Investigation of photocatalytic behavior of undoped ZnO and Cr-doped ZnO nanoparticles for the degradation of dye

Nanosized ZnO and Cr-doped ZnO nanoparticles (NPs) were prepared by co-precipitation method, which were employed as photocatalysts for the degradation of murexide dye in aqueous media. The nanoparticles were characterized by FTIR, SEM, XRD and TGA. The morphological study illustrated that both ZnO and Cr-doped ZnO NPs are irregular round shaped. The XRD results presented that the crystallite size of undoped ZnO and Cr-doped ZnO were 30.07 and 28.14 nm, respectively. The band gap of undoped ZnO and Cr-doped ZnO were 3.4 and 3 eV, respectively. The precursor decomposition to ZnO after annealing at ∼500 °C was confirmed by TGA. The photodegradation study presented that the Cr-doped ZnO and undoped ZnO NPs degraded about 92 and 89% dye within 100 min, respectively. The effect of different parameters like dye initial concentration, contact time, pH and temperature on the photocatalytic degradation of dye was studied. The activity of recovered catalyst was also studied.