Preparation method of NiO / Co3O4 composite film for electrochromism

Abstract

The invention discloses a preparation method of a NiO / Co3O4 composite film for electrochromism, which comprises the following steps: preparing a NiO film by adopting an optimized hydrothermal method, and depositing Co3O4 nanoparticles on the NiO film by taking the NiO film as a reaction substrate and adopting an electrodeposition method to finally obtain the NiO / Co3O4 composite film. According to the prepared composite film, the response time of NiO is prolonged, the electrochromism efficiency is improved, the improvement of the electrochromism performance is promoted, the preparation method is simple and easy to operate, and the overall cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of electrochromic thin film materials, and in particular relates to a method for preparing a NiO / Co3O4 composite thin film for electrochromism. Background Art

[0002] With the growth of population, environmental pollution and energy shortage have become serious problems facing the world. Among them, the energy crisis (energy shortage) is mainly caused by the excessive consumption of fossil fuels, and has become one of the serious problems facing today's society. Among the existing urban and rural buildings in my country, the vast majority are still energy-consuming buildings. Windows, as an important component of buildings, are one of the main ways of energy loss in buildings. According to statistics, the energy lost through windows and the energy consumed by indoor heating and air conditioning each year account for 60% of the total energy consumption. At present, although the ordinary glass used in buildings has good light transmission performance, the heat insulation effect is poor, resulting in more than 50% of the energy consumption of buildings being lost from doors and windows. Therefore, energy saving in doors and windows is very important. At present, domestic and foreign buildings mainly use hollow glass, vacuum glass, and blinds for heat insulation and light adjustment, but they have the disadvantages of fixed thermal conductivity and light transmittance, and cannot be adjusted according to seasons, weather, and light. The electrochromic smart window made based on the electrochromic effect can perfectly solve the above problems.

[0003] Since the concept of electrochromism was first proposed by foreign scholar Plat in the 1960s, the electrochromism phenomenon has attracted widespread attention. In the 1970s, people discovered that many transition metal oxides also have electrochromic properties. NiO material undergoes electrochromic reaction in LiClO4 / PC solution. It is generally believed that its electrochromic mechanism is the same as that of WO3 cathode electrochromic material, but its color change is opposite. NiO in Li + When embedded (reduced state), a fading reaction occurs, while in Li + When NiO is released (oxidized state), a coloring reaction occurs. + When electrochromic reaction occurs in organic solution, its volume change rate is very small and its stability is good. However, the light modulation range of NiO is relatively small, and it can only switch between gray and colorless. The long electrochromic response time limits its application. The performance of a single electrochromic material can no longer meet the needs of practical applications, and composite nano-electrochromic materials are gaining more and more attention. Summary of the invention

[0004] In order to solve the above-mentioned problems of NiO nanosheets in electrochromism, the purpose of the present invention is to provide a method for preparing an electrochromic composite film, which can improve the electrochromic performance of NiO.

[0005] In order to achieve the above object, the present invention provides a method for preparing an electrochromic composite film, comprising the following steps performed in sequence:

[0006] (1) Nickel acetate is dissolved in deionized water, hexamethylenetetramine is added, and the mixture is stirred for a period of time to prepare a NiO precursor reaction solution. The FTO glass is placed obliquely in a hydrothermal reactor with the conductive surface facing downward. After a certain period of hydrothermal reaction at a certain temperature, the sample after the reaction is dried. The FTO glass is transferred to a Fresnel furnace for treatment to obtain a NiO film attached to the FTO conductive glass.

[0007] (2) A certain molar ratio of cobalt nitrate, sodium acetate and potassium nitrate is dissolved in deionized water and stirred for a period of time to prepare a Co3O4 electrodeposition reaction solution.

[0008] (3) The prepared NiO film is deposited by electrochemical deposition to obtain a NiO / Co3O4 composite film, the NiO film prepared in step (1) is used as a working electrode, Ag / AgCl is used as a reference electrode, the Pt sheet is used as a counter electrode, the electrolyte is a Co3O4 electrodeposition reaction solution, and a NiO / Co3O4 composite electrochromic film is obtained under certain deposition conditions.

[0009] In step (1), the solubility of the nickel acetate solution is 0.15-0.4M, 2-2.5 g of hexamethylenetetramine is added, the stirring time is 30-45 min, the temperature and time of the hydrothermal reaction are 120-150°C and 2-4 h respectively, the reaction is dried in an oven for 0.5-1 h, and the FTO glass is heat-treated in a furnace at a temperature of 300-450°C for 1-2 h.

[0010] In step (2), 1.4-1.6 g of cobalt nitrate hexahydrate, 0.3-0.8 g of sodium acetate, and 0.5-1 g of potassium nitrate are added to the electrodeposition reaction solution, and the stirring time is 30-45 min.

[0011] In step (3), the Co3O4 electrodeposition reaction solution is used as the deposition solution. The deposition conditions are room temperature, cyclic voltammetry electrodeposition is applied, and a three-electrode system is used to cycle one circle in the range of -1.5V to 1.5V at a scanning speed, followed by anodic deposition at a voltage of 1.5V for a deposition time of 150 to 300s.

[0012] The present invention provides a method for preparing a NiO / Co3O4 composite film for electrochromic properties, which has the following beneficial effects:

[0013] (1) The present invention can effectively enhance the efficiency of electrochromism and promote the entry and extraction of ions and electrons.

[0014] (2) The preparation method of the present invention is simple and easy to operate, and the overall cost is low.

[0015] (3) The present invention has the advantages of having a large active surface area and being able to provide diffusion channels for ions, so that it has the effect of enhancing the electrochromic performance. The incorporation of cobalt improves the conductive properties of the NiO film. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of the obtained NiO / Co3O4 composite film. DETAILED DESCRIPTION

[0017] The following examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0018] Example 1

[0019] A method for preparing a NiO / Co3O4 composite film for electrochromic properties comprises the following steps:

[0020] (1) Add 3.11g of nickel acetate to 50mL of deionized water under constant stirring, then add 1.75g ​​of hexamethylenetetramine and stir for 40min to prepare a NiO precursor solution. Place the FTO glass obliquely into a hydrothermal reactor with the conductive surface facing downward, and then maintain it at 120°C for 2h through hydrothermal reaction. Place the prepared glass in an oven and dry it for 0.5h. Then transfer the FTO glass to a Fresnel furnace for treatment, heat it to 350°C at a heating rate of 2°C / min, keep it warm for 1h, and cool it to room temperature. A NiO film attached to the FTO conductive glass can be obtained.

[0021] (2) Dissolve 1.46 g of ferric nitrate hexahydrate, 0.68 g of sodium acetate, and 1.49 g of potassium nitrate in 50 mL of deionized water, and stir the solution magnetically for 30 min.

[0022] (3) NiO film was used as the working electrode, Ag / AgCl as the reference electrode, Pt sheet as the counter electrode, Co3O4 electrodeposition reaction solution as the deposition solution, and the deposition conditions were room temperature, cyclic voltammetry electrodeposition was applied, and a three-electrode system was used to cycle one cycle in the range of -1.5V to 1.5V at a scanning speed, followed by anodic deposition at a voltage of 1.5V for 150s. Finally, the NiO / Co3O4 composite film was repeatedly washed with distilled water.

[0023] Example 2

[0024] A method for preparing a NiO / Co3O4 composite film for electrochromic properties comprises the following steps:

[0025] (1) Add 6.22g of nickel acetate to 100mL of deionized water under constant stirring, then add 3.5g of hexamethylenetetramine and stir for 40min to prepare a NiO precursor solution. Place the FTO glass obliquely into a hydrothermal reactor with the conductive surface facing downward, and then maintain it at 140°C for 3h through hydrothermal reaction. Place the prepared glass in an oven and dry it for 0.5h. Then transfer the FTO glass to a Fresnel furnace for treatment, heat it to 400°C at a heating rate of 2°C / min, keep it warm for 1.5h, and cool it to room temperature. A NiO film attached to the FTO conductive glass can be obtained.

[0026] (2) Dissolve 2.92 g of ferric nitrate hexahydrate, 1.36 g of sodium acetate, and 2.98 g of potassium nitrate in 100 mL of deionized water, and stir the solution magnetically for 30 min.

[0027] (3) NiO film was used as the working electrode, Ag / AgCl as the reference electrode, Pt sheet as the counter electrode, Co3O4 electrodeposition reaction solution as the deposition solution, and the deposition conditions were room temperature, cyclic voltammetry electrodeposition was applied, and a three-electrode system was used to cycle one cycle in the range of -1.5V to 1.5V at a scanning speed, followed by anodic deposition at a voltage of 1.5V for 300s. Finally, the NiO / Co3O4 composite film was repeatedly washed with distilled water.

[0028] Example 3

[0029] A method for preparing a NiO / Co3O4 composite film for electrochromic properties comprises the following steps:

[0030] (1) Add 9.33g of nickel acetate to 150mL of deionized water under constant stirring, then add 5.25g of hexamethylenetetramine and stir for 40min to prepare a NiO precursor solution. Place the FTO glass obliquely into a hydrothermal reactor with the conductive surface facing downward, and then maintain the hydrothermal reaction at 160°C for 1.5h. Place the prepared glass in an oven and dry it for 0.5h. Then transfer the FTO glass to a Fresnel furnace for treatment, heat it to 300°C at a heating rate of 2°C / min, keep it warm for 2h, and cool it to room temperature. A NiO film attached to the FTO conductive glass can be obtained.

[0031] (2) Dissolve 1.46 g of ferric nitrate hexahydrate, 0.68 g of sodium acetate, and 1.49 g of potassium nitrate in 50 mL of deionized water and stir the solution magnetically for 30 min.

[0032] (3) NiO film was used as the working electrode, Ag / AgCl as the reference electrode, Pt sheet as the counter electrode, Co3O4 electrodeposition reaction solution as the deposition solution, and the deposition conditions were room temperature, cyclic voltammetry electrodeposition was applied, and a three-electrode system was used to cycle one cycle in the range of -1.5V to 1.5V at a scanning speed, followed by anodic deposition at a voltage of 1.5V for 200s. Finally, the NiO / Co3O4 composite film was repeatedly washed with distilled water.

Claims

1. A method for preparing a NiO / Co3O4 composite film for electrochromic properties, characterized in that: The preparation method is carried out in order by the following steps: (1) Nickel acetate is dissolved in deionized water, hexamethylenetetramine is added, and the mixture is stirred for a period of time to prepare a NiO precursor reaction solution. The FTO glass is placed obliquely in a hydrothermal reactor with the conductive surface facing downward. After a certain period of hydrothermal reaction at a certain temperature, the sample after the reaction is dried. The FTO glass is transferred to a Fresnel furnace for annealing to obtain a NiO film attached to the FTO conductive glass. (2) A certain molar ratio of cobalt nitrate, sodium acetate and potassium nitrate is dissolved in deionized water and stirred for a period of time to prepare a Co3O4 electrodeposition reaction solution. (3) The prepared NiO film is deposited by electrochemical deposition to obtain a NiO / Co3O4 composite film, the NiO film prepared in step (1) is used as a working electrode, Ag / AgCl is used as a reference electrode, the Pt sheet is used as a counter electrode, the electrolyte is a Co3O4 electrodeposition reaction solution, and a NiO / Co3O4 composite electrochromic film is obtained under certain deposition conditions.

2. The method for preparing the NiO / Co3O4 composite film for electrochromism according to claim 1, characterized in that: In step (1), the solubility of the nickel acetate solution is 0.15-0.4M, 1-2.5 g of hexamethylenetetramine is added, the stirring time is 30-45 min, the temperature and time of the hydrothermal reaction are 120-150°C and 2-4 h respectively, and the reaction is dried in an oven for 0.5-1 h. The FTO glass is heat treated in a furnace at a temperature of 300°C-450°C and the insulation time is 1-2 h.

3. The method for preparing the NiO / Co3O4 composite film for electrochromism according to claim 1, characterized in that: In step (2), 1.4-1.6 g of cobalt nitrate hexahydrate, 0.3-0.8 g of sodium acetate, and 0.5-1 g of potassium nitrate are added to the electrodeposition reaction solution, and the stirring time is 30-45 min.

4. The method for preparing the NiO / Co3O4 composite film for electrochromism according to claim 1, characterized in that: In step (3), the Co3O4 electrodeposition reaction solution is used as the deposition solution, and the deposition conditions are room temperature, cyclic voltammetry electrodeposition is applied, and a three-electrode system is used to cycle one cycle in the range of -1.5V to 1.5V at a scanning speed, followed by anodic deposition at a voltage of 1.5V for a deposition time of 150 to 300s. Finally, the NiO / Co3O4 composite film is repeatedly washed with distilled water to obtain.

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