10.1021/acs.nanolett.6b03909.s001 Wenshou Wang Wenshou Wang Ji Feng Ji Feng Yifan Ye Yifan Ye Fenglei Lyu Fenglei Lyu Yi-sheng Liu Yi-sheng Liu Jinghua Guo Jinghua Guo Yadong Yin Yadong Yin Photocatalytic Color Switching of Transition Metal Hexacyanometalate Nanoparticles for High-Performance Light-Printable Rewritable Paper American Chemical Society 2016 phase separation issue High-Performance Light-Printable Rewritable Paper Transition Metal Hexacyanometalate Nanoparticles photoreversible color resource sustainability TiO 2 nanoparticles Photocatalytic Color Switching rewritable paper 2016-11-22 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Photocatalytic_Color_Switching_of_Transition_Metal_Hexacyanometalate_Nanoparticles_for_High-Performance_Light-Printable_Rewritable_Paper/4557892 Developing efficient photoreversible color switching systems for constructing rewritable paper is of significant practical interest owing to the potential environmental benefits including forest conservation, pollution reduction, and resource sustainability. Here we report that the color change associated with the redox chemistry of nanoparticles of Prussian blue and its analogues could be integrated with the photocatalytic activity of TiO<sub>2</sub> nanoparticles to construct a class of new photoreversible color switching systems, which can be conveniently utilized for fabricating ink-free, light printable rewritable paper with various working colors. The current system also addresses the phase separation issue of the previous organic dye-based color switching system so that it can be conveniently applied to the surface of conventional paper to produce an ink-free light printable rewritable paper that has the same feel and appearance as the conventional paper. With its additional advantages such as excellent scalability and outstanding rewriting performance (reversibility >80 times, legible time >5 days, and resolution >5 μm), this novel system can serve as an eco-friendly alternative to regular paper in meeting the increasing global needs for environment protection and resource sustainability.