Supporting the photocatalysts on ZrO2: An effective way to enhance the photocatalytic activity of SrSnO3

• Azo-dye discolorization increased 1.8 times after deposition of SrSnO 3 on ZrO 2 . • After deposition SrSnO 3 had higher amount of Sn(II) species and better dispersion. • Photocatalytic activity was correlated to the band gap structures determined by EIS. • Formation of OH by H 2 O reaction with holes was confirmed using scavengers. Photocatalysts based on SrSnO 3 and SrSnO 3 @ZrO 2 were prepared by the modified-Pechini method and applied in the photocatalytic degradation of a textile azo-dye under UV radiation. The photohydroxylation of terephthalic acid and scavengers were employed in order to evaluate the participation of each active species, such as hydroxyl radical, and photogenerated electrons and holes on the photocatalytic process. The band gap structure was evaluated using the Mott Schottky method in combination with UV–visible spectrophotometry. Both samples had high photocatalytic activity, although SrSnO 3 @ZrO 2 showed the best decolorization performance ranging from 32% to 98%. This behavior was assigned to the best dispersion of the active phase on the support and to the Sn(II) reduced states, observed by XPS. The participation of hydroxyl radicals in the reaction was confirmed when terephthalic acid was used as probe and by using isopropanol as hydroxyl radical scavenger, which resulted in the inhibition of the photocatalytic process.