Phase transformation and heterojunction nanostructures of bismuth iron oxide

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 Fe 3+ and calcination temperature. As a result, the feeding ratios of bismuth ferrite materials Bi 2 Fe 4 O 9 , BiFeO 3 /Bi 2 Fe 4 O 9 , BiFeO 3 , BiFeO 3 /Bi 25 FeO 40 , and Bi 25 FeO 40 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 BiFeO 3 to Bi 2 Fe 4 O 9 . Moreover, BiFeO 3 /Bi 2 Fe 4 O 9 and BiFeO 3 /Bi 25 FeO 40 heterojunction nanostructures display strong interactions between BiFeO 3 –Bi 2 Fe 4 O 9 and Bi 25 FeO 40 . Besides, BiFeO 3 /Bi 25 FeO 40 heterojunction nanostructures exhibit obvious grain boundary with the smallest bandgap. This study presents far-reaching implications and provides pathways to prepare BiFeO 3 /Bi 2 Fe 4 O 9 and BiFeO 3 /Bi 25 FeO 40 heterojunction nanostructures.