Enhancement of Photocatalysis of Zinc Oxide by Controlling its Particle Morphology

A variety of ZnO nanoparticles differing in their morphology were prepared by precipitating method where ZnCl2 aqueous solution was dropped into aqueous alkali solution. The prepared ZnO nanoparticles were employed for photocatalytic degradation of methylene blue dye. When NaHCO3 aqueous solution was used for the preparing operation, the precipitate consisting of basic-ZnCO3 was calcined at 300℃ for turning it to ZnO nanoparticle. A decrease in a ZnCl2 / NaHCO3 equivalent molar ratio from 0.4 to 0.05 caused an increase in a surface area of the ZnO nanoparticle formed into uneven shape, from 19.6 m2 / g to 79.8 m2 / g. Although the increase in the surface area enhanced the photocatalytic activity, this activating effect was weakened obviously beyond 50 m2 / g of the surface area. On the other hand, NaOH aqueous solution was used for the preparing operation with the result that ZnO nanoparticle shaped like rod was directly precipitated. The use of the diluted NaOH aqueous solution allowed ZnO nanoparticle to be shaped like nut. It seemed that the photocatalytic activity of ZnO nanoparticle was independent of its geometric shape. Additionally, the photocatalytic degradation of acetaldehyde was carried out for studying practical use of ZnO nanoparticle as a photocatalyst.