Post-illumination activity of SnO(2) nanoparticle-decorated Cu(2)O nanocubes by H(2)O(2) production in dark from photocatalytic “memory”

Most photocatalysts only function under illumination, while many potential applications require continuous activities in dark. Thus, novel photocatalysts should be developed, which could store part of their photoactivity in “memory” under illumination and then be active from this “memory” after the illumination is turned off for an extended period of time. Here a novel composite photocatalyst of SnO(2) nanoparticle-decorated Cu(2)O nanocubes is developed. Their large conduction band potential difference and the inner electrostatic field formed in the p-n heterojunction provide a strong driving force for photogenerated electrons to move from Cu(2)O to SnO(2) under visible light illumination, which could then be released to react with O(2) in dark to produce H(2)O(2) for its post-illumination activity. This work demonstrates that the selection of decoration components for photocatalysts with the post-illumination photocatalytic “memory” could be largely expanded to semiconductors with conduction band potentials less positive than the two-electron reduction potential of O(2).