Experimental Evidence for the Carrier Transportation Enhanced Visible Light Driven Photocatalytic Process in Bismuth Ferrite (BiFeO₃) One-Dimensional Fiber Nanostructures

Abstract

The effective carrier transportation schemes in one-dimensional (1D) nanofibers of bismuth ferrite (BFO) have been experimentally demonstrated in comparison with their 3D particulate nanostructures. The structural analysis using X-ray diffraction technique revealed the rhombohedral crystal structure with R3c space group of BiFeO3 particulate and fiber nanostructures. The influences of dimension on the optical properties are analyzed using UV–visible absorption/diffuse reflectance spectroscopy, where the band gap energy is found to be increased for fibers (∼2.39 eV) as compared to the particulates (∼2.32 eV). The photoluminescence (PL) spectroscopy analysis indicated a reduced radiative-emission in BFO fibers that could be attributed to the slower recombination of excited electron–hole pairs in fibers as compared to particulates, which is also experimentally confirmed by estimating their fluorescence lifetime measurements. The room temperature photocurrent conductivity measurements showed an enhanced photocurrent for the fibers, which revealed that the transportation of charge carriers is improved in fibers due to the delocalization of electrons in its conduction band and subsequent delayed recombination owing to the 1D confinement. The photocatalytic efficiency on the degradation of organic dyes (methylene blue and rhodamine B) under the simulated solar light irradiation showed an enhanced degradation rate for BFO fibers as compared to particulates. This could be attributed to the observed modifications in band energy structures and enhanced photocurrent conductivity of the fibers. Further, the effective carrier transportation-induced photocatalytic reactions that resulted from the increased number of *OH radicals is also probed by PL spectroscopy using terephthalic acid as a probing molecule.