Ag3PO4/BiPO4 p-n heterojunction nanocomposite prepared in room-temperature ionic liquid medium with improved photocatalytic activity

A visible-light-active Ag3PO4/BiPO4 nanocomposite with a p-n heterojunction structure was fabricated via a co-precipitation hydrothermal process using 2-hydroxylethylammonium formate (RTIL) as a room-temperature ionic liquid. The resulting catalysts were characterized by various techniques. The photocatalytic activity of the photocatalysts was evaluated by the photodegradation of phthalocyanine Reactive Blue 21 (RB21) under both visible and UV light irradiations. The results reveal that the heterojunction composite prepared in RTIL noticeably exhibited an improvement in both efficiency and rate of RB21 photodegradation in comparison with pure Ag3PO4 and BiPO4. The enhanced photocatalytic activity of Ag3PO4/BiPO4 heterostructure prepared in RTIL is mainly ascribed to the internal electric field built at the heterojunction interface and efficient charge separation and transfer across the p-n junction. RTIL can also assist in decreasing the crystalline size, orderly distributing the particles, preventing the collapse of pore structures, and losing of composite surface area.