Bandgap-tailored NiO nanospheres: an efficient photocatalyst for the degradation of crystal violet dye solution

Bandgap-tailored NiO nanospheres were successfully synthesized by facile precipitation method for the first time and characterized by XRD, EDX, SEM, TEM, FTIR, UV and PL. Interestingly, the modification of the band gap was observed using UV-Vis (DRS) spectroscopy, and the observed band gap is 3.31 eV. The morphology of the materials was analysed by SEM and TEM which show the sphere like structures of NiO with the particle size of similar to 20 nm. The efficiency of the materials was examined by the degradation of crystal violet dye under UV light illumination. The complete degradation was achieved within 60 min, and the mechanism of the degradation were also been proposed. In addition, the degradation of rhodamine B (RhB) and methylene blue dye solution was also carried out to extend the practical applications of NiO nanospheres. The involvement of reactive oxidative species (ROS) was found out by trapping experiment, and the ROS is superoxide radical anion.