Highly reversible photochromism in composite WO3/nanocellulose films

Abstract

Reversible photochromic hybrid organicinorganic films containing nanocrystalline cellulose as a matrix and tungsten oxide as a photochromic component (CNC/WO 3 ) were obtained via a simple and quick solvent casting method. The films were studied by scanning electron microscopy, together with element mapping, FT-IR spectroscopy and X-ray diffraction, confirming successful incorporation of WO 3 nanoparticles into a nanocellulose matrix.Thermal analysis data indicated that the modification of a nanocellulose matrix with WO 3 increases its thermal stability. The CNC/WO 3 films showed a quick coloration-bleaching transition with good reversibility within 20 min, without notable degradation of photochromic properties after 10 cycles. The synthetic method proposed allows for scalable preparation of highly efficient low-cost WO 3 -based photochromic materials.

UV Photochromism in Transition Metal Oxides and Hybrid Materials

“…Reproduced with permission. [ 173 ] Copyright 2019, Springer. e) Transmittance of composite cesium doped WO 3 films prepared with nanoparticles with different bead milling times.…”

“…A reversible photochromic hybrid organic–inorganic film containing nanocrystalline cellulose (CNC) and WO 3 (CNC/WO 3 ) was prepared via a solvent casting method (Figure 4d). [ 173 ] WO 3 nanoparticles incorporated into the CNC matrix increase thermal stability, enhance coloration‐bleaching transition with reversibility occurring within 20 min, without degradation of photochromic properties even after 10 cycles. Incorporating WO 3 nanoparticles in CNC slows down photochromic reversal (0–3 min) making these approaches suitable for tuning or slowing down reversal rates.…”

Chromogenic Technologies for Energy Saving

“…As well known, WO 3 exhibits PC properties due to W 6+ to W 5+ reduction upon UV irradiation, activating a charge transfer from oxygen to metal. WO 3 -with a bandgap ranging from 2.7 to 3.1 eV-can suitably work as a PC component in a cellulose matrix, being deposited by the solvent casting method, reporting full cycles of coloration/bleaching, from pale yellow into dark blue in about 1 min, and gradually recovering its bleached form in the dark within 20 min, lasting about 20 min [77].…”

Bionic smart recycled paper endowed with amphiphobic, photochromic, and UV rewritable properties

“…3b and c, the infrared spectra of TT and MTT have the same vibration peaks at 3386 cm À1 (structured water), 1625 cm À1 (symmetrical OH tensile and bending vibration), 1384 cm À1 and 798 cm À1 (W-O-W). [34][35][36][37] In addition, the vibration peaks of MTT at 1208 cm À1 (C-F 3 group) and 1073 cm À1 (Si-O vibration) indicate that the chemical modication was successful. 35,38 As shown in Fig.…”