Photocatalytic degradation of organic pollutants using magnetic Pd-doped BiFeO3 composites under visible light irradiation

Abstract

Highly effective Pd-doped coral-like BiFeO3 (Pd-BFO) composites were prepared using hydrothermal method and characterized via a X-ray diffraction (XRD), UV-vis diffused reflectance spectroscopy (UV-vis DRS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) mapping and magnetic hysteresis (M-H) loop techniques. FESEM and EDX mapping images showed that the metallic Pd was uniformly dispersed on the whole surface of BFO. The M-H loop exhibited that the magnetization value of pure BFO and Pd-BFO composites were around 4.85 emu/g and 4.15 emu/g, respectively. The prepared Pd-BFO composites showed improved visible-light photodegradation activity towards the degradation of phenol and malachite green (MG) dye than that of the pure BFO as well as commercial TiO2 (P25). The improvement in the photodegradation activity was credited to the enhanced optical properties and construction of heterojunction among metallic Pd and BFO, which was favourable to decrease the recombination of photogenerated electron-hole pairs as confirmed by TA-PL analysis. The removal of Pd-BFO composites from the aqueous solution was also found to be easy owing to its higher magnetic properties. Moreover, electrical energy per order (EEO) was determined to compare the electrical energy consumption. The Pd-BFO composites displayed the best energy efficiency than those of the pure BFO and P25 in the both MG dye and phenol photodegradation systems. The synthesized photocatalysts can also efficiently utilize sunlight to degrade MG dye as well as phenol and their photodegradation activities were again much higher to those of the visible-light irradiation under the same experimental conditions.