Preparation method and application of nickel hydrogen phosphate electrochromic nanomaterial

Abstract

This invention belongs to the field of materials technology and relates to a method for preparing and applying nickel hydrogen phosphate electrochromic nanomaterials. It overcomes the technical problems of existing nickel-based electrochromic materials, such as low transmittance, small optical modulation range, and difficulty in large-size fabrication after film deposition on transparent conductive substrates. The method for preparing the described nickel hydrogen phosphate electrochromic film employs room-temperature electrodeposition technology. The prepared nickel hydrogen phosphate electrochromic material exhibits small, uniform nanoparticle size and allows for the construction of large-size in-situ films (10 × 10 cm). 2 The characteristics of this method make it suitable for constructing high-performance electrochromic films. The prepared films have the characteristics of high transmittance in the faded state, wide spectral modulation range, and high coloring efficiency. Moreover, the preparation process is low-cost and efficient, and can be mass-produced, making it easy to realize industrial production. It has broad application prospects in the fields of electrochromism, flexible wearables, and smart displays.

Description

Technical Field

[0001] This invention belongs to the field of materials technology and relates to a method for preparing and applying nickel hydrogen phosphate electrochromic nanomaterials. Background Technology

[0002] Electrochromism (EC) refers to the phenomenon where the optical properties of a material undergo stable and reversible changes under the influence of an applied electric field. It can be applied in fields such as smart windows, energy-saving displays, anti-glare rearview mirrors, and electronic tags. Inorganic transition metal oxide-based electrochromic materials possess advantages such as high color purity and good chemical stability. Among them, nickel-based electrochromic materials have been extensively studied and have achieved considerable commercial prospects due to their low cost and neutral coloring properties. However, the low intrinsic conductivity and limited electrochemical activity of currently widely studied nickel oxide electrochromic materials result in problems such as a small optical modulation range and low coloring efficiency during the electrochromic process, greatly limiting their application in the field of smart windows. Therefore, researchers have been committed to enhancing the electrochemical activity of nickel-based electrochromic materials through structural design, thereby accelerating the co-intercalation / deintercalation of ions and electrons in the electrode material to improve the controllability of smart windows.

[0003] From a compositional design perspective, exploring electrochromic materials with high electrochemical activity is a wise and powerful approach to significantly improve their performance. In this regard, transition metal phosphates (TMPs) are a highly promising candidate material. Benefiting from their layered structure formed by metal-oxygen hexahedrons and phosphorus-oxygen tetrahedra, they possess a large number of unsaturated coordination surface atoms, thus exposing more active sites. Simultaneously, the HPO4 coordinated in TMPs... 2- Due to their Lewis acid properties, anions can act as hydroxide ion traps, effectively enhancing the adsorption capacity of hydroxide ions. Therefore, compared to transition metal oxides, TMP-type electrode materials exhibit improved electrochemical activity and electronic conductivity in alkaline electrolytes. Nickel hydride phosphate, as a typical TMP nanomaterial, has demonstrated its potential application value in multiple fields such as electrochemical energy storage and electrocatalysis through recent research.

[0004] Currently reported methods for preparing nickel hydrogen phosphate nanomaterials mainly include hydrothermal and solvothermal methods (Wang Z., Wu Y., Cui M., et al. 1D NiHPO4 nanotubes prepared using dissolutionequilibrium as bifunctional electrocatalyst for high-efficiency watersplitting[J]. Journal of Power Sources, 2021, 513: 230543.; Wang Z., Chen F., Kannan P., et al. Nickel phosphate nanowires directly grown on Ni foam as binder-free electron for pseudocapacitors[J]. Materials Letters, 2019, 257: 126742.). These reactions usually require high temperature and high pressure conditions, which places high demands on equipment, has poor safety performance, and makes it difficult to expand the container. Moreover, the high cost and complex process limit the practical application of large-area electrochromic films. Therefore, exploring a simple and scalable synthesis technology for nickel hydrogen phosphate electrochromic materials is of great practical and scientific significance for the development of high-performance, large-area smart windows. Summary of the Invention

[0005] To address the technical problems of low transmittance, limited optical modulation range, and difficulty in large-size fabrication of existing nickel-based electrochromic materials on transparent conductive substrates, this invention proposes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their applications. The preparation method provided by this invention has the advantages of enabling large-size fabrication at room temperature and pressure. The prepared nickel hydrogen phosphate electrochromic nanomaterials have nanoscale particle sizes and uniform distribution, making them suitable for constructing high-performance electrochromic thin films. The constructed films exhibit advantages such as ultra-wide optical modulation range, high coloring efficiency, and fast conversion speed. Furthermore, the film preparation process is simple, low-cost, highly scalable, and easily scalable for industrial production.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for preparing nickel hydrogen phosphate electrochromic nanomaterials, comprising the following steps:

[0008] Nickel salt and phosphate were dissolved in a mixed solution to prepare a precursor solution. The precursor solution was then used as an electrolyte and deposited on a conductive substrate by electrodeposition. After drying, nickel hydrogen phosphate electrochromic nanomaterials were obtained.

[0009] Furthermore, the nickel salt is any one or more of nickel salts such as nickel nitrate hexahydrate, nickel chloride, or nickel sulfate; the phosphate is any one or more of phosphates such as sodium hypophosphite, potassium phosphite, or potassium hypophosphite; and the mixed solution is a mixture of deionized water and / or an alcohol solvent in any proportion, wherein the alcohol solvent is any one or more of alcohols such as methanol, ethanol, or isopropanol.

[0010] Furthermore, the nickel salt is nickel nitrate hexahydrate; the phosphate is sodium hypophosphite.

[0011] Preferably, the mixed solution is a mixture of deionized water and alcohol solvent in a volume ratio of 1:9 to 9:1.

[0012] Furthermore, the concentration of the nickel salt in the precursor solution is 0.1 mmol / L to 1 mol / L, and the concentration of the phosphate in the precursor solution is 0.1 mmol / L to 1 mol / L.

[0013] Furthermore, it is preferable to use stirring or ultrasound to completely dissolve the raw materials.

[0014] Furthermore, the conductive substrate needs to be cleaned before electrodeposition to remove surface contaminants.

[0015] Furthermore, electrodeposition technology is performed using a three-electrode system or a two-electrode system. In the three-electrode system, a conductive substrate is used as the working electrode, graphite, platinum sheet, or conductive glass is used as the counter electrode, and Ag / AgCl, calomel electrode, hydrogen electrode, or mercury / mercury oxide electrode is used as the reference electrode. In the two-electrode system, a conductive substrate is used as the working electrode, and graphite, platinum sheet, or conductive glass is used as the counter electrode.

[0016] Preferably, electrodeposition is performed using a three-electrode system, wherein the three-electrode system uses a conductive substrate as the working electrode, any one of graphite, platinum sheet or conductive glass as the counter electrode, and any one of Ag / AgCl, calomel electrode, hydrogen electrode or mercury / mercury oxide electrode as the reference electrode.

[0017] Furthermore, the electrodeposition technique is any one of constant voltage deposition, constant current deposition, or cyclic voltammetry deposition, with a deposition potential range of -1.5 to 0.7 V (vs. Ag / AgCl) and a deposition current range of 0.01 to 5 mA cm⁻¹. -2 The scan rate is 1–200 mV / s.

[0018] Furthermore, the drying temperature is 40-90℃, and the drying time is 5-24 hours.

[0019] Furthermore, the nickel hydrogen phosphate electrochromic nanomaterials prepared by the above method.

[0020] Furthermore, the application of the nickel hydrogen phosphate electrochromic nanomaterial in the preparation of nickel hydrogen phosphate electrochromic thin films.

[0021] Furthermore, a conductive substrate was selected for preparing the nickel hydrogen phosphate electrochromic thin film.

[0022] Preferably, a transparent conductive substrate is used to prepare the nickel hydrogen phosphate electrochromic thin film.

[0023] The present invention has the following beneficial effects:

[0024] 1. This invention employs a room-temperature electrodeposition synthesis technique to prepare nickel hydrogen phosphate electrochromic nanomaterials with uniform particle size and distribution. Simultaneously, high-quality electrochromic films are constructed on various transparent conductive substrates. This synthesis technique can be carried out at room temperature and pressure, and has advantages such as simple preparation process, low cost, and strong scalability. Therefore, this invention is more suitable for industrial production.

[0025] 2. The nickel hydrogen phosphate electrochromic film prepared by this invention has a large area and exhibits higher electrochemical activity and conductivity, wherein the construction area of ​​the nickel hydrogen phosphate electrochromic film reaches 10 × 10 cm. 2 Furthermore, the transmittance is close to 100% in the 300-800nm ​​wavelength range, and remains consistent across different locations, thus exhibiting excellent large-area uniformity. Simultaneously, this film demonstrates high optical modulation (90.8% at 500nm wavelength), fast conversion speed (color conversion time of 7.1s, fading time of 9.6s), and high coloring efficiency (coloring efficiency of 75.4cm). 2 C -1 With its advantages such as electrochromism, it can be applied not only to the field of electrochromism, but also has broad application prospects in fields such as electrochemical energy storage, electrocatalysis and photocatalysis. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0027] Figure 1 This refers to a 10×10 cm substrate prepared on a transparent conductive FTO (fluorine-doped tin oxide) substrate, as described in Example 1 of the present invention. 2 Nickel phosphate thin film. Wherein, a is a digital photograph of the thin film sample, and b is the transmittance spectrum of the thin film at three different locations in the wavelength range of 300-800 nm.

[0028] Figure 2 Example 1 of the present invention is performed at -1.2 to 0.2V vs. Ag. + / Ag potential window and 20mV s -1 Deposition curves of nickel hydrogen phosphate thin films prepared by cyclic voltammetry under the specified conditions.

[0029] Figure 3 The X-ray diffraction patterns are those of the nickel hydrogen phosphate thin film and the standard card prepared by electrodeposition in Example 1 of this invention.

[0030] Figure 4 The images show the morphology and elemental distribution of the nickel hydrogen phosphate thin film prepared in Example 1 of this invention. In the images, a represents the surface under a scanning electron microscope, b represents a cross-section, c represents a transmission electron microscope image, and d represents a schematic diagram of the elemental distribution using EDS.

[0031] Figure 5 The X-ray photoelectron spectrum and surface elemental ratio analysis of the nickel hydrogen phosphate thin film prepared in Example 1 of this invention are shown.

[0032] Figure 6 The nanomaterial films of Example 1 and Comparative Example 1 of this invention were tested in 1M KOH electrolyte at -1.2 to 0.2 V vs. Ag. + Within the potential window of / Ag, at 20mV s -1 Cyclic voltammetry curves from the sweep rate test.

[0033] Figure 7 This is a comparison chart of the Nyquist curves of the nanomaterial thin films prepared in Example 1 and Comparative Example 1 of the present invention.

[0034] Figure 8 This diagram shows the electrochemical and electrochromic properties of the nickel hydride phosphate thin film prepared in Example 1 of this invention. Where a is represented by 10 mV s⁻¹. -1 Cyclic voltammetry curves and in-situ response spectra at 500 nm were measured using a scan rate; b represents colored (0.7V vs. Ag). + / Ag) and fading (0V vs. Ag) + The transmittance spectrum of the film in the Ag state at wavelengths of 300–800 nm is shown in the inset. The inset is a digital photograph of the faded and colored states; c represents the transmittance spectra of the film at 0 and 0.7 V (vs. Ag). + The current density and in-situ spectral response were collected at 500 nm after 30 s of alternating potential ( / Ag); d is the relationship curve between the optical density and charge density of the thin film at 500 nm.

[0035] Figure 9 This is a data comparison chart of the optical modulation range and state transition time of the nickel hydrogen phosphate thin films prepared in Examples 1, 3, 4 and 5 of this invention.

[0036] Figure 10 This is a data comparison chart of the optical modulation range of nickel hydrogen phosphate thin films prepared in Examples 1, 6 and 7 of the present invention.

[0037] Figure 11 The cycling stability curve of the nickel hydrogen phosphate thin film prepared in Example 1 of this invention was measured at a wavelength of 500 nm using chronoamperometry and in-situ response spectroscopy.

[0038] Figure 12 The nickel hydride phosphate prepared in Example 1 of this invention was prepared at concentrations of 0.4, 0.6, 0.8, 1.2, 1.6, and 2.4 Ag. -1 At current densities of 0–0.5V (vs. Ag), + Constant current charge-discharge curves within the potential range of / Ag).

[0039] Figure 13 The nickel hydrogen phosphate thin film prepared in Example 1 of this invention, where a represents the current density at 0.4 Ag. -1 b is the constant current charge-discharge curve at time t and the in-situ response spectrum corresponding to 500 nm; b is the optical modulation range and the relationship between specific capacity and current density of the thin film.

[0040] Figure 14 The diagram shows the structural configuration and electrochromic properties of the integrated multifunctional smart window made of nickel hydrogen phosphate film and titanium dioxide ion storage layer film prepared in Example 1 of this invention. Specifically, a is a schematic diagram of the multifunctional smart window structure; b is the transmittance spectrum of the multifunctional smart window in the colored (2.2V) and faded (-1.5V) states within the wavelength range of 300–800 nm; c is the in-situ transmittance response spectrum obtained at 500 nm after applying square wave voltages of 2.2V and -1.5V for 40 s; and d is the curve showing the change in optical density of the smart window at 500 nm as a function of charge density.

[0041] Figure 15 The 10×10cm integrated in Embodiment 1 of the present invention 2 The multifunctional electrochromic smart window model is shown in the following states: a) colored state, b) faded state, and c) digital photo driven by a power source.

[0042] Figure 16 In Example 2 of this invention, nickel hydrogen phosphate is deposited on an ITO / PET (indium tin oxide / polyethylene terephthalate) flexible transparent conductive substrate, where a represents coloring in the wavelength range of 300–800 nm (0.8V vs. Ag). + / Ag) and fading (-0.1V vs. Ag) +a) Transmittance spectrum in the / Ag) state; b) Digital photographs of the film in the bleached and colored states in the bent state. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0046] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., a solvent consisting of deionized water and anhydrous ethanol in a 1:1 volume ratio. Second, dissolve 0.2385 g of nickel nitrate hexahydrate and 0.1053 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thus obtaining the precursor solution.

[0047] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 4 cycles. Afterward, the material was vacuum dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic film with a thickness of 122 nm.

[0048] Example 2

[0049] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their flexible thin films, with the following steps:

[0050] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., a solvent consisting of deionized water and anhydrous ethanol in a 1:1 volume ratio. Second, dissolve 0.2385 g of nickel nitrate hexahydrate and 0.1053 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thus obtaining the precursor solution.

[0051] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 A flexible ITO / PET electrode (sheet resistance: 15 Ω / sq) was used as a transparent conductive substrate and ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol. It was then removed and dried with nitrogen gas for later use. Next, a three-electrode system was used for electrochemical deposition, with the conductive substrate, platinum sheet, and Ag / AgCl serving as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 4 cycles. The electrodeposition was then vacuum-dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on the transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0052] The difference between this embodiment and embodiment 1 is that in step S2, this embodiment utilizes 2×5cm 2 Flexible ITO / PET electrodes are used as transparent conductive substrates.

[0053] Example 3

[0054] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0055] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., a solvent consisting of deionized water and anhydrous ethanol in a 1:1 volume ratio. Second, dissolve 0.2385 g of nickel nitrate hexahydrate and 0.1053 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thus obtaining the precursor solution.

[0056] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 2 cycles. Afterward, the material was vacuum-dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0057] The difference between this embodiment and embodiment 1 is that in step S2, the deposition cycle is 2 cycles, while the other steps are the same as in embodiment 1.

[0058] Example 4

[0059] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0060] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., a solvent consisting of deionized water and anhydrous ethanol in a 1:1 volume ratio. Second, dissolve 0.2385 g of nickel nitrate hexahydrate and 0.1053 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thus obtaining the precursor solution.

[0061] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 6 cycles. Afterward, the material was vacuum-dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0062] The difference between this embodiment and Embodiment 1 is that in step S2, the deposition cycle is 6 cycles, while the other steps are the same as in Embodiment 1.

[0063] Example 5

[0064] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0065] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., a solvent consisting of deionized water and anhydrous ethanol in a 1:1 volume ratio. Second, dissolve 0.2385 g of nickel nitrate hexahydrate and 0.1053 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thus obtaining the precursor solution.

[0066] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 8 cycles. Afterward, the material was vacuum-dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0067] The difference between this embodiment and embodiment 1 is that in step S2, the deposition cycle is 8 cycles, while the other steps are the same as in embodiment 1.

[0068] Example 6

[0069] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0070] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., using deionized water and ethanol in a volume ratio of 1:1 as solvents. Second, dissolve 0.1590 g of nickel nitrate hexahydrate and 0.0702 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thereby obtaining the precursor solution.

[0071] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.5 to 0.5 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 4 cycles. Afterward, the material was vacuum dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0072] The difference between this embodiment and Embodiment 1 is that in step S1, the mass of nickel nitrate hexahydrate and sodium hypophosphite are 0.1590g and 0.0702g, respectively, while the other steps are the same as in Embodiment 1.

[0073] Example 7

[0074] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0075] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, which is a solvent of deionized water and isopropanol in a volume ratio of 1:1. Second, dissolve 0.1193 g of nickel nitrate hexahydrate and 0.0527 g of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thereby obtaining the precursor solution.

[0076] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.5 to 0.5 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 4 cycles. Afterward, the material was vacuum dried at 60 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0077] The difference between this embodiment and Embodiment 1 is that in step S1, the masses of nickel nitrate hexahydrate and sodium hypophosphite are 0.1193g and 0.0527g, respectively, while the other steps are the same as in Embodiment 1.

[0078] Example 8

[0079] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0080] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, which is a solvent of deionized water and isopropanol in a volume ratio of 1:9. Second, dissolve 0.01 mmol of nickel chloride and 0.01 mmol of potassium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 rpm for 30 min to ensure complete dissolution of the raw materials, thereby obtaining the precursor solution.

[0081] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, a three-electrode system was used for electrochemical deposition, with a conductive substrate, graphite, and calomel electrodes serving as the working, counter, and reference electrodes, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.5 to 0.5 V, a scan rate of 50 mV / s, and a deposition cycle of 6 cycles. Subsequent vacuum drying at 40 °C for 24 h yielded nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0082] Example 9

[0083] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0084] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, which is a solvent of deionized water and isopropanol in a volume ratio of 9:1. Second, dissolve 10 mmol of nickel sulfate and 10 mmol of potassium phosphite in 100 mL of a mixed solvent, and magnetically stir at 500 rpm for 30 min to ensure complete dissolution of the raw materials, thereby obtaining the precursor solution.

[0085] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 The FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, a three-electrode system was used for electrochemical deposition, with the conductive substrate, conductive glass, and hydrogen electrode serving as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.5 to 0.5 V, a scan rate of 10 mV / s, and a deposition cycle of 8 cycles. Afterward, the material was vacuum-dried at 70 °C for 12 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0086] Example 10

[0087] This embodiment describes a method for preparing nickel hydrogen phosphate electrochromic nanomaterials and their thin films, with the following steps:

[0088] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, which is a solvent of deionized water and isopropanol in a volume ratio of 9:1. Second, dissolve 100 mmol of nickel nitrate hexahydrate and 100 mmol of sodium hypophosphite in 100 mL of the mixed solvent, and magnetically stir at 500 rpm for 30 min to ensure complete dissolution of the raw materials, thereby obtaining the precursor solution.

[0089] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a two-electrode system, with a conductive substrate and a platinum sheet as the working and counter electrodes, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V, a scan rate of 200 mV / s, and a deposition cycle of 4 cycles. Afterward, the material was vacuum dried at 90℃ for 5 h to obtain nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic thin film.

[0090] Comparative Example 1

[0091] This comparative example demonstrates a method for preparing phosphorus-free electrochromic nanomaterials and their thin films, with the following steps:

[0092] S1. Dissolve the obtained nickel nitrate hexahydrate and sodium hypophosphite in a mixed solution of deionized water and anhydrous ethanol to prepare a precursor solution. Specifically, first, obtain a precursor solution for electrodeposition of the target product, i.e., a solvent consisting of deionized water and anhydrous ethanol in a 1:1 volume ratio. Second, dissolve 0.2385 g of nickel nitrate hexahydrate in 100 mL of the mixed solvent and magnetically stir at 500 r / min for 30 min to ensure complete dissolution of the raw materials, thus obtaining the precursor solution.

[0093] S2. Using the precursor solution obtained in step S1 as the electrolyte, nickel hydrogen phosphate nanomaterials and thin films are prepared on a conductive substrate by electrodeposition. Specifically, firstly, the substrate is divided into 2×5cm... 2 FTO (sheet resistance: 7Ω / sq) conductive glass was ultrasonically cleaned for 15 min each with acetone, deionized water, and anhydrous ethanol, and then dried with nitrogen gas for later use. Next, electrochemical deposition was performed using a three-electrode system, with a conductive substrate, a platinum sheet, and Ag / AgCl as the working electrode, counter electrode, and reference electrode, respectively. Cyclic voltammetry was used for electrodeposition, with a deposition potential range of -1.2 to 0.2 V (vs. Ag / AgCl), a scan rate of 20 mV / s, and a deposition cycle of 8 cycles. Subsequent vacuum drying at 60 °C for 12 h yielded nickel hydrogen phosphate nanomaterials on a transparent conductive substrate, simultaneously constructing an electrochromic film with a thickness of 122 nm.

[0094] The difference between this comparative example and Example 1 is that in step S1, when preparing the precursor solution for electrodeposition, only 0.2385g of nickel nitrate hexahydrate is dissolved in 100mL of mixed solvent. The other steps are the same as in Example 1 and will not be repeated here.

[0095] The nickel hydrogen phosphate electrochromic nanomaterials and thin films prepared in Example 1 and Application Example 1 were characterized and their performance was tested. At the same time, the performance of Examples 2, 3, 4, 5, 6, 7 and Comparative Example 1 was tested to further illustrate the advantages of the nickel hydrogen phosphate electrochromic nanomaterials and thin films prepared in Example 1.

[0096] Performance testing

[0097] (1) First, the composition, morphology and performance of the nickel hydrogen phosphate nanomaterial thin film obtained in Example 1 were characterized and analyzed. The specific results are as follows:

[0098] Figure 1 This refers to a 10×10 cm substrate prepared on a transparent conductive FTO (fluorine-doped tin oxide) substrate, as described in Example 1 of the present invention. 2 The image shows a nickel phosphate thin film, where a is a digital photograph of the film sample, and b is the transmittance spectrum of the film at three different locations in the wavelength range of 300–800 nm. Figure 1 As shown in figure a, the area that can be controlled by cyclic voltammetry is 10 × 10 cm². 2 Nickel hydride thin films exhibit excellent visualization properties, derived from... Figure 1 b shows that the transmittance of the film in the wavelength range of 300-800nm ​​is close to 100%, and the transmittance remains consistent at three different locations, which confirms the spatial uniformity of the large-area film.

[0099] Figure 2 In Embodiment 1 of the present invention, the temperature is between -1.2 and 0.2 V vs. Ag. + / Ag potential window and 20mVs -1 Deposition curves of nickel hydride phosphate thin films prepared by cyclic voltammetry under the specified conditions. Figure 2 As shown, the deposition curve during the thin film preparation process, NO during this electrochemical reaction. 3- OH- is generated on the FTO surface by reduction. - OH - Further with H2PO 2- The reaction yields HPO4 2- Meanwhile, the positively charged Ni in the electrolyte... 2+ Migrating to the negatively charged FTO surface, with HPO4 2- Nickel hydrogen phosphate film is formed directly on the FTO surface.

[0100] Figure 3 The images show the X-ray diffraction patterns of the nickel hydrogen phosphate thin film and the standard card prepared by electrodeposition in Example 1 of this invention. Figure 3As shown, X-ray diffraction (XRD) was performed on the electrodeposited film to determine its crystal structure, but almost no diffraction peaks other than FTO were detected, confirming the amorphous nature of the nickel hydrogen phosphate film. This amorphous structure typically endows electrode materials with enhanced charge transfer properties and improved electrochemical reaction kinetics.

[0101] Figure 4 The images show the morphology and elemental distribution of the nickel hydrogen phosphate thin film prepared in Example 1 of this invention, where a is the surface image under a scanning electron microscope, b is the cross-section, c is the image under a transmission electron microscope, and d is a schematic diagram of the elemental distribution under EDS. Figure 4 As shown in figure a, the morphology of the prepared nickel hydrogen phosphate film was characterized by field emission scanning electron microscopy (FESEM), and the results showed that nanoparticles with a particle size of approximately 100–120 nm grew uniformly on the FTO substrate. Figure 4 The elemental distribution characteristics of the prepared thin film were detected using X-ray energy dispersive spectroscopy (ESD). The test results showed that Ni, P, and O elements were present and uniformly distributed in the film. Therefore, it is demonstrated that P element was successfully introduced into the nickel-based electrochromic material using the electrodeposition strategy described in Example 1. Figure 4 As shown in Figure e, cross-sectional scanning using FESEM revealed a film thickness of approximately 122 nm. Further microstructural analysis was performed using transmission electron microscopy (TEM). Figure 4 f shows that the diameter of the nickel hydrogen phosphate nanoparticles is approximately 100 nm, which is consistent with the FESEM test results.

[0102] Figure 5 The X-ray photoelectron spectroscopy (XPS) and surface elemental composition analysis are shown for the nickel hydrogen phosphate thin film prepared in Example 1 of this invention. Figure 5 As shown in Figure a, the X-ray photoelectron spectroscopy (XPS) of the nickel hydrogen phosphate thin film prepared by electrodeposition in Example 1 revealed the presence of Ni, P, O, and C elements. Figure 5 In b, the 2p spectrum of Ni can be fitted to Ni 2+ (854.8 eV and 872.5 eV) and Ni 3+ The two spin-orbit double peaks (856.2 eV and 873.9 eV) are accompanied by two satellite peaks (860.8 eV and 879.1 eV). From Figure 5 The P2p spectrum in c shows two peaks at 132.9 eV and 133.7 eV, corresponding to the 2p3 / 2 and 2p1 / 2 of phosphorus-containing species, respectively. Furthermore, Figure 5The oxygen-containing bonds in the film were measured, and the O1s spectrum was divided into O1 (530.2 eV), O2 (530.7 eV), and O3 (531.5 eV), which are attributed to Ni-OP, POH, and H2O, respectively. These results demonstrate that nickel hydrogen phosphate films were successfully prepared via a one-step electrodeposition method.

[0103] (2) Next, cyclic voltammetry and electrochemical impedance spectroscopy were performed on the electrode materials prepared in Example 1 and Comparative Example 1.

[0104] Figure 6 The nanomaterial films of Example 1 and Comparative Example 1 of this invention were tested in 1M KOH electrolyte at -1.2 to 0.2 V vs. Ag. + Within the potential window of / Ag, at 20mV s -1 The cyclic voltammetry curves from the sweep rate test. (Example:) Figure 6 As shown, the electrochemical activity of the obtained nickel hydrogen phosphate film was significantly improved after the introduction of a phosphorus source.

[0105] Figure 7 This is a comparison of the Nyquist curves of the nanomaterial thin films prepared in Example 1 and Comparative Example 1 of the present invention. Figure 7 The Nyquist plots shown indicate that the charge transfer impedance of the thin-film electrode was 38.6 Ω before the introduction of phosphorus, and decreased to 33.5 Ω after the introduction of phosphorus. Therefore, the introduction of phosphorus into the electrode material reduces the charge transfer impedance, thereby promoting electron transfer between the current collector and the electrode material.

[0106] (3) Furthermore, the electrochemical and electrochromic properties of the nickel hydrogen phosphate film in Example 1 in 1M KOH electrolyte were investigated using a spectroelectrochemical three-electrode system.

[0107] Figure 8 This is a graph showing the electrochemical and electrochromic properties of the nickel hydride phosphate thin film prepared in Example 1 of this invention, where a is expressed as 10 mV s. -1 Cyclic voltammetry curves and in-situ response spectra at 500 nm were measured using a scan rate; b represents colored (0.7V vs. Ag). + / Ag) and fading (0V vs. Ag) + The transmittance spectrum of the film in the Ag state at wavelengths of 300–800 nm is shown in the inset. The inset is a digital photograph of the faded and colored states; c represents the transmittance spectra of the film at 0 and 0.7 V (vs. Ag). + The current density and in-situ spectral response were collected at 500 nm after 30 s of alternating potentials ( / Ag); d is the relationship curve between the optical density and charge density of the thin film at 500 nm. Figure 8 As shown in a, at 10mV s -1Cyclic voltammetry was performed on the thin film at a scan rate of 0.3–0.7 V (vs. Ag+ / Ag), and its in-situ spectral response at 500 nm was also measured. + During the oxidation of / Ag) OH - When embedded in the electrode material, the transmittance of the nickel hydride phosphate film gradually decreases, until the potential returns to 0V (vs. Ag). + / Ag) when, with OH - As the film's permeability dynamically increases, it exhibits good electrochemical reversibility. For example... Figure 8 As shown in b, the nickel hydrogen phosphate film prepared in Example 1 fades (0V vs. Ag). + Ag maintains nearly 100% transmittance in the wavelength range of 300–800 nm, and after coloring (0V vs. Ag) + The transmittance of the film ( / Ag) at 500 nm is only 8.7%, thus achieving an optical modulation of up to 90.8% at 500 nm. The insets are digital photographs of the film in faded and colored states, respectively. Additionally, as... Figure 8 As shown in c and d, the transition times between the colored and faded states of the film are 7.1 s and 9.6 s, respectively, with a coloring efficiency of 75.4 cm⁻¹. 2 C -1 .

[0108] Figure 9 This is a comparison chart of the optical modulation range and state transition time of the nickel hydrogen phosphate thin films prepared in Examples 1, 3, 4, and 5 of this invention. Figure 9 As shown, the optical modulation range and conversion time of the nickel hydrogen phosphate films prepared in Examples 1, 3, 4, and 5 were compared. The test results show that with the increase of the electrodeposition cycle, the optical modulation begins to decrease, and the conversion time continues to prolong. This is mainly because the electrode material is deposited too thickly on the FTO surface, resulting in a decrease in the transmittance of the faded state and a prolongation of the ion and electron transport paths.

[0109] Figure 10 This is a data comparison chart of the optical modulation range of nickel hydrogen phosphate thin films prepared in Examples 1, 6 and 7 of the present invention. Figure 10 The raw material mass was compared with that of Example 1, where the raw material mass of Example 6 was 2 / 3 of that of Example 1, and the raw material mass of Example 7 was 1 / 2 of that of Example 1. The results show that the amount of active material in the precursor solution used for electrodeposition is positively correlated with the preparation efficiency of nickel hydride phosphate films; more active material accelerates film formation and enables greater optical modulation.

[0110] also, Figure 11The cycling stability curves of the nickel hydrogen phosphate thin film prepared in Example 1 of this invention were measured at a wavelength of 500 nm using chronoamperometry and in-situ response spectroscopy. Figure 11 As shown, after 300 electrochromic cycles, the optical modulation range of the nickel hydrogen phosphate film prepared in Example 1 remained at 76.1% of its initial value, indicating that the film has good cycling stability.

[0111] Considering the excellent electrochromic properties of the thin film in Example 1, further [the experiment was conducted] at 0–0.5V (vs. Ag). + The energy storage properties of the thin film were tested within the range of / Ag). Figure 12 The nickel hydride phosphate prepared in Example 1 of this invention was prepared at concentrations of 0.4, 0.6, 0.8, 1.2, 1.6, and 2.4 Ag. -1 At current densities of 0–0.5V (vs. Ag), + The constant current charge-discharge curves within the potential range of / Ag) are obtained. This is achieved through... Figure 12 Analysis of the data reveals that the charge-discharge curves at different current densities fall within the ranges of 0.36–0.42 V and 0.34–0.29 V (vs. Ag). + The film exhibits a pair of distinct plateaus, corresponding to the charging (oxidation) and discharging (reduction) processes of the Ag film, respectively. Furthermore, the symmetrical charge-discharge curves of the film in Example 1 demonstrate its high coulombic efficiency and electrochemical reversibility. These plateaus are observed at Ag values ​​of 0.4, 0.6, 0.8, 1.2, 1.6, and 2.4. -1 At current densities of [values ​​missing], their specific capacities reached 47.8, 44.6, 42.4, 37.4, 35.2, and 28.3 mAh g, respectively. -1 .

[0112] At the same time, with 0.4Ag -1 When the current density was used for charge and discharge testing, the in-situ response spectrum was recorded at a wavelength of 500 nm. Figure 13 The nickel phosphate thin film prepared in Example 1 of this invention, a, is subjected to a current density of 0.4 Ag -1 a) Constant current charge-discharge curves and in-situ response spectrum at 500 nm; b) Optical modulation range and specific capacity versus current density curves of the thin film. Figure 13 During the charging process shown in Figure a, the transmittance of the thin film prepared in Example 1 gradually decreases with the change in color. When the charging potential reaches 0.5V (vs. Ag), the transmittance decreases further. + When Ag is discharged, the film appears brownish-black. In the reverse process, the film discharges to 0V (vs. Ag). + When / Ag), the color gradually fades until it returns to high transmittance. It is worth noting that... Figure 12 b, even with a current density as high as 2.4Ag-1 The optical modulation still reaches 40%, proving the excellent rate capability of the film.

[0113] at last, Figure 14 This document presents the structural configuration and electrochromic properties of the integrated multifunctional smart window, comprising a nickel phosphate thin film and a titanium dioxide ion storage layer thin film prepared in Example 1 of this invention. Figure a shows a schematic diagram of the multifunctional smart window; figure b shows the transmittance spectra of the multifunctional smart window in the colored (2.2V) and faded (-1.5V) states within the wavelength range of 300–800 nm; figure c shows the in-situ transmittance response spectrum obtained at 500 nm after applying square wave voltages of 2.2V and -1.5V for 40 s; and figure d shows the curve of optical density versus charge density at 500 nm for the smart window. Based on the nickel phosphate thin film prepared in Example 1, according to… Figure 14 The device structure in a further integrates a 10×10cm 2 Smart window models, such as Figure 14 As shown in b, c, and d, this smart window achieves 73.5% optical modulation range at a single wavelength of 500 nm, with coloring and fading rates of 21.6 s and 26.6 s, respectively, and a coloring efficiency of 66.5 cm⁻¹. 2 C -1 .

[0114] Figure 15 The 10×10cm integrated in Embodiment 1 of the present invention 2 The multifunctional electrochromic smart window model is shown in states a (colored), b (faded), and c (digital photographs driven by a power source). Figure 15 It can be observed that the colored smart window significantly reduces the field of view, thus protecting the privacy of the residents. When returning... Figure 15 As shown in b, the faded state restores the field of view of the smart window, enabling intelligent management of incident natural light and laying a solid foundation for the application of Example 1 in energy-efficient buildings. Furthermore, the designed smart window not only possesses the aforementioned optical modulation capabilities but also has energy storage properties. A 10×10cm... 2 The smart window can provide sufficient energy to power the digital meter. Therefore, the smart window integrated based on Embodiment 1 achieves energy saving while realizing the recovery and reuse of electrical energy, which is an effective way to implement the energy conservation and emission reduction strategy.

[0115] To verify the feasibility of the strategy in Example 1 on different substrates, a nickel hydrogen phosphate electrochromic film was electrodeposited on a flexible ITO / PET transparent conductive substrate. The electrochromic properties of the nickel hydrogen phosphate film in Example 2 in 1M KOH electrolyte were investigated using a spectroelectrochemical system.

[0116] Figure 16In Example 2 of this invention, nickel hydrogen phosphate is deposited on an ITO / PET (indium tin oxide / polyethylene terephthalate) flexible transparent conductive substrate, where a represents coloring in the wavelength range of 300–800 nm (0.8V vs. Ag). + / Ag) and fading (-0.1V vs. Ag) + Transmittance spectrum in the / Ag) state; b. Digital photographs of the film in the bleached and colored states under bending conditions. Figure 16 As shown in figure a, 76.7% of the optical modulation range can be achieved at 500 nm. Meanwhile, through... Figure 16 The digital photographs shown in b are of the colored and faded states on the flexible ITO / PET substrate. The film still exhibits stable electrochromic behavior in the bent state, further confirming the feasibility of the electrodeposition strategy proposed in Example 1.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing nickel hydrogen phosphate electrochromic nanomaterials, characterized in that: Nickel salt and phosphate were dissolved in a mixed solution to prepare a precursor solution. Then, the precursor solution was used as an electrolyte and deposited on a conductive substrate by electrodeposition technology. After drying, nickel hydrogen phosphate electrochromic nanomaterials were obtained. The nickel salt is any one or more of nickel nitrate hexahydrate, nickel chloride, or nickel sulfate; the phosphate is any one or more of sodium hypophosphite, potassium phosphite, or potassium hypophosphite phosphate; the mixed solution is a mixture of deionized water and / or an alcohol solvent in any proportion, wherein the alcohol solvent is any one or more of methanol, ethanol, or isopropanol. The concentration of the nickel salt in the precursor solution is 0.1 mmol / L to 1 mol / L; The concentration of the phosphate in the precursor solution is 0.1 mmol / L to 1 mol / L; The deposition potential ranges from -1.5 to 0.7 V, and the deposition current ranges from 0.01 to 5 mA cm⁻¹. -2 The scan rate is 1~200mV / s.

2. The method for preparing nickel hydrogen phosphate electrochromic nanomaterials according to claim 1, characterized in that: Before performing electrodeposition, the conductive substrate needs to be cleaned to remove surface contaminants.

3. The method for preparing nickel hydrogen phosphate electrochromic nanomaterials according to claim 2, characterized in that: Electrodeposition technology is performed using a three-electrode system or a two-electrode system. In the three-electrode system, a conductive substrate is used as the working electrode, graphite, platinum sheet, or conductive glass is used as the counter electrode, and Ag / AgCl, calomel electrode, hydrogen electrode, or mercury / mercuric oxide electrode is used as the reference electrode. In the two-electrode system, a conductive substrate is used as the working electrode, and graphite, platinum sheet, or conductive glass is used as the counter electrode.

4. The method for preparing nickel hydrogen phosphate electrochromic nanomaterials according to claim 3, characterized in that: The electrodeposition technique is any one of constant voltage deposition, constant current deposition, or cyclic voltammetry mode.

5. The method for preparing nickel hydrogen phosphate electrochromic nanomaterials according to claim 4, characterized in that: The drying temperature is 40~90℃, and the drying time is 5~24h.

6. Nickel hydrogen phosphate electrochromic nanomaterials prepared by any one of claims 1-5.

7. The application of the nickel hydrogen phosphate electrochromic nanomaterial according to claim 6 in the preparation of nickel hydrogen phosphate electrochromic thin films.

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