Nickel-tetrahydroxybenzene coordination polymer film as well as preparation method and application thereof

Abstract

The invention discloses a nickel-tetrahydroxybenzene coordination polymer film as well as a preparation method and application thereof, and belongs to the technical field of electrochromic film materials. The polymer film comprises a redox active ligand 1, 2, 4, 5-tetrahydroxybenzene and transition metal coordination center nickel ions. The preparation method comprises the following steps: dissolving tetrahydroxy benzene in water to obtain a solution A; dissolving nickel salt in water to obtain a solution B; and putting the film carrier into the solution B, adding the solution A, and stirring. According to the invention, the simple synthesis of the high-performance color-changing film is realized, the technical bottlenecks of low optical contrast and slow response speed of the traditional electrochromic material are solved, the obtained film realizes reversible switching between light brown and black brown under the driving of + / -0.8 V voltage, the optical contrast reaches 62.41% at the wavelength of 600nm, the coloring / fading response time is 12.3 s and 21.4 s respectively, and the color-changing effect is good. The method is suitable for building intelligent windows, automobile anti-dazzle rearview mirrors, electronic paper displays and other devices.

Description

Technical Field

[0001] This invention belongs to the field of electrochromic thin film materials technology, specifically relating to a nickel-tetrahydroxybenzene coordination polymer thin film, its preparation method, and its application. Background Technology

[0002] In the global energy transition, reducing carbon emissions has become a core objective of energy policy. Among the major drivers of energy consumption, buildings consume approximately 40% of energy, even surpassing industry and transportation, making them a key target for emissions reduction. Half of building energy is used for ventilation and temperature control, such as heating and cooling. Furthermore, in published low-cost emissions reduction projections, reducing CO2 emissions from buildings ranks first. The high energy consumption of buildings is primarily due to the fact that traditional windows cannot allow reverse heat transfer, preventing buildings from gaining heat in summer and releasing it in winter. Electrochromic materials, which exhibit stable and reversible color changes in their optical properties (reflectivity, transmittance, etc.) under an applied electric field, have a significant application as smart windows. Through a lithium insertion / extraction process, they can switch between colored and fading states to achieve color control. By selectively absorbing or reflecting external heat radiation, they can prevent heat diffusion, thereby storing and utilizing energy and reducing building energy consumption. Materials exhibiting reversible changes in color and transparency have immense development potential.

[0003] Since Deb first invented electrochromic devices in 1969, most electrochromic materials can be divided into inorganic transition metal oxides and a small number of organic small molecules and organic conductive polymers. Inorganic transition metal oxides achieve color change through the synergistic insertion and extraction of ions and electrons. These traditional inorganic materials mainly include WO3, V2O5, and NiO2, which have the advantages of stability and long cycle life, but disadvantages such as limited material variety, simple structure, poor conductivity, and monotonous color changes. Organic electrochromic materials mainly include viologen, polypyrrole, and polythiophene, whose color-changing principle is to change light absorption through redox reactions. They have the advantages of fast response, multiple colors, and easy molecular structure design, but due to their reduced dimensionality and active properties, organic electrochromic materials usually have poor stability and short lifespan. Since 2014, the electrochromic effects of newly discovered materials such as reduced graphene oxide (RGO), coordination nanosheets (CONASH), copper chalcogenides, covalent organic frameworks (COF), transition metal carbides / nitrides / carbonitrides (MXenes), and hydrogen-bonded organic frameworks (HOF) have been reported, greatly rekindling research interest. Compared with traditional materials, emerging 2D materials exhibit unique physical and chemical properties, and these differences may greatly enhance electrochromic performance in many cases. However, current materials face the following problems: (1) Traditional electrochromic materials have certain drawbacks. Inorganic materials have long cycle life, but few types and slow color change speed; (2) Organic materials have fast color change speed and many colors, but are not resistant to long-term ultraviolet radiation from sunlight; (3) There are few electrochromic materials with a large range of transmission changes. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a nickel-tetrahydroxybenzene coordination polymer film, its preparation method, and its applications.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The present invention provides a nickel-tetrahydroxybenzene coordination polymer film comprising a redox active ligand 1,2,4,5-tetrahydroxybenzene and a transition metal coordination center nickel ion.

[0007] As a preferred embodiment of the present invention, the chemical formula of the ligand 1,2,4,5-tetrahydroxybenzene is:

[0008]

[0009] The present invention also provides a method for preparing a nickel-tetrahydroxybenzene coordination polymer film according to the above-described method, comprising the following steps: dissolving tetrahydroxybenzene in water to obtain ligand solution A; dissolving a nickel salt in water to obtain solution B; placing a film carrier in solution B; adding solution A to solution B and stirring to obtain the nickel-tetrahydroxybenzene coordination polymer film.

[0010] As a preferred embodiment of the present invention, the concentration of the ligand solution A is 0.025 mol / L.

[0011] As a preferred embodiment of the present invention, the nickel salt includes nickel chloride, and the concentration of nickel ions in solution B is 0.1 mol / L.

[0012] As a preferred embodiment of the present invention, the molar ratio of nickel ions to tetrahydroxybenzene is 4:1.

[0013] As a preferred embodiment of the present invention, the thin film carrier comprises FTO glass.

[0014] As a preferred embodiment of the present invention, the stirring is carried out at room temperature and pressure for 16 hours.

[0015] The present invention also provides an application of the nickel-tetrahydroxybenzene coordination polymer film described above in electrochromic materials.

[0016] As a preferred technical solution of the present invention, the electrochromic material includes smart windows for buildings, anti-glare rearview mirrors for automobiles, and electronic paper displays.

[0017] This invention focuses on developing novel electrochromic materials, particularly electrochromic materials of metal-organic coordination polymers with controllable structures. The metal refers to a transition metal, which is formed through coordination with an organic compound. These polymers possess tunable structures, large specific surface areas, and high redox activity, offering significant advantages in constructing electrochromic materials highly sensitive to electrochemical signals. 1,2,4,5-Tetrahydroxybenzene, due to its large π-conjugated system and reversible intrinsic redox activity, exhibits a controllable optical modulation range after coordination with Ni. Furthermore, as a type of metal-organic coordination polymer, its structure is tunable. A class of polymers can be synthesized by replacing different transition metals such as Cu and Fe with organic ligands of varying structures. The synthesis method is simple, and this approach can continuously inject new high-performance materials into the field of electrochromism.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The nickel-tetrahydroxybenzene coordination polymer film provided by the present invention achieves a simple synthesis of high-performance color-changing film by optimizing the ratio of ligands to metal ions. It has the advantages of fast response speed, long cycle life and better electrochromic performance. It solves the technical bottleneck of low optical contrast and slow response speed of traditional electrochromic materials. The obtained film achieves reversible switching between light brown (faded state) and dark brown (colored state) under ±0.8V voltage drive. The optical contrast reaches 62.41% at a wavelength of 600nm. The coloring / fading response times are 12.3s and 21.4s, respectively. It is suitable for devices such as smart windows in buildings, anti-glare rearview mirrors in automobiles and electronic paper displays.

[0020] (2) The nickel-tetrahydroxybenzene coordination polymer film provided by the present invention uses 1,2,4,5-tetrahydroxybenzene (THB) as a redox active ligand and nickel ions as transition metal coordination centers. The transition metal coordination polymer film is prepared by chemical bath method. The synthesis method is simple and can inject new high-performance new materials into the field of electrochromism. It is suitable for large-scale promotion and application. Attached Figure Description

[0021] 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.

[0022] Figure 1 The photochromic images of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer film prepared in Example 1 at -0.8V / 0.8V.

[0023] Figure 2 CV diagram of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer film prepared in Example 1;

[0024] Figure 3 Optical contrast diagram of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer film prepared in Example 1;

[0025] Figure 4 The response time diagram is shown for the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer film prepared in Example 1. Detailed Implementation

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0032] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0033] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0034] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value and an intermediate value within the stated range, as well as any other stated value or an intermediate value within the stated range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described herein. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in embodiments or test examples of this application. All references to this specification are generally incorporated herein by reference to disclose and describe methods and / or materials associated with said references. In the event of any conflict with any incorporated references, the content of this application shall prevail.

[0036] It should be noted that all raw materials and / or reagents and / or instruments in the embodiments of this application were purchased on the market or prepared in accordance with conventional methods known to those skilled in the art.

[0037] The room temperature mentioned in the following examples refers to 20-35°C, and the normal pressure refers to standard atmospheric pressure, which will not be repeated below.

[0038] The technical solution of the present invention will be further illustrated by the following embodiments.

[0039] Example 1

[0040] The preparation steps of 1,2,4,5-tetrahydroxyphenylnickel coordination polymer films are as follows:

[0041] (1) Take 2×1.5cm 2 The FTO conductive glass was cut into pieces measuring 2×5cm. 2 The conductive surfaces were identified using a conductivity test. The FTO conductive glass was then ultrasonically treated in deionized water, ethanol, and acetone solutions for 15 minutes each. After that, the FTO conductive glass was dried in an oven at 60°C for later use.

[0042] (2) Weigh 0.0711 g of tetrahydroxybenzene using an electronic balance, and mix and dissolve the weighed sample in 20 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0043] (3) Weigh 0.2390 g of nickel chloride hexahydrate using an electronic balance, and mix and dissolve the weighed sample in 10 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0044] (4) The cleaned FTO glass obtained in step (1) is used as a substrate and fixed in the solution prepared in step (3).

[0045] (5) The solution obtained in step (2) is slowly poured into the solution obtained in step (4) while stirring at room temperature and normal pressure. After stirring for 16 hours, FTO glass with a 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer film is deposited.

[0046] Example 2

[0047] The preparation steps of 1,2,4,5-tetrahydroxyphenylnickel coordination polymer films are as follows:

[0048] (1) Prepare a size of 2×5cm 2 The FTO conductive glass was ultrasonically treated in deionized water, ethanol, and acetone solutions for 15 minutes in sequence, and then dried in an oven at 60°C for later use.

[0049] (2) Weigh 0.0711 g of tetrahydroxybenzene using an electronic balance, and mix and dissolve the weighed sample in 20 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0050] (3) Weigh 0.2390 g of nickel chloride hexahydrate using an electronic balance, and mix and dissolve the weighed sample in 10 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0051] (4) The cleaned FTO glass obtained in step (1) is used as a substrate and fixed in the solution prepared in step (3).

[0052] (5) The solution obtained in step (2) is slowly poured into the solution obtained in step (4) while stirring at room temperature and normal pressure. After stirring for 8 hours, FTO glass with a 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer film is deposited.

[0053] Example 3

[0054] The preparation steps of 1,2,4,5-tetrahydroxyphenylnickel coordination polymer films are as follows:

[0055] (1) Prepare a size of 2×5cm 2 The FTO conductive glass was ultrasonically treated in deionized water, ethanol, and acetone solutions for 15 minutes in sequence, and then dried in an oven at 60°C for later use.

[0056] (2) Weigh 0.0711 g of tetrahydroxybenzene using an electronic balance, and mix and dissolve the weighed sample in 20 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0057] (3) Weigh 0.4780 g of nickel chloride hexahydrate using an electronic balance, and mix and dissolve the weighed sample in 10 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0058] (4) The cleaned FTO glass obtained in step (1) is used as a substrate and fixed in the solution prepared in step (3).

[0059] (5) The solution obtained in step (2) is slowly poured into the solution obtained in step (4) while stirring at room temperature and normal pressure. After stirring for 16 hours, FTO glass with a 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer film is deposited.

[0060] Example 4

[0061] The preparation steps of 1,2,4,5-tetrahydroxyphenylnickel coordination polymer films are as follows:

[0062] (1) Prepare a size of 2×5cm 2 The FTO conductive glass was ultrasonically treated in deionized water, ethanol, and acetone solutions for 15 minutes in sequence, and then dried in an oven at 60°C for later use.

[0063] (2) Weigh 0.1422 g of tetrahydroxybenzene using an electronic balance, and dissolve the weighed sample in 20 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0064] (3) Weigh 0.2390 g of nickel chloride hexahydrate using an electronic balance, and mix and dissolve the weighed sample in 10 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0065] (4) The cleaned FTO glass obtained in step (1) is used as a substrate and fixed in the solution prepared in step (3).

[0066] (5) The solution obtained in step (2) is slowly poured into the solution obtained in step (4) while stirring at room temperature and normal pressure. After stirring for 16 hours, FTO glass with a 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer film is deposited.

[0067] Comparative Example 1

[0068] (1) Take 2×1.5cm 2 The FTO conductive glass was cut into pieces measuring 2×5cm. 2The conductive surfaces were identified using a conductivity test. The FTO conductive glass was then ultrasonically treated in deionized water, ethanol, and acetone solutions for 15 minutes each. After that, the FTO conductive glass was dried in an oven at 60°C for later use.

[0069] (2) Weigh 0.0711 g of tetrahydroxybenzene using an electronic balance, and mix and dissolve the weighed sample in 20 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0070] (3) The cleaned FTO glass obtained in step (1) is used as a substrate and fixed in the solution prepared in step (3); and stirred for 16 hours at room temperature and normal pressure.

[0071] The results showed that film could not be formed on FTO glass.

[0072] Comparative Example 2

[0073] (1) Take 2×1.5cm 2 The FTO conductive glass was cut into pieces measuring 2×5cm. 2 The conductive surfaces were identified using a conductivity test. The FTO conductive glass was then ultrasonically treated in deionized water, ethanol, and acetone solutions for 15 minutes each. After that, the FTO conductive glass was dried in an oven at 60°C for later use.

[0074] (2) Weigh 0.2390 g of nickel chloride hexahydrate using an electronic balance, and dissolve the weighed sample in 10 mL of deionized water solvent. Stir with a magnetic stirrer for 30 minutes.

[0075] (3) The cleaned FTO glass obtained in step (1) is used as a substrate and fixed in the solution prepared in step (2); and stirred for 16 hours at room temperature and normal pressure.

[0076] The results showed that film could not be formed on FTO glass.

[0077] Effect verification

[0078] 1. Film color-changing properties

[0079] The electrochromic properties of the polymer films prepared in Examples 1-4 were verified. The electrochromic test was conducted in a three-electrode system with pure platinum wire as the counter electrode, pure silver wire as the reference electrode, and the prepared polymer film as the working electrode in 1M KOH electrolyte.

[0080] The results showed that only the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer film prepared in Example 1 exhibited discoloration, while the polymer films in Examples 2 to 4 did not show discoloration.

[0081] Figure 1These are photographs showing the color change of the 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer film prepared from the organic compound 1,2,4,5-tetrahydroxyphenyl by a chemical bath method in Example 1 of this invention. It can be seen that when a voltage of +0.8V is applied, the film color changes from light brown to dark brown. The film exhibits stable performance and uniform color change during the testing process.

[0082] In addition, the film described in this invention was not damaged during the preparation process, the preparation process is simple and easy, and the film has good performance.

[0083] 2. Electrochemical performance

[0084] Figure 2 The cyclic voltammetric characteristic (CV) curves of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer electrochromic thin film prepared in Example 1 of this invention characterize the electrochemical performance of the electrochromic thin film.

[0085] Electrochemical testing was conducted using a three-electrode system with a silver wire electrode as the reference electrode, a platinum wire electrode as the counter electrode, and the prepared 1,2,4,5-tetrahydroxyphenyl nickel-copper coordination polymer electrochromic film as the working electrode. 1M KOH was used as the electrolyte. Cyclic voltammetry (CV) was employed at a scan rate of 0.02 V / s within the range of -0.8 to 0.8 V.

[0086] The 1,2,4,5-tetrahydroxyphenylnickel coordination polymer electrochromic film exhibits a pair of reversible redox peaks, indicating that the film possesses electrochemical activity and reversible cycling performance. Furthermore, the small potential difference between the oxidation and reduction peaks suggests a rapid electron transfer rate, indicating a lower driving force for the redox process. These results demonstrate that the 1,2,4,5-tetrahydroxyphenylnickel film can establish a superior donor-acceptor system to promote electron transfer, thereby achieving superior electrochromic performance.

[0087] 3. Optical contrast image

[0088] To investigate the optical properties of 1,2,4,5-tetrahydroxyphenylnickel coordination polymer electrochromic films under different voltages, their spectroelectrochemical behavior was studied using a UV-Vis spectrometer and an electrochromic cycling tester. Figure 3 The optical contrast (ΔT) image of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer electrochromic film prepared in Example 1 of this invention.

[0089] Voltage-dependent UV-Vis transmittance curves are as follows Figure 3As shown, the transmittance of the colored films decreases significantly in the wavelength range of 300-1300 nm. Notably, the 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer exhibits genuine dark brown electrochromic behavior in the colored state. Furthermore, the 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer electrochromic films all exhibit a reversible process between light brown and dark brown, which is caused by reversible redox pairs under electrochemical bias.

[0090] 4. Response time graph

[0091] Figure 4 The image shows the response time of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer electrochromic film prepared in Example 1. The electrochromic switching speed of the 1,2,4,5-tetrahydroxyphenylnickel coordination polymer electrochromic film was evaluated at a wavelength of 600.0 nm. The response time is defined as the time required for the optical transmittance change to reach an optical contrast of 62.41%.

[0092] The results in the figure show that the coloring / bleaching response times (tc / tb) of the 1,2,4,5-tetrahydroxyphenyl nickel coordination polymer electrochromic film are 12.3 s and 21.4 s, respectively. Due to the fast electrochemical response of the film, it exhibits a shorter coloring time and bleaching time.

[0093] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0094] The above are merely preferred embodiments of the present invention, but 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 nickel-tetrahydroxybenzene coordination polymer film, characterized in that, It includes the redox-active ligand 1,2,4,5-tetrahydroxybenzene and the transition metal coordination center nickel ion.

2. A method for preparing a nickel-tetrahydroxybenzene coordination polymer film according to claim 1, characterized in that, The process includes the following steps: dissolving tetrahydroxybenzene in water to obtain ligand solution A; dissolving a nickel salt in water to obtain solution B; placing a film carrier in solution B; adding solution A to solution B and stirring to obtain the nickel-tetrahydroxybenzene coordination polymer film.

3. The preparation method according to claim 2, characterized in that, The concentration of the ligand solution A is 0.025 mol / L.

4. The preparation method according to claim 2, characterized in that, The nickel salt includes nickel chloride, and the concentration of nickel ions in solution B is 0.1 mol / L.

5. The preparation method according to claim 2, characterized in that, The molar ratio of nickel ions to tetrahydroxybenzene is 4:

1.

6. The preparation method according to claim 2, characterized in that, The thin film carrier includes FTO glass.

7. The preparation method according to claim 2, characterized in that, The stirring was carried out at room temperature and pressure for 16 hours.

8. The application of the nickel-tetrahydroxybenzene coordination polymer film according to claim 1 in electrochromic materials.

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