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

A novel Co3O4-BiFeO3 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 Co3O4 nanoparticles were successfully anchored on the BiFeO3. The photocatalytic activities of prepared photocatalysts were evaluated by removal of Cr(VI) under visible light (300W Xe lamp irradiation). The results indicate that the 0.8% CO3O4-BiFeO3 (Co0.8Bi) sample calcined at 500 degrees C for 4h 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 BiFeO3 and Co3O4, respectively. More importantly, the CO3O4-BiFeO3 catalyst exhibited highly chemical stability with Co leaching of lower than 34.5 mu gL(-1), which is attributed to a strong interaction between Bi and Co components in Co3O4-BiFeO3. The effects of Co3O4 loading, calcination temperature and initial pH on catalytic activity and cobalt leaching were optimized.