Reprintable paper realized employing ZnO-based photocatalytic color conversion of dyes

Abstract

The invention of paper as a writing material greatly promoted the development and spread of civilization. However, its large-scale production and utilization has also brought about huge environmental and sustainability concerns. It is desirable to develop a strategy for paper that can be used in a reprintable manner. In this work, ZnO-based photocatalytic reactions have been applied in preparing a reprintable paper that works through the color conversion of methylene blue. The resulting paper does not require additional ink and can be repeatedly printed for 20 cycles keeping over 77% of the initial contrast ratio. The reprintable raw materials can be retained for more than 2 months in the ambient environment. A fast color-switching time of about 10 s has been achieved, which can be attributed to the high photo-induced electron transfer rate from the ZnO to the dyes.