Effect of terbium doping in bismuth ferrite nanoparticles for the degradation of organic pollutant under sunlight irradiation

Herein, we have studied the influence of terbium (Tb) doping in bismuth ferrite (BiFeO3/BFO) nanoparticles towards its photocatalytic activity by varying the concentration of Tb such as Bi1-xTbxFeO3, x = 0, 1, 3, 5% through a simple hydrothermal method. The obtained samples are characterized using XRD, TEM, XPS, and UV-Vis diffuse reflectance spectroscopy and studied their photocatalytic properties by degrading the rhodamine B (RhB) dye molecules under sunlight illumination. The XRD results confirmed a gradual transformation of crystal structure of BFO from rhombohedral to orthorhombic structure with the increasing concentration of Tb. Dopant induced size reduction in particles is confirmed through TEM and the obtained results revealed the average particles size of 5% Tb dopant BFO around 40 to 80 nm for 5% Tb doped BFO. It indicates that the Tb doping in BFO could considerably affect the photocatalytic activity, and accordingly, the photocatalytic performance is gradually enhanced with increasing Tb content up to an optimum level. To understand the improved mechanism of photocatalytic degradation by Tb-doped BFO, the free radicals trapping tests and photoluminescence are carried out. Based on these outcomes, the improved catalytic activity of Tb-doped BFO is attributed to its reduced bandgap energy from 2.35 to 2.29 eV, improved optical absorption profile, the effective charge separation and transfer of photo-induced charge carriers with increased recombination resistance in the system and accordingly, a possible photocatalytic mechanism of Tb-doped BFO is also proposed.