Novel and facile synthesis of Ba-doped BiFeO3 nanoparticles and enhancement of their magnetic and photocatalytic activities for complete degradation of benzene in aqueous solution.

In this work, Bi1-x Ba-x FeO3 (x = 0.05, 0.1 and 0.2 mol%) multiferroic materials as visible-light photocatalysts were successfully synthesized via a simple and rapid sol-gel method, at a low temperature and with rapid calcination. Ba loading brought about a distorted structure of BiFeO3 magnetic nanoparticles (BFO MNP5) consisting of small, randomly oriented and non-uniform grains, leading to increased surface area and improved magnetic and photocatalytic activities. Doping of Ba2+ into pure BFO (Bi1-x Ba-x FeO3, x=0.2 mol%) greatly increased magnetic saturation to 3.0 emu/g and significantly decreased the band gap energy to 1.79 eV, as compared to 2.1 emu/g and 2.1 eV, respectively, for pure BFO. Bi1-x Ba-x FeO3 of x=0.2 mol% exhibited the greatest photocatalytic degradation effect after 60 min of visible light irradiation, and reached 97% benzene removal efficiency, leading to production of a high concentration of carbon dioxide (CO2), with 93% and 82% reductions in chemical oxygen demand (COD) and total organic carbon (TOC), respectively. The identified major intermediate products of photodegradation enabled prediction of the proposed benzene degradation pathway. The enhanced photocatalytic activity of benzene removal is due to both mechanisms, photocatalytic and photo-Fenton catalytic degradation. (C) 2016 Elsevier B.V. All rights reserved.