Green synthesis of Ce-doped ZnO nanoparticles using Hedyotis capitellata Leaf extract for efficient photocatalytic degradation of Methyl Orange

This work presents a green route to synthesize single phase Ce-doped ZnO nanoparticles using Hedyotis capitellata leaf extract (HC-Ce@ZnO) as an effective reactant. The phase composition and crystalline nature of HC-Ce@ZnO with various weight% Ce-doping concentrations were examined by X-ray diffraction (XRD) method. The organic functional groups that played the key role in the transformation of Zn2+ into ZnO were recognized by Fourier-transform infrared spectroscopy (FT-IR). The transmission electron microscopy (TEM) image revealed that HC-Ce@ZnO nanoparticles were mainly spherical with the diameter of 2-6 nm. The biosynthesized HC-Ce@ZnO nanoparticles were then applied for the treatment of methyl orange (MO) using UV-Vis measurement. It's been found that Ce3+ ions were easily incorporated into ZnO crystal lattice to form single crystals of Ce@ZnO. The optimal 1 %Ce-doped ZnO nanoparticles can remove 92 % MO within 240 min under irradiation of visible light. The study on photocatalytic degradation kinetics showed that the reaction has pseudo first-order nature with the rate constant k = 0.0133 min(-1).