Elucidation of the photocatalytic degradation mechanism of an azo dye under visible light in the presence of cobalt doped TiO2 nanomaterials.

In this study, Co-TiO2 nanoparticles were successfully synthesized using sol-gel and precipitation methods. The effect of Co amount on the physicochemical properties of these nanomaterials was investigated using various techniques. The obtained results showed that the structural and optical properties of the synthesized Co-TiO2 nanomaterials depended closely on the weight percent of Co added to TiO2. It was found that, for 1%Co-TiO2, a substitution of Ti4+ and Co2+/Co3+ within the lattice of TiO2 was happened. The results of the photocatalytic degradation of methyl orange (MO) experiments carried out in the presence of the as prepared nanomaterials showed that under visible light, the sample 1%Co-TiO2 exhibited the best MO conversion. The enhanced photocatalytic activity has been attributed to the efficient charge separation of electrons and holes. The mechanistic studies revealed that O2-, h+ and OH are the major active species, and a possible mechanism degradation pathway of MO dye is proposed.