Ag3PO4/Fe2O3 composite photocatalysts with an n–n heterojunction semiconductor structure under visible-light irradiation

Highly active Ag3PO4/Fe2O3 composite photocatalysts with an n–n heterojunction semiconductor structure have been prepared by ultrasound-assisted precipitation. These photocatalysts were characterized by XPS, XRD, SEM, TEM, UV–vis and PL spectroscopy. The photodegradation of methyl orange in aqueous solution under visible-light irradiation has been investigated over Ag3PO4-based photocatalysts consisting of different Ag3PO4/Fe2O3 mass ratios. Ag3PO4/Fe2O3 composite photocatalysts were shown to have a higher photocatalytic destruction rate than Ag3PO4 mainly due to electrostatic-field-driven electron–hole separation in Ag3PO4/Fe2O3 composite photocatalysts. The best Ag3PO4/Fe2O3 composite photocatalyst with mass ratio of Ag3PO4:Fe2O3 of 10:1 showed approximately 6 times higher photocatalytic activity than pure Ag3PO4. The role of n–n Ag3PO4–Fe2O3 heterojunction was discussed in view of theory of semiconductor physics.