Method for preparing fe2o3 / biVO4 heterojunction by photo-selective deposition and application in photocatalytic degradation of antibiotics
By controlling the raw material ratio and photodeposition method, a heterojunction catalyst with selective Fe2O3 deposition on the BiVO4{110} plane was prepared, which solved the problem of Fe2O3 deposition on specific crystal planes of BiVO4 and achieved the effect of efficient degradation of norfloxacin.
Patent Information
- Application Number
- CN202310292102.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-23
- Publication Date
- 2026-01-23
- Estimated Expiration
- 2043-03-23
AI Technical Summary
Existing technologies make it difficult to selectively deposit Fe2O3 on specific crystal planes of BiVO4, resulting in insufficient photocatalytic activity of BiVO4/Fe2O3 heterojunctions, especially in the degradation of antibiotics such as norfloxacin.
By controlling the proportion of raw materials, hydrothermal reaction conditions, and photodeposition methods, Fe2O3 was selectively deposited on the {110} surface of BiVO4 to form a Fe2O3/BiVO4 heterojunction. Using ammonium metavanadate, bismuth nitrate pentahydrate, and ferrous sulfate heptahydrate as raw materials, combined with xenon lamp irradiation and sintering treatment, a heterojunction catalyst was obtained.
The method achieved efficient degradation of norfloxacin via Fe2O3/BiVO4 heterojunction, significantly improving catalyst activity and increasing the degradation rate by 1.7 times. The method is simple and suitable for industrialization.
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Figure CN117839711B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of catalyst preparation and photocatalytic removal of antibiotics, and in particular to a preparation method of Fe2O3 / BiVO4 heterojunction and its application in degradation of antibiotics. BACKGROUND
[0002] At present, pure BiVO4 has visible light response, but the electron hole is easy to recombine, and the activity of degrading norfloxacin and other antibiotics is not very good. Unlike other semiconductor materials, the {110} and {010} crystal plane ratio of the surface of BiVO4 can be regulated by a suitable method. When the photon energy is greater than the band gap of the catalyst, the electrons will gather on the {010} surface, and the holes will gather on the {110} surface, and the reduction reaction will occur. This makes a variety of metals or metal oxides can be selectively deposited on the specific crystal plane of BiVO4, thereby improving the separation efficiency of the photo-generated electron hole. Fe2O3 has a narrow band gap, which can effectively utilize sunlight, and the E CB (0.49eV) of BiVO4 is more positive than the E CB (0.44eV) of Fe2O3, and the E VB (2.32eV) of Fe2O3 is more negative than the E VB (2.83eV) of BiVO4, which is beneficial to the formation of Z-type heterojunction, can widen the light response range of BiVO4 and reduce the electron hole recombination rate.
[0003] Constructing a heterojunction catalyst is also a hot research direction in the field of photocatalysis, and depositing different catalysts or different proportions of the same catalyst will greatly affect the activity of the catalyst. Therefore, it is necessary to explore the influence of the loading amount of Fe2O3 on BiVO4 on the norfloxacin degradation efficiency to obtain the best proportion of Fe2O3 / BiVO4 heterojunction catalyst. At present, there are many reports on the preparation of Fe2O3 / BiVO4 heterojunction by hydrothermal method, but the deposition of Fe2O3 on the surface of BiVO4 is not specific. It is still a major challenge to selectively deposit Fe2O3 on the specific crystal plane of BiVO4 by a simple and efficient method with relatively mild experimental conditions. SUMMARY
[0004] Based on the problems existing in the prior art, the present application provides a method for preparing Fe2O3 / BiVO4 heterojunction by light selective deposition, aiming to obtain a photocatalyst that can efficiently degrade norfloxacin and other antibiotics.
[0005] To achieve the above purpose, the present application adopts the following technical solutions:
[0006] The application discloses a method for preparing Fe2O3 / BiVO4 heterojunction through light selective deposition, and has the characteristics that: firstly, BiVO4 with a ten-hedron structure exposing {110} and {010} surfaces is synthesized through a hydrothermal method by using ammonium metavanadate NH4VO3 and bismuth nitrate pentahydrate Bi(NO3)3.5H2O as raw materials; then, Fe2O3 is selectively deposited on the {110} surface of the ten-hedron structure BiVO4 through xenon lamp light irradiation and sintering by using ferrous sulfate heptahydrate FeSO4.7H2O as raw material and NaIO3 as an electron sacrificial agent, so as to obtain the Fe2O3 / BiVO4 heterojunction.
[0007] Step 1: 10mmol NH4VO3 and 10mmol Bi(NO3)3.5H2O are added into a 100mL polytetrafluoroethylene reaction kettle, then 60mL 2.0mol / L HNO3 solution is added into the reaction kettle, NH3.H2O is used to adjust the pH to 0.5, after a light yellow precipitate appears, the stirring is continued for 2h; the reaction kettle is sealed in a steel jacket, and hydrothermal reaction is carried out at 180℃ for 10h; after the reaction is completed, the reaction kettle is cooled to room temperature, the precipitate is collected through centrifugation, and the precipitate is washed with deionized water and ethanol alternately, and dried at 80C for 10h, so as to obtain the ten-hedron structure BiVO4 exposing {110} and {010} surfaces;
[0008] Step 2: 0.1-1g of the ten-hedron structure BiVO4 is mixed with 100mL 0-0.5mol / L NaIO3 solution, 1g / L FeSO4.7H2O solution is added, xenon lamp light irradiation is carried out for 1-4h, the product is washed with deionized water and ethanol alternately, and dried at 80C for 10h; then the product is placed into a tube furnace and sintered at 200-500℃ for 1-5h under N2 atmosphere, so as to obtain the Fe2O3 / BiVO4 heterojunction.
[0009] Further, in step 2, the loading ratio of Fe2O3 in the product Fe2O3 / BiVO4 is changed by changing the volume of the added FeSO4.7H2O solution.
[0010] Compared with the prior art, the application has the beneficial effects that:
[0011] The application first obtains the BiVO4 with the ten-hedron structure exposing the {110} surface and the {010} surface by controlling the raw material ratio of NH4VO3 and Bi(NO3)3·5H2O, controlling the pH of the system adjusted by nitric acid and ammonia water and controlling the hydrothermal reaction condition. Then, the Fe2O3 / BiVO4 heterojunction is obtained by controlling the ratio of BiVO4 and FeSO4·7H2O solution, controlling the amount of the electron sacrificial agent NaIO3 and combining the method of light deposition, so that Fe2O3 is selectively deposited on the {110} surface of the ten-hedron structure BiVO4. The synthesis method of the application is simple, the reaction condition is mild and the yield is high. The Fe2O3 / BiVO4 heterojunction obtained by the method has good activity in degrading norfloxacin and has important application prospect in degrading antibiotic pollution. BRIEF DESCRIPTION OF DRAWINGS
[0012] Figure 1 The XRD diagram of the BiVO4 synthesized in Example 1 and the Fe2O3 / BiVO4 heterojunctions with different ratios synthesized in Example 2.
[0013] Figure 2 The SEM diagram of the BiVO4 synthesized in Example 1.
[0014] Figure 3 The SEM diagram of the 10% Fe2O3 / BiVO4 heterojunction synthesized in Example 2.
[0015] Figure 4 The activity diagram of the BiVO4 and the Fe2O3 / BiVO4 heterojunctions with different ratios in Example 3 in adsorbing norfloxacin.
[0016] Figure 5 The activity diagram of the BiVO4 and the Fe2O3 / BiVO4 heterojunctions with different ratios in Example 3 in degrading norfloxacin under visible light.
[0017] Figure 6 The rate diagram of the BiVO4 and the Fe2O3 / BiVO4 heterojunctions with different ratios in Example 3 in degrading norfloxacin under visible light.
[0018] Figure 7 The SEM diagram of the 10% Fe2O3 / BiVO4 heterojunction prepared by the hydrothermal method. DETAILED DESCRIPTION
[0019] The application will be further described below in combination with specific examples. The description of the specific examples is only an example in nature. The following examples are based on the technical scheme of the application and give detailed implementation modes and specific operation processes, but the protection scope of the application is not limited to the following examples.
[0020] Example 1
[0021] The BiVO4 with a ten-faced structure was prepared according to the following steps:
[0022] 10 mmol of NH4VO3 and 10 mmol of Bi(NO3)3·5H2O were weighed and added into a 100 mL polytetrafluoroethylene reactor; 60 mL of 2.0 mol / L HNO3 solution was added into the reactor, and the pH was adjusted to 0.5 by using NH3·H2O (25%-28 wt%) until a light yellow precipitate appeared, and then the stirring was continued for 2 h; the reactor was sealed in a steel jacket, and hydrothermal reaction was carried out at 180 °C for 10 h; after the reaction, the reactor was cooled to room temperature, and the precipitate was collected by centrifugation, and then washed with deionized water and ethanol alternately, and dried at 80 °C for 10 h, thereby obtaining the BiVO4 with a ten-faced structure exposing {110} and {010} faces.
[0023] As shown in FIG. 2, the XRD diffraction peaks of the BiVO4 prepared in this example were consistent with those of the pure-phase BiVO4 with a standard card number of 14-0688. Figure 1 As shown in FIG. 3, the BiVO4 prepared in this example had a ten-faced structure with {110} and {010} crystal faces. Figure 2
[0024] Example 2
[0025] The Fe2O3 / BiVO4 heterojunction was prepared according to the following steps:
[0026] 0.5 g of the BiVO4 prepared in Example 1 was mixed with 100 mL of 0.1 mol / L NaIO3 solution, 50 mL of 1 g / L FeSO4·7H2O solution was added, and the mixture was irradiated by a xenon lamp for 2 h, and then washed with deionized water and ethanol alternately, and dried at 80 °C for 10 h; then the mixture was calcined in a tube furnace at 300 °C for 3 h in a N2 environment, thereby obtaining the Fe2O3 / BiVO4 heterojunction with a Fe2O3 loading ratio of 10%, which was recorded as 10% Fe2O3 / BiVO4.
[0027] The morphology of the 10% Fe2O3 / BiVO4 prepared in this example is shown in FIG. 4, and it can be seen that Fe2O3 was mainly deposited on the {110} face of BiVO4. Figure 3
[0028] By adjusting the volume of the FeSO4·7H2O solution, different loadings of the heterojunction were prepared in this example, which were 1% Fe2O3 / BiVO4, 2% Fe2O3 / BiVO4, 5% Fe2O3 / BiVO4, 15% Fe2O3 / BiVO4, and 20% Fe2O3 / BiVO4
[0029] Example 3
[0030] The embodiment tests the performance of BiVO4 and Fe2O3 / BiVO4 heterojunction as catalysts in the photodegradation of norfloxacin under visible light according to the following steps:
[0031] Step 1, 0.1 g of catalyst is weighed and added to 100 mL of 10 mg / L norfloxacin solution, and the mixture is stirred until uniform.
[0032] Step 2, under the condition of no light, the mixture is stirred for 30 minutes to complete the dynamic balance of adsorption-desorption.
[0033] Step 3, turn on the light, and irradiate (the light is visible light with a wavelength greater than 420 nm), and take the mixed solution after a given interval.
[0034] Step 4, first centrifuge the reaction solution, take 3 mL of supernatant after centrifugation and put it into a quartz cuvette, and detect the absorbance at 273 nm by using a UV-visible absorption spectrometer.
[0035] As shown in Figure 4 , except that the adsorption performance of 1% Fe2O3 / BiVO4 is slightly lower than that of pure phase BiVO4, the adsorption performance of other load ratio heterojunction catalysts for norfloxacin is improved, but the overall effect is not great, and the highest adsorption rate is 12% right.
[0036] As shown in Figure 5 , the photocatalytic performance of BiVO4 can be significantly improved by depositing Fe2O3 on the {110} surface of BiVO4, and the catalytic performance of 10% Fe2O3 / BiVO4 is the best when irradiated for 60 min. Although the degradation efficiency of pure phase BiVO4 is faster in the first 20 minutes, the oxidation capacity is insufficient in the later period, and norfloxacin cannot be further removed.
[0037] As shown in Figure 6 , the degradation rate of 10% Fe2O3 / BiVO4 for norfloxacin is 0.0103 min -1 , which is 1.7 times that of pure phase BiVO4.
[0038] From the above results, it can be seen that the Fe2O3 / BiVO4 heterojunction prepared by light selective deposition has controllable morphology, good photocatalytic effect, and the preparation method is simple, easy to operate and suitable for industrialization.
[0039] Comparative Example 1
[0040] This comparative example synthesizes 10% Fe2O3 / BiVO4 heterojunction by hydrothermal method, and the steps are as follows:
[0041] First, 31.25 mL of 0.02 mol / L Fe(NO3)3·9H2O solution was accurately prepared and measured, then 1.2625 g of urea was added, after completely dissolved, 0.5 g of BiVO4 was added, after stirring for 30 min, it was transferred to a hydrothermal reactor, reacted at 125℃ for 2.5 h. After cooling to room temperature, it was washed with water and anhydrous ethanol alternately for 3 times and centrifuged, the solid was transferred to a glass dish and dried at 105℃. Then the dried powder sample was placed in a tube furnace, calcined at 300℃ for 1 h under air atmosphere.
[0042] The results show that the SEM image of the 10% Fe2O3 / BiVO4 heterojunction prepared by the hydrothermal method shows that Fe2O3 is randomly distributed on each crystal surface of BiVO4. Figure 7 Therefore, this method is not selective for the deposition of Fe2O3.
[0043] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing Fe2O3 / BiVO4 heterojunctions by photoselective deposition, characterized in that: First, using ammonium metavanadate NH4VO3 and bismuth nitrate pentahydrate Bi(NO3)3·5H2O as raw materials, BiVO4 with an exposed {110} and {010} facets was synthesized via a hydrothermal method. Then, using ferrous sulfate heptahydrate FeSO4·7H2O as raw material and NaIO3 as an electron sacrificial agent, Fe2O3 was selectively deposited on the {110} facets of the decahedral BiVO4 to obtain a Fe2O3 / BiVO4 heterojunction after xenon lamp irradiation and sintering.
2. The method according to claim 1, characterized in that, Includes the following steps: Step 1: Add 10 mmol NH4VO3 and 10 mmol Bi(NO3)3·5H2O to a 100 mL polytetrafluoroethylene reactor, then add 60 mL of 2.0 mol / L HNO3 solution to the reactor. Adjust the pH to 0.5 with NH3·H2O. After a pale yellow precipitate appears, continue stirring for 2 h. Seal the reactor in a steel sleeve and perform a hydrothermal reaction at 180 °C for 10 h. After the reaction is complete, cool to room temperature, centrifuge to collect the precipitate, wash it alternately with deionized water and ethanol, and dry it at 80 °C for 10 h to obtain BiVO4 with a decahedral structure exposing the {110} and {010} faces. Step 2: Mix 0.1-1g of decahedral BiVO4 with 100mL of 0-0.5mol / L NaIO3 solution, add 1g / L FeSO4·7H2O solution, irradiate with xenon lamp for 1-4h, wash with deionized water and ethanol alternately, and dry at 80℃ for 10h; then place in a tube furnace and sinter at 200-500℃ for 1-5h under N2 atmosphere to obtain Fe2O3 / BiVO4 heterojunction.
3. The preparation method according to claim 2, characterized in that: In step 2, the loading ratio of Fe2O3 in the product Fe2O3 / BiVO4 is changed by altering the volume of the added FeSO4·7H2O solution.
4. An Fe2O3 / BiVO4 heterojunction prepared by the method described in any one of claims 1 to 3.
5. The application of the Fe2O3 / BiVO4 heterojunction as described in claim 4 as a photocatalyst in the photocatalytic degradation of antibiotics.
6. The application according to claim 5, characterized in that: The antibiotic in question is norfloxacin.