Phase transformation and heterojunction nanostructures of bismuth iron oxide

Abstract

The construction of an efficient bismuth iron oxide shows great potential in excellent crystal structure properties and visible light photocatalysis. However, it is challenging to synthesize nanostructures with the desired morphologies. For the first time, the bismuth iron oxide is fabricated using sol–gel synthesis method, exhibiting the desired crystallite size and tuning the types of heterojunction nanostructures by regulating the concentration of Fe3+ and calcination temperature. As a result, the feeding ratios of bismuth ferrite materials Bi2Fe4O9, BiFeO3/Bi2Fe4O9, BiFeO3, BiFeO3/Bi25FeO40, and Bi25FeO40 are 2:1, 1.5:1, 1:1, 0.75:1, 0.5:1, and 0.04:1, respectively. Besides, the calcination temperature not only influences the granularity of bismuth iron oxide but also promotes the phase transformation from BiFeO3 to Bi2Fe4O9. Moreover, BiFeO3/Bi2Fe4O9 and BiFeO3/Bi25FeO40 heterojunction nanostructures display strong interactions between BiFeO3–Bi2Fe4O9 and Bi25FeO40. Besides, BiFeO3/Bi25FeO40 heterojunction nanostructures exhibit obvious grain boundary with the smallest bandgap. This study presents far-reaching implications and provides pathways to prepare BiFeO3/Bi2Fe4O9 and BiFeO3/Bi25FeO40 heterojunction nanostructures.