Efficient degradation of endocrine-disrupting compounds by heterostructured perovskite photocatalysts and its correlation with their ferroelectricity

Abstract

The growing contamination of water with endocrine-disrupting compounds (EDCs) is posing a serious threat to the reproductive, neuro, and other endocrine-related functions in humans and animals. One of the promising approach for degrading EDCs is photocatalytic degradation, because of its low energy consumption, mild reaction conditions and the absence of any secondary pollution. The visible light-active perovskite photocatalyst- bismuth ferrite (BiFeO₃) possesses distinctive intrinsic polarization properties and its modification to design heterostructured BiFeO₃–NiS₂, BiFeO₃–Bi₂S₃, and BiFeO₃–NaNbO₃ photocatalysts for EDCs degradation is reported. Upon modification of BiFeO₃ with Bi₂S₃, the morphology changes from nanoparticles to rod-like structures. The BiFeO₃–Bi₂S₃ photocatalyst exhibits higher degradation efficiency (98% and 96% for 17-β-estradiol and estrone, respectively, at pH 8) as compared to those of bare and modified BiFeO₃ and follows pseudo-first-order kinetics. The dielectric constant (57 300) and polarization measurements undertaken demonstrate that the high dipole constant and high degree of polarization observed in the case of BiFeO₃–Bi₂S₃ facilitate efficient separation of excitons and high dielectric loss owing to better conductivity enabling faster charge-carrier transfer kinetics, which eventually give rise to improved degradation of EDCs. Such improvement in the EDCs degradation efficacy is ascribed to the synergized effect of enhanced visible light harvesting, faster charge transfer kinetics, greater degree of excitons separation, and higher dielectric constant.