Decomposition of Methylene Blue on Transition Metals Doped SnO2 Nanoparticles

Transition metals (M=Zn, Ni, Co, and Mn) doped stannic oxide MxSn1-xO2 at x=0.1, 0.2, and 0.3 molar ratios have been successfully prepared. The results revealed that X-ray diffraction peaks position exhibited the rutile tetragonal structure of cassiterite phase of SnO2 and there are no extra peaks of doped metal oxides at 0.1 and 0.2 molar ratio. However, secondary phase of doped metal oxides ZnO, NiO, Co3O4, and Mn2O3 were detected at 0.3 molar ratio. The average particles size of undoped SnO2 and doped samples were amounted to be approximate to 5.8, 7.8, 11.8, 14.3, and 17.4nm for SnO2, Zn0.3Sn0.7O2, Ni0.3Sn0.7O2, Co0.3Sn0.7O2, and Mn0.3Sn0.7O2 samples, respectively. The prepared samples have been evaluated by photodegradation of methylene blue (MB). The results indicated that Zn2+ doping SnO2 (Zn0.3Sn0.7O2) was remarked the highest photocatalytic activity for the MB photodegradation. The improvement in the photocatalytic activity of Zn0.3Sn0.7O2 is attributed to hetero-junctions of the ZnO/SnO2. The effect of doping Ni, Co, and Mn ions on the photocatalytic properties are insignificant in the photocatalytic activity of SnO2. The recycling tests indicated that ZnO/SnO2 was quite stable and there is no decrease in photocatalytic activity after five times repetition, indicating a promising catalyst for commercial applications.