Elucidating Structural Disorder in Ultra-Thin Bi-Rich Bismuth Oxyhalide Photocatalysts

Area of Science:

• Materials Science
• Solid State Chemistry
• Photocatalysis

Background:

• Bismuth oxyhalides are promising photocatalysts but their complex structures hinder understanding.
• High disorder and similar compounds make structural determination challenging.

Purpose of the Study:

• To elucidate the crystal structure of layered, Bi-rich bismuth oxyhalides.
• To establish the structure-property relationship for these ultra-thin photocatalysts.

Main Methods:

• Utilized multiple scattering techniques (electron, X-ray, neutron probes).
• Determined crystal phase as layered Bi24O31X10 (X = Cl, Br).
• Employed femtosecond transient absorption spectroscopy (fs-TAS) to measure excited state lifetimes.

Main Results:

• Identified layered Bi24O31X10 with anisotropic, platelet-shaped domains.
• Observed in-plane ordering but disorder in layer stacking.
• Found increased synthesis pH led to larger domains and longer excited state lifetimes.
• Determined increased surface area provided the most significant photocatalytic improvement.

Conclusions:

• Phase allocation of complex bismuth oxyhalides achieved.
• Structure-property relationships for ultra-thin photocatalysts discussed.
• Surface area identified as a critical factor for enhanced photocatalytic activity.