ZnO / BTO photo-anode and preparation method and application thereof

Abstract

The invention relates to the technical field of new energy materials, in particular to a ZnO / BTO photo-anode and a preparation method and application thereof. The preparation method comprises the following steps: mixing a bismuth source solution and a titanium source solution, and drying to obtain a BTO precursor; the preparation method comprises the following steps: mixing a BTO precursor, a solvent 1 and a Nafion film solution, coating the surface of FTO conductive glass with the mixture, and calcining to obtain BTO; and mixing ZIF-8, a solvent 2 and the Nafion film solution, coating the surface of BTO with the mixture, and calcining to obtain the ZnO / BTO photo-anode. The ZnO / BTO heterojunction photo-anode with double vacancies (Biv / Ov) is successfully prepared through a sol-gel method and a high-temperature calcination method, the ZnO / BTO heterojunction photo-anode is applied to treatment of real coal chemical industry high-salt water, the removal rate of high-concentration Na < + > and Cl <-> exceeds 90%, the removal rate of other ions reaches 87.6% or above, and the ZnO / BTO heterojunction photo-anode shows excellent cycle stability.

Description

Technical Field

[0001] This invention relates to the field of new energy materials technology, and in particular to a ZnO / BTO photoanode, its preparation method, and its application. Background Technology

[0002] With the continued expansion of the global economy and the advancement of large-scale industrial production, water pollution has become increasingly serious, severely threatening the freshwater resources upon which humanity depends for survival. Seawater and high-salinity industrial wastewater represent abundant water resources and provide an important solution to the freshwater crisis. Among these, the treatment and desalination of high-salinity industrial wastewater has become one of the key technological pathways for obtaining freshwater. Against this backdrop, a new solar-driven redox flow desalination technology has emerged. This technology utilizes photoelectrochemical reactions, with the synergistic effect of ion exchange membranes, to achieve a desalination process without external electrical energy input. Solar energy, as a clean and sustainable energy source, has broad development prospects. Solar-driven photoelectrochemical desalination technology integrates light energy and electrochemical principles, representing an innovative desalination method. This technology achieves zero energy consumption in the desalination process, providing an important pathway to address global water scarcity and the energy crisis.

[0003] Currently, there are various brine desalination technologies, mainly including membrane-based reverse osmosis (RO) and electrodialysis (ED), as well as thermal methods such as multi-effect evaporation (MED) and multi-stage flash evaporation (MSF). However, these technologies generally suffer from high costs, high energy consumption, and secondary pollution.

[0004] Solar-driven photoelectrochemical desalination technology is an emerging technology that removes salt from brackish water using solar energy without an external bias voltage. Solar-driven photoelectrochemical flow battery desalination (SPRD) mainly includes photoelectric conversion and redox processes: the former converts solar energy into electrical energy through photoelectric conversion materials, while the latter uses a redox electrolyte to continuously extract ions from the brine. The desalination unit consists of a photoanode, a photocathode, a redox electrolyte, and cation (anion) exchange membranes (CEM and AEM). The selection of photoelectrode materials and the redox electrolyte plays a crucial role in the performance of photoelectrochemical desalination. It has potential applications in brackish water desalination, seawater desalination, wastewater treatment, and the extraction of high-value-added ions.

[0005] The core of solar-driven photoelectrochemical desalination technology is the photoelectrode. Developing efficient and stable photoanode materials is key to improving the performance of solar-driven photoelectrochemical desalination (SD-PED) technology. However, existing photoanode materials suffer from problems such as easy photocorrosion and low photocurrent density, which limit the development of solar-driven photoelectrochemical desalination technology. Summary of the Invention

[0006] The purpose of this invention is to provide a ZnO / BTO photoanode, its preparation method, and its application, so as to realize solar-driven photoelectrochemical desalination without consuming electrical energy and its application in treating real coal chemical high-salinity water.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a ZnO / BTO photoanode, comprising the following steps: (1) Mix the bismuth source solution and the titanium source solution and dry them to obtain the BTO precursor; (2) After mixing the BTO precursor, solvent 1 and Nafion film solution, the mixture is coated on the surface of FTO conductive glass and calcined to obtain BTO. (3) After mixing ZIF-8, solvent 2 and Nafion film solution, the mixture is coated onto the BTO surface and calcined to obtain ZnO / BTO photoanode.

[0008] Optionally, the bismuth source solution includes a bismuth nitrate solution; the bismuth source solution is obtained by dispersing a bismuth source in a solvent; the solvent is a mixed solution of glacial acetic acid and water; the volume ratio of glacial acetic acid to water is 1:1.

[0009] Optionally, the concentration of the bismuth source solution is 0.1225~0.1230 mol / L; the pH of the bismuth source solution is 4~5.

[0010] Optionally, the titanium source solution includes a tetrabutyl titanate solution; the titanium source solution is obtained by dispersing a titanium source in ethanol; the concentration of the titanium source solution is 1.4~1.45 mol / L.

[0011] Optionally, the molar ratio of bismuth source to titanium source is 0.7:1.

[0012] Optionally, the drying temperature is 60°C and the time is 8 hours.

[0013] Optionally, the ratio of the BTO precursor to solvent 1 is 10~50 mg: 470 μL; the volume ratio of solvent 1 to Nafion membrane solution is 15~16:1. In step (2), the calcination temperature is 550℃ and the time is 3h.

[0014] Optionally, the volume ratio of ZIF-8 to solvent 2 is 2~20 mg: 470 μL; the volume ratio of solvent 2 to Nafion membrane solution is 15~16: 1; In step (3), the calcination temperature is 550℃ and the time is 2h.

[0015] The present invention also provides a ZnO / BTO photoanode prepared by the above preparation method.

[0016] This invention also provides the application of the above-mentioned ZnO / BTO photoanode in solar-driven photoelectrochemical desalination.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention successfully prepared a ZnO / BTO heterojunction photoanode with dual vacancies (Biv / Ov) via a sol-gel method and high-temperature calcination, and applied it to treat high-salinity coal chemical processes. Under illumination (zero bias), the ZnO / BTO photoanode achieved a photocurrent density as high as 4.65 mA / cm². 2 The salt removal rate was 148.52 μg / (cm³). 2 Compared to pure BTO, its desalination performance was significantly improved by 65.94% (·min). Simultaneously, it reduced the salt concentration from 6912 ppm to 966 ppm, effectively addressing high concentrations of Na+. + and Cl - The removal rates of all ions exceeded 90%, and the removal rates of other ions also reached over 87.6%. It exhibited excellent cycle stability. This superior desalination performance is attributed to the synergistic effect of the porous layered structure of ZnO / BTO and the engineering of dual-vacancy defects: the built-in electric field at the heterojunction interface effectively promoted the separation and migration of photogenerated carriers, while simultaneously expanding the reaction interface between the photoelectrode and the electrolyte. This work provides a new strategy for designing high-performance, stable SD-PED desalination materials and demonstrates the enormous application potential of this technology in treating high-salinity industrial wastewater. Attached Figure Description

[0018] Figure 1 This is a roadmap for the ZnO / BTO photoanode fabrication technology of this invention; Figure 2 SEM image of the ZnO / BTO photoanode; Figure 3 The desalination performance test results for BTO and ZnO / BTO composite photoanodes are shown in the figure. Figure 4 Graphs showing the initial and final water quality analysis of high-salinity coal chemical processes treated by solar-driven photoelectrochemical desalination technology. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0023] 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.

[0024] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.

[0025] The room temperature mentioned in this invention is 25±2℃.

[0026] This invention provides a method for preparing a ZnO / BTO photoanode, comprising the following steps: (1) Mix the bismuth source solution and the titanium source solution and dry them to obtain the BTO precursor; (2) After mixing the BTO precursor, solvent 1 and Nafion film solution, the mixture is coated on the surface of FTO conductive glass and calcined to obtain BTO. (3) After mixing ZIF-8, solvent 2 and Nafion film solution, the mixture is coated onto the BTO surface and calcined to obtain ZnO / BTO photoanode.

[0027] The present invention involves slowly adding a titanium source solution dropwise to a bismuth source solution until a sol is formed, and then drying the resulting sol to convert it into a gel, thereby obtaining a BTO precursor.

[0028] In this invention, the bismuth source solution includes a bismuth nitrate solution, specifically a bismuth nitrate pentahydrate solution; the bismuth source solution is obtained by dispersing a bismuth source in a solvent; the solvent is a mixed solution of glacial acetic acid and water; the volume ratio of glacial acetic acid to water is 1:1.

[0029] In some embodiments of the present invention, the bismuth source is dissolved in a mixed solution of glacial acetic acid and water, and the pH of the solution is adjusted with ammonia to obtain a bismuth source solution.

[0030] In this invention, the concentration of the bismuth source solution is 0.1225~0.1230 mol / L, preferably 0.1225 mol / L; the pH of the bismuth source solution is 4~5, preferably 4.

[0031] In this invention, the titanium source solution includes a tetrabutyl titanate solution; the titanium source solution is obtained by dispersing a titanium source in ethanol; the concentration of the titanium source solution is 1.4~1.45 mol / L, preferably 1.4 mol / L.

[0032] In some embodiments of the present invention, the titanium source is dissolved in anhydrous ethanol to obtain the titanium source.

[0033] In this invention, the molar ratio of bismuth source to titanium source is 0.7:1.

[0034] In this invention, the drying temperature is 60°C and the time is 8~12h, preferably 12h.

[0035] This invention involves adding solvent 1 to a BTO precursor, sonicating for 1 hour, then adding Nafion film solution and continuing sonication for another hour to obtain a uniformly dispersed solution. This solution is then spin-coated onto an FTO conductive glass surface and calcined in air to obtain Bi₄Ti₃O₃. 12 Photoanode, denoted as BTO.

[0036] In this invention, the ratio of the BTO precursor to solvent 1 is 10-50 mg: 470 μL; the volume ratio of solvent 1 to Nafion membrane solution is 15-16:1; and solvent 1 is anhydrous ethanol. In step (2), the calcination temperature is 550℃ and the time is 3h.

[0037] This invention involves adding solvent 2 to ZIF-8, ultrasonicating for 1 hour, then adding Nafion film solution and continuing ultrasonication for another hour to obtain a uniformly dispersed ZIF-8 solution. The ZIF-8 solution is then spin-coated onto the surface of FTO conductive glass and calcined in air to obtain ZnO / Bi4Ti3O. 12 Photoanode, denoted as ZnO / BTO photoanode.

[0038] In this invention, the volume ratio of ZIF-8 to solvent 2 is 2~20 mg: 470 μL; the volume ratio of solvent 2 to Nafion membrane solution is 15~16:1; and solvent 2 is anhydrous ethanol. In step (3), the calcination temperature is 550℃ and the time is 2h.

[0039] In some embodiments of the present invention, the preparation method of ZIF-8 includes: dissolving zinc nitrate hexahydrate in water to obtain a zinc nitrate hexahydrate solution; mixing sodium dodecyl sulfate and the zinc nitrate hexahydrate solution evenly to obtain solution A; dissolving 2-methylimidazole in water to obtain a 2-methylimidazole solution; and rapidly mixing solution A and the 2-methylimidazole solution to react and obtain the ZIF-8 precursor.

[0040] In this invention, the concentration of the zinc nitrate hexahydrate solution is 0.0425 mol / L; the molar ratio of sodium dodecyl sulfate to zinc nitrate hexahydrate is 1:16~17; the concentration of the 2-methylimidazole solution is 0.355 mol / L; the molar ratio of zinc nitrate hexahydrate to zinc nitrate hexahydrate is 8~9:1; the reaction is carried out by stirring at room temperature for 2 hours and then standing for 12 hours; after the reaction is completed, the mixture is washed three times each with deionized water and anhydrous ethanol, and then the white substance is dried at 60°C for 12 hours.

[0041] The present invention also provides a ZnO / BTO photoanode prepared by the above preparation method.

[0042] This invention also provides the application of the above-mentioned ZnO / BTO photoanode in solar-driven photoelectrochemical desalination.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] In the embodiments of this invention, all chemicals were of analytical grade. These included zinc nitrate hexahydrate (Aladdin, 99.0%), 2-methylimidazole (Aladdin, 99.0%), anhydrous ethanol (Macklin, 100%), glacial acetic acid (Sinopharm, 35%), bismuth nitrate pentahydrate (Macklin, 99.0%), tetrabutyl titanate (Aladdin, 98%), ammonia (Macklin, 25-28%), naphthol membrane solution (Macklin, D520, 95.0%), deionized water, sodium hydroxide (Macklin, 95.0%), and potassium sulfate (Macklin, 99.0%).

[0045] Preparation Example 1 Preparation of ZIF-8 precursor Weigh 1.70 mmol of zinc nitrate hexahydrate and dissolve it in 40.0 mL of deionized water to obtain a zinc nitrate hexahydrate solution; then, add 0.104 mmol of sodium dodecyl sulfate to the zinc nitrate hexahydrate solution, mix well, and denote this as solution A; Weigh 14.20 mmol of 2-methylimidazole and dissolve it in 40.0 mL of deionized water, and denote this as solution B; Solution A and solution B were rapidly mixed and stirred for 2 h. After standing at room temperature for 12 h, the mixture was washed three times each with deionized water and anhydrous ethanol. Then, the white substance was dried at 60 °C for 12 h to obtain the ZIF-8 precursor.

[0046] Preparation Example 2 Bi4Ti3O 12 Photoanode preparation Weigh 0.0049 mol of bismuth nitrate pentahydrate and dissolve it in 40.0 mL of a mixed solution of glacial acetic acid and water (VDI:VHAc = 1:1). Adjust the pH of the solution to about 4 with ammonia water and denote it as solution A. Weigh 0.007 mol of tetrabutyl titanate and dissolve it in 5.0 ml of anhydrous ethanol, and denote it as solution B; Solution B was slowly added dropwise to solution A until a sol was formed. The resulting sol was dried in a 60°C drying oven for 12 hours to transform it into a gel, which was denoted as the BTO precursor. Weigh out 10.0 mg, 20.0 mg, 30.0 mg, 40.0 mg, and 50.0 mg of BTO precursor, respectively, and add 470.0 μL of anhydrous ethanol. Sonicate for 1 h, then add 30.0 μL of Nafion membrane solution and continue sonicating for 1 h to obtain a uniformly dispersed solution. Spin-coat this solution onto an FTO conductive glass surface and calcine at 550 °C for 3 h in air to obtain Bi₄Ti₃O₃. 12 Photoanodes are designated BTO-10, BTO-20, BTO-30, BTO-40, and BTO-50.

[0047] Example 1 Preparation of ZnO / BTO photoanodes Weigh 15.0 mg of ZIF-8 precursor, add 470.0 μL of anhydrous ethanol, sonicate for 1 h, then add 30.0 μL of Nafion membrane solution, and continue sonicating for 1 h to obtain a uniformly dispersed ZIF-8 solution. ZnO / Bi4Ti3O was obtained by spin-coating ZIF-8 solution onto BTO-30 and calcining it at 550°C for 2 h in air. 12 Photoanode, denoted as 15-ZnO / BTO. The preparation technique is as follows: Figure 1 As shown.

[0048] Example 2 Weigh 5.0 mg of ZIF-8 precursor, add 470.0 μL of anhydrous ethanol, sonicate for 1 h, then add 30.0 μL of Nafion membrane solution, and continue sonicating for 1 h to obtain a uniformly dispersed ZIF-8 solution. ZnO / Bi4Ti3O was obtained by spin-coating ZIF-8 solution onto BTO-30 and calcining it at 550°C for 2 h in air. 12 Photoanode, denoted as 5-ZnO / BTO.

[0049] Example 3 Weigh 10.0 mg of ZIF-8 precursor, add 470.0 μL of anhydrous ethanol, sonicate for 1 h, then add 30.0 μL of Nafion membrane solution, and continue sonicating for 1 h to obtain a uniformly dispersed ZIF-8 solution. ZnO / Bi4Ti3O was obtained by spin-coating ZIF-8 solution onto BTO-30 and calcining it at 550°C for 2 h in air. 12 Photoanode, denoted as 10-ZnO / BTO.

[0050] Example 4 Weigh 20.0 mg of ZIF-8 precursor, add 470.0 μL of anhydrous ethanol, sonicate for 1 h, then add 30.0 μL of Nafion membrane solution, and continue sonicating for 1 h to obtain a uniformly dispersed ZIF-8 solution. ZnO / Bi4Ti3O was obtained by spin-coating ZIF-8 solution onto BTO-30 and calcining it at 550°C for 2 h in air. 12 Photoanode, denoted as 20-ZnO / BTO.

[0051] Figure 2 These are SEM images of BTO-30 and 15-ZnO / BTO photoanodes, from... Figure 2 It can be seen that ZnO nanomaterials are loaded onto the surface of BTO layered structure to form a ZnO / BTO composite photoanode with a heterostructure.

[0052] Desalination performance test of composite photoanode: The initial salt concentration of the high-salt water in the coal chemical industry was 6912 ppm, and the test was conducted under the light intensity of one sun.

[0053] Desalination performance tests showed that the 15-ZnO / BTO photoanode exhibited the best desalination performance, with a desalination efficiency of 148.52 μg / (cm³). 2 ·min).

[0054] Figure 3 These are test graphs showing the desalination performance of BTO-30 and 15-ZnO / BTO composite photoanodes. Figure 3 (a) It can be known that BTO Comm The photocurrent densities of (commercial), BTO, and ZnO / BTO were increased to approximately 3.42 mA / cm². 2 3.70 mA / cm 2 and 4.65 mA / cm 2 .Depend on Figure 3 (b) It can be known that BTO Comm The desalination rates of three photoanodes—BTO, ZnO / BTO, and ZnO / BTO—for high-salinity coal chemical processes were 44.20, 89.50, and 148.52 μg / (cm³), respectively. 2 ·min). By Figure 3 (c) It can be seen that the photoanode exhibits 4.65 mA / cm² in the initial stage. 2 The photocurrent density decreased gradually in subsequent cycles, while the photocurrent curve remained consistent. Figure 3 (d) It can be seen that after five consecutive tests, the desalination rates of 15-ZnO / BTO were 148.52, 148.32, 148.09, 147.83 and 147.80 μg / (cm²·min).

[0055] Figure 4 Analysis of initial and final water quality for high-salinity coal chemical processes treated by solar-driven photoelectrochemical desalination technology, by... Figure 4 It can be seen that the ion concentrations in the initial high-salinity coal chemical solution and the diluted solution after desalination were determined by inductively coupled plasma optical emission spectrometry (ICP-OES, Agilent 5110) and ion chromatography (IC, Thermo Fisher Scientific AQUION RFIC), respectively. The highest concentration of Na in the high-salinity solution was found to be... + and Cl - The removal rates all exceeded 90%, and the removal efficiency for other cations and anions was also high, with the overall removal rate all above 87.6%, which is consistent with the overall desalination performance trend mentioned above.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a ZnO / BTO photoanode, characterized in that, Includes the following steps: (1) Mix the bismuth source solution and the titanium source solution and dry them to obtain the BTO precursor; (2) After mixing the BTO precursor, solvent 1 and Nafion film solution, the mixture is coated on the surface of FTO conductive glass and calcined to obtain BTO. (3) After mixing ZIF-8, solvent 2 and Nafion film solution, the mixture is coated onto the BTO surface and calcined to obtain ZnO / BTO photoanode.

2. The preparation method according to claim 1, characterized in that, The bismuth source solution includes a bismuth nitrate solution; the bismuth source solution is obtained by dispersing a bismuth source in a solvent; the solvent is a mixed solution of glacial acetic acid and water; the volume ratio of glacial acetic acid to water is 1:

1.

3. The preparation method according to claim 2, characterized in that, The concentration of the bismuth source solution is 0.1225~0.1230 mol / L; the pH of the bismuth source solution is 4~5.

4. The preparation method according to claim 1, characterized in that, The titanium source solution includes a tetrabutyl titanate solution; the titanium source solution is obtained by dispersing a titanium source in ethanol; the concentration of the titanium source solution is 1.4~1.45 mol / L.

5. The preparation method according to claim 1, characterized in that, The molar ratio of bismuth source to titanium source is 0.7:

1.

6. The preparation method according to claim 1, characterized in that, The drying temperature is 60℃, and the time is 8~12h.

7. The preparation method according to claim 1, characterized in that, The ratio of BTO precursor to solvent 1 is 10~50 mg: 470 μL; the volume ratio of solvent 1 to Nafion membrane solution is 15~16:

1. In step (2), the calcination temperature is 550℃ and the time is 3h.

8. The preparation method according to claim 1, characterized in that, The volume ratio of ZIF-8 to solvent 2 is 2~20 mg: 470 μL; the volume ratio of solvent 2 to Nafion membrane solution is 15~16: 1; In step (3), the calcination temperature is 550℃ and the time is 2h.

9. The ZnO / BTO photoanode prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the ZnO / BTO photoanode as described in claim 9 in solar-driven photoelectrochemical desalination.

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