Precise Adjustment of Forbidden Bandwidth in Bifeo3/Bi25feo40 Heterojunction Structure

Abstract

It is challenging to synthesize perovskites with the desired morphology and structure because perovskites typically require harsh synthesis conditions, such as high pressure and high temperature. Herein, we designed and synthesized BiFeO3/Bi25FeO40 heterojunction nanoparticles using the sol-gel method. We can achieve the precise control of particle size and phase composition content for BiFeO3/Bi25FeO40 by adjusting the concentration of Fe3+. As a result, the BiFeO3/Bi25FeO40 heterojunction exhibits a lower band gap than BiFeO3, Bi2Fe4O9, Bi25FeO40, and BiFeO3/Bi2Fe4O9. The reduced band gap of BiFeO3/Bi25FeO40 is due to the existence of a heterojunction structure. Meanwhile, the three strategies of heterojunction synthesis, increasing calcination temperature, and decreasing Fe3+ concentration can narrow the band gap. These findings not only provide guidance for the construction of perovskite heterostructures but also promote the application of BFO in photocatalytic and other redox reactions.

Keywords: BiFeO3/Bi25FeO40, heterojunction nanoparticles, sol-gel method, forbidden bandwidth