Influence of pH on the photocatalytic activity of ZnO nanorods

Abstract

Zinc oxide (ZnO) nanorods were prepeared on glass substrates through the chemical bath deposition (CBD) method. The growth of vertically array ZnO nanorods was promoted by seeding the substrates with ZnO nanoparticle layers. Surface morphology that investagated through field-emission scanning electron microscopy (FESEM) show that hexagonal ZnO nanorods (wurtzite) are formed with diameters ranging from 10 nm to 130 nm. The optical absorption of the grown ZnO nanorods exhibited high absorption edge with an energy gap of 3.26 eV. The photocatalytic activity of the prepared ZnO nanorods was investigated against methylene blue dye at room temperature using different pH values and UV exposure times. Degradation ratio of dye increased when irradiation time and pH were increased. The degradation ratio for dye with pH 6 increased from 42% to 89% when exposure time increased from 30 min to 240 min, whereas the degradation ratio of the dye with pH 11 increased from 65% to 94% under the same exposure time.