Vanadium dioxide coatings with enhanced optical and thermochromic performances

Abstract

Vanadium dioxide (VO2), a prospect intelligent heat-controlling materials, could be extensively applied in construction and automobiles as smart window coating for energy saving. However, the state-of-the-art VO2 coatings suffer from low solar modulation efficiency (ΔTsol) and unsatisfied transmittance in the visible region (Tvis), owing to the unreasonable particle size, small porosity as well as low-purity. In this line, herein, a simple, facile and cost-effective approach: i.e., annealing assisted solution strategy, was adopted to prepare VO2 coating with uniform particle size, high porosity and high-purity by using cetyltrimethylammonium bromide (CTAB) and home-made ammonium citrato-oxovanadate (IV) as dispersant and precursor, respectively. It is noticeable that the amount of CTAB is of vital importance for the particle size and porosity control, which in turn affects the overall performance of as-obtained VO2 coatings. The results demonstrate that the sample with small particle size and high porosity shows good local surface plasmon resonance behavior, high Tvis and enhanced ΔTsol. In correlation with simulation results, the sample prepared under molar ratio of CTAB to V is 0.1 displays superior ΔTsol of 13.4% and Tvis of 70.6%. Our work might provide a guidance for the modulation of the optical transmittance of VO2 nanoparticle coatings towards smart window coatings.