Efficient dye degradation and concurrent electricity generation using silver bromide-embedded titanium dioxide

Removal of dissolved organic matters, like dyes, from industrial wastewater is challenging due to complexity with their exceptional stability and ability to pass through filters. In this study, we have synthesized silver bromide nanoparticles-embedded polycrystalline titania (AgBr-x/TiO2) by a simple one-pot synthesis route. The degradation of reactive green dye with simultaneous electrical energy generation is demonstrated with developed AgBr-x/TiO2 photo-anodes. The structural and morphological analyses reveal that the fine AgBr nanocrystals are embedded in submicron sized TiO2 particles. The composite particles with various AgBr compositions were synthesized. The embedded-structure gives better heterojunction between AgBr and TiO2, and facilitates the transfer of photogenerated electrons compared to simple mixture. The visible light absorption of the composite was monotonically increased with AgBr composition. A flat optical absorption profile was obtained at 50% AgBr composition. The developed AgBr-x/TiO2 photo-anode shows the initial rate of dye degradation four-fold higher than the commercial grade TiO2 nanoparticles, where the generated power was 2.6 times high. The degradation by-product contains water-insoluble sludge which has the similar optical absorption profile of feed water. It is observed that the dye removal is predominantly through decolourization and coagulation. Conclusively, the developed AgBr-x/TiO2 photo-anode could realize a self-sustained wastewater treatment unit where the required electricity is produced by dye degradation.