Electrochemical Synthesis of Amorphous VO2 Colloids and Their Rapid Thermal Transforming to VO2(M) Nanoparticles with Good Thermochromic Performance

• Published in: Chemistry : a European journal Vol. 22; no. 49; pp. 17627 - 17634
• Main Authors: Wu, Hao, Li, Ming, Zhong, Li, Luo, Yuan Yuan, Li, Guang Hai
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 05.12.2016; Wiley Subscription Services, Inc
• Subjects: amorphous materials; Chemistry; electrochemistry; nanoparticles; thermochromic performance; vanadium
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201604101

Amorphous VO2 (a‐VO2) colloids were synthesized by electrochemical anodic oxidation of metallic vanadium. It was found that the a‐VO2 colloids have a cotton‐like morphology composed of very small clusters, and that the crystallization temperature of the a‐VO2 colloids can be adjusted either by the electrolyte of the anodic oxidation or/and the dispersion agent of the colloids. VO2(M) nanoparticles (NPs) (and a NP film) with an average size of about 50 nm can be obtained by a rapid thermal annealing of the a‐VO2 colloids at 310 °C under air, which is beneficial for practical applications. The VO2(M) NP film shows an obvious metal–semiconductor transition with a resistance less than 10 Ω in the metallic state. An integral visible transmittance of 40.7 %, a solar transmittance modulation of 9.4 %, and a resistance modulation in the order of 5×104 were realized in the VO2(M) NP film. Perfect film: A VO2(M) nanoparticle film obtained by rapid thermal annealing of amorphous VO2 colloids from electrochemical anodic oxidation of metallic vanadium (see figure) shows an integral visible transmittance of 40.7 %, a solar transmittance modulation of 9.4 %, and a resistance modulation in the order of 5×104.