Efficient Solar Light Photocatalyst Made of Ag 3 PO 4 Coated TiO 2 -SiO 2 Microspheres.

Solar light active photocatalyst was prepared as silver phosphate (Ag 3 PO 4 ) coating on titania-silica (TiO 2 -SiO 2 ) microspheres. Titania-silica microsphere was obtained by spray drying TiO 2 -SiO 2 colloidal solutions, whereas Ag 3 PO 4 was applied by wet impregnation. XRD on the granules and SEM analysis show that the silver phosphate particles cover the surface of the titania-silica microspheres, and UV-visible diffuse reflectance analysis highlights that Ag 3 PO 4 /TiO 2 -SiO 2 composites can absorb the entire visible light spectrum. BET measurements show higher specific surface area of the composite samples compared to bare Ag 3 PO 4 . Photocatalytic activity was evaluated by dye degradation tests under solar light irradiation. The prepared catalysts follow a pseudo-first-order rate law for dye degradation tests under solar light irradiation. The composite catalysts with an Ag 3 PO 4 /TiO 2 -SiO 2 ratio of 1:1.6 wt% show better catalytic activity towards both rhodamine B and methylene blue degradation and compared with the results with uncoated TiO 2 -SiO 2 microspheres and the benchmark commercial TiO 2 (Evonik-P25) as a reference. The composite photocatalyst showed exceptional efficiency compared to its pristine counterparts and reference material. This is explained as having a higher surface area with optimum light absorption capacity.