LAUSR

Abstract Silver phosphate (Ag 3 PO 4 ) could be considered as visible light induced photocatalyst for pollutants degradation, due to its narrow band gap (∼2.4 eV). However, Ag 3 PO 4 photoactivity depends on surface properties and synthesis route. In this study, differently shaped Ag 3 PO 4 photocatalysts have been synthesized through the precipitation, ion exchange, soft-chemical or hydrothermal method. To correlate surface properties with photoactivity all samples were characterized towards morphology, crystal structure, specific surface area, optical properties, chemical composition and activity in phenol degradation upon visible light irradiation (λ > 420 and 455 nm). It is worthwhile noting that the most active Ag 3 PO 4 samples possessed almost the same activity in phenol degradation upon irradiation from visible range (λ > 455 nm) that P25 TiO 2 upon UV light. Phenol degradation rate equaled to 3.31 and 3.23 μmol/dm 3 /min in the presence of branched and rhombic dodecahedral Ag 3 PO 4 particles, while it reached 3.36 μmol/dm 3 /min in the presence of P25 and UV light. Analysis of the degradation intermediates indicated that the benzoquinone was the primary byproducts of phenol degradation. Scavengers-assisted photocatalytic test confirmed that mainly O 2 − has been involved in phenol degradation under visible radiation. Surface composition analysis by XPS suggested that higher total silver content favors photoactivity, while higher ratio of Ag 0 to Ag + suppress photoactivity. Long term photocatalytic tests also implies that increase in Ag 0 amount at the Ag 3 PO 4 surface, due to photoreduction of Ag ions, rusulted in activity drop.