Photocatalytic colour switching of redox dyes for ink-free light-printable rewritable paper

Abstract

The invention of paper as writing materials has greatly contributed to the development and spread of civilization. However, its large-scale production and usage have also brought significant environment and sustainability problems to modern society. To reduce paper production and consumption, it is highly desirable to develop alternative rewritable media that can be used multiple times. Herein we report the fabrication of a rewritable paper based on colour switching of commercial redox dyes using titanium oxide-assisted photocatalytic reactions. The resulting paper does not require additional inks and can be efficiently printed using ultraviolet light and erased by heating over 20 cycles without significant loss in contrast and resolution. The legibility of prints can retain over several days. We believe this rewritable paper represents an attractive alternative to regular paper in meeting the increasing global needs for sustainability and environmental protection.

Printable and Rewritable Full Block Copolymer Structural Color

“…[1][2][3][4][5] By controlling dielectric constants, dimensions, and shapes of the structural elements, the SC can be tuned for displays, [6][7][8][9] media boards, [10,11] and sensors. [26,29] Printing APS on a BCP SC film with a modified commercial office ink-jet machine, followed by ethanol swelling, enables us to develop a variety of full-colored SC information images with a resolution comparable to images obtained with multi-ink commercial inkjet printers. This allows a full-colored SC writing process with a single ink, thus having advantages over conventional displays requiring at least three inks.…”

“…[14,16,18,[20][21][22] To control visible color, swelling agents such as solvents [17] and ionic liquids [6,23] are usually employed and the soft BCP ordered gel is responsive to either solvent quality [24] or crosslinking of the polymer chains in the swellable microdomain. [25][26][27][28][29] Localizing and spatially addressing a reversible external stimulus to write/erase the SC in a BCP-based PC using an ink-jet printer would enable production of low cost, Rewritable displays. [25][26][27][28][29] Localizing and spatially addressing a reversible external stimulus to write/erase the SC in a BCP-based PC using an ink-jet printer would enable production of low cost, Rewritable displays.…”

Photoelectrochemical cell for simultaneous electricity generation and heavy metals recovery from wastewater

“…The TiO 2 nanocrystals were synthesized according to a recent study [20]. In brief, a mixture of TiCl 4 (1 mL), NH 4 OH (1 mL), P123 (0.6 g) and DEG (20 mL) was heated at 220 °C in air with vigorous stirring (600 rpm) for 3h.…”

“…This procedure was repeated multiple times to produce a 18 mL stock solution. The presence of P123 in this synthesis plays a multiple role: it limits the growth of TiO 2 nanocrystals, it caps them and, most importantly, it acts as sacrificial electron donor to scavenge the photogenerated holes [20,21]. To prepare the photoanode, 6 g of PVA were firstly added into 14 mL of boiled water (100 °C) to produce a viscous liquid.…”

Porous Particle‐Based Inkjet Printing of Flexible Fluorescent Films: Enhanced Sensing Performance and Advanced Encryption

“…[40,41] Thus, we tried to use our ink in confidential information encryption and decryption process. Many important documents such as credentials, passports, and checks are based on paper, and thereby information encryption on paper is of great importance.…”