Photocatalytic degradation of methyl orange using Bi2MNbO7 (M = Al, Fe, Ga, In) semiconductor films on stainless steel

Semiconductor Bi2MNbO7 (M = Al, Fe, Ga, In) films on AISI/SAE 304 stainless steel were prepared by sol–gel dip-coating followed by a thermal treatment at 500 °C. The films were made by depositing different number of layers (1, 3 and 5) at different withdrawal speeds (5.0, 7.5 and 10.0 cm/min). They were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray fluorescence. The photocatalytic activity of Bi2MNbO7 films was evaluated by the degradation of methyl orange. The photodegradation kinetics was investigated and compared with those of TiO2 films prepared by a similar procedure. The films exhibited the following photocatalytic performance: Bi2GaNbO7 > Bi2FeNbO7 > Bi2AlNbO7 > TiO2 ≥ Bi2InNbO7 ≫ UV light. It is worth noting that the photoactivity of Bi2MNbO7 films toward methyl orange degradation was higher or equivalent than that of TiO2 films.