Fabrication of Ag-Decorated CaTiO₃ Nanoparticles and Their Enhanced Photocatalytic Activity for Dye Degradation

CaTiO₃ nanoparticles of 30–40 nm in size were synthesized via a polyacrylamide gel route. Ag nanoparticles with size of 8–16 nm were deposited onto CaTiO₃ particles by a photochemical reduction method to yield CaTiO₃@Ag composites. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under ultraviolet irradiation. It is demonstrated that Ag-decorated CaTiO₃ particles exhibit an enhanced photocatalytic activity compared to bare CaTiO₃ particles. After 60 min of photocatalysis, the degradation percentage of MO increases from 54% for bare CaTiO₃ particles to 72% for CaTiO₃@Ag composites. This can be explained by the fact that photogenerated electrons are captured by Ag nanoparticles and photogenerated holes are therefore increasingly available to react with OH−/H₂O to generate hydroxyl (^•OH) radicals. ^•OH radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing an enhanced yield on the irradiated CaTiO₃@Ag composites. In addition, it is found that the addition of ethanol, which acts as an ^•OH scavenger, leads to a quenching of ^•OH radicals and simultaneous decrease in the photocatalytic efficiency. This suggests that ^•OH radicals are the dominant active species responsible for the dye degradation.