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Herein we study point defects and correlation to photoluminescence in ZnO nanorod. ZnO mirco/nanorod structure was successfully fabricated by co-precipitation method with highly homogeneous characteristics. When ion Mn+2 introduced into ZnO structure, the d-spacing distance of ZnO was increased from 0.248 nm to 0.295 nm due to the larger ionic radius of Mn2+ in comparison to Zn2+. The photoluminescence emission evolution of ZnO through doping and annealing processes hinted the relation of point defect transformations. We found that zinc interstitial, zinc vacancy and its related defects were responsible mainly for photoluminescence emission in annealing and/or Mn2+ doped samples.

Uniform and magnetic recyclable hollowsphere Zn doped Fe3O4 were successfully synthesized via simple one-pot solvothermal route. Morphology and structure of as-obtained products was characterized by XRD, SEM, HRTEM methods. The Zn-doped Fe3O4 hollowsphere exhibited high photocatalytic activity for degradation of hexavalent chromium under visible light irradiation. The effects of reaction conditions such as initial pH, photocatalyst dosage and hexavalent chromium contratentation were also studied systematically. The stability of the catalysts and and possible catalytic mechanism was also proposed. The results indicate that Zn doped Fe3O4 can be promising catalyst for photo-reduction of hexavalent chromium.

Herein we report a simple fabrication of graphene and titanium dioxide nanotube composite using hydrothermal method. Photoluminescence emission of the composite were investigated to study defect states in bandgap of nanotubes when the content of graphene varied from 1 wt% to 8 wt%. With the content of graphene lower than 5 wt%, the photoluminescence spectra form of the composite showed similar to that of pristine titanium dioxide nanotube. When the content of graphene reached 8 wt%, the emission positions were unchanged. However the spectrum form was dramatically changed, the intensity of green emission at about 530 nm was dominated. Thanks to the formation of graphene and titanium dioxide nanotube, excited electron was easy to diffuse from nanotube to graphene. The recombination of excited electron and trap hole on nanotube surface induced by oxygen vacancy in titanium dioxide anatas phase was enhanced which was attributed to the 530 nm emission.

This work reports photoluminescence evolution of hydrothermally homogeneous ZnO nanorods under thermal annealing at various temperatures. The crystalline structure and morphology of synthesized samples were characterized by X-ray diffractometry and Scanning electron microscopy. The optical properties which induced defect state transition were investigated by photoluminescence emission. Besides defect states induced emissions in the visible range, the photocatalytic activity of annealed samples was evaluated which indicated that the higher visible photoluminescence intensity gives the better catalytic activity.