A highly stable BiVO4@TiOx electrode, its preparation method, and its application in the degradation of Rhodamine B.

Abstract

A kind of high-stable BiVO4@TiO x Electrode, preparation method thereof and application in degrading rhodamine B.The present application belongs to the field of organic dye degradation.The present application is to solve the technical problems of the current photoelectrocatalytic electrode being expensive and the photocatalyst on the electrode being easy to fall off.The method of the present application uses titanium sheet as the conductive substrate, by pretreating and prehydroxylating the titanium sheet, depositing BiOI on the prehydroxylated titanium sheet, hydroxylating makes BiOI more easily deposited on the titanium sheet, and not easy to fall off, thin layer titanium oxide is formed in the process of converting BiVO4 by heat annealing, which is conducive to the direct tunneling of BiVO4 electrons to the conductive substrate or forming a heterojunction structure of TiO2 and BiVO4 to promote the efficient degradation of organic dyes in the way of electron charge separation. X The electrode has excellent photoelectric conversion ability and rhodamine B photoelectrocatalytic degradation performance.

Description

Technical Field

[0001] This invention belongs to the field of organic dye degradation, specifically relating to a highly stable BiVO4@TiO4 method. x Electrode, its preparation method, and its application in the degradation of Rhodamine B. Background Technology

[0002] Rhodamine B, also known as Rhodamine B, Rose Red B, Rose Essence B, and Basic Rose Essence, has the chemical formula C. 28 H 31 C l Rhodamine B (N2O3) is a synthetic dye with a bright pink color. It is readily soluble in water and ethanol, and slightly soluble in acetone, chloroform, hydrochloric acid, and sodium hydroxide solution. It is widely used in the textile industry for dyeing wool fabrics. Furthermore, in other industries such as papermaking, plastics, printing, biomedicine, and leather, Rhodamine B is commonly used as a colorant, photosensitizer, water tracer, and fluorescent marker for microstructural analysis and biological staining in biomedical research. Therefore, it is a common component of wastewater discharged from these industries. Even at very low concentrations, it can cause poisoning and light penetration to aquatic organisms, leading to biological pathology, thus requiring degradation treatment.

[0003] Currently, common methods for the degradation and removal of Rhodamine B mainly include: adsorption, chemical oxidation, electrochemical and biodegradation, photo-Fenton oxidation, and photocatalysis. Adsorption methods have limited adsorption capacity, low decolorization rates, and are inconvenient to reuse. Chemical oxidation requires oxidants, which can easily cause secondary pollution. Electrochemical methods, while convenient and fast, are energy-intensive, requiring excessive electrical energy. Biodegradation involves cultivating bacteria resistant to organic dyes, which is difficult and requires specific environmental conditions. Photo-Fenton oxidation and photocatalysis are novel advanced oxidation technologies for treating organic dye wastewater. Although these two methods are green treatment methods, the recovery and reuse of catalysts are cumbersome, and the photo-Fenton oxidation method can cause secondary pollution from iron ions and hydrogen peroxide.

[0004] Photoelectrocatalysis (PEC) is an advanced oxidation technology that combines photocatalysis with electrolysis. It involves transferring electrons from the valence band to the conduction band of a semiconductor photocatalyst under light irradiation, generating holes. By applying an external bias potential to the photocatalyst, the photogenerated electrons are extracted to the cathode of the electrolytic cell, avoiding the rapid recombination of electron / hole pairs formed in PEC. Organic matter can be directly oxidized by holes, hydroxyl radicals, and other reactive oxygen species. Unlike photocatalysis, the applied bias voltage in photoelectrocatalysis increases the band bending of the photocatalyst, greatly promoting the effective separation of photogenerated electrons and holes, significantly increasing the number of hydroxyl radicals and photogenerated holes. Therefore, as the applied bias voltage gradually increases, the generation rate of photogenerated holes and hydroxyl radicals continuously increases, the photoelectrochemical response significantly improves, and the photocurrent and photocatalytic degradation rate continuously increase. Because the photocatalyst is fixed on a conductive substrate, the recycling of electrodes and subsequent wastewater treatment become convenient.

[0005] Currently, research on photoelectrocatalytic degradation mainly focuses on depositing photocatalyst materials onto transparent conductive glass via hydrothermal, vapor-phase, or liquid-phase deposition. While these methods exhibit some degradation performance for organic dyes, the conductive film on the conductive glass is easily damaged by external factors, causing the photocatalyst to detach from the film and thus affecting the photoelectrocatalytic degradation performance. Furthermore, the high cost of conductive glass also limits its large-scale application. Summary of the Invention

[0006] To overcome the above-mentioned technical problems, the present invention provides a highly stable BiVO4@TiO4 x Electrode, its preparation method, and its application in the degradation of Rhodamine B.

[0007] The technical solution of the present invention is as follows:

[0008] One of the objectives of this invention is to provide a highly stable BiVO4@TiO x The electrode is prepared by means of the following steps:

[0009] S1: Hydroxylation of the pretreated titanium sheet;

[0010] S2: Using hydroxylated titanium sheets as the working electrode and BiOI solution as the deposition solution, deposition was performed in a three-electrode system to obtain titanium-based BiOI. After cleaning and drying, acetylacetone vanadium oxide (VO(acac)2) solution was added dropwise, followed by calcination. After calcination, the mixture was allowed to cool naturally and then immersed in sodium hydroxide solution, cleaned, and dried to obtain highly stable BiVO4@TiO. x electrode.

[0011] Further specifying the pretreatment process in S1: first, alkaline washing in NaOH solution, followed by acid washing in oxalic acid solution.

[0012] Further specifying, the hydroxylation in S1 is achieved by immersion in anhydrous ethanol.

[0013] Further specify the preparation of the sedimentation solution in S2: adjust the pH of the aqueous solution of KI to 1.5-2, then add Bi(NO3)3·5H2O, stir until dissolved, then add anhydrous ethanol solution of p-benzoquinone, and stir until dissolved.

[0014] Further, the deposition potential in S2 is -0.3 to -0.7 V vs SCE, and the deposition coulomb amount is 0.4-2 C.

[0015] Further specify the calcination process in S2: heat to 350-450℃ at a rate of 2-5℃ / min, and hold for 1-3 hours.

[0016] The second objective of this invention is to provide a highly stable BiVO4@TiO4 prepared by the above method. x electrode.

[0017] The third objective of this invention is to provide a method for the photoelectrocatalytic degradation of Rhodamine B, the method comprising the following steps:

[0018] In a quartz glass reactor, the above-mentioned BiVO4@TiO x The electrode is the working electrode, sodium chloride is used as the electrolyte, and a solar xenon lamp is used as the simulated light source. Under the standard three-electrode system, a bias voltage of 0.5-1.5V is applied to perform photoelectrocatalytic degradation of the solution containing Rhodamine B.

[0019] Further, the concentration of Rhodamine B in the solution to be treated is specified to be 5-90 mg / L.

[0020] Further specified, the electrolyte concentration in the solution to be treated is 0.05-0.2 mol / L.

[0021] Further limiting, the power of the simulated light source is 300-700W.

[0022] Further, the distance between the solar xenon lamp and the liquid to be treated is 20-40cm.

[0023] Further, the photoelectrocatalysis time is specified as 0.1-1 h.

[0024] The fourth objective of this invention is to provide an application of the above-mentioned method in the photoelectrocatalytic degradation of dyeing and printing wastewater.

[0025] The advantages of this invention compared to existing technologies are:

[0026] (1) In view of the shortcomings of existing degradation technologies, this invention proposes a method based on BiVO4@TiO4. X A method for photoelectrocatalytic degradation of Rhodamine B using electrodes. A titanium sheet is used as the conductive substrate. The titanium sheet is pretreated and pre-hydroxylated. BiOI is deposited on the pre-hydroxylated titanium sheet. Hydroxylation makes BiOI easier to deposit on the titanium sheet and less prone to detachment. During thermal annealing, a thin layer of titanium oxide is formed, which facilitates the direct tunneling of BiVO4 electrons to the conductive substrate or the formation of a heterojunction structure between TiO2 and BiVO4 to promote electron charge separation, thus achieving efficient degradation of the organic dye. The resulting BiVO4@TiO2 electrode... X The electrode possesses excellent photoelectric conversion capability and Rhodamine B photoelectrocatalytic degradation performance.

[0027] (2) The present invention prepares BiVO4@TiO by using titanium sheets as a substrate. X The electrode has good charge transfer capability. By selecting the optimal coulomb amount, the charge carrier density and photocurrent density of the photoanode are significantly improved, resulting in a significant improvement in photoelectrocatalytic degradation performance. This achieves a degradation rate of over 90% for 25 mL of 70 mg / L Rhodamine B solution in 0.5 h. Attached Figure Description

[0028] Figure 1 XPS spectrum of pre-hydroxylated titanium sheet O1s in Example 1;

[0029] Figure 2 BiVO4@TiO4 was deposited in different coulomb amounts in Examples 1-2 and 5. X XRD pattern of the electrode;

[0030] Figure 3 BiVO4@TiO prepared in Examples 1-5 X Linear scan voltammogram of the electrode;

[0031] Figure 4 BiVO4@TiO prepared in Examples 1-5 X Rhodamine B degradation efficiency graph of the electrode;

[0032] Figure 5 The graph shows the degradation efficiency of Rhodamine B after treatment with Examples 1-2.

[0033] Figure 6 The graph shows the degradation efficiency of Rhodamine B after treatment with Examples 1, 3 and Comparative Example 1.

[0034] Figure 7 The graph shows the degradation efficiency of Rhodamine B after treatment with Examples 1, 4 and Comparative Example 2.

[0035] Figure 8 The graph shows the degradation efficiency of Rhodamine B after treatment with Application Example 1 and Comparative Examples 2-3. Detailed Implementation

[0036] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used in the following detailed description, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0037] This invention provides a highly stable BiVO4@TiO x The electrode is prepared according to the following steps:

[0038] (1) First, wash the titanium sheet with NaOH solution at 80-100℃ and 4-6% by mass for 1-3 hours, then wash it with oxalic acid solution at 80-100℃ and 8-12% by mass for 1-3 hours, and finally rinse it with deionized water and dry it.

[0039] (2) The titanium sheet pretreated in step (1) is soaked in anhydrous ethanol to obtain hydroxylated titanium sheet.

[0040] (3) Weigh 3.32g of KI and dissolve it in 50mL of deionized water. Stir magnetically until completely dissolved. Then, add concentrated HNO3 dropwise to adjust the pH to 1.7 and continue stirring. Add 0.97g of Bi(NO3)3·5H2O and stir until dissolved. In a separate clean beaker, weigh 0.5g of p-benzoquinone and dissolve it in 20mL of anhydrous ethanol. Stir until dissolved. Finally, mix the solutions from the two beakers thoroughly to obtain a BiOI solution.

[0041] (4) Using the hydroxylated titanium sheet obtained in step (2) as the working electrode, the BiOI solution obtained in step (3) as the deposition solution, the platinum wire electrode as the counter electrode, and the saturated calomel electrode as the reference electrode, deposition is carried out in a three-electrode system. The deposition potential is -0.3 to -0.7 V vs SCE, preferably -0.4 to -0.6 V vs SCE, and most preferably -0.5 V vs SCE. The deposition coulomb amount is 0.4-2 C, preferably 0.46-1.38 C, and most preferably 1.15 C, to obtain titanium-based BiOI. After cleaning and drying, acetylacetone vanadium oxide solution is added dropwise, and then the temperature is raised to 350-450 °C at a rate of 2-5 °C / min and held for 1-3 h for calcination. After calcination, the temperature is naturally cooled, and then soaked in sodium hydroxide solution, cleaned and dried to obtain highly stable BiVO4@TiO x electrode.

[0042] This invention provides a method for photoelectrocatalytic degradation of Rhodamine B, wherein the method includes:

[0043] In a quartz glass reactor, the above-mentioned BiVO4@TiO x The electrode is the working electrode, the platinum wire electrode is the counter electrode, and the saturated calomel electrode (SCE) is the reference electrode. Sodium chloride is used as the electrolyte, and a solar xenon lamp is used as the simulated light source. Under the standard three-electrode system, a bias voltage of 0.5-1.5V is applied to perform photoelectrocatalytic degradation of the solution containing Rhodamine B. The photoelectrocatalytic time is 0.1-1h.

[0044] In the above specific embodiments: the concentration of Rhodamine B in the solution to be treated is 5-90 mg / L, and the concentration of electrolyte in the solution to be treated is 0.05-0.2 mol / L, preferably 0.1 mol / L.

[0045] In the above specific implementation: the simulated light source power is 300-700W, the distance between the solar xenon lamp and the liquid to be treated is 20-40cm, and the bias voltage is preferably 1.0V.

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0048] Example 1: The highly stable BiVO4@TiO in this example x The electrode is prepared according to the following steps:

[0049] (1) The laser-cut 2×2cm titanium sheet is first washed with alkali in a 5% NaOH solution at 90℃ for 2 hours, then washed with oxalic acid solution at 10% oxalic acid at 90℃ for 2 hours, and finally rinsed with deionized water and dried.

[0050] (2) The titanium sheet pretreated in step (1) is soaked in anhydrous ethanol to obtain hydroxylated titanium sheet.

[0051] (3) Weigh 3.32g of KI and dissolve it in 50mL of deionized water. Stir magnetically until completely dissolved. Then, add concentrated HNO3 dropwise to adjust the pH to 1.7 and continue stirring. Add 0.97g of Bi(NO3)3·5H2O and stir until dissolved. In a separate clean beaker, weigh 0.5g of p-benzoquinone and dissolve it in 20mL of anhydrous ethanol. Stir until dissolved. Finally, mix the solutions from the two beakers thoroughly to obtain a BiOI solution.

[0052] (4) Using the hydroxylated titanium sheet obtained in step (2) as the working electrode, the BiOI solution obtained in step (3) as the deposition solution, the platinum wire electrode as the counter electrode, and the saturated calomel electrode as the reference electrode, deposition was carried out in a three-electrode system. The deposition potential was -0.5V vs SCE, and the deposition coulombic amount was 1.15C, to obtain titanium-based BiOI. After cleaning and drying, 0.2M acetylacetone vanadium oxide solution was added dropwise, and then the temperature was raised to 450℃ at a rate of 2℃ / min and held for 2h for calcination. After calcination, it was naturally cooled and then soaked in 1M sodium hydroxide solution for 30min, cleaned and dried to obtain highly stable BiVO4@TiO x electrode.

[0053] Example 2:

[0054] The difference between this embodiment and Embodiment 1 is that the deposition coulomb amount in step (4) is 0.46C. The other steps and parameters are the same as in Embodiment 1.

[0055] Example 3:

[0056] The difference between this embodiment and Embodiment 1 is that the amount of coulomb deposited in step (4) is 0.69C. The other steps and parameters are the same as in Embodiment 1.

[0057] Example 4:

[0058] The difference between this embodiment and Embodiment 1 is that the deposition coulomb amount in step (4) is 0.92C. The other steps and parameters are the same as in Embodiment 1.

[0059] Example 5:

[0060] The difference between this embodiment and Embodiment 1 is that the deposition coulomb amount in step (4) is 1.38C. The other steps and parameters are the same as in Embodiment 1.

[0061] Figure 1 The XPS spectrum of the pre-hydroxylated titanium sheet O1s in Example 1 shows that there are a large number of hydroxyl groups on the titanium sheet.

[0062] Figure 2 BiVO4@TiO4 was deposited in different coulomb amounts in Examples 1-2 and 5. XThe XRD images of the electrodes show that the intensity of the diffraction peaks of the monoclinic scheelite BiVO4 crystal planes increases with the increase of deposition amount.

[0063] The BiVO4@TiO4 prepared in Examples 1-5 X The electrode was immersed in 0.1M Na₂SO₄ electrolyte solution and irradiated by a 500W solar xenon lamp equipped with a 400nm cutoff filter. The experimental group from Example 1 under dark (1.15C) conditions served as a blank control. The LSV curves are shown below. Figure 3 As shown, the results indicate that under a deposition coulombic amount of 1.15C and a RHE bias of 1.23V, BiVO4@TiO2... X The photocurrent density of the electrode is 0.56 mA / cm². 2 .

[0064] Application Example 1:

[0065] Take 25 mL of a 70 mg / L Rhodamine B solution with 0.146 g (0.1 mol / L) of sodium chloride and add it to a cylindrical quartz glass reactor. Use a 500W xenon lamp to simulate sunlight irradiation, with a distance of 30 cm between the xenon lamp and the sample Rhodamine B solution. Prepare BiVO4@TiO4 using the method described in Examples 1-5. X The electrode is the working electrode (effective electrode area is 2×2cm). 2 A platinum wire electrode is used as the counter electrode, and a saturated calomel electrode (SCE) is used as the reference electrode, forming a three-electrode photoelectrocatalytic reaction system. The photoelectrocatalytic degradation was carried out for 30 min under an applied bias voltage of 1.0 V.

[0066] The absorbance of the reaction solution after degradation in Application Example 1 was measured. The results are as follows: Figure 4 As shown, under the same conditions, the amount of deposited coulombs significantly affects the degradation efficiency. Furthermore, with increasing deposit amount, the efficiency of photoelectrocatalytic degradation of Rhodamine B exhibits a trend of first increasing and then decreasing. This is particularly evident in BiVO4@TiO4 with a deposited coulomb amount of 1.15C. X When the electrode is used as the working electrode, the degradation rate is the highest at 91% and the degradation amount is the largest at 1.59 mg.

[0067] Application Example 2:

[0068] The difference between this application example and Application Example 1 is that the concentrations of Rhodamine B in the Rhodamine B solutions are 5 mg / L, 20 mg / L, 40 mg / L, and 90 mg / L, respectively. All other steps and parameters are the same as in Application Example 1.

[0069] The absorbance of the solution after degradation in Example 1-2 was measured. The results are as follows: Figure 5As shown, under the same conditions, the degradation amount increases with increasing Rhodamine B concentration, and further increases with increasing concentration of BiVO4@TiO4. X The catalytic sites of the electrode were fully utilized, and the degradation rate was almost saturated.

[0070] Application Example 3:

[0071] The difference between this application example and Application Example 1 is that the concentrations of sodium chloride in the Rhodamine B solution are 0.05 mol / L and 0.2 mol / L, respectively. All other steps and parameters are the same as in Application Example 1.

[0072] Comparative Example 1:

[0073] The difference between this comparative example and Application Example 1 is that the concentration of sodium chloride in the Rhodamine B solution is 0.01 mol / L. All other steps and parameters are the same as in Application Example 1.

[0074] The absorbance of the solutions after degradation in Examples 1, 3, and Comparative Example 1 was measured. The results are as follows: Figure 6 As shown, under the same conditions, the addition of sodium chloride can significantly improve the degradation efficiency. Moreover, with the increase of sodium chloride mass, the efficiency of photoelectrocatalytic degradation of Rhodamine B shows a trend of first increasing and then decreasing, with the highest degradation rate and the largest degradation amount at 0.1 mol / L.

[0075] Application Example 4:

[0076] The difference between this application example and Application Example 1 is that a bias voltage of 0.5V and 1.5V are applied respectively. The other steps and parameters are the same as in Application Example 1.

[0077] Comparative Example 2:

[0078] The difference between this comparative example and Application Example 1 is that a 0V bias voltage is applied. All other steps and parameters are the same as in Application Example 1.

[0079] The absorbance of the solutions after degradation in Examples 1, 4, and Comparative Example 2 was measured. The results are as follows: Figure 7 As shown, when the applied bias voltage is 0V, the effective separation efficiency of photogenerated electrons and photogenerated holes is low, the number of hydroxyl radicals and photogenerated holes is small, and the degradation rate of Rhodamine B is only 24.3%; when the applied bias voltage is 1.0V, the photoelectrocatalytic degradation efficiency is as high as 93.3% in the same time.

[0080] Comparative Example 3:

[0081] The difference between this comparative example and Application Example 1 is that there is no light. All other steps and parameters are the same as in Application Example 1.

[0082] The absorbance of the solutions after degradation in Examples 1 and 2-3 was measured. The results are as follows: Figure 8As shown, the results indicate that Comparative Example 2 exhibited low photocatalytic degradation rate of Rhodamine B under illumination, while Comparative Example 3 showed low electrocatalytic degradation rate of Rhodamine B under a 1.0V bias voltage, significantly lower than the photoelectrocatalytic degradation rate over the same time period. Compared to previous studies under individual illumination and 1.0V bias voltage conditions, the complete photoelectrocatalytic system demonstrated higher efficiency and better performance in degrading Rhodamine B.

[0083] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for photoelectrocatalytic degradation of Rhodamine B, characterized in that, The method described: In a quartz glass reactor, highly stable BiVO4@TiO x The electrode is the working electrode, sodium chloride is used as the electrolyte, and a solar xenon lamp is used as the simulated light source. Under the standard three-electrode system, a bias voltage of 0.5-1.5 V is applied to perform photoelectrocatalytic degradation of the solution containing Rhodamine B. The highly stable BiVO4@TiO x Electrode preparation method: S1: Hydroxylation of the pretreated titanium sheet; S2: Using hydroxylated titanium sheet as the working electrode and BiOI solution as the deposition solution, deposition was carried out in a three-electrode system to obtain titanium-based BiOI. After cleaning and drying, acetylacetone-vanadium oxide solution was added dropwise, followed by calcination. After calcination, it was naturally cooled and then immersed in sodium hydroxide solution, cleaned and dried to obtain highly stable BiVO4@TiO. x electrode.

2. The method according to claim 1, characterized in that, The pretreatment process in S1 involves first washing with NaOH solution, then washing with oxalic acid solution, and hydroxylation is achieved by immersion in anhydrous ethanol.

3. The method according to claim 1, characterized in that, Preparation of sedimentation solution in S2: Adjust the pH of the aqueous solution of KI to 1.5-2, then add Bi(NO3)3·5H2O and stir until dissolved. Then add anhydrous ethanol solution of p-benzoquinone and stir until dissolved.

4. The method according to claim 1, characterized in that, The deposition potential in S2 is -0.3 to -0.7 V vs SCE, and the deposition coulomb amount is 0.4-2 C. The calcination process is as follows: the temperature is increased to 350-450 ℃ at a rate of 2-5 ℃ / min and held for 1-3 h.

5. The method according to claim 1, characterized in that, The concentration of Rhodamine B in the solution to be treated is 5-90 mg / L, and the concentration of electrolyte in the solution to be treated is 0.05-0.2 mol / L.

6. The method according to claim 1, characterized in that, The simulated light source power is 300-700 W, and the distance between the solar xenon lamp and the liquid to be treated is 20-40 cm.

7. The method according to claim 1, characterized in that, The photoelectrocatalysis time is 0.1-1 h.

8. The application of the method according to any one of claims 1-7 in the photoelectrocatalytic degradation of dyeing and printing wastewater.

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