Self-doped Br in Bi5O7Br ultrathin nanotubes: Efficient photocatalytic NO purification and mechanism investigation

Bismuth-rich Bi5O7Br is a promising photocatalyst for pollutant removal owing to its stability and appropriate band structure in comparison with bismuth oxybromide. However, bulk-phase Bi5O7Br suffers from poor light absorption and high charge recombination rates resulting in poor activity. Elemental doping is a powerful strategy to enhance photocatalytic activity. In this study, we prepared a series of Br auto-doped ultrathin Bi5O7Br nanotubes and explored the effect of Br doping on photocatalytic NO removal. The optimal doping content was determined via a photocatalytic NO removal experiment, which revealed the optimal ratio of Bi and Br was approximately 3:1. In situ diffuse reflectance infrared Fourier transform spectroscopy (In situ DRIFT) and density functional theory (DFT) studies revealed that NO removal mechanism catalyzed by Br doped Bi5O7Br. Our work presents a new strategy for the enhancement of photocatalytic pollutant degradation by bismuth oxyhalide photocatalysts.