OICC Press Journal of Nanostructure in Chemistry 2193-8865 8 4 (December 2018) 2018 11 26 Fabrication and characterization of pure and modified Co3O4 nanocatalyst and their application for photocatalytic degradation of eosine blue dye: a comparative study 10.1007/s40097-018-0287-0 EN Prashant Bhimrao Koli Research Centre in Chemistry and PG Department of Chemistry, Pratap College of Arts, Science and Commerce, Affiliated to North Maharashtra University Jalgaon, Jalgaon, MH, 425401, IN Kailas Haribhau Kapadnis Research Centre in Chemistry and PG Department of Chemistry, Loknete Vyankatrao Hiray Arts, Science and Commerce College, Affiliated to SPPU, Pune, MH, 422003, IN Uday Gangadhar Deshpande Research Centre in Chemistry and PG Department of Chemistry, Pratap College of Arts, Science and Commerce, Affiliated to North Maharashtra University Jalgaon, Jalgaon, MH, 425401, IN Manohar Rajendra Patil Nanochemistry Research Laboratory, Gajmal Tulshiram Patil Arts, Science and Commerce College, Affiliated to NMU, Jalgaon, MH, 425412, IN Journal Article 2018 11 26 Abstract The present work deals with the synthesis of cobalt oxide, and Fe 2+ - and Ni 2+ -doped cobalt oxide nanoparticles as a catalyst. The study is investigating the different factors in obtaining cobalt oxide, and Fe 2+ - and Ni 2+ -doped cobalt oxide nanoparticles. Photocatalytic degradation studies are carried out for water-soluble eosine blue (EB) dye using cobalt oxide, and Fe 2+ - and Ni 2+ -doped cobalt oxide nanoparticles in aqueous solution. Different parameters such as initial dye concentration, dose of catalyst, contact time and pH have been studied to optimize reaction conditions. It is observed that photocatalytic degradation is a more effective and faster mode of removing EB dye by cobalt oxide, and Fe 2+ - and Ni 2+ -doped cobalt oxide nanoparticles than work done before. The optimum conditions for the removal of the EB dye are initial concentration 40 mg/L, photocatalyst dose 0.8 g/L, and pH 7.5. The EDS technique gives the elemental composition of synthesised cobalt oxide, and Fe 2+ - and Ni 2+ -doped cobalt oxide nanoparticles. The TEM and XRD studies are carried for morphological feature characteristics of synthesized cobalt oxide, and Fe 2+ - and Ni 2+ -doped cobalt oxide nanoparticles. Pseudo-first-order kinetic has been investigated for both pure and doped cobalt oxide catalysts. Almost 95% dye degradation has been observed for doped cobalt oxide nanoparticles. Graphical abstract Graphical abstract for photocatalytic degradation of eosine blue dye by cobalt oxide nanocatalyst.