A review of Fe₂O₃-based S-scheme heterojunction photocatalysts for pollutant removal

Fe₂O₃, an n-type semiconductor, has garnered widespread research interest for diverse photocatalytic applications owing to its unique properties, including a small bandgap, visible light response, low cost, earth abundance, and ease of recovery. Until now, there has been no review published on Fe₂O₃-based S-scheme photocatalysts for pollutant removal. To facilitate a deeper understanding of the design and charge transfer mechanisms, a preliminary discussion includes the crystal structures and photocatalytic properties of Fe₂O₃. The review subsequently provides the photocatalytic mechanisms, benefits, and challenges associated with Fe₂O₃-based type II, Z-scheme, and S-scheme heterojunctions, formed by integrating Fe₂O₃ with other semiconductors. Moreover, the discussion of advanced characterization techniques is provided to authenticate the charge migration mechanism in Fe₂O₃-based S-scheme systems. The review then presents the recent advances and applications of Fe₂O₃-based S-scheme photocatalysts for pollutant removal. Finally, it proposes the research challenges of Fe₂O₃-based S-scheme photocatalysts and discusses future perspectives.