Eco-friendly hybrid Paper-AgBr-TiO₂ for efficient photocatalytic aerobic mineralization of ethanol

In this study, a facile and effective route to prepare hybrid photocatalysts (paper-TiO₂, paper-TiO₂-AgBr and paper-AgBr-TiO₂) has been reported. The preparation procedure consisted of the direct adsorption of the previously synthesized titania nanoparticles (TiO₂ sol) to generate the TiO₂ nanosphere and the immersion process in an aqueous suspension of AgBr to form the AgBr nanoclusters on paper fibers. The synthesis technology is economic, efficient, environmentally friendly and easy to implement even at industrial scale. A cellulose-based structure with well dispersed TiO₂ particles of around 1 μm and a pseudo-liquid coating of Ag⁺ and AgBr species was obtained. All the prepared photocatalysts demonstrated effective photocatalytic performance in gaseous phase ethanol degradation with simulated sunlight illumination, through the direct mineralization to CO₂ and the parallel reaction via acetaldehyde degradation. A relevant improvement in the photocatalytic activity was noticed when TiO₂ was associated with AgBr nanocrystals, with a higher effect observed when AgBr was loaded onto the paper surface prior to TiO₂. Ag-Ti interaction reduces the pair recombination rate and increases the available charge carriers generating reactive OH- radicals from both Ag-species and TiO₂, and O₂^- radicals from Ag⁺-AgBr species, which would be involved in the ethanol degradation process.