Evaluation of the photocatalytic efficiency of cobalt oxide nanoparticles towards the degradation of crystal violet and methylene violet dyes

The present work deals with the synthesis, characterization, and testing towards the photochemical degradation efficiency of cobalt oxide (Co3O4) nanoparticles (NPs). Following the synthesis of Co3O4 NPs by the hydrothermal method, the NPs are confirmed to be formed in their cubic lattice structure with the spherical shape morphology. The testing studies revealed that the Co3O4 NPs degraded the Methylene violet (MV) and Crystal violet (CV) dyes very efficiently under the UV light irradiation. A Langmuir-Hinshelwood (L-H) model has been effectively used to display the adsorption of CV and MV dye molecules taking place using surface monolayer exposure to the UV light. The kinetics and reaction mechanism behind the elimination of CV and MV dyes shows for a pseudo-second-order kinetics model. With these Co3O4 NPs as photocatalysts, the maximum photodegradation rate was observed to be 92 % and 64 % for the MV and CV (respectively) within the same period of 45 min and this enhanced photocatalytic performance is due to the effective reduction of electron-hole recombination process by the Co3O4 NPs.