Dual halogen layers diversify band engineering in Sillén oxyhalide photocatalysts: electronic structure control of SrBi ₃ O ₄ X ₃ (X = Cl, Br, I) via halogen substitution

In Sillén oxyhalides SrBi 3 O 4 X 3 (X = Cl, Br, I) with single/double halogen layers, substitution with larger halogens enables both the conduction band edge lowering and bandgap narrowing, offering a new strategy for band engineering in Sillén oxyhalides.