Design and evaluation of plasmonic metal-TiO2 nanostructures for photocatalytic degradation of BPA as a model pollutant
Špela Slapničar, Gregor Žerjav, Miklós Németh, Janez Zavašnik, Albin Pintar
Abstract
This study investigates the improvement of the photocatalytic activity of TiO 2 -based catalysts modified with plasmonic metal nanoparticles (PM). Gold (Au), silver (Ag) and platinum (Pt) nanoparticles were uniformly deposited on TiO 2 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 2 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 2 •- ) 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 2 •- 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.