CN104724758B - A kind of WO3The preparation method of nanoscale twins material - Google Patents

Abstract

The invention discloses a preparation method of a multi-nano sheet WO ₃ array material, which belongs to the technical field of preparation of nanometer materials. The method of the present invention directly uses conductive glass as a substrate, uses sodium tungstate as a tungsten source, controls the solution under a certain pH value condition, and utilizes a one-step hydrothermal method to synthesize WO ₃ nano sheet array material. The method of the present invention is simple and safe, has low preparation cost and is easy to control; the prepared nano-array has uniform morphology and is directly grown on the FTO substrate, which can form a better conductive channel with the conductive substrate, and is used in the field of solar cells and photocatalysis It will have broader application prospects, and it is also an ideal material for preparing electrochromic films, photochromic films, and gas sensors.

Description

A kind of preparation method of WO3 nano sheet material

Technical field:

The invention belongs to the technical field of nanomaterial preparation, and in particular relates to a preparation method _of WO3 nanosheet material. The material has broad application prospects in photocatalytic degradation, photolysis of water to produce hydrogen, preparation of solar cell electrodes, electrochromic thin films, photochromic thin films, and gas sensors.

Background technique:

WO ₃ is an important semiconductor material, which has a wide range of applications in photochromism, electrochromism, photocatalytic degradation, gas sensor, solar cell, etc. It has attracted much attention as a typical n-type semiconductor. The performance in these aspects depends largely on the size, morphology of WO ₃ nanostructure units and their assembled nanostructures, precisely because the structure of the material plays a decisive role in its performance.

There are many methods for preparing WO ₃ nanoarrays, including thermal evaporation, sol-gel preparation, and chemical methods reported in the literature. The thermal evaporation method requires a high temperature of 900-1000 °C, the growth process conditions are harsh, the equipment requirements are high, and the repeatability is poor; the sol-gel preparation method has a simple preparation process, but there are few reports on direct growth on the substrate material, and it is difficult to obtain arrays. Ordered nanostructures; the adhesion of nanostructures grown on the surface of the substrate by chemical methods is weak, which limits its application; while the one-step hydrothermal method used in this method is relatively simple, requires low equipment, and the product is pure and reproducible. For large-scale production, ordered arrays of WO ₃ nanosheets can be grown directly on conductive glass substrates.

Compared with ordinary WO ₃ materials, WO ₃ nanosheet array materials have greater advantages. First, the WO ₃ nanosheet array has a larger specific surface area, which can provide more electrical contacts between particles, increase the electron transport rate, and improve the catalytic activity. Secondly, the WO ₃ nanosheet array is dense and orderly, which avoids many defects inside ordinary WO ₃ materials and reduces recombination. In addition, the WO ₃ nanosheet array prepared by this method is directly grown on the FTO, which has better contact with the conductive substrate, faster electron injection and transmission rates, and thus improves the performance of the material. Therefore, multi-nanosheet WO ₃ array materials have broad application prospects.

Invention content:

The invention aims to provide a method for preparing a multi-nanometer sheet WO ₃ array material.

A preparation method of multi-nanosheet WO ₃ array material is a simple one-step hydrothermal method, using FTO as a growth substrate, using Na ₂ WO ₄ ·2H ₂ O as raw materials, oxalic acid and (NH ₄ ) ₂ SO ₄ is a stabilizer, and then HNO ₃ is added dropwise to adjust the pH value of the precursor solution to 1-1.5. The concrete steps of this method are as follows:

(1) Clean the conductive glass substrate, remove the stained layer on the surface of the conductive glass substrate, and obtain a clean conductive glass substrate, treat it with ozone under a UV lamp for 15 to 30 minutes to form a hydrophilic surface, and then place it in a drying oven Drying at 60°C;

(2) according to the volume ratio of deionized water and 16mol/LHNO3 solution is 1: ₁ preparation _HNO3 reaction solution a;

(3) Add Na ₂ WO ₄ ·2H ₂ O powder into deionized water to form a sodium tungstate solution with a concentration of 0.023-0.024mol/L;

( ₄ ) Adding HNO3reaction solution a dropwise to the solution obtained in step (3) to regulate the pH value of the sodium tungstate solution to 1～1.5;

(5) Add oxalic acid with a molar ratio of 1:10 to 1:40 to Na ₂ WO ₄ ·2H ₂ O and (NH ₄ ) ₂ SO ₄ with a molar ratio of 1:3 to 1:6 to the obtained product in step (4). solution, fully stirred to obtain the final reaction precursor solution;

(6) Place the conductive glass substrate in step (1) in a high-pressure reactor lined with polytetrafluoroethylene, and inject the precursor solution obtained in step (5), and use the hydrothermal synthesis reaction method to maintain the reaction at 180 °C 8 hours, then naturally cooled to room temperature;

(7) After the reaction, the conductive glass was taken out, washed repeatedly with deionized water and absolute ethanol until neutral, and then dried in a drying oven at 60°C to obtain the multi-nanosheet WO ₃ array material.

The chemical reaction formula of the whole reaction process can be expressed as follows:

Na ₂ WO ₄ +2H ⁺ →H ₂ WO ₄ +2Na ⁺

H ₂ WO ₄ →WO ₃ +H ₂ O

The present invention has the following advantages:

The method of the invention has a simple manufacturing process, and the prepared WO ₃ nanometer array has uniform appearance and consistent size, and is directly grown on the FTO substrate to form a better conductive channel with the conductive substrate, which is more conducive to electron transmission.

Description of drawings:

Figure 1 is a scanning electron microscope image of the multi-nanosheet WO ₃ array material

detailed description:

(1) Clean the FTO substrate: use acetone to ultrasonically clean for 10 minutes, then use absolute ethanol and deionized water to ultrasonically clean for 20 minutes each. Remove the contamination layer on the FTO surface to obtain a clean FTO substrate, treat it with ozone under a UV lamp for 15 minutes, and then put it in a drying oven for drying at 60°C. The resistivity of the ultrapure water used must be above 16Ω·cm;

(2) Measure 20ml each of deionized water and 16mol/L _HNO3 solution into a 50ml beaker, stir magnetically for 10min and evenly disperse to obtain clear reaction solution a;

(3) Measure 30ml of deionized water into a 100ml beaker, weigh 0.231g of NaWO ₃ 2H ₂ O with an electronic balance, add it to the deionized water, and stir magnetically for 10 minutes until fully dissolved;

(4) Use a pH meter to monitor the pH of the solution in step (3), and slowly add the reaction solution a dropwise until the pH of the solution is in the range of 1 to 1.5, at which time the solution produces a yellow precipitate;

(5) Add 1.26g of oxalic acid to the above solution with an electronic balance, stir magnetically for 5 minutes, then weigh 0.32g (NH ₄ ) ₂ SO ₄ with an electronic balance, add it to the solution, and stir magnetically for 10 minutes until the precipitate dissolves ;

(6) Add deionized water to the solution after the precipitation is dissolved, and set the volume of the solution to 70ml, and stir fully and evenly to obtain the reaction precursor solution;

(7) Put the conductive glass in step (1) upright into a 50ml autoclave lined with polytetrafluoroethylene, take 40ml of the precursor solution in step (6) and slowly inject it into the autoclave, and react at 180°C for 8 hours, then naturally cooled to room temperature;

(8) Take out the FTO, rinse the residue deposited on the FTO after the reaction with deionized water and absolute ethanol, a layer of light yellow tungsten oxide film can be seen on the FTO glass, and then carry out the reaction in a 60°C drying oven. After drying for 6 hours, the multi-nanosheet WO ₃ array material was prepared on the FTO. The added oxalic acid and tungstic acid formed a complex, thus inhibiting the precipitation, and the added sodium sulfate promoted the growth of WO ₃ towards the array. The prepared WO ₃ nanosheet array material is shown in Fig. 1 .

Claims (1)

1. a kind of preparation method of WO ₃ nano sheet material is to adopt one-step simple hydrothermal method, it is characterized in that, comprises steps as follows: (1) Clean the FTO substrate, remove the contaminated layer on the surface of the FTO substrate, and obtain a clean FTO substrate, treat it with ozone under a UV lamp for 15-30 minutes, and then place it in a drying oven for drying treatment at 60°C; (2) Prepare HNO ₃ reaction solution a according to the volume ratio of deionized water and 16M HNO ₃ solution at 1:1; (3) Add Na ₂ WO ₄ 2H ₂ O powder into deionized water to form a sodium tungstate solution with a concentration of 0.023~0.024mol/L; (4) Add HNO ₃ reaction solution a dropwise to the solution obtained in step (3) to adjust the pH value of the sodium tungstate solution to 1~1.5; (5) Add oxalic acid with a molar ratio of 1:10 to 1:40 to Na ₂ WO ₄ ·2H ₂ O and (NH ₄ ) ₂ SO ₄ with a ratio of 1:3 to 1:6 to the obtained product in step (4) solution, fully stirred to obtain the final reaction precursor solution; (6) Place the FTO substrate in step (1) in a high-pressure reactor lined with polytetrafluoroethylene, and inject the precursor solution obtained in step (5), and use the hydrothermal synthesis reaction method to keep 180 ° C for 8 hours, then naturally cooled to room temperature; (7) After the reaction, the conductive glass was taken out, washed repeatedly with deionized water and absolute ethanol until neutral, and then dried in a drying oven at 60°C to obtain the multi-nanosheet WO ₃ array material.