A Sn3O4-Ag-Ag2O photoelectric material based on TiO2 nanotubes and its preparation method
By constructing Ag2O/Sn3O4 Z-type heterojunction on TiO2 nanotubes, the problem of low efficiency of traditional photocatalysts is solved, efficient dyeing wastewater treatment and H2 generation are achieved, and the stability and activity of the photocatalysts are improved.
Patent Information
- Application Number
- CN202310377911.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-11
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2043-04-11
AI Technical Summary
Traditional treatment methods cannot effectively destroy the high stability and toxicity of azo dyes. The existing Sn3O4/TiO2 NTs photocatalysts have low photocatalytic performance, and insufficient research on Ag2O photocatalysts, resulting in low treatment efficiency of dyeing wastewater.
Ag2O/Sn3O4 Z-type heterojunction was constructed on TiO2 nanotubes, and Sn3O4-Ag-Ag2O nanoparticles were prepared by hydrothermal method to form an indirect Z-type heterojunction to improve photocatalytic performance.
High-efficiency photocatalytic degradation of dyed wastewater was achieved, with the removal rates of MO, RhB, MB and Cr(VI) reaching 90.89%, 81.42%, 83.84% and 66.67%, respectively. The visible light-driven photocatalytic H2 generation rate was as high as 55.79μmol·cm⁻²·h⁻¹, and the photocatalyst stability and activity were significantly improved.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of photoelectric materials, and in particular relates to a Sn3O4-Ag-Ag2O photoelectric material based on TiO2 nanotubes and a preparation method thereof. Background Art
[0002] The rapidly developing printing and dyeing industry has created a global environmental problem, with tens of thousands of tons of wastewater discharged annually posing a serious threat to the aquatic environment, the ecological environment, and human health. However, traditional treatment methods such as adsorption, precipitation, and reverse osmosis are unable to destroy the high stability and toxicity of azo dyes, necessitating an urgent need for new and effective dye wastewater treatment technologies. Photocatalysis has become an attractive and efficient method for decomposing organic dyes due to its advantages such as low toxicity, low cost, mild conditions, high efficiency, and wide application range. In recent years, photocatalysis and photoelectrocatalysis have been extensively studied, with TiO2 nanotube arrays (TiO2 NTs) in particular demonstrating promising results for dye photodegradation. Professor Erusappan reported high photocatalytic efficiency (nearly 100%) for the degradation of synthetic dyes using TiO2, and Macak's group also studied the high photocatalytic activity and stability of TiO2 NTs. To further enhance visible light absorption and solar response, narrow-bandgap semiconductors have been synthesized on TiO2 NTs to simultaneously achieve efficient visible light absorption and photoelectron transfer. Sn3O4 is an important semiconductor with a band gap of ~2.8 eV, and its photocatalytic ability has been widely demonstrated by many scientists. The photocatalytic activity of Sn3O4 / TiO2 NTs heterojunctions is partially limited by the weakened redox activity of photogenerated charge carriers. Consequently, conventional Sn3O4 / TiO2 NTs photocatalysts have low photocatalytic performance and have been rarely studied. However, recently reported Z-scheme heterojunctions can maintain the original redox activity of photoelectrons and holes through the recombination of charge carriers with weak redox abilities. The construction and formation of Z-scheme heterojunctions require the recombination of electrons and holes with similar work functions. BiVO4@Sn3O4, NaNbO3-Au-Sn3O4, and C3N4-Sn3O4 photocatalysts with Z-scheme heterojunctions have demonstrated excellent photocatalytic activity and revealed the crucial role of the Z-scheme heterojunction in photocatalytic performance and charge carrier transfer. Interestingly, Ag2O photocatalysts also exhibit high photocatalytic performance in degrading organic dyes, with their energy band position being suitable for forming a Z-type heterojunction with Sn3O4. However, research on Ag2O-based Z-type heterojunctions is limited. Therefore, this paper synthesizes an Ag2O / Sn3O4 Z-type heterojunction on TiO2NTs to enhance its photocatalytic application in dye wastewater. Summary of the Invention
[0003] The purpose of the present invention is to provide a Sn3O4-Ag-Ag2O photoelectric material based on TiO2 nanotubes and a preparation method thereof, and to construct an indirect Z-type heterojunction by hydrothermal Sn3O4-Ag-Ag2O nanoparticles on a TiO2 nanotube array to improve the photocatalytic application of dyeing wastewater.
[0004] The purpose of the present invention can be achieved through the following technical solutions:
[0005] A method for preparing a Sn3O4-Ag-Ag2O photoelectric material based on TiO2 nanotubes comprises the following steps:
[0006] Step 1: Dissolve SnCl2, sodium citrate, urea and AgNO3 in deionized water and stir continuously for 25 minutes to make a transparent solution;
[0007] In the second step, the solution is poured into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and the TiO2 nanotube array (TiO2 NTs) is placed vertically in the solution for hydrothermal treatment. After the hydrothermal treatment, the autoclave is cooled at room temperature and the product is ultrasonically cleaned to obtain the photoelectric material.
[0008] Furthermore, the ratio of the amount of SnCl2, sodium citrate, urea, AgNO3 and deionized water is 2mmol:2mmol:2mmol:0.8mmol:30mL.
[0009] Furthermore, the parameters of the hydrothermal heating are specifically as follows: temperature 160° C., heating time 14 hours.
[0010] Furthermore, the TiO2 nanotube arrays (TiO2 NTs) were synthesized by anodizing Ti foil at 60 V in NH4F electrolyte.
[0011] Beneficial effects of the present invention:
[0012] The present invention adopts hydrothermal method to prepare Z-type heterojunction photocatalyst composed of Sn3O4-Ag-Ag2O and TiO2NTs. + The concentration of O2 has a significant impact on the morphology, optics and photoelectrocatalytic performance of the photocatalyst. The construction of the Z-type heterojunction promotes the improvement of photoelectron transfer and photoelectrocatalytic activity, while the O2 - The formation of OH radicals further proves the mechanism. The removal rates of MO, RhB, MB and Cr(VI) reached 90.89%, 81.42%, 83.84% and 66.67% respectively, and the visible light-driven photocatalytic H2 generation rate was as high as 55.79 μmol cm -2 ･h -1The high photocatalytic ability and stability make the prepared photocatalyst highly anticipated in industrial wastewater treatment and H2 generation. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be further described below with reference to the accompanying drawings.
[0014] Figure 1 XRD patterns of the materials prepared in Examples 1-4;
[0015] Figure 2 Scanned images of materials prepared in Examples 1-4;
[0016] Figure 3 TEM and HRTEM images (a) and elemental maps (b) of the material prepared in Example 3;
[0017] Figure 4 XPS spectra of the material prepared in Example 3: (a) total spectrum, (b) Ti 2p, (c) O 1s, (d) Sn 3d, and (e) Ag 3d.
[0018] Figure 5 DRS, band gap (a) and PL spectra (b) of the materials prepared in Examples 1-4;
[0019] Figure 6 Visible light driven instantaneous photocurrent (a), photovoltage (b), linear scan curve (c) and EIS (d) of the materials prepared in Examples 1-4;
[0020] Figure 7 Photocatalytic H2 production (a) and rate (b) for the materials prepared for Examples 1-4;
[0021] Figure 8 Photocatalytic performance of the material prepared in Example 3 for the degradation of MO (a), RhB (b) and MB (c);
[0022] Figure 9 Photocatalytic performance of the material prepared in Example 3 after adding a quencher (a) and the ESR signal of free radicals using DMPO as a scavenger (b);
[0023] Figure 10 Cyclic MB photodegradation of the material prepared in Example 3 for 4 times (a), photocatalytic Cr(VI) removal (b), and comparison of photocatalytic performance with / without voltage (c);
[0024] Figure 11 Schematic diagram of photocatalytic dye degradation and water separation. DETAILED DESCRIPTION
[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.
[0026] Example 1
[0027] Photoelectric material (Ag-0) was prepared according to the following steps:
[0028] Step 1: Dissolve 2 mmol of SnCl2, 2 mmol of sodium citrate, and 2 mmol of urea in 30 mL of deionized water and stir continuously for 25 minutes to form a transparent solution.
[0029] In the second step, the solution was poured into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and the TiO2 nanotube array (TiO2 NTs) was placed vertically in the solution. The solution was hydrothermally treated at 160°C for 14 hours. After the hydrothermal treatment, the autoclave was cooled at room temperature and the product was ultrasonically cleaned to obtain the photoelectric material.
[0030] Example 2
[0031] Photoelectric material (Ag-0.2) was prepared according to the following steps:
[0032] Step 1: Dissolve 2 mmol of SnCl2, 2 mmol of sodium citrate, 2 mmol of urea, and 0.2 mmol of AgNO3 in 30 mL of deionized water and stir continuously for 25 minutes to form a transparent solution.
[0033] In the second step, the solution was poured into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and the TiO2 nanotube array (TiO2 NTs) was placed vertically in the solution. The solution was hydrothermally treated at 160°C for 14 hours. After the hydrothermal treatment, the autoclave was cooled at room temperature and the product was ultrasonically cleaned to obtain the photoelectric material.
[0034] Example 3
[0035] Photoelectric material (Ag-0.8) was prepared according to the following steps:
[0036] Step 1: Dissolve 2 mmol of SnCl2, 2 mmol of sodium citrate, 2 mmol of urea, and 0.8 mmol of AgNO3 in 30 mL of deionized water and stir continuously for 25 minutes to form a transparent solution.
[0037] In the second step, the solution was poured into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and the TiO2 nanotube array (TiO2 NTs) was placed vertically in the solution. The solution was hydrothermally treated at 160°C for 14 hours. After the hydrothermal treatment, the autoclave was cooled at room temperature and the product was ultrasonically cleaned to obtain the photoelectric material.
[0038] Example 4
[0039] Photoelectric material (Ag-1.2) was prepared according to the following steps:
[0040] Step 1: Dissolve 2 mmol of SnCl2, 2 mmol of sodium citrate, 2 mmol of urea, and 1.2 mmol of AgNO3 in 30 mL of deionized water and stir continuously for 25 minutes to form a transparent solution.
[0041] In the second step, the solution was poured into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and the TiO2 nanotube array (TiO2 NTs) was placed vertically in the solution. The solution was hydrothermally treated at 160°C for 14 hours. After the hydrothermal treatment, the autoclave was cooled at room temperature and the product was ultrasonically cleaned to obtain the photoelectric material.
[0042] Performance testing:
[0043] Samples of the materials prepared in Examples 1-4 were analyzed using TEM (FEI Tecnai F20), SEM (SU 8010), XRD (Ultima IV), and XPS (Thermo Kalpha) to investigate their morphology, microstructure, phase, and elemental composition. DRS (PE lambda 750) and PL (FLS1000) were used to evaluate solar energy collection and luminescence performance.
[0044] The homemade photocell has three electrodes: an Ag / AgCl reference electrode, a Pt wire counter electrode, and the sample as the working electrode. Photoelectric performance was tested. The sample photocell, in a 0.2 mol / L Na₂SO₄ electrolyte, was illuminated by a Xe lamp (CEL-HXF300) with a filter (λ ≥ 420 nm). Transient photocurrent, linear sweep voltammetry, photovoltage, and electrochemical impedance spectroscopy (EIS) were measured.
[0045] The photocatalytic activity of methyl orange (MO), rhodamine B (RhB), methylene blue (MB) and hexavalent chromium was studied under solar irradiation with a Xe lamp (CEL-S500) with an AM1.5 filter. For the photodegradation of the dyes, a bias of 1.0 V was added to improve the photoelectron separation, and a 0.1 mol / L Na2SO4 solution was used as the electrolyte. For the photoreduction of Cr(VI), a bias of 0.5 V was used, and a 0.1 mol / L potassium hydrogen phthalate buffer solution was used as the electrolyte. After solar irradiation, the concentration changes of the pollutants were studied by the absorbance changes using a 721 UV-visible spectrophotometer. In order to study the active groups, scavengers such as BQ, EDTA-2Na and BuOH were added to the dye solutions, and their photodegradation performance was recorded. In addition, the ESR technique was used to study the -O2 - and the formation of -OH radicals.
[0046] These samples were tested for visible light-driven photocatalytic H₂ production in a photocatalytic activity evaluation system (CEL-PAEM-D8). The sample photoelectrodes were vertically illuminated in an electrolyte solution of 0.35M Na₂S and 0.25M Na₂SO₃, and the generated H₂ was injected into a gas chromatograph. A bias of -0.6V was applied to enhance photocatalytic activity. The quantum efficiency of photocatalytic H₂ production was calculated using the following formula.
[0047] (1)
[0048] Results and Discussion
[0049] The XRD patterns of all samples were Figure 1 Displayed in 25.3 o , 37.8 o , 40.1 o , 53.9 o and 55.1 o There are obvious diffraction peaks at 27.1°, which are the (1 0 1), (0 0 4), (2 0 0), (1 0 5) and (2 1 1) crystal planes of anatase (PDF#21-1272) after annealing, indicating high crystallinity. o , 31.7 o and 37.1 o The new diffraction peaks are the (1 1 1), (2 1 0) and (1 3 0) crystal planes of Sn3O4 (PDF#16-0737). When AgNO3 is added to the solution, a 34.2 o and 52.1 o diffraction peaks, and with the Ag+ The peak intensity increases with increasing concentration. A careful study of these two new peaks revealed that they are completely consistent with the characteristic peaks of Ag2O (PDF#42-0874).
[0050] The morphology of the material Figure 2 As shown. The obvious morphological changes show that Ag + The concentration has a significant effect on the deposition of Sn3O4-Ag-Ag2O. + In the case of Ag, the amount of Sn3O4 deposited is very small, and the dispersed Sn3O4 nanoparticles cover the nanotube mouth of TiO2NTs. + With the increase of Sn3O4-Ag-Ag2O, the surface of the nanotubes becomes rough and the amount of Sn3O4-Ag-Ag2O deposition increases significantly. In Ag-1.2, the open mouth of TiO2 NTs becomes very small due to the large amount of deposition.
[0051] Figure 3 The TEM images in Figure 2 further explore the deposition of Sn3O4-Ag-Ag2O in the nanotubes. The hollow structure of TiO2 NTs can be noted, and the sensitized particles on the nanotube walls can be clearly observed. The HRTEM image shows clearly distinguishable lattice fringes, with lattice spacings of 0.352 nm and 0.262 nm corresponding to the (1 0 1) crystal plane of anatase TiO2 and the (0 0 3) crystal plane of Ag2O. In addition, the interplanar spacing of 0.329 nm comes from the SnO 34 The (1 1 1) surface of the TiO2 NTs confirmed the effective deposition of Ag2O-Sn3O4 on the TiO2 NTs. Figure 3 In b, the distribution of sensitizer particles on the nanotube wall was further tested by EDS spectrum, and Ti, O, Ag and Sn elements can be clearly observed, indicating the uniform deposition of Ag2O-Sn3O4 on the entire nanotube.
[0052] Figure 4 The elemental composition and chemical state of Ag-0.8 were investigated in this study. Ti, O, Sn, Ag, and C were observed in the XPS spectrum, and the XPS peak positions of all elements were corrected by the C 1s at 284.5 eV. Figure 4 The two XPS peaks at 458.8 eV and 464.5 eV in the Ti spectrum in b are Ti2p 3 / 2 and Ti 2p 1 / 2 , which is consistent with the TiO2 4+ The irregular O 1s peak can be split into two: the strong peak at 530.72 eV is attributed to crystalline oxygen in the metal oxide, and the weak shoulder at 532.1 eV is attributed to adsorbed oxygen from H2O or other hydroxyl-containing contaminants. Figure 4The Sn 3d XPS peak in d is divided into four peaks, and the peaks at 487.1 eV and 495.5 eV correspond to the Sn 4+ , the other peaks at 486.4 eV and 494.9 eV are attributed to Sn 2+ , which strongly confirms the formation of Sn3O4. Figure 4 The Ag 3d XPS peaks in e are also divided into four, and the strong peaks at 373.7 eV and 367.7 eV correspond to the Ag from Ag2O. + ions, and the peaks at 373.6 eV and 367.6 eV are attributed to Ag 0 metal, which confirms the formation of Ag on the surface of Ag2O. XPS data further provide valid evidence for the formation of Sn3O4-Ag-Ag2O on TiO2 NTs.
[0053] Figure 5 The optical properties of all samples were studied, including solar absorption and fluorescence spectra. The solar absorption of TiO2 NTs is mainly limited to the ultraviolet region, and the weak solar response is attributed to a wide band gap (3.2 eV). After hydrothermal sensitization, the visible light absorption is significantly enhanced. Sn3O4 deposited on the Ag-0 sample extends the visible light response region between 400 nm and 550 nm, which can be confirmed by the calculated band gap (2.2 eV). With the addition of Ag + With the addition of ions, the obvious surface plasmon resonance absorption peak at 425nm comes from the precious metal Ag 0 , while the entire visible light absorption is attributed to the sensitization of Ag2O. + As the concentration increases, the visible light absorption intensity further increases, and the calculated band gaps of Ag-0.2, Ag-0.8, and Ag-1.2 are 1.8 eV, 1.7 eV, and 1.4 eV, respectively. Strong solar absorption is a prerequisite for high photocatalytic performance, and photoexcited electron recombination is also an influencing factor. Figure 5 The PL spectrum in (b) was used to investigate photoelectron recombination. The PL peak intensity of the TiO2 NTs increased dramatically, revealing significant photoelectron recombination. Fortunately, this significant electron recombination was suppressed by the Sn3O4-Ag-Ag2O sensitization, as evidenced by the weakened PL peak. Ag-0.8 exhibited the smallest PL peak intensity, reflecting its excellent photoelectron separation and transfer capabilities.
[0054] exist Figure 6These samples were prepared as working electrodes for studying photoelectric conversion. Discontinuous illumination generated intermittent photocurrents, resulting in different photocurrent performance. The Ag-0.8 photoelectrode exhibited a higher visible-light photocurrent than the other samples, however, its photocurrent decay was significant. The Ag-0.8 photoelectrode also exhibited a high visible-light photovoltage (-0.48 V), surpassing that of the other samples. Figure 6 The linear sweep curve in c studies the change of photocurrent along with the external voltage. The excellent performance of Ag-0.8 is consistent with the performance of photocurrent and photovoltage. The excellent photoelectric performance is attributed to the strong solar absorption and efficient electron transfer. Figure 6 The photoelectron transport properties are examined in Figure d. The ESI curve shows the efficient electron transport properties of Ag-0.8. The sample's excellent photoelectric capabilities reveal its promising application in solar cells.
[0055] In addition to photoelectric conversion, photoelectron reduction to generate H2 is also an important application of photoelectrode materials. Figure 7 The H2 production of the prepared samples under visible light was studied. The low photocatalytic H2 performance of TiO2 NTs was mainly attributed to the weak visible light reaction, but the H2 production of the Ag-0 sample was also negligible, which may be due to the low interface characteristics and mismatched band structures of Sn3O4 and TiO2 NTs. Fortunately, the formation of Ag-Ag2O improved the band structure of the hybrid photocatalyst, which can achieve high H2 production. In particular, Ag-0.8 showed the best photocatalytic water separation ability, obtaining 195.25 μmol･cm after 210 minutes of visible light irradiation. -2 The H2 generation rate of all these samples is as follows: Figure 7 As shown in b, the highest value is 55.79 μmol･cm for the Ag-0.8 photoelectrode. -2 ･h -1 , which are 12.43, 16.08, 2.71 and 2.61 times that of TiO2 NTs, Ag-0, Ag-0.2 and Ag-1.2.
[0056] Figure 8 The photocatalytic degradation of organic dyes was studied. Figure 8 In the MO photodegradation of a, only the Ag-0.8 sample showed outstanding photocatalytic activity. After 3 h of solar irradiation, 90.89% of the MO dye molecules were decomposed, and the first-order photocatalytic rate constant reached 1.029×10 -2 min -1 , which is 2 times higher than that of other samples. Similarly, the photocatalytic degradation of RhB and MB dyes was also carried out, and the corresponding data are listed in Figure 8b and 8c. For the degradation of RhB and MB, the order of photocatalytic ability is as follows: Ag-0.8 > Ag-1.2 > Ag-0.2 > Ag-0. The photocatalytic efficiency of Ag-0.8 for the degradation of RhB and MB is 81.42% / 3 hours and 83.84% / 1 hour, respectively, and the corresponding photocatalytic rate constants are 8.87×10 -3 min -1 and 3.07×10 -2 min -1 .
[0057] The excellent dye photodegradation performance is attributed to the active species with high oxidative activity. Figure 9 aThe photocatalytic performance of the best Ag-0.8 sample after adding several quenchers was studied. For the degradation of MO, the addition of BQ showed a significant inhibitory effect, with only 11.07% of MO molecules being decomposed, indicating that ･O2 - Free radicals are the decisive groups for the photodegradation of MO. The addition of t-BuOH and EDTA-2Na also showed a partial inhibitory effect, and the results showed that OH and holes also played a promoting role in the photodegradation of the dye. For the photodegradation of RhB, each quencher plays a vital role in the decomposition of the dye, and all quenchers can reduce the photocatalytic activity of the photocatalyst. However, the photodegradation of MB is difficult to be inhibited by the addition of a single scavenger, which shows that each quencher can achieve the decomposition of MB molecules. The different degradation properties of these dyes are attributed to their stability. Previous reports on dye decomposition have shown that the color base of MO molecules with high stability is difficult to be destroyed. In addition, Figure 9 The ESR data in (b) directly confirm the formation of free radicals. No signal is generated in the dark, but ESR peaks appear once visible light is irradiated. When the sample is irradiated in methanol solution, the six stronger ESR peaks are ･O2 - Typical characteristics of free radicals, four signal peaks with intensities of 1:2:2:1 reveal the formation of OH radicals. Active ･O2 - and ･OH radicals are active species in the decomposition of dyes.
[0058] according to Figure 11 The photocatalytic data and electron transfer pathways in the schematic diagram show the photoelectrocatalytic mechanism of dye degradation and H2 production. The typical pn heterojunction band theory is not reasonable in our experiment because ･O2 - The formation potential is more negative than the conduction band potential of TiO2 NTs and Ag2O. Only the electrons in the conduction band of Sn3O4 have enough ability to reduce O2 to generate ･O2 - Free radicals. Therefore, a Z-type heterojunction was proposed to explain the generation of active species. Fortunately, indirect Z-type heterojunctions have been widely reported and studied when noble Ag nanoparticles are present at the interface of two semiconductors, with similar work functions in the conduction band of one semiconductor and the valence band of the other. In our photocatalytic system, solar-driven photoelectrons from Ag2O and holes from Sn3O4 are transferred to Ag. After recombination, the high reducing power of electrons in the conduction band of Sn3O4 is retained, thereby inducing the formation of ･O2 - In addition, the holes in the valence band of TiO2 can convert H2O / OH - Oxidized to OH radicals, and O2 - The degradation of the dye is achieved by the generation of OH radicals and Cr(VI). Regarding the removal of Cr(VI) and the photocatalytic generation of H2, electrons in the Sn3O4 conduction band also participate in the reduction of Cr(VI) and the decomposition of water, as shown in Equations 2 and 3 below.
[0059] ;
[0060] Stability and recycling rate are important indicators for evaluating the application prospects of photocatalysts. Four MB degradation cycles were carried out continuously. Figure 10 The data in a show that the cyclic photocatalytic performance of Ag-0.8 does not show a significant slowdown, confirming the high stability of the photocatalyst. In addition to dye degradation, photocatalytic applications in heavy metal ion treatment, such as Figure 10 As shown in Figure 2b, all photocatalysts showed high photocatalytic activity for the removal of Cr(VI). Ag-0.8 photocatalyst showed the best photocatalytic ability, and 66.67% of Cr(VI) was removed after 3 hours of visible light irradiation. The excellent photocatalytic performance of dye degradation and Cr(VI) removal can be attributed to the high activity of the photocatalyst and the accelerating effect of the external voltage. Figure 10 The role of external voltage in photocatalytic performance was investigated in Figure c. The results showed that external voltage accelerated the removal of all pollutants. In the absence of external voltage, the photocatalytic efficiency of MO degradation alone even decreased to 75.52%, revealing a significant inductive effect of external voltage. Previous studies have reported similar results, attributing the voltage-assisted enhancement of photocatalytic performance primarily to the reduced electron / hole recombination.
[0061] The above detailed description of the analytical methods involved in the present invention provides a detailed introduction. It should be noted that the above description is intended solely to help those skilled in the art better understand the methods and concepts of the present invention, and is not intended to limit the relevant content. Without departing from the principles of the present invention, those skilled in the art may make appropriate adjustments or modifications to the present invention, and such adjustments and modifications shall also fall within the scope of protection of the present invention.
Claims
1. A method for preparing a Sn3O4-Ag-Ag2O photocatalyst based on TiO2 nanotubes, characterized in that: The steps include: Step 1: Dissolve SnCl2, sodium citrate, urea and AgNO3 in deionized water and stir continuously for 25 minutes to make a transparent solution; In the second step, the solution is poured into a high-pressure hydrothermal reactor lined with polytetrafluoroethylene, and the TiO2 nanotube array is placed vertically in the solution for hydrothermal treatment. After the hydrothermal treatment, the high-pressure hydrothermal reactor is cooled at room temperature, and the product is ultrasonically cleaned to obtain the photocatalyst; the photocatalyst is a Z-type heterojunction photocatalyst composed of Sn3O4-Ag-Ag2O and TiO2 nanotube array.
2. The method for preparing a Sn3O4-Ag-Ag2O photocatalyst based on TiO2 nanotubes according to claim 1, characterized in that: The ratio of the amount of SnCl2, sodium citrate, urea, AgNO3 and deionized water is 2mmol:2mmol:2mmol:0.8mmol:30mL.
3. The method for preparing a Sn3O4-Ag-Ag2O photocatalyst based on TiO2 nanotubes according to claim 1, characterized in that: The parameters of the hydrothermal heating are as follows: temperature 160°C, heating time 14 hours.
4. The method for preparing a Sn3O4-Ag-Ag2O photocatalyst based on TiO2 nanotubes according to claim 1, characterized in that: The TiO2 nanotube arrays were synthesized by anodizing Ti foil at 60 V in NH4F electrolyte.
5. A Sn3O4-Ag-Ag2O photocatalyst based on TiO2 nanotubes, characterized in that: Prepared according to the method according to any one of claims 1 to 4.