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

摘要

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 degrees 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 Omega 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 x 10(4) were realized in the VO2(M) NP film.