Synthesis of plate-like Fe-doped SrBi4Ti4O15 using Na2SO4/K2SO4 molten salt method: XRD, Raman spectroscopy, SEM, and UV–VIS DRS studies

SrBi4Ti4O15 is a four-layer member of the Aurivillius compound and reported to have photocatalyst properties with a band gap energy of 3.0 eV (420 nm). Doped with metal elements is a strategy to reduce the band gap energy of photocatalyst material in order to increase its utilization under a wider energy spectrum of visible light. Here in, Fe-doped SrBi4Ti4O15 was synthesized using Na2SO4/K2SO4 molten salt method. The diffractogram revealed that all samples were successfully synthesized in the A21am space group with no impurity phase. Raman spectra confirmed the existence of a typical Raman vibration peak for a four-layer Aurivillius family compound and the local changes in TiO6 structure due to Fe dopant mirrored by vibration mode at 559 cm−1. SEM images showed that the all samples morphology is plate-like however, the particle size of Fe-doped SrBi4Ti4O15 is bigger than the undoped compound. Meanwhile, the UV–Vis DRS spectra revealed that Fe dopant could effectively reduce the band gap energy resulting in obvious red shift absorption to the wider visible light region (530–705 nm).