Effect of Cobalt Doping on Structural, Optical, and Photocatalytic Properties of ZnO Nanostructures

Investigation of Co-doped ZnO nanostructures (NS) is of importance to improve ZnO photocatalysis. Co-doped ZnO NS were grown by atmospheric pressure chemical vapor deposition from acetylacetonates Zn and Co in various proportions. The effect of cobalt doping on the structure, morphology, photoluminescence and Raman spectra of ZnO NS was studied. Photocatalysis of Co-doped ZnO NS was investigated by the decomposition of methyl orange dye at Hg lamp excitation. Unlike pure ZnO NS which demonstrate intense deep level emission in PL spectrum, obliged to excess of oxygen vacancies, deposited Co-doped ZnO NS exhibit suppressed emission in visible part of optical spectrum. By the help of Raman spectroscopy cobalt-related secondary phase in ZnO was detected. It was demonstrated that Co-doping reduces the photocatalytic activity of ZnO, presumable, due to absence of oxygen vacancies and reduced possibility to charge transfer from semiconductor to dye molecules.