A BiOI / WO3 nanorod array composite photoelectrode, its preparation method and application
Patent Information
- Application Number
- CN202411751172.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2026-09-15
- Estimated Expiration
- 2044-12-02
AI Technical Summary
但是现有复合光电极仍存在表面积小，活性位点少以及光电催化性能较差的问题
[0032] (1) In the BiOI/WO3 nanorod array composite photoelectrode prepared by the present invention, BiOI ultrathin nanosheets are uniformly attached to the surface of WO3 composite nanorod array to form a three-dimensional structure, with fully exposed active sites and large specific surface area, which effectively improves catalytic performance.
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Figure CN119409290B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental new materials and their application technology, and particularly relates to a BiOI / WO3 nanorod array composite photoelectrode, its preparation method and application. Background Technology
[0002] With the widespread use of various antibiotic drugs, antibiotics and their metabolites have entered the environmental system in large quantities, posing a potential threat to the ecological environment and human health. Antibiotics are non-biodegradable organic compounds, and traditional wastewater treatment methods are not effective in treating antibiotic wastewater. Therefore, there is an urgent need to develop new technologies that can effectively treat antibiotic wastewater. Advanced oxidation methods are one of the most effective methods for treating antibiotic wastewater. Photocatalysis and photoelectrocatalysis (PEC) are new advanced oxidation methods that have good effects on antibiotic degradation and have attracted widespread attention from researchers. Photoelectrocatalysis technology has the following advantages: (1) The catalyst on the photoelectrode is fixed, does not need to be separated, and is easy to reuse, solving the problem of separation and recovery of nanoparticle photocatalysts; (2) The bias voltage applied to the photoelectrode can drive photogenerated electrons to transfer to the external circuit, thereby effectively improving the separation efficiency of photogenerated electrons and holes. Therefore, photoelectrocatalysis is more efficient in degrading antibiotics in wastewater. The research and development of highly catalytically active photoelectrodes is a key link in photocatalysis technology.
[0003] Compared to ordinary WO3 thin films, WO3 nanorod arrays possess a three-dimensional structure, making them an ideal basis for constructing composite photoelectrodes. WO3, with its narrow bandgap, is a visible-light-responsive n-type photocatalyst and has been extensively studied for its photocatalytic removal of organic pollutants in water. However, single WO3 still suffers from rapid photoelectron-hole recombination, resulting in low photocatalytic activity. Constructing heterojunction photoelectrodes combined with other photocatalysts is one of the most effective methods to improve the photocatalytic activity of WO3. However, existing composite photoelectrodes still suffer from small surface area, few active sites, and poor photoelectrocatalytic performance.
[0004] Therefore, there is an urgent need to provide a BiOI / WO3 nanorod array composite photoelectrode with a large specific surface area, multiple active sites, strong light absorption and utilization ability, and efficient degradation of antibiotics, as well as its preparation method. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention proposes a BiOI / WO3 nanorod array composite photoelectrode, its preparation method, and its application.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] One of the technical solutions of this invention:
[0008] A method for fabricating a BiOI / WO3 nanorod array composite photoelectrode includes the following steps:
[0009] Bismuth and iodine sources are dissolved in an organic solvent to form a mixed solution;
[0010] An FTO glass coated with a WO3 nanorod array film was immersed in the mixed solution, heated, and cooled to obtain the BiOI / WO3 nanorod array composite photoelectrode.
[0011] Preferably, the bismuth source is Bi(NO3)3·5H2O; and the iodine source is KI.
[0012] Beneficial effects: The bismuth source in this invention is limited to Bi(NO3)3·5H2O because it has good solubility and can react better with the iodine source in the limited solvent.
[0013] Furthermore, the molar ratio of the bismuth source to the iodine source is 1:1.
[0014] Preferably, the organic solvent is ethylene glycol methyl ether, ethylene glycol, or a mixture of ethanol and ethylene glycol (volume ratio 1:1).
[0015] Preferably, the conditions during the heating process are: reacting at 150-170°C for 10-14 hours.
[0016] Preferably, the preparation process of the FTO glass with a WO3 nanorod array film on its surface is as follows:
[0017] WO3 nanorod array films were prepared on the surface of fluorine-doped tin dioxide (FTO) conductive glass using a hydrothermal method and annealed at 500℃ for 3 h.
[0018] The second technical solution of this invention:
[0019] A BiOI / WO3 nanorod array composite photoelectrode was prepared by the above-described method.
[0020] Preferably, the BiOI / WO3 nanorod array composite photoelectric element has an irregular three-dimensional porous structure.
[0021] The third technical solution of this invention:
[0022] Application of the BiOI / WO3 nanorod array composite photoelectrode in the field of photoelectrocatalytic purification of antibiotic wastewater.
[0023] Preferably, the antibiotic is CIP (ciprofloxacin).
[0024] Fourth technical solution of the present invention:
[0025] A method for photoelectrocatalytic degradation of CIP involves using a two-electrode or three-electrode system of the BiOI / WO3 nanorod array composite photoelectrode to degrade CIP under external light irradiation and bias voltage.
[0026] Preferably, the three-electrode system is as follows:
[0027] Using 0.1M Na2SO4 as the electrolyte solution, BiOI / WO3 nanorod array photoelectrode as the working electrode, Ag / AgCl (3.0M KCl) as the reference electrode, and platinum sheet electrode as the counter electrode.
[0028] Preferably, the illumination conditions are: using a 500W xenon lamp as the light source, and filtering out light with wavelengths less than 400nm; and / or
[0029] The bias voltage is 1.2-1.6V.
[0030] Furthermore, the bias voltage is 1.2V.
[0031] Compared with the prior art, the present invention has the following advantages and technical effects:
[0032] (1) In the BiOI / WO3 nanorod array composite photoelectrode prepared by the present invention, BiOI ultrathin nanosheets are uniformly attached to the surface of WO3 composite nanorod array to form a three-dimensional structure, with fully exposed active sites and large specific surface area, which effectively improves catalytic performance.
[0033] (2) The BiOI / WO3 nanorod array composite photoelectrode prepared by the present invention can effectively separate photogenerated carriers under light and electric field, thereby fundamentally improving the performance of catalytic degradation and efficiently degrading organic pollutants. Attached Figure Description
[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0035] Figure 1 The XRD patterns of the BiOI / WO3 nanorod array photoelectrodes prepared in Examples 1-5 are shown below.
[0036] Figure 2 SEM images of the WO3 nanorod arrays (a, b) and BIW-1.2 (c, d) prepared in Example 1;
[0037] Figure 3 TEM image (ae) and (fk) EDX elemental analysis diagram of the BIW-1.2 nanorods prepared in Example 1;
[0038] Figure 4 The X-ray photoelectron spectrum of the BIW-1.2 nanorods prepared in Example 1 is shown.
[0039] Figure 5 The graphs show (a) linear scan voltammetry and (b) transient photocurrent response curves of the BiOI / WO3 nanorod array photoelectrodes prepared in Examples 1-5.
[0040] Figure 6 The ultraviolet diffuse reflectance spectra (a), Tauc curves (b), Mott-Schottky curves (c), and band distribution diagrams (d) of the BiOI / WO3 nanorod array photoelectrodes prepared in Examples 1-5 are shown.
[0041] Figure 7 The image shows a comparison of the CIP degradation performance of the BiOI / WO3 nanorod array photoelectrode prepared in Example 1 using different catalysts (a) and different catalytic methods (b); as well as the effect of bias voltage on degradation efficiency (c) and cyclic degradation test (d);
[0042] Figure 8 For DMPO-·O2 - EPR spectra of adducts (a) and DMPO-·OH adducts (b), and PEC degradation images of CIP by different free radical scavengers (c);
[0043] Figure 9 This is a schematic diagram of the charge separation and PEC degradation mechanism of the BIW-1.2 nanorod array prepared in Example 1;
[0044] Figure 10 This is a comparison diagram of the BIW-1.2 nanorod array prepared in Example 1 of the present invention and the degradation of CIP by BiOI(7h) / WO3 as a photoelectrode in Comparative Example 1. Detailed Implementation
[0045] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0046] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0047] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0048] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0049] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0050] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.
[0051] All raw materials used in this invention were purchased from the market.
[0052] The technical solution of the present invention will be further illustrated by the following embodiments.
[0053] Example 1
[0054] BiOI was deposited on the surface of a WO3 nanorod array using a solvothermal method to prepare a BiOI / WO3 nanorod array photoelectrode. The specific process is as follows:
[0055] First, a WO3 nanorod array film was prepared on the surface of fluorine-doped tin dioxide (FTO) conductive glass using a hydrothermal method, and then annealed at 500℃ for 3 hours. The specific hydrothermal method steps are as follows:
[0056] 0.8 g of ammonium metatungstate was added to 75 mL of deionized water and stirred until completely dissolved. Then, 2.5 mL of concentrated HCl was added and stirred thoroughly for 30 minutes. 2 mL of H2O2 was added and stirred vigorously for 1 hour until the solution became transparent. Fluorine-doped tin dioxide (FTO) conductive glass was placed in a 100 mL hydrothermal reactor, and the prepared solution was slowly poured in. The reactor was sealed and heated at 160 °C for 4 hours. After the reaction was completed, the hydrothermal reactor was allowed to cool naturally to room temperature. The FTO glass was removed and rinsed with deionized water. It was then dried in an oven at 80 °C for 30 minutes. The dried FTO was placed in a box-type resistance furnace and calcined at 500 °C for 3 hours to obtain FTO glass with a WO3 nanorod array film on its surface.
[0057] Next, the BiOI / WO3 nanorod array was synthesized: 1.2 mmol Bi(NO3)3·5H2O and 1.2 mmol KI were dissolved in 80 mL of ethylene glycol methyl ether; then, the mixed solution was slowly poured into a 100 mL stainless steel hydrothermal reactor lined with two FTO glass plates (with WO3 nanorod array films prepared on their surfaces), and reacted at 160 °C for 12 h. Afterward, the mixture was allowed to cool naturally to room temperature, the prepared photoelectrode was removed, rinsed with distilled water, and dried in a forced-air drying oven at 75 °C to obtain the BiOI / WO3 nanorod array, labeled BIW-1.2.
[0058] Examples 2-5
[0059] Based on Example 1, different BiOI / WO3 nanorod arrays were prepared by adding different amounts of Bi(NO3)3·5H2O and KI. The remaining steps and parameters were the same as in Example 1, as detailed below:
[0060] Bi(NO3)3·5H2O 0.4mmol, KI 0.4mmol; labeled as BIW-0.4 (Example 2);
[0061] Bi(NO3)3·5H2O 0.8mmol, KI 0.8mmol; labeled as BIW-0.8 (Example 3);
[0062] Bi(NO3)3·5H2O 1.6mmol, KI 1.6mmol; labeled as BIW-1.6 (Example 4);
[0063] Bi(NO3)3·5H2O 2mmol, KI 2mmol, labeled as BIW-2 (Example 5).
[0064] Comparative Example 1
[0065] See the preparation process of BiOI(7h) / WO3 in the literature "Bidirectionally Regulated Ultraviolet and Visible Dual-Band Photoresponse Characteristics of Self-Powered BiOI / WO3 Photodetectors".
[0066] Effect verification
[0067] (I) Measurement of photoelectric properties of photoelectrodes
[0068] An electrochemical workstation (CHI 660E, Shanghai Chenhua Instruments) employs a three-electrode system. In a 0.1M Na₂SO₄ electrolyte solution, a BiOI / WO₃ nanorod array photoelectrode is used as the working electrode, Ag / AgCl (3.0M KCl) as the reference electrode, and a platinum sheet electrode as the counter electrode. Electrochemical and photoelectric performance are tested. A 500W xenon lamp is used as the light source, and an electric shutter is applied at the light source outlet to measure open-circuit potential, transient photocurrent, and linear sweep voltammetry.
[0069] (II) BiOI / WO3 nanorod array photoelectrode PEC degradation of CIP
[0070] Experiments were conducted on the degradation of CIP by PEC in a small photoelectrochemical reactor with a quartz glass window. A 500W xenon lamp was used for illumination. A UV-cut 400 filter was installed at the light source outlet to filter out light with wavelengths less than 400 nm. The above-described three-electrode system was used, with a BiOI / WO3 nanorod array as the working electrode (effective area 2 cm²). 2 In the experiment, 15 mL of a CIP solution with an initial concentration of 20 mg / L was added to the photoelectrophotonic reactor. The absorbance of CIP was measured at 272 nm using a UV spectrophotometer, and the concentration of CIP was calculated based on the absorbance-concentration standard curve. At the beginning of the experiment, the reactor containing the CIP solution was placed in darkness for 30 min to allow the catalyst and CIP to reach adsorption equilibrium. The initial concentration of CIP (CO) was measured before illumination. After the light reaction began, the solution was extracted every 0.5 h, and the concentration of CIP (CO) was measured. t The concentration of ) is calculated using η = (C0 - C). t The degradation efficiency was calculated using CIP / C0. The light source was blocked and the photocatalytic reaction was paused each time the CIP concentration was measured. During the photoelectrode stability cycle test, the photoelectrode remained unchanged, and a new CIP solution was used after each degradation reaction process.
[0071] This invention utilizes a solvothermal method to prepare a series of BiOI / WO3 nanorod array composite photoelectrodes. The BiOI nanosheets grown on the surface of the WO3 nanorods exhibit strong bonding, resulting in a three-dimensional photoelectrode structure with a large specific surface area, numerous active sites, and strong light absorption and utilization capabilities. The morphology, composition, photoelectric properties, and band structure of this series of photoelectrodes were systematically characterized and studied. The catalytic degradation activity of the photoelectrodes was evaluated using a photocatalytic degradation method for ciprofloxacin (CIP). Furthermore, the photoelectrochemical properties, band structure, and types of free radicals involved in the degradation reaction of the photoelectrodes were analyzed, and the photocatalytic degradation mechanism was also investigated.
[0072] Figure 1The XRD patterns of the BiOI / WO3 nanorod array (NRAs) photoelectrodes prepared in Examples 1-5 are shown. The diffraction peaks of the WO3 nanorod array indicate that it belongs to monoclinic crystal (JCPDS card number 43-1035). BiOI belongs to pure tetragonal crystal (JCPDS card number 10-0445), and the characteristic diffraction peaks at 29.6°, 31.7°, 45.4° and 55.2° correspond to the (102), (110), (200) and (212) crystal planes, respectively. For the BIW composite material, as the BiOI increases, the diffraction peak intensity of BiOI gradually increases, while the diffraction peak intensity of WO3 gradually decreases, indicating that the WO3 phase and BiOI phase coexist in the composite photoelectrode material. The photoelectrode has SnO2 diffraction peaks, which is the signal of SnO2 in the FTO glass conductive layer.
[0073] Figure 2 SEM images of the WO3 nanorod arrays (a, b) and BIW-1.2 (b, d) prepared in Example 1 are shown below. Figure 2 As shown in a and b, the WO3 nanorod array covers the FTO substrate and is uniformly distributed, with many pores between the nanorods; Figure 2 Images c and d are SEM images of the BIW-1.2 photoelectrode, showing that interwoven BiOI nanosheets grow on the WO3 nanorods, forming an irregular three-dimensional porous structure. This three-dimensional structure has a huge specific surface area, providing more catalytic active sites and improving photon absorption and utilization efficiency, thereby enhancing photocatalytic performance.
[0074] Figure 3 The images shown are TEM (ae) and EDX elemental analysis plots of the BIW-1.2 nanorods prepared in Example 1. Figure 3 As shown in Figure a, after ultrasonic dispersion, the nanorods removed from the BIW-1.2 film showed that the BiOI nanosheets were also tightly bonded to the surface of the WO3 nanorods, indicating a strong crystallization force between them; the BiOI nanosheets and WO3 nanorods were tightly bonded and had an interlaced interface ( Figure 3 In sections b and e), the contact interface is conducive to photocarrier transfer; from Figure 3 As can be seen from the image, the (002) crystal plane of WO3 has very clear lattice fringes, indicating good crystallinity, and the lattice spacing is 0.382 nm; the lattice fringe spacing is 0.276 nm, corresponding to the (110) crystal plane of BiOI. Figure 3 In the figure, hk represents the elemental mapping of Bi, O, I and W in BIW-1.2. It is easy to see from the elemental distribution diagram that the distribution of each element is consistent with the shape of the composite material, which further proves that BiOI is uniformly distributed on the surface of WO3 nanorods, which is consistent with the SEM results.
[0075] Figure 4The X-ray photoelectron spectrum of the BIW-1.2 nanorods prepared in Example 1 is shown below. Figure 4 As shown in Figure a, W, Bi, I, and O were observed in the scanning spectrum, indicating that BiOI and WO3 were successfully assembled together; Figure 4 In the middle b, two distinct peaks appear at 159.34 eV and 164.64 eV, corresponding to Bi 4f, respectively. 7 / 2 and Bi 4f 5 / 2 atomic orbitals; Figure 4 In the middle c, there are two peaks centered at 619.23 eV and 630.71 eV, which correspond to I 3d respectively. 5 / 2 and I 3d 3 / 2 Orbit-related; in addition, Figure 4 The two peaks in the middle d region, located at binding energies of 35.75 eV and 37.87 eV, belong to W 4f, respectively. 7 / 2 and W 4f 5 / 2 O1s spectrum ( Figure 4 In the middle (e), there are three peaks. The two peaks with binding energies of 530.15 eV and 531.99 eV belong to the lattice oxygen of Bi-O and WO bonds, respectively, while the peak at 530.82 eV belongs to the hydroxyl group.
[0076] Figure 5 The figures show (a) linear scan voltammetry and (b) transient photocurrent response curves of the BiOI / WO3 nanorod array photoelectrodes prepared in Examples 1-5; Figure 5 As shown in Figure a, the effect of bias voltage on photocurrent was studied using linear sweep voltammetry (LSV). In the dark (shutter closed) state, no current was generated on the photoelectrodes. However, when the bias voltage was higher than approximately 1.5V, current began to appear on all photoelectrodes, which was the current generated by the breakdown of the photocatalyst film. When light irradiated the photoelectrodes (shutter open), the photocurrent appeared instantaneously. As the bias voltage increased, the photocurrent density also increased rapidly. When the bias voltage reached approximately 1.2V, the increase in photocurrent decreased. This is because photogenerated electrons flowed towards the counter electrode under the drive of the bias voltage, which is the driving force. When the bias voltage increased to 1.2V, most of the free photogenerated electrons were driven by the bias to migrate to the external circuit. Since there were fewer remaining photoelectrodes, further increases in bias voltage resulted in a correspondingly smaller increase in current. The photocurrent density of the BIW-1.2 nanorod array photoelectrode was higher than that of the WO3 photoelectrode, indicating that this photoelectrode could generate more photogenerated electrons and holes, i.e., its PEC performance was better.
[0077] To further investigate the photoelectric properties of the photoelectrode, transient photocurrent measurements were performed. Figure 5In section b), the bias voltage applied to the electrodes is 1.2V. When the shutter is closed, the current in the circuit is zero; when the shutter in front of the xenon lamp is opened, a momentary current instantaneously appears on the electrodes, initially large, then stabilizing at a relatively constant value. The photocurrent of the WO3 nanorod array is the lowest, remaining at -0.05mA / cm. 2 The photocurrent on the photoelectrode gradually increases with the increase of BiOI content on WO3, reaching a maximum of approximately -0.1 mA / cm². 2 However, the photocurrent of the BIW-1.6 nanorod array decreased. This result indicates that the current is generated by photoexcitation of the photocatalyst on the photoelectrode, and the higher the photoelectron concentration, the higher the photocurrent density. The BIW-1.2 nanorod array has the highest photocurrent density because WO3 and BiOI form a pn heterojunction with a three-dimensional structure, which greatly improves the separation efficiency of photogenerated electrons.
[0078] Figure 6 The ultraviolet diffuse reflectance spectrum (a), Tauc curve (b), Mott-Schottky curve (c), and band structure (d) of the BiOI / WO3 nanorod array photoelectrode prepared in Example 1 are shown below. Figure 6 In (a), the light absorption boundary of the BiOI / WO3 composite nanorod array is approximately 540 nm, which is about 90 nm higher than the 450 nm of the WO3 photoelectrode alone, indicating that the BiOI / WO3 composite nanorod array can absorb and utilize a wider range of visible light. Figure 6 Analysis in (b) shows that the band gap energy (Eg) of WO3 is 2.70 eV, and that of BiOI is 1.93 eV; Figure 6 From (c), we can conclude that the slope of the Mott-Schottky curve for BiOI is negative, indicating that BiOI is a p-type semiconductor with a valence band (VB) potential of 2.26V (vs. Ag / AgCl); WO3 is an n-type photocatalyst, therefore its flat band potential (E) can be considered... fb The value of ) and its conduction band potential (E) CB The band structure of WO3 has been studied and is approximately equal to that of NH3. The formula is: E(NHE) = E(Ag / AgCl) + 0.212V and E... VB =E CB +Eg, the E of BiOI can be calculated. VB The value is 2.47V (vs. NHE), E CB It is 0.54V; Figure 6 The middle (d) diagram shows the band structure distribution of BiOI and WO3.
[0079] Figure 7The figures show a comparison of the CIP degradation performance of a series of BiOI / WO3 nanorod array photoelectrodes prepared in Examples 1-5 using different catalysts (a) and different catalytic methods (b); the effect of bias voltage on degradation efficiency (c) and cyclic degradation experiments (d); and the results from... Figure 7 As shown in (a), the photoelectrochemical degradation efficiency of CIP by a single WO3 nanorod array is relatively low. With the increase of BiOI content on the WO3, the degradation efficiency first increases and then decreases. The BIW-1.2 nanorod array exhibits the highest degradation efficiency. This is because the BIW-1.2 nanorod array has the optimal BiOI to WO3 ratio, more active sites, and more photogenerated charges, thus possessing the best catalytic activity. Figure 6 The results of the photoelectric performance analysis are consistent with those of the previous analysis.
[0080] The effects of different catalytic systems on CIP degradation, such as Figure 7 In Figure (b), with an applied bias voltage of 1.2V in the dark, the BIW-1.2 nanorod array underwent electrocatalytic (EC) degradation of CIP. After 3 hours, the CIP showed virtually no degradation, indicating that the photoelectrode did not perform electrocatalytic degradation of CIP at this voltage. When no catalyst was added to the CIP solution and no bias voltage was applied to the electrode, only 5.6% was degraded after 3 hours, indicating that CIP is relatively stable under visible light and not easily photodegraded. When the BIW-1.2 nanorod array was irradiated with a xenon lamp source without a bias voltage, the system achieved a CIP degradation rate of 41.2%, which is the effect of photocatalytic (PC) degradation. When the photoelectrode was irradiated with light and a 1.2V bias voltage was applied, the efficiency of the BIW-1.2 nanorod array in degrading CIP was significantly improved, reaching 97.1% after 3 hours, which is 2.1 times that of photocatalytic degradation alone. The reason for this experimental result is that the bias voltage on the photoelectrode can drive a large number of photogenerated electrons into the external circuit, thus greatly reducing the recombination probability of photogenerated electrons and holes, and fundamentally improving the catalytic performance of the photocatalyst.
[0081] from Figure 7As shown in (c), with the increase of the bias voltage applied to the BIW-1.2 nanorod array photoelectrode, the degradation efficiency of CIP initially increases rapidly, then remains flat, and finally decreases. When the applied bias voltage increases from 0.4V to 1.2V, the degradation efficiency of CIP increases significantly, reaching 97.1% at a bias voltage of 1.2V. Further increases in bias voltage result in a very slow increase in CIP degradation efficiency. When the bias voltage reaches 2.0V, the degradation efficiency of CIP actually decreases. The reason for this is that the bias voltage effectively transfers photogenerated electrons, thereby reducing the recombination of photogenerated electrons and holes. When the bias voltage on the photoelectrode increases to 1.2V, almost all the ionized photogenerated electrons have been driven into the external circuit by the bias voltage; therefore, further increases in bias voltage do not significantly increase the degradation efficiency. When the bias voltage increases to 2.0V, due to the high potential, O2 may be generated on the electrode surface, leading to a decrease in the amount of free radicals generated on the electrode, thus reducing the CIP degradation efficiency. Comprehensive analysis shows that 1.2V is a more suitable bias voltage.
[0082] from Figure 7 As shown in (d), the photostability of the BIW-1.2 nanorod array was investigated by repeatedly degrading CIP using photoelectrodes. After four cycles, the degradation efficiency of the BIW-1.2 nanorod array for CIP decreased only slightly, indicating its good stability and reusability.
[0083] Figure 8 For DMPO-·O2 - EPR spectra of adducts (a) and DMPO-·OH adducts (b), and PEC degradation images of CIP by different free radical scavengers (c); from Figure 8 As can be seen from the results, free radical electron paramagnetic resonance (EPR) tests were performed under xenon lamp irradiation using DMPO (5,5-dimethyl-1-pyrrolline-N-oxide) as a scavenger to analyze ·OH and ·O2. - The existence of. For example... Figure 8 As shown in (a) and (b), no peak appears in the absence of light; when illuminated, as... Figure 8 As shown in (a), the four characteristic peaks of DMPO-·OH indicate the formation of ·OH. The longer the irradiation time, the greater the intensity of the characteristic peaks, indicating that ·OH is generated by light irradiating the photoelectrode. Figure 8 As shown in (b), when illuminated, six peaks appeared, two of which were overlapping, indicating that DMPO-·O2 - The characteristic peaks indicate that the BIW-1.2 nanorod array generated ·O2 under light irradiation. -The active substances in the photocatalytic process of the BIW-1.2 nanorod array were studied through free radical capture experiments, such as... Figure 8 As shown in (c), when the CIP solution contains the scavenging agents tert-butanol (TBA) or triethanolamine (TEOA), the CIP degradation efficiency is reduced by more than half compared to when no scavenging agent is added. This indicates that ·OH and holes are the main active substances in the photoelectrocatalytic degradation of CIP by the BIW-1.2 nanorod array. When benzoquinone (BQ) is added to the CIP solution, the degradation efficiency decreases from 97.1% to 58.5%, indicating that ·O2... - The BIW-1.2 nanorod array also played an important role in the photoelectrocatalytic degradation of CIP. The results of the trapping agent experiment and the EPR experiment were consistent.
[0084] Figure 9 This is a schematic diagram illustrating the charge separation and PEC degradation mechanism of the BIW-1.2 nanorod array prepared in Example 1. Under visible light irradiation, both WO3 nanorods and BiOI nanosheets can generate photogenerated electrons and holes. BiOI is a p-type semiconductor with its Fermi level close to VB; WO3 is an n-type semiconductor with its Fermi level near CB. When a BiOI / WO3 pn heterojunction is formed, the energy level of BiOI rises while the energy level of WO3 falls until the Fermi levels of BiOI and WO3 reach equilibrium. In equilibrium, an internal electric field is formed, with the p-type BiOI region carrying a negative charge and the n-type WO3 region carrying a positive charge. Therefore, photoelectrons in the CB of BiOI are transferred to the CB of WO3 under the influence of the electric field, and flow to the counter electrode under the drive of the bias voltage, interacting with O adsorbed on the counter electrode. 2 The reaction forms O2 - This enables rapid electron transfer and separation. Simultaneously, holes in the VB of WO3 migrate to the VB of BiOI, reacting with H2O to generate ·OH. Therefore, the photogenerated electrons and holes of the BIW-1.2 nanorod array are effectively separated, and ·OH and ·O2 are generated. - Furthermore, some unreacted holes in the VB of BiOI participate in the photoelectrocatalytic degradation of CIP. In addition, the BIW-1.2 nanorod array, due to its three-dimensional structure, can provide more active sites, thereby enhancing its PEC degradation activity for CIP. Overall, the embedded electric field in the pn heterojunction formed in the BIW-1.2 nanorod array promotes the separation of photogenerated electrons and holes, and the bias voltage further improves the charge separation efficiency, enhancing the PEC degradation activity of the BIW-1.2 nanorod array.
[0085] Figure 10The figure shows a comparison of the degradation of CIP by the BIW-1.2 nanorod array prepared in Example 1 and the BiOI(7h) / WO3 in Comparative Example 1. As can be seen from the figure, when the photoelectrode is irradiated with light and a bias voltage of 1.2V is applied, the degradation efficiency of CIP by the BIW-1.2 nanorod array reaches 97.1% after 3h, while the degradation efficiency of CIP by BiOI(7h) / WO3 is 71.3%.
[0086] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. An application of a BiOI / WO3 nanorod array composite photoelectrode for photoelectrocatalytic purification of antibiotics in wastewater, characterized in that... The preparation method of the BiOI / WO3 nanorod array composite photoelectrode for photoelectrocatalytic purification of antibiotics in wastewater includes the following steps: A bismuth source and an iodine source are dissolved in an organic solvent to form a mixed solution; the bismuth source is Bi(NO3)3•5H2O; the iodine source is KI; the molar ratio of the bismuth source to the iodine source is 1:1; the organic solvent is ethylene glycol methyl ether. An FTO glass coated with a WO3 nanorod array film was immersed in the mixed solution, heated, and cooled to obtain the BiOI / WO3 nanorod array composite photoelectrode. The conditions for the heating process are: reacting at 150-170℃ for 10-14 h.
2. A BiOI / WO3 nanorod array composite photoelectrode for photoelectrocatalytic purification of antibiotics in wastewater, characterized in that, It is prepared by the preparation method in claim 1.
3. The BiOI / WO3 nanorod array composite photoelectrode for photoelectrocatalytic purification of antibiotics in wastewater according to claim 2, characterized in that, The BiOI / WO3 nanorod array composite optoelectronics has an irregular three-dimensional porous structure.
4. A method for photoelectrocatalytic degradation of CIP, characterized in that, Under external light and bias conditions, CIP is degraded using a two-electrode or three-electrode system comprising the BiOI / WO3 nanorod array composite photoelectrode for photoelectrocatalytic purification of antibiotics in wastewater as described in claim 2.
5. The method for photoelectrocatalytic degradation of CIP according to claim 4, characterized in that, The illumination conditions are: using a 500 W xenon lamp as the light source, and filtering out light with wavelengths less than 400 nm; and / or The bias voltage is 1.2-1.6V.