Defect structure controlling on TIO₂ nanocrystal and its applications

Abstract

The objectives of this work are the study for understanding surface defect (Ti³+) TiO₂ nanocrystal in anatase phase in the points of controlling, probing, and investigating its effect on the thermal stability, photoactivity, metal-support strong interaction, and the forming of metal-support compound. In this work, the surface defect (Ti³+) has been successfully controlled on TiO₂ nanocrystal at the same time with the preparation of anatase via sol-gel technique. This new method consumes less step and energy than the common technique. For the application of TiO₂ having different amount of surface defect on the photocatalysis, it was found that the increase in number of surface defect can enhance the photoactivity of TiO₂ nanocrystal because it can inhibit the recombination process between photo-electron and hole generated after UV irradiation. For another application of TiO₂ nanocrystal as a support of cobalt, it can be concluded that the increase in number of surface defect (Ti³+) can enhance the cobalt dispersion on TiO₂ support and also inhibit the formation of Co-SCF after standard reduction which led to increase in activity of cobalt for CO-hydrogenation. In this work, moreover, the effect of surface defect on the thermal stability was also investigated via the Piyasan's equation showing that the increase in number of surface defect have no effect on the rate of crystal growth and the surface defect can be created as mush as required. In the last part, the probing surface defect by using metal carbonyls in the atom level was also studied. It can monitor the behavior of surface defect and make a deeply understanding over it.