Blue/red light-triggered reversible color switching based on CeO2−x nanodots for constructing rewritable smart fabrics

Abstract

Photoreversible color switching systems (PCSSs) have attracted increasing attention in various applications, but in most PCSSs the discoloration process usually relies on harmful UV light as a stimulus and the recoloration requires high temperature. To solve these problems, we have designed and prepared CeO_2−x nanodots as novel photocatalytic components in PCSSs that respond to two kinds of visible light. CeO_2−x nanodots are prepared by a solvothermal reaction with L-ascorbic acid as the reducing agent. CeO_2−x nanodots with a size of ∼2 nm have a high concentration of oxygen vacancies, which confers a broadened photoabsorption with an edge at 500 nm, as well as a weak photoabsorption tail in the visible region (500–800 nm). To realize the color switching, both the CeO_2−x/Dye/H₂O solution and CeO_2−x/dye/hydroxyethyl cellulose (HEC)-coated fabrics have been prepared. Under blue (450 nm) light irradiation, both the solution and fabric show a rapid discoloration in 30 s and 150 s, respectively, due to the efficient photocatalytic reduction of the redox dye by CeO_2−x. Conversely, red (630 nm) light irradiation with air confers a rapid recoloration in 35 s for the solution and 200 s for the fabric, resulting from CeO_2−x-mediated self-catalyzed oxidation. In particular, the required images and letters can be remotely printed on CeO_2−x/Dye/HEC-coated T-shirts with a 450 nm laser pen, and then erased with 630 nm light, with high reversibility and stability. Therefore, the present CeO_2−x/Dye/HEC PCSSs have great potential to construct rewritable smart fabrics for various applications.