Heterojunction built sillenite/ perovskite (Bi25Fe2O39-SrTiO3) composite of distinct light sensitive nature for an interactive solar photocatalysis performance

Abstract

In the present study a heterojunction was built in between visible light and UV light sensitive materials (Bi25Fe2O39/SrTiO3) of sillenite and perovskite nature with varied Bismuth ferrite (BFe) loading on fixed SrTiO3 (STO). The predominance of sillenite phase (Bi25Fe2O39) in the bulk of bismuth iron oxide was confirmed through diffraction and XPS analysis. The as obtained composites resulted in an improved crystal characteristic, in terms of increased crystal size and reduced lattice strain. Several locations in the FESEM and HRTEM images revealed formation of interface between BFe and STO. The shifting of binding energies for the elements further supported the formation of the heterojunction features. The band energy for composites was reduced to greater extent with low charge-carrier recombination. The solar photocatalytic degradation of Bisphenol A (BPA) demonstrated a highest removal efficiency (∼95 %) and apparent quantum efficiency (1.75 ×10−2) for B 1.5 S composite. The optimum crystal packing between BFe/STO had significant contribution for the band formation and prompted charge transfer between the built-in junction interfaces through a type II heterojunction charge transfer mechanism. The photocatalysis of the BPA was predominately driven by the ⁕O2- radical. The obtained ferromagnetic characteristics of the composite (B 1.5 S: 0.0742 emu/g (Mr), 15.013 Oe (Hc)) revealed ease separation of the photocatalyst from the liquid stream.