Synthesis and facet-dependent enhanced photocatalytic activity of Bi2SiO5/AgI nanoplate photocatalysts

Abstract

Novel Bi₂SiO₅/AgI nanoplate photocatalysts with exposed {100} facets on the surfaces of Bi₂SiO₅ nanoplates were synthesized via an in situ precipitation method. Acid red G aqueous solution and gaseous formaldehyde were chosen as model organic pollutants to evaluate the photocatalytic activities of the as-prepared catalysts. Under visible light irradiation (>420 nm), the Bi₂SiO₅/AgI nanoplates exhibited enhanced photocatalytic activities as compared to pure Bi₂SiO₅ or AgI. X-ray photoelectron spectroscopy (XPS) reveals that a small amount of metallic Ag was formed on the surface of AgI during the photocatalytic reaction, thus leading to the transformation from Bi₂SiO₅/AgI to Bi₂SiO₅/AgI@Ag. The excellent photocatalytic activities of the Bi₂SiO₅/AgI nanoplates can be ascribed to the photocatalytic system composed of Bi₂SiO₅, AgI and metallic Ag and the inner electric field caused by the exposure of {100} facets on the Bi₂SiO₅ nanoplates. The as-prepared catalysts retained good photocatalytic activity after four recycles and the radical species involved in the degradation process have been investigated by using PL spectra and trapping experiments.