Preparation method, product and application of bimetallic hole transport layer composite photoanode in solar-driven photoelectrochemical desalination.

Abstract

This invention relates to the field of new energy materials, and in particular to a method for preparing a bimetallic hole transport layer composite photoanode, the product thereof, and its application in solar-driven photoelectrochemical desalination. The method for preparing the bimetallic hole transport layer composite photoanode includes the following steps: dissolving 2-methylimidazole, a Co source, a Ni source, and polyvinylpyrrolidone in water to prepare a Ni-Co-MOF precursor solution; immersing a BiVO4 film in the Ni-Co-MOF precursor solution for in-situ growth to obtain Ni-Co-MOF / BiVO4; and calcining the Ni-Co-MOF / BiVO4 to obtain the bimetallic hole transport layer composite photoanode. The loading of the Ni-Co bimetallic hole transport layer effectively protects the composite photoanode from photocorrosion, achieves effective separation and transfer of photogenerated electron-hole pairs, and significantly improves photoelectric conversion efficiency and photoelectrochemical desalination performance.

Description

Technical Field

[0001] This invention relates to the field of new energy materials, and in particular to a method for preparing a bimetallic hole transport layer composite photoanode, the product thereof, and its application in solar-driven photoelectrochemical desalination. Background Technology

[0002] Water is the source of life and a core element of sustainable social development. It is estimated that by 2030, approximately 47% of the global population will live in areas with severe water scarcity. Meanwhile, freshwater pollution further exacerbates the water shortage crisis. The global demand for water scarcity and brine desalination technology is increasingly urgent. Currently, various brine desalination technologies exist, including multi-stage flash evaporation, multi-effect distillation, and electrodialysis. These methods generally suffer from high costs, high energy consumption, and secondary pollution. For example, in reverse osmosis technology, electricity consumption accounts for 50% of the total cost; while in multi-stage flash evaporation and multi-effect distillation, electricity and heat costs account for approximately 77% and 66%, respectively.

[0003] Solar energy, as a clean and sustainable energy source, has enormous development potential. Solar-driven photoelectrochemical desalination technology, which combines solar energy with photoelectrochemistry, is an emerging desalination technology that achieves zero-energy consumption and has become an important approach to solving the aforementioned problems.

[0004] The core of solar-driven photoelectrochemical desalination technology is the photoelectrode. However, the photoelectrodes in the current technology generally suffer from problems such as photocorrosion, low photoelectric conversion efficiency, and low photoelectrochemical desalination performance. Summary of the Invention

[0005] Based on the above, this invention provides a method for preparing a bimetallic hole transport layer composite photoanode, a product thereof, and its application in solar-driven photoelectrochemical desalination.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of this invention is a method for preparing a bimetallic hole transport layer composite photoanode, comprising the following steps:

[0008] Ni-Co-MOF precursor solution was prepared by dissolving 2-methylimidazolium, Co source, Ni source and polyvinylpyrrolidone in water;

[0009] BiVO4 films were immersed in the Ni-Co-MOF precursor solution for in-situ growth to obtain Ni-Co-MOF / BiVO4.

[0010] The bimetallic hole transport layer composite photoanode is obtained by calcining the Ni-Co-MOF / BiVO4.

[0011] The second technical solution of the present invention is a bimetallic hole transport layer composite photoanode prepared by the above-mentioned preparation method.

[0012] The third technical solution of this invention is the application of the above-mentioned bimetallic hole transport layer composite photoanode in solar-driven photoelectrochemical desalination.

[0013] The fourth technical solution of the present invention is a photoelectrochemical desalination system, which uses the aforementioned bimetallic hole transport layer composite photoanode as the photoanode.

[0014] Solar-driven photoelectrochemical desalination technology, combining solar energy and photoelectrochemistry, is an emerging desalination technology. It utilizes solar energy to remove salt from saline water without an external bias voltage. This invention constructs a composite photoanode with a bimetallic hole transport layer that matches the energy levels of perovskite ferroelectric (PF) semiconductor materials. The porous bimetallic hole transport layer promotes the separation and transfer of photogenerated electron-hole pairs, mitigating electron-hole recombination. The bimetallic hole transport layer effectively protects the photoelectrode from photocorrosion, significantly improving the photocurrent and the stability of the desalination system. This highly efficient and stable photoelectrochemical desalination system possesses energy storage and brine desalination capabilities, demonstrating broad development prospects and application potential.

[0015] The core of solar-driven photoelectrochemical desalination technology is the photoelectrode. This invention constructs a bimetallic hole transport layer composite photoanode, achieving solar-driven photoelectrochemical desalination without consuming electrical energy. It is a green, environmentally friendly, highly efficient, and clean photoelectrochemical desalination method operating at room temperature and ambient pressure.

[0016] The present invention discloses the following technical effects:

[0017] This invention constructs a bimetallic hole transport layer composite photoanode (NiO@Co3O4 / BiVO4) using an in-situ growth method. The method is simple and easily applicable to industrial applications.

[0018] The loading of the Ni-Co bimetallic hole transport layer in the composite photoanode of this invention effectively protects the composite photoanode from photocorrosion, realizes the effective separation and transfer of photogenerated electron-hole pairs in the NiO@Co3O4 / BVO photoanode, and significantly improves the photoelectric conversion efficiency and photoelectric desalination performance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 SEM image of the bimetallic hole transport layer composite photoanode BCN-120 prepared in Example 1.

[0021] Figure 2 The image shows the performance test results of the bimetallic hole transport layer composite photoanode BCN-120 prepared in Example 1. Detailed Implementation

[0022] 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.

[0023] 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. Any stated value or intermediate value within a stated range, as well as each smaller range between 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.

[0024] 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.

[0025] 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 apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] 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.

[0027] One of the technical solutions of this invention is a method for preparing a bimetallic hole transport layer composite photoanode, comprising the following steps:

[0028] Ni-Co-MOF precursor solution was prepared by dissolving 2-methylimidazolium, Co source, Ni source and polyvinylpyrrolidone in water;

[0029] BiVO4 films were immersed in the Ni-Co-MOF precursor solution for in-situ growth to obtain Ni-Co-MOF / BiVO4.

[0030] The bimetallic hole transport layer composite photoanode is obtained by calcining the Ni-Co-MOF / BiVO4.

[0031] In some specific embodiments of the present invention, the preparation method of Ni-Co-MOF precursor solution is as follows:

[0032] Dissolve 2-methylimidazole in water to obtain solution A;

[0033] Co source and polyvinylpyrrolidone were dissolved in water, and Ni source was added to obtain solution B;

[0034] The solution A and the solution B are mixed evenly to obtain the Ni-Co-MOF precursor solution.

[0035] In a preferred embodiment of the present invention, the molar ratio of the Co source to the Ni source is 1:4-4:1 (more preferably 1:1); the molar ratio of the 2-methylimidazole to the Co source is 10:1; and the ratio of the Co source to the polyvinylpyrrolidone is 0.002mol:30mg.

[0036] In a preferred embodiment of the present invention, the concentration of the Co source in the Ni-Co-MOF precursor solution is 0.025 mol / L.

[0037] In a preferred embodiment of the present invention, the Co source is Co(NO3)2·6H2O; and the Ni source is Ni(NO3)2·6H2O.

[0038] In a preferred embodiment of the present invention, the in-situ growth specifically involves standing at room temperature for 80-140 minutes.

[0039] In a preferred embodiment of the present invention, the calcination specifically refers to calcination at 450°C for 2 hours under a nitrogen atmosphere.

[0040] In this invention, if the calcination temperature is too low, Ni-Co-MOF cannot be transformed into NiO@Co3O4; if the calcination temperature is too high, the BiVO4 film decomposes. Both excessively high and low calcination temperatures will affect the performance of the prepared bimetallic hole transport layer composite photoanode.

[0041] In a preferred embodiment of the present invention, before immersing the BiVO4 film in the Ni-Co-MOF precursor solution, the method further includes a step of stirring and washing the BiVO4 film with 0.1M NaOH solution for 30 minutes (rotation speed 100 r / min).

[0042] The purpose of cleaning the BiVO4 film with 0.1M NaOH solution is to make it form a porous structure.

[0043] By immersing BiVO4 films in a Ni-Co-MOF precursor solution at room temperature for in-situ growth, Ni-Co-MOF precursors are deposited on the surface of BiVO4 films, thus achieving the decoration of BiVO4 by Ni-Co-MOF nanosheets.

[0044] In some specific embodiments of the present invention, the BiVO4 thin film is prepared by electrodeposition and thermal annealing, including the following steps:

[0045] 0.02 mol KI was dissolved in 50 mL of deionized water, and the pH was adjusted to approximately 1.7 by adding HNO3 solution dropwise to obtain a KI solution. 0.002 mol Bi(NO3)2·5H2O was added to the KI solution and stirred; this solution was labeled A. 0.005 mol p-benzoquinone was dissolved in 20 mL of anhydrous ethanol and stirred continuously; this solution was labeled B. Solution B was added to solution A to form a homogeneous mixture. Then, a nanostructured BiOI was electrochemically deposited on an FTO substrate at a potential of -0.1 V (relative to Ag / AgCl). After deposition, the substrate was washed and dried to obtain a BiOI film. 0.0006 mol VO(acac)2 was dissolved in 3 mL of DMSO and coated onto the BiOI film. The BiOI film was annealed at 450 °C for 2 hours and then cooled to room temperature to obtain a BiVO4 film. The BiVO4 film prepared using this method exhibited a coral-like porous structure.

[0046] The second technical solution of the present invention is a bimetallic hole transport layer composite photoanode prepared by the above-mentioned preparation method.

[0047] The third technical solution of this invention is the application of the above-mentioned bimetallic hole transport layer composite photoanode in solar-driven photoelectrochemical desalination.

[0048] The fourth technical solution of the present invention is a photoelectrochemical desalination system, which uses the aforementioned bimetallic hole transport layer composite photoanode as the photoanode.

[0049] In a photoelectrochemical desalination system (device), using the NiO@Co3O4 / BVO prepared in this invention as the photoanode, a power output of 3.01 mA / cm² was achieved under zero bias conditions, driven by light. 2 The initial photocurrent and 88.76 μg / (cm) 2 The salt removal rate was 100 μg / (cm³), while the salt removal rate of pure BiVO₄ was 37.05 μg / (cm³). 2 (·min). Using existing desalination systems, the salt concentration of high-concentration brine can be reduced from 3227 ppm to 173 ppm in applications, and the solar desalination capacity of this photoanode is 0.231 μmol / J. This invention provides a feasible and effective method for developing long-term, stable, and efficient solar-driven photoelectrochemical desalination technology.

[0050] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0051] All chemicals used in the embodiments of this invention are of analytical grade: bismuth(III) nitrate pentahydrate (Aladdin, 99.0%), potassium iodide (Aladdin, 99.0%), p-benzoquinone (Macklin, 99.0%), nitric acid (Sinopharm, 65%–68%), anhydrous ethanol (Macklin, 100%), vanadium acetylacetonate (Aladdin, 98%), dimethyl sulfoxide (Macklin, 99.8%), cobalt(II) nitrate hexahydrate (Macklin, 99.0%), nickel(II) nitrate hexahydrate (Macklin, 99.0%), 2-methylimidazole (Macklin, 98.0%), N-methylpyrrolidone (Macklin, 99%), polyvinylidene fluoride (Macklin, 99.0%), polyvinylpyrrolidone (PVPK-30), sodium hydroxide (Macklin, 95.0%), and sodium sulfate (Macklin, 99.0%).

[0052] 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.

[0053] Example 1

[0054] (1) Preparation of BVO (BiVO4) photoanode

[0055] After sonicating an FTO substrate (3.0 cm × 3.0 cm) in a mixture of acetone, ethanol, and deionized water (1:1:1) for 30 minutes, the FTO was washed with deionized water and then placed in anhydrous ethanol for later use. First, 0.02 mol KI was dissolved in 50 mL of deionized water, and the pH of the KI solution was adjusted to approximately 1.7 by adding HNO3 solution dropwise. 0.002 mol Bi(NO3)2·5H2O was added to the KI solution and stirred, labeled as solution A. 0.005 mol p-benzoquinone was dissolved in 20 mL of anhydrous ethanol and stirred continuously, labeled as solution B. Solution B was added to solution A to form a homogeneous mixture. Next, a nanostructured BiOI was electrochemically deposited on the FTO substrate surface at a potential of -0.1 V (relative to Ag / AgCl). After deposition, the formed BiOI film was rinsed three times with deionized water and three times with anhydrous ethanol, and then dried at 80 °C. Finally, 0.0006 mol VO(acac)₂ was dissolved in 3 mL DMSO and coated onto a BiOI film. The BiOI film was annealed at 450 °C for 2 hours and then cooled to room temperature. The sample was washed with 0.1 M NaOH solution to obtain a porous BVO film.

[0056] (2) Preparation of NiO@Co3O4 / BiVO4 bimetallic hole transport layer composite photoanode

[0057] First, 0.02 mol C4H6N2 was dissolved in 40 mL of deionized water to form solution A. Simultaneously, 0.002 mol Co(NO3)2·6H2O and 30 mg PVP were dissolved in 40 mL of deionized water, and 0.002 mol Ni(NO3)2·6H2O was added to this solution to form solution B. Solutions A and B were mixed and stirred for 60 min to form a Ni-Co-MOF precursor solution. Next, the porous BVO film prepared in step (1) was immersed in the Ni-Co-MOF precursor solution at room temperature for a certain period of time (80 min, 100 min, 120 min, and 140 min, respectively) for in-situ growth to obtain sheet-like Ni-Co-MOF / BiVO4. Finally, the sheet-like Ni-Co-MOF / BiVO4 film was calcined at 450℃ and under N2 atmosphere for 2 hours to obtain a Ni-Co-MOF-derived bimetallic hole transport layer composite photoanode NiO@Co3O4 / BiVO4, labeled as BCN-x (x represents the in-situ growth time).

[0058] Figure 1 This is a SEM image of the bimetallic hole transport layer composite photoanode BCN-120 prepared in Example 1. Figure 1 It can be seen that the NiO@Co3O4 bimetallic hole transport layer was successfully grown on the BiVO4 surface.

[0059] Figure 2 Performance test results for the bimetallic hole transport layer composite photoanode BCN-120 prepared in Example 1. Figure 2 It can be seen that the BCN-120 photoanode with a bimetallic hole transport layer structure exhibits excellent photoelectric desalination performance. The salt removal rate and solar desalination capacity of BCN-120 are 88.76 μg / (cm³). 2 The concentrations were 0.231 μmol / J (·min), higher than the 37.05 μg / (cm³) of pure BVO. 2 ·min) and 0.085μmol / J.

[0060] Based on Example 1, this invention also verified the initial photocurrent and salt removal rate of NiO@Co3O4 / BiVO4 prepared under different Ni:Co ratio conditions (i.e., based on Example 1, the amount of Co(NO3)2·6H2O added was fixed at 0.002 mol, and then the amount of Ni(NO3)2·6H2O added was adjusted to make the Ni:Co molar ratio 1:4 and 4:1, respectively, the in-situ growth time was 120 min, and the other step parameters were the same as in Example 1; the prepared bimetallic hole transport layer composite photoanodes with corresponding Ni:Co molar ratios were labeled as Co:Ni 4:1 and Co:Ni 1:4, respectively). The results showed that when the Ni:Co molar ratio was 1:1, the initial photocurrent of the prepared NiO@Co3O4 / BiVO4 was 3.01 mA / cm. 2 The salt removal rate was 88.76 μg / (cm³). 2 When the Ni:Co molar ratio is 1:4, the initial photocurrent of the prepared NiO@Co3O4 / BiVO4 is 2.86 mA / cm². 2 The salt removal rate was 84.21 μg / (cm³). 2 (·min); When the Ni:Co molar ratio is 4:1, the initial photocurrent of the prepared NiO@Co3O4 / BiVO4 is 2.76 mA / cm. 2 The salt removal rate was 83.18 μg / (cm³). 2 ·min).

[0061] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to analyze Bi content in the redox electrolyte, diluent, and concentrate after desalination. 3+ V 5+ Co 2+ and Ni 2+ Elemental content tests are shown in Table 1. The redox electrolyte of the pure BiVO4 photoanode contains trace amounts of Bi. 3+ and V 5+ Ions, V 5+and Bi 3+ The ions originated from BiVO4 nanoparticles, indicating that BiVO4 photoanodes are prone to photocorrosion during solar redox desalination. Meanwhile, the redox electrolyte of the BCN-120 photoanode contains Bi... 3+ V 5+ The content was extremely low; Bi was not detected in either the diluent or the concentrate. 3+ V 5+ Co 2+ and Ni 2+ This indicates that the photocorrosion resistance and stability of the BCN-120 photoanode have been significantly improved; the NiO@Co3O4 bimetallic hole transport layer protects the coral-like structure of BiVO4. The photoelectric conversion efficiency of the photoelectrode is shown in Table 2.

[0062] Table 1. ICP data of pure BVO and BCN-120 samples.

[0063]

[0064] In the table, " / " indicates that the substance is not present, and "-" indicates that it was not detected.

[0065] Table 2 Solar desalination capacity (photovoltaic conversion efficiency) of photoanodes.

[0066]

[0067] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. The application of a bimetallic hole transport layer composite photoanode in solar-driven photoelectrochemical desalination, characterized in that, The method for preparing the bimetallic hole transport layer composite photoanode includes the following steps: Ni-Co-MOF precursor solution was prepared by dissolving 2-methylimidazolium, Co source, Ni source and polyvinylpyrrolidone in water; BiVO4 films were immersed in the Ni-Co-MOF precursor solution for in-situ growth to obtain Ni-Co-MOF / BiVO4. The bimetallic hole transport layer composite photoanode is obtained by calcining the Ni-Co-MOF / BiVO4.

2. The application according to claim 1, characterized in that, The molar ratio of the Co source to the Ni source is 1:1; the molar ratio of the 2-methylimidazole to the Co source is 10:1; and the ratio of the Co source to the polyvinylpyrrolidone is 0.002 mol: 30 mg.

3. The application according to claim 1, characterized in that, The concentration of the Co source in the Ni-Co-MOF precursor solution is 0.025 mol / L.

4. The application according to claim 1, characterized in that, The Co source is Co(NO3)2·6H2O; the Ni source is Ni(NO3)2·6H2O.

5. The application according to claim 1, characterized in that, The in-situ growth process specifically involves standing at room temperature for 80-140 minutes.

6. The application according to claim 1, characterized in that, The calcination process specifically involves calcining at 450°C for 2 hours under a nitrogen atmosphere.

7. The application according to claim 1, characterized in that, Before immersing the BiVO4 film in the Ni-Co-MOF precursor solution, the process further includes washing the BiVO4 film with 0.1M NaOH solution for 30 minutes.

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