytic material of this invention exhibits excellent sulfamethoxazole degradation performance under actual wastewater conditions, and has potential for practical engineering applications. At the same time, the preparation method is simple, the conditions are mild, and the raw materials are readily available, making it suitable for large-scale promotion and application. Attached Figure Description

[0020] Figure 1 The XRD diffraction patterns are those of the photoelectrocatalytic materials prepared in Examples 1, 4-6 and Comparative Example 1.

[0021] Figure 2 The images show the SEM image and EDS elemental mapping of the photoelectrocatalytic material prepared in Example 1.

[0022] Figure 3 STEM image and EDS elemental mapping image of the photoelectrocatalytic material prepared in Example 1.

[0023] Figure 4 The electrochemical CV diagrams are for the photoelectrocatalytic materials prepared in Examples 1, 4-6 and Comparative Example 1.

[0024] Figure 5 The graph shows a comparison of the SMX degradation performance of the photoelectrocatalytic materials prepared in Examples 1, 4-6 and Comparative Example 1.

[0025] Figure 6 This is a cyclic experiment diagram of the degradation of SMX by the photoelectrocatalytic material prepared in Example 1.

[0026] Figure 7 The graph shows a comparison of the SMX degradation performance of the photoelectrocatalytic material prepared in Example 1 in simulated wastewater and actual wastewater treatment plant effluent. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention. Example 1

[0028] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment includes the following steps: S1. Cut high-purity titanium foil (Ti≥99.99%, thickness 0.3mm) into rectangles of 3.0cm×4.0cm. Wash the titanium foil by ultrasonic washing with acetone, anhydrous ethanol and ultrapure water in sequence for 15 minutes each time. Then perform chemical polishing. The polishing solution is prepared by mixing hydrofluoric acid, nitric acid and water in a volume ratio of 1:4:5. The polishing time is 45 seconds. S2. The titanium foil treated in step S1 is placed in an electrolyte as the anode and a titanium plate as the cathode. A DC voltage is applied for anodic oxidation. The electrolytic oxidation voltage is 30V and the electrolytic oxidation time is 2h. After that, the oxidized titanium foil is washed with ultrapure water. Then, the titanium foil is placed in a muffle furnace for annealing. The muffle furnace is set to heat to 450℃ at a heating rate of 5℃ / min and held at that temperature for 2h. After natural cooling, anatase TiO2 nanotube substrate material is obtained. The electrolyte is prepared by mixing water and ethylene glycol at a volume ratio of 1:50 to obtain a solvent. Then, ammonium fluoride is added to the solvent at a mass ratio of 1:400 to obtain the electrolyte. S3. Dissolve 0.10 mmol manganese nitrate tetrahydrate, 0.10 mmol calcium nitrate tetrahydrate, 0.10 mmol zinc nitrate hexahydrate, 0.10 mmol cobalt nitrate hexahydrate, 0.10 mmol ferric nitrate nonahydrate and 1.00 mmol citric acid in 20 mL of ultrapure water. Add 30 mL of ethylene glycol while stirring. Stir magnetically for 1 h at 600 r / min to obtain a precursor solution of multi-metal oxides. S4. The precursor solution of the multi-metal oxide and the anatase TiO2 nanotube substrate material were loaded into a 100mL polytetrafluoroethylene liner and sealed in a stainless steel high-pressure reactor for hydrothermal reaction at a reaction temperature of 180℃ for 12h. After the reactor was naturally cooled to room temperature, the reaction product was obtained. Then the reaction product was washed with ultrapure water and anhydrous ethanol in sequence. S5. The washed reaction product was placed in a muffle furnace for annealing. The temperature was increased from room temperature to 400℃ at a rate of 5℃ / min and kept at the temperature in air for 2 hours to obtain a photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide. Example 2

[0029] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment is based on Example 1, but differs from Example 1 in that: the polishing time in step S1 is 55s; the hydrothermal reaction temperature in step S4 is 150℃ and the reaction time is 10h. Example 3

[0030] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment is based on Example 1, except that the hydrothermal reaction temperature in step S4 is 200°C. Example 4

[0031] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment is based on Example 1, except that in step S3, 0.01 mmol manganese nitrate tetrahydrate, 0.01 mmol calcium nitrate tetrahydrate, 0.01 mmol zinc nitrate hexahydrate, 0.01 mmol cobalt nitrate hexahydrate, 0.01 mmol ferric nitrate nonahydrate and 0.10 mmol citric acid are dissolved in 20 mL of ultrapure water. Example 5

[0032] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment is based on Example 1, except that in step S3, 0.05 mmol manganese nitrate tetrahydrate, 0.05 mmol calcium nitrate tetrahydrate, 0.05 mmol zinc nitrate hexahydrate, 0.05 mmol cobalt nitrate hexahydrate, 0.05 mmol ferric nitrate nonahydrate and 0.50 mmol citric acid are dissolved in 20 mL of ultrapure water. Example 6

[0033] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment is based on Example 1, except that in step S3, 0.15 mmol manganese nitrate tetrahydrate, 0.15 mmol calcium nitrate tetrahydrate, 0.15 mmol zinc nitrate hexahydrate, 0.15 mmol cobalt nitrate hexahydrate, 0.15 mmol ferric nitrate nonahydrate and 1.50 mmol citric acid are dissolved in 20 mL of ultrapure water. Example 7

[0034] The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides in this embodiment is based on Example 1, but differs from Example 1 in the following ways: the polishing time in step S1 is 47.5 s; the electrolytic oxidation time in step S2 is 2 h 15 min, with the temperature in a muffle furnace increased to 500 °C at a rate of 4.5 °C / min and held for 2 h 15 min; in step S3, 0.08 mmol manganese nitrate tetrahydrate, 0.08 mmol calcium nitrate tetrahydrate, 0.08 mmol zinc nitrate hexahydrate, 0.08 mmol cobalt nitrate hexahydrate, 0.08 mmol ferric nitrate nonahydrate, and 0.80 mmol citric acid are dissolved in 20 mL of ultrapure water; the hydrothermal reaction temperature in step S4 is 175 °C and the reaction time is 11 h; in step S5, the temperature is increased from room temperature to 425 °C at a rate of 5 °C / min and held in air for 2 h 15 min.

[0035] Example 8: Photoelectrocatalytic degradation experiment (performance test) Comparative Example 1: Comparative Example 1 is a method for preparing TiO2 nanotubes. This method is based on Example 1, but does not include steps S3, S4, and S5, that is, it directly obtains anatase TiO2 nanotube substrate material.

[0036] The photocatalytic, electrocatalytic, and photoelectrocatalytic experiments conducted in this study used catalytic materials prepared according to the methods described in Examples 1 (0.10 MMO-TNTAs), 4 (0.01 MMO-TNTAs), 5 (0.05 MMO-TNTAs), 6 (0.15 MMO-TNTAs), and Comparative Example 1 (TNTAs). All experiments were conducted in a self-made plexiglass reactor (7.0 cm × 5.0 cm × 5.5 cm), with a degradation reaction time of 60 min. The simulated wastewater volume was 150 mL, with an initial SMX (sulfamethoxazole) concentration of 10 mg / L. Sodium sulfate was used as the electrolyte. The prepared catalytic materials were used as the photoanode, and C-PTFE as the photocathode. The photoanode and cathode were placed in parallel and connected to the positive and negative terminals of a DC regulated power supply, respectively. An irradiance of 100 mW / cm² was used. 2 The xenon lamp simulates sunlight irradiation, and the DC regulated power supply provides the electric field driving force required for the EC and PEC processes. Simultaneously, temperature control is implemented through a cryogenic cooling circulating pump, ensuring that the temperature of the photoelectrocatalytic device is stably maintained within the range of 25.0 ± 1.0 °C.

[0037] The products prepared in Examples 1, 4, 5, 6, and Comparative Example 1 were subjected to transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), cyclic voltammetry (CVT), and degradation experiments, respectively. The results are as follows: Figure 1-5 As shown.

[0038] pass Figure 1 It can be seen that the TiO2 nanotube material prepared by the method of the present invention belongs to the anatase phase, and the doping of multi-metal oxides does not change the phase state of the material. The photoelectrocatalytic material of TiO2 nanotubes supported by multi-metal oxides still belongs to the anatase phase.

[0039] pass Figure 2 (ac) shows the highly ordered, vertically oriented nanotube array structure of TiO2. Figure 2 (df) indicates that the original tubular structure of TiO2 nanotubes was not destroyed after being loaded with multi-metal oxides. This demonstrates that the preparation method of this invention has good stability and can successfully prepare nanoarray composite electrodes of TiO2 loaded with multi-metal oxides.

[0040] pass Figure 3(ad) shows the characteristic crystal planes of the multi-metal oxides CaO (200), Mn3O4 (112), Fe2O3 (110), Co3O4 (311), ZnO (100), and TiO2 (101), indicating that a close contact is formed between the metal oxides and the TiO2 nanotube substrate. The close interface structure provides a direct channel for the effective separation and rapid transfer of photogenerated carriers between the components, which is the key microscopic evidence for the excellent photoelectric synergistic effect of the composite material.

[0041] pass Figure 4 It can be seen that the TiO2 material prepared by the method in Comparative Example 1 did not show an oxidation peak, indicating that its electrochemical activity was poor. The photoelectrocatalytic materials prepared by the methods in Examples 4-6 showed clear redox peaks, indicating that they had certain electrochemical activity. The oxidation peak of 0.10 MMO-TNTAs in Example 1 was further improved compared with Examples 4-6, indicating that Example 1 had better electrochemical performance than Examples 4-6, and also had redox ability.

[0042] pass Figure 5 As can be seen, the 0.10 MMO-TNTAs material in Example 1 exhibits stronger catalytic activity in photoelectrocatalysis, achieving a high degradation efficiency of 94.20% during the SMX degradation process.

[0043] pass Figure 6 It can be seen that the 0.10 MMO-TNTAs material in Example 1 had a degradation rate of 81.10% within 60 minutes after 5 cycles of SMX degradation, indicating that the photoanode of TiO2 nanotubes supported by multi-metal oxides has strong operational stability and reusability potential.

[0044] pass Figure 7 It can be seen that the 0.10 MMO-TNTAs material in Example 1 has a degradation rate of 89.20% for SMX in the effluent matrix of an actual wastewater treatment plant, indicating that the multi-metal oxide-supported TiO2 nanotube photoelectrocatalytic material can still maintain good pollutant removal performance when treating actual water bodies with complex compositions.

[0045] In summary, this invention effectively enhances the light absorption capacity of TiO2 nanotubes and significantly improves the photocatalytic performance of the composite material by preparing a multi-metal oxide-supported TiO2 nanotube photocatalytic material. It also demonstrates a highly efficient degradation capability for sulfonamide antibiotics (SMX), providing an effective technical approach for the treatment of new pollutants.

Claims

1. A method for preparing a photoelectrocatalytic material of multi-metal oxide loaded TiO2 nanotube, characterized in that Includes the following steps: S1. First, wash the titanium foil, then perform chemical polishing; S2. The titanium foil treated in step S1 is placed in an electrolyte as an anode, and a DC voltage is applied for anodic oxidation. After that, the oxidized titanium foil is washed and then annealed to obtain anatase TiO2 nanotube substrate material. S3. Dissolve manganese nitrate tetrahydrate, calcium nitrate tetrahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, and citric acid in ultrapure water, and add ethylene glycol during stirring to obtain a precursor solution of multi-metal oxides. S4. The precursor solution of the multi-metal oxide is subjected to a hydrothermal reaction with the anatase TiO2 nanotube substrate material to obtain the reaction product, and then the reaction product is washed. S5. Anneal the washed reaction product to obtain a photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide.

2. The method for preparing a photoelectrocatalytic material of multi-metal oxide supported TiO2 nanotubes according to claim 1, characterized in that In step S1, the titanium foil has a Ti ≥ 99.99% purity, a thickness of 0.3 mm, and a size of 3.0 cm × 4.0 cm. The polishing solution for chemical polishing in step S1 is prepared by mixing hydrofluoric acid, nitric acid, and water in a volume ratio of 1:4:5, and the polishing time is 35 s to 60 s.

3. The method for preparing the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 1, characterized in that... The electrolyte in step S2 is prepared by mixing water and ethylene glycol at a volume ratio of 1:50 to obtain a solvent, and then adding ammonium fluoride to the solvent at a mass ratio of 1:400 to obtain the electrolyte.

4. The method for preparing the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 1, characterized in that... The electrolytic oxidation voltage in step S2 is 30V, and the electrolytic oxidation time is 1.5h~3h.

5. The method for preparing the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 1, characterized in that... The annealing temperature for step S2 is 450℃~550℃, the heating rate is 3℃ / min~6℃ / min, and the holding time is 1.5h~3h.

6. The method for preparing the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 1, characterized in that... In step S3, the amounts of manganese nitrate tetrahydrate, calcium nitrate tetrahydrate, zinc nitrate hexahydrate, cobalt nitrate hexahydrate, and ferric nitrate nonahydrate are equal, ranging from 0.01 mmol to 0.15 mmol. The amount of citric acid is 0.10 mmol to 1.50 mmol. The amount of ultrapure water is 20 ml, and the amount of ethylene glycol is 30 ml. The stirring time of the precursor solution is 0.5 h to 2 h, and the stirring speed is 550 r / min to 650 r / min.

7. The method for preparing the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 1, characterized in that... The hydrothermal reaction temperature for step S4 is 150℃~200℃, and the reaction time is 10h~12h.

8. The method for preparing the photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 1, characterized in that... The annealing temperature for step S5 is 350℃~500℃, the heating rate is 5℃ / min, and the holding time is 1.5h~3h.

9. A photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to any one of claims 1 to 8.

10. The application of a photoelectrocatalytic material of TiO2 nanotubes supported by a multi-metal oxide according to claim 9 in the degradation of sulfamethoxazole.

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