Photocatalytic Properties of Bismuth Oxyhalides

Bismuth oxyhalides (BiOX, where X = Cl, Br, I) comprise a family of layered semiconductors distinguished by their unique crystal structure, tunable electronic properties and robust chemical stability. In these materials, alternating [Bi₂O₂] slabs and halide layers create internal electric fields that promote separation of photogenerated electrons and holes. Controlled modification of the halogen content and deliberate formation of solid solutions enable continuous adjustment of the optical band gap across the visible spectrum, thus optimising light absorption and redox potential for targeted applications. Key practical outcomes include efficient degradation of organic pollutants under solar irradiation, visible-light-driven water splitting and removal of nitrogen oxides in construction materials. Advances in nanostructuring—such as two-dimensional nanoplates, heterojunction composites and porous microspheres—further enhance surface area, charge transport pathways and reactive site availability. Collectively, these features make bismuth oxyhalides a versatile platform for sustainable environmental remediation and solar-to-chemical energy conversion.

Research from Nature Portfolio

Recent studies have demonstrated that BiOBrₓI₁₋ₓ solid-solution nanoplates with exposed {001} facets exhibit finely tuned band gaps between 1.9 and 2.9 eV, enabling optimised light harvesting and direct hole-driven oxidation reactions for dye degradation. Investigations into bilayer heterostructures, notably BiOBr/BiOI, reveal a spatial separation mechanism whereby electrons localise on BiOBr layers to drive hydrogen evolution and holes reside on BiOI layers to facilitate oxygen evolution, thereby promoting high efficiency in photoelectrochemical water splitting. Complementary theoretical work on BiOX₁₋ₓYₓ solid solutions clarifies the miscibility of Cl, Br and I substitutions and correlates compositional variation with linear shifts in band-gap energy, providing a predictive framework for designing solid solutions with bespoke optical and electronic characteristics.

Photocatalytic Properties of Bismuth Oxyhalides publication trend

The graph below shows the total number of articles in photocatalytic properties of bismuth oxyhalides across all publications each year (not limited to Nature Index journals).

Technical terms

Band gap: Energy difference between valence and conduction bands that determines the onset of light absorption in a semiconductor.

Heterojunction: Interface formed between two semiconductors with differing band structures, used to enhance charge separation and transfer.

Electron–hole pair separation: Process whereby photoexcited electrons and holes are spatially or energetically separated to minimise recombination and drive redox reactions.

Polaron: Localised charge carrier accompanied by lattice distortion, which can influence mobility and recombination in photocatalysts.

Reactive oxygen species: Highly reactive oxygen-derived radicals (e.g. superoxide, hydroxyl) generated during photocatalysis that initiate pollutant degradation.

References

1. Visible-Light-Active Iodide-Doped BiOBr Coatings for Sustainable Infrastructure. ACS Applied Materials & Interfaces (2023).
2. Fabrication of BiOBrxI1−x photocatalysts with tunable visible light catalytic activity by modulating band structures. Scientific Reports (2016).
3. Spatial separation of photo-generated electron-hole pairs in BiOBr/BiOI bilayer to facilitate water splitting. Scientific Reports (2016).
4. Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity. Nanomaterials (2017).
5. Structural, Electronic and Optical Properties of BiOX1−xYx (X, Y = F, Cl, Br and I) Solid Solutions from DFT Calculations. Scientific Reports (2016).
6. Structure-Dependent Photocatalytic Performance of BiOBrxI1−x Nanoplate Solid Solutions. Catalysts (2017).
7. Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity. Catalysts (2020).
8. Ab Initio Insights into Charge Localization in Bismuth Oxyhalides BiOX (X = F, Cl, Br, I). The Journal of Physical Chemistry C (2022).
9. Preparation of Porous Ellipsoidal Bismuth Oxyhalide Microspheres and Their Photocatalytic Performances. Materials (2022).
10. Efficient visible-light-driven photocatalysis: simultaneous degradation of multiple pollutants with bismuth oxyhalide solid solutions. Environmental Science Water Research & Technology (2024).