Photocatalytic deposition of Ag nanoparticles on TiO2: Metal precursor effect on the structural and photoactivity properties

A series of 1 wt.% Ag–TiO2 photocatalysts were obtained by photodeposition using different organic (acetylacetonate, Ag-A) and inorganic (nitrate, Ag-N, and perchlorate, Ag-C) silver precursors in order to determinate the influence of the silver precursor on final properties of the photocatalysts. The resulting photocatalytic materials were characterized by different techniques (UV–Vis DRS, TEM/HRTEM and XPS) and their photocatalytic activity was evaluated in the degradation of rhodamine B (used as model pollutant) in aqueous solution under simulated solar light. The photocatalytic reduction of Ag species to Ag0 on TiO2 was higher with silver nitrate as precursor compared to acetylacetonate or perchlorate. All the Ag-modified TiO2 photocatalysts exhibited a surface plasmon resonance effect in the visible region (400–530 nm) indicating different metal particle sizes depending on the Ag precursor used in their synthesis. A higher photocatalytic activity was obtained with all the Ag/TiO2 samples compared with non-modified TiO2. The descending order of photocatalytic activity was as follows: Ag-A/TiO2 ≈ Ag-N/TiO2 > Ag-C/TiO2 > TiO2-P25. The enhanced photoactivity was attributed to the presence of different amounts Ag0 nanoparticles homogeneously distributed on Ag2O and TiO2, trapping the photogenerated electrons and avoiding charge recombination.