Synthesis, characterisation and photocatalytic activity of Co–doped ZnO nanoparticles

Co-doped ZnO nanoparticles were synthesised by combustion method using polyvinyl alcohol and zinc nitrate. Both X-ray diffraction (XRD) and selected area electron diffraction (SAED) analyses showed the single phase of hexagonal structure (PDF2 card: 01-070-8072) in all the samples. Transmission electron microscopy (TEM) and HRTEM images show that most of the particles have spherical shape and their grain size is ranging from 10 nm to 60 nm in diameter, which depended on both the Co ratio and the annealing temperatures. Energy-dispersive X-ray (EDX) spectrum analysis showed the proportion of elements in the nanoparticles in accordance with the original composition. The photocatalytic activity of samples was studied by measuring the decomposition of methylene blue in aqueous solution using UV-VIS spectroscopy. The results showed that the photocatalytic ability to decompose methylene blue reached 70% with ZnO and 98% with Zn0.97Co0.03O samples after 150 min of irradiation.