Optimizing the photocatalytic properties Er-doped bismuth ferrite for the degradation of mixed dyes under sunlight irradiation

Abstract

In this study, the erbium (Er)-doped bismuth ferrite (BiFeO3/BFO) with the chemical formulation of Bi1-xErxFeO3 (x = 0, 5, 10, and 15 mol%) are synthesized using hydrothermal method. It is found that Er-doping induces structural distortions in BFO, leading to improved electronic and optical properties in BFO as confirmed by XRD, XPS, UV–visible absorption and PL spectral analysis. The particle size of BFO is found to be decreasing in the range of 60–30 nm with Er-doping, observed from their TEM images. Further, the photocatalytic efficiencies of the synthesized Bi1-xErxFeO3 nanoparticles are studied towards the degradation of methylene blue (MB), rhodamine B (RhB) dyes and their mixture under solar irradiation. While all the Er-BFO showed improved efficiency compare to pristine, the 10 mol% Er-doped BFO showed the highest degradation of ∼99 and 94 % for MB and RhB dyes, respectively in 180 min. More interestingly, while the pristine BFO selectively degraded only the MB dye in the MB-RhB mixture, the Er-BFO greatly degraded both the dyes in the mixture, which attributed to their improved electronic, electric field and optical band structure properties, especially to the 10 % Er-BFO degraded around 93 and 78 % of MB and RhB dye in the MB-RhB mixture. The cyclical use of 10 mol% Er-BFO is tested toward the degradation dye mixture, which showed a consistent photocatalytic performance up to 5 cycles, suggesting that the Er-doped BFO is photochemically stable and suitable for sustainable photocatalytic applications.