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Novel Z-scheme Bi2SiO5/AgI nanoplate photocatalysts with the exposure of {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 the pure Bi2SiO5 or AgI. X-ray photoelectron spectroscopy (XPS) reveals that few 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 Z-scheme photocatlytic system composed of Bi2SiO5, AgI and metallic Ag and the inner electric field caused by exposure of {100} facets on the Bi2SiO5 nanoplates. The as-prepared catalysts remained good photocatalytic activity after four recycles and the radical species involved in the degradation process have been investigated by the PL spectra and trapping experiments.