Construction of cobalt ferrite nanoparticles anchored on mesoporous WO3 for accelerated photoreduction of Cr(VI)

In this contribution, the synthesis of mesoporous WO3 nanoparticles (NPs) by the utilization of cationic surfactant by a facile hydrothermal approach was performed. A series of heterojunction CoFe2O4/WO3 photocatalysts were synthesized by impregnation and calcination for Cr(VI) photoreduction during visible light exposure. The TEM images of 12%CoFe2O4/WO3 nanocomposite revealed a beans-like structure with highly crystalline particles with a length of 200 nm and a diameter of 30 nm. The obtained CoFe2O4/WO3 nanocomposites indicated the occurrence of mesostructures with a high surface area. With an optimized 12% CoFe2O4/WO3 nanocomposite, 100% of Cr(VI) photoreduction was achieved after 45 min illumination, which was enhanced 2.85 folds greater than bare WO3 NPs. The reaction rate constant of 12% CoFe2O4/WO3 nanocomposite amounted to about 0.0947 min-1, which was fostered 6.1 times larger than that of bare WO3 (0.0155 min-1). The enhanced Cr(VI) removal efficiency can be ascribed to the design of heterostructures CoFe2O4/WO3, which functionally promoted the mobility and separation of photoinduced charge carriers. The increased surface area and the extended visible light region of CoFe2O4/WO3 nanocomposites contributed to the enhancement of the Cr(VI) reduction efficiency. Accordingly, a possible mechanism for Cr(VI) photoreduction over heterojunction CoFe2O4/WO3 photocatalyst was illustrated. The 12% CoFe2O4/WO3 nanocomposite exhibited 94% Cr(VI) reduction ability after five cycles with high stability. The results showed that the obtained p-n heterojunctions CoFe2O4/WO3 nanocomposites have considerable potential in Cr(VI) removal from wastewater.