Decomposition of Methylene Blue on Transition Metals Doped Sn O 2 Nanoparticles

Transition metals (M = Zn, Ni, Co, and Mn) doped stannic oxide M x Sn 1−x O 2 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 SnO 2 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, Co 3 O 4 , and Mn 2 O 3 were detected at 0.3 molar ratio. The average particles size of undoped SnO 2 and doped samples were amounted to be ∼5.8, 7.8, 11.8, 14.3, and 17.4 nm for SnO 2 , Zn 0.3 Sn 0.7 O 2 , Ni 0.3 Sn 0.7 O 2 , Co 0.3 Sn 0.7 O 2 , and Mn 0.3 Sn 0.7 O 2 samples, respectively. The prepared samples have been evaluated by photodegradation of methylene blue (MB). The results indicated that Zn 2+ doping SnO 2 (Zn 0.3 Sn 0.7 O 2 ) was remarked the highest photocatalytic activity for the MB photodegradation. The improvement in the photocatalytic activity of Zn 0.3 Sn 0.7 O 2 is attributed to hetero‐junctions of the ZnO/SnO 2 . The effect of doping Ni, Co, and Mn ions on the photocatalytic properties are insignificant in the photocatalytic activity of SnO 2 . The recycling tests indicated that ZnO/SnO 2 was quite stable and there is no decrease in photocatalytic activity after five times repetition, indicating a promising catalyst for commercial applications.