Tungsten Oxide - Vanadium Pentoxide Core-shell Nanowire Array Electrochromic Material

Electrochromism refers to the reversible and lasting change of light transmittance and / or reflectivity associated with electrochemical redox reaction when the material is applied with appropriate voltage. The applications of electrochromic devices mainly include: intelligent windows for cars and buildings, controllable light reflection or light transmission display devices (for optical information and storage), controllable aircraft canopies, reusable price tags, spacecraft thermal control, etc.

Therefore, the fabrication of tungsten oxide - V₂O₅ core-shell nanowire array electrochromic materials can integrate the advantages of both: the specific steps are as follows:

(1)Place the FTO conductive glass in acetone, ethanol and deionized water for ultrasonic cleaning, and dry it under the infrared lamp after cleaning;

(2)Preparation of peroxytungstic acid solution: dissolve the tungstic acid powder in the mixed solution of 30% hydrogen peroxide and deionized water, stir the solution until it is clear, then dilute the solution with deionized water to a concentration of 0.05-0.1mol/l, and the diluted solution is peroxytungstic acid solution;

(3)Preparation of precursor solution: prepare the mixed solution of the peroxytungstic acid solution prepared in step (2) with acetonitrile and deionized water, and then adjust the pH of the mixed solution to 0.5-1 with hydrochloric acid to prepare the precursor solution;

(4)Add the precursor solution prepared in step (3) to the high-pressure reactor, immerse the FTO conductive glass vertically and fix it in the precursor solution, heat the high-pressure reactor to 150-220 ℃, keep it for 6-12h; after the hydrothermal reaction, take out the FTO conductive glass, wash the surface with deionized water, and dry it at room temperature to prepare the WO₃ nanowire array film;

(5)The FTO conductive glass containing WO₃ nanowire array film obtained in step (4) is used as the working electrode, platinum wire as the counter electrode, Ag / AgCl electrode as the reference electrode, vanadium sulfate, sodium dodecyl sulfate and sodium chloride are dissolved in the mixed solution of absolute ethanol and deionized water as the electrodeposition solution, and the working electrode is subjected to cyclic voltammetric deposition;

(6)The product obtained in step (5) was washed with ethanol and then put on the filter paper and dried with infrared lamp. A dense and uniform yellow green film was obtained on the FTO conductive glass, which is the electrochromic material of tungsten trioxide / V₂O₅ nanowire.

The color of tungsten trioxide and vanadium pentoxide cathodes is similar. When the cathodes are colored, there is a synergistic effect, which greatly improves the contrast of electrochromic materials. The interface between them is effectively hybridized and plays a complementary role.

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