Photocatalytic enhancement of immobilized TiO2-polyaniline bilayer (TiO2-PBL) system for decolorization of methyl orange dye

Highlights: • TiO₂-PANI bilayer (TiO₂-PBL) system was fabricated via dip-coating technique. • MO decolorization by TiO₂-PBL system was two times better than TiO₂ monolayer. • TiO₂-PBL showed better optical properties than TiO₂ monolayer. • PANI exhibited a multi-functional role in TiO₂-PBL system. • Photoetched TiO₂-PBL system removed MO more effectively than as-prepared system. - Abstract: Immobilized TiO₂-polyaniline (PANI) bilayer (TiO₂-PBL) was fabricated on a glass plate for decolorization of methyl orange (MO). The thickness of TiO₂-PBL was 25.55 μm with the ratio of 0.62:0.38 for TiO₂ to PANI layer. It was observed that the TiO₂-PBL system emitted less photoluminescence (PL) intensity than the TiO₂ monolayer corresponding to better ^• OH radicals production with reduced band gap energy. The removal of MO from the solution after 90 min of treatment was 97% by TiO₂-PBL and 53% by TiO₂ monolayer which indicates the efficacy of the former system due to the synergistic photocatalytic-adsorption processes. The effect of prewashing (photoetching) of TiO₂-PBL plate was pronounced as better removal efficiency of MO was observed for ten cycles under UV–vis and visible light irradiations. The results showed that the TiO₂-PBL system has visible light active properties, reduces the recombination of photogenerated active species and enhances the photocatalytic oxidation of MO.