Design and evaluation of plasmonic metal-TiO nanostructures for photocatalytic degradation of BPA as a model pollutant.

This study investigates the improvement of the photocatalytic activity of TiO-based catalysts modified with plasmonic metal nanoparticles (PM). Gold (Au), silver (Ag) and platinum (Pt) nanoparticles were uniformly deposited on TiO nanorods (TNR) by a wet impregnation method, achieving a uniform metal loading of 1.0 wt%, which was confirmed by SEM-EDXS analysis. The size of the metallic particles varied, with Pt being the smallest (1.5 nm) and Au the largest (45 nm), while all exhibited a uniform distribution over the TiO surface. The size of the PM nanoparticles was influenced by the pH of the precursor solutions and the isoelectric point of the TNR support. Photoluminescence (PL) measurements showed that TNR-Pt exhibited the lowest charge carrier recombination rate and the highest photocatalytic performance. Tests with reactive oxygen species (ROS) under visible-light exposure showed that TNR-Pt generated the most superoxide anion (O) and hydroxyl (OH) radicals and achieved the highest degradation rate of bisphenol A (BPA). In contrast, TNR-Au showed the lowest ROS formation and BPA conversion rate. The superior performance of the TNR-Pt photocatalyst is attributed to its energy band distribution, which accelerates the oxygen reduction reaction. The results show that O are the primary reactive species responsible for the degradation of BPA, with the small size of Pt nanoparticles promoting ROS production and pollutant degradation, making TNR-Pt the most effective catalyst among the solids investigated in this study.