Facile synthesis of a novel WO 3 /Ag 2 MoO 4 particles-on-plate staggered type II heterojunction with improved visible-light photocatalytic activity in removing environmental pollutants.

A novel WO 3 /Ag 2 MoO 4 heterojunction has been synthesized through a facile precipitation method with Ag 2 MoO 4 particles firmly deposited on the surface of WO 3 nanoplates, forming "particles-on-plate" type II heterojunction structures. This heterojunction exhibited improved photocatalytic activities for the degradation of rhodamine B (RhB), 4 chlorophenol (4-CP) and tetracycline hydrochloride (TC) under visible-light irradiation compared to pure Ag 2 MoO 4 and WO 3 . In addition, the heterojunction with 10 wt% Ag 2 MoO 4 displays the best photocatalytic performance, which was about 2 times better than that of pure WO 3 or Ag 2 MoO 4 . The TC photodegradation rate reaches up to 91% within 90 min visible light irradiation. Furthermore, the photocatalytic efficiency of the Ag 2 MoO 4 /WO 3 heterojunction is 1.3 times higher than that of the mixture of the two individual photocatalysts. This remarkable enhanced photocatalytic performance results from the staggered bandgap between Ag 2 MoO 4 and WO 3 , which can suppress the recombination of electron-hole pairs efficiently. Moreover, based on the radical trapping experiment, the superoxide radical anions (·OH) and photogenerated holes (h + ) are the crucial active oxidizing species.