Drastic photocatalytic degradation of methylene blue dye by neodymium doped zirconium oxide as photocatalyst under visible light irradiation

Nanocrystalline ZrO2 and neodymium doped ZrO2 (Nd-ZrO2) were successfully prepared by a polymer- assisted, sol-gel method and characterized by XRD, SEM, HRTEM, XPS and UV-vis techniques. X-Ray diffraction studies revealed the formation of highly crystalline structures of ZrO2 and (Nd-ZrO2) samples. SEM images proved the evenly distributed nano - structured, spherically - shaped ZrO2 particles of size 40 nm, which was reduced to 20 nm, when doped with neodymium. Light absorption properties of the nanoparticles were studied by UV-vis spectrophotometer. Nd - doped ZrO2 was having a band gap of 2.8 ev, while that of ZrO2, was 2.6 ev. Thus, Nd substituted ZrO2 effected substantial shifting of the absorption edge of zirconium oxide to red and resulting in the enhancement of visible light absorption The increase in band gap of Nd-ZrO2 was resulted in an increasing light absorbtion tendency of Nd − ZrO2, which promoted the photocatalytic efficiency of it. XPS results confirmed substitution of Nd in ZrO2. Photocatalytic results for the degradation of methylene blue had indicated the fact that neodymium substitution dramatically enhanced the catalytic activity of zirconium oxide. This means that the neodymium − substituted zirconium oxide has the highest photocatalytic activity under visible light irradiation.