Planar-defect-rich zinc oxide nanoparticles assembled on carbon nanotube films as ultraviolet emitters and photocatalysts

Structural defects in zinc oxide (ZnO) nanoparticles are complex and hard to be controlled during the synthesis, however, diversifying the chemical and physical performances. Here we report a rapid and low-temperature deposition method to fabricate planar-defect-rich ZnO nanoparticles on freestanding and aligned carbon nanotube films, different from common treatments which remove structural defects as many as possible. The defect energy states are very close to the valence band of ZnO and serve as recombination centers for a nearly monochromatic ultraviolet luminescence within a wavelength range of 373-376 nm. The absence of point defects, especially of oxygen vacancies whose energy level is <1 eV below the conduction band, allows photoinduced electrons and holes to take parts in possible photocatalytic reactions rather than to recombine at the shallow energy levels of planar defects.