Rewritable Paper Based on Layered Metal–Organic Frameworks with NIR-Triggered Reversible Color Switching

Photoreversible color-switching materials, which can reversibly change color in response to external light stimuli, have attracted increasing attention for their applications in time-sensitive information storage and optical data storage fields. But most of the related materials are dyes or redox compounds with ultraviolet as the light source, dramatically limiting the cycling stability during discoloration processes. To address this problem, a near-infrared (NIR)-responsive rewritable paper via doping layered Co-metal–organic frameworks (MOFs) into the stable polyvinylidene fluoride matrix is reported for the first time. Layered Co-MOF shows a rapid color-switching characteristic between orange and black blue upon NIR illumination on/off because of the interlayer spacing changes. Benefiting from the soft network structures of the matrix, Co-MOF can be homogeneously distributed to deliver an outstanding reversibility performance, including rapid response, coloration in a short period, and decoloration within about 3 min in ambient air. The fabrication of new photoreversible color switching system holds great potential in communication security, which offers a viable pathway to achieve ink-free photoreversible printing.