LAUSR

Designing photochromic systems that exhibit tunable print/erase responses is seldom studied but critical to the implementation of rewritable paper. Previous systems printed information with photocatalysts limited to specific wavelengths and light sources and rarely considered how polymers used in film formation affect erasing of information. Herein, different visible/UV light responses are achieved by engineering the formation of oxygen vacancy defects in titanium dioxide/reduced graphene oxide composite photocatalysts. Defects are manipulated during synthesis by controlling the water concentration in a mixed solvent system, which leads to tunable photochromic response of redox dyes. Furthermore, because the accessibility of ambient oxygen directly impacts the kinetics of recoloration, tailoring the oxygen barrier properties of polyvinyl alcohol via modulating inherent polymer structure as well as the external environment, the recoloration can be further tuned to meet various application purposes. The resulting insight will assist fellow researchers in tailoring defects in photocatalyst systems for superior functional design.