One-Step Hydrothermal Synthesis of W-Doped VO2 (M) Nanorods with a Tunable Phase-Transition Temperature for Infrared Smart Windows.

Abstract

Vanadium dioxide (VO2), with reversible metal–semiconductor transition near room temperature, is a compelling candidate for thermochromic windows. Nanocomposite coatings derived from VO2 nanoparticles are particularly superior to VO2 films due to their advantages in large-scale preparation, flexible shaping, and regulation of optical properties. In this work, we developed a novel method for one-step hydrothermal synthesis of W-doped VO2 (M) nanorods and studied their application in large-scale infrared smart windows. On introducing tartaric acid as a new reductant, VO2 underwent a two-stage phase evolution from the pure phase comprising VO2 (A) nanobelts to VO2 (M) nanorods, instead of the conventional three-stage B–A–M phase evolution during hydrothermal synthesis. This transition is very favorable for the large-scale hydrothermal synthesis of VO2 (M). The phase-transition temperature of VO2 (M) nanoparticles can be regulated systematically by W doping, with a reduction efficiency of about 24.52 °C/atom % W. Moreover, VO2 (M) composite films were fabricated using a convenient roller coating method, which exhibited significant midinfrared transmission switching up to 31%, with a phase-transition temperature of about 37.3 °C. This work demonstrates the significant progress in the one-step hydrothermal synthesis of VO2 (M) nanorods and provides significant insights into their applications in infrared smart windows.