Direct Sunlight Catalytic Decomposition of Organic Pollutants via Sm- and Ce-Doped BiFeO 3 Nanopowder Synthesized by a Rapid Combustion Technique

In the development of photocatalytic processes towards waste water treatment, we have been long faced three foremost obstacles, including catalyst mass production, photon-energy cost and finally catalyst separation process after the treatment. In this study, such problems were addressed through the development of samarium and cerium-doped BiFeO3 (BFO) nanoparticles (NPs) (BixRExFeO3; RE = Sm, Ce, x = 0.00, 0.01, 0.03, 0.05;) employing a rapid solution combustion synthesis (SCS). This technique is greatly capable of large scale nanopowder production at low temperature. In the SCS procedure, different amount of oxidant-to-fuel (glycine-to-nitrate ion, Gly/NO3−) were investigated (Gly/NO3− = 0.2, 0.3, 0.37, 0.56, and 0.8). Moreover, a catalytic sunlight irradiation was employed to study the effect of Sm and Ce dopant contents on the photodegradation of benzene and methyl orange (MO) in the aqueous solution. The as-synthesized catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV–Visible diffuse reflectance spectroscopy (UV–Vis DRS) and Brunauer–Emmett–Teller (BET)/Barrett-Joyner Halenda (BJH) techniques. The band gap energy of BFO decreaed from 2.14 to 2.06 eV with the increase of Sm3+ contents while it increased up to 2.22 eV in the case of Ce-doped BFO. The solar decomposition of the organic pollutants demonstrated the superior performance of Bi1-xSmxFeO3 photocatalyst rather than using cerium in the BFO crystalline structure which is attributed to the increased surface area and visible light harvesting.