Exploring the reactivity of multicomponent photocatalysts: insight into the complex valence band of BiOBr.

The band structure of multicomponent semiconductor photocatalysts, as well as their reactivity distinction under different wavelengths of light, is still unclear. BiOBr, which is a typical multicomponent semiconductor, may have two possible valence-band structures, that is, two discrete valence bands constructed respectively from O 2p and Br 4p orbitals, or one valence band derived from the hybridization of these orbitals. In this work, aqueous photocatalytic hydroxylation is applied as the probe reaction to investigate the nature and reactions of photogenerated holes in BiOBr.

Detection of intermediates in the TiO2-assisted photodegradation of Rhodamine B under visible light irradiation.

The photocatalytic degradation of dye Rhodamine B (RhB) in the presence of TiO2 nanostripe or P25 under visible light irradiation was investigated. The degradation intermediates were identified using Infrared spectra (IR spectra), 1H nuclear magnetic resonance (1HNMR) spectra, and gas chromatography-mass spectroscopy (GC-MS). The IR and the 1HNMR results showed that the large conjugated chromophore structure of RhB was efficiently destroyed under visible light irradiation in both the photocatalytic systems (TiO2 nanostripe or P25 and Rhodamine B systems).