Anchoring Co3O4 on BiFeO3: achieving high photocatalytic reduction in Cr(VI) and low cobalt leaching

A novel Co 3 O 4 –BiFeO 3 nanocomposite was successfully prepared via a facile hydrothermal method followed by an impregnation process and well characterized with XRD, TEM, FTIR, XPS, UV–Vis DRS and PL spectrum. XPS and TEM analyses reveal that Co 3 O 4 nanoparticles were successfully anchored on the BiFeO 3 . The photocatalytic activities of prepared photocatalysts were evaluated by removal of Cr(VI) under visible light (300 W Xe lamp irradiation). The results indicate that the 0.8% CO 3 O 4 –BiFeO 3 (Co0.8Bi) sample calcined at 500 °C for 4 h showed the best performance, and the rate constant k of Cr(VI) reduction over Co0.8Bi is about 13.7- and 23.3-fold compared with pure BiFeO 3 and Co 3 O 4 , respectively. More importantly, the CO 3 O 4 -BiFeO 3 catalyst exhibited highly chemical stability with Co leaching of lower than 34.5 μgL −1 , which is attributed to a strong interaction between Bi and Co components in Co 3 O 4 –BiFeO 3 . The effects of Co 3 O 4 loading, calcination temperature and initial pH on catalytic activity and cobalt leaching were optimized.