Coupling of solid-solution and heterojunction in a 2D-1D core-shell-like BiOCl0.5I0.5/Bi5O7I hierarchy for promoting full-spectrum photocatalysis and molecular oxygen activation.

We herein describe the coupling of solid-solution and heterojunction in a 2D-1D BiOCl0.5I0.5/Bi5O7I hierarchical architecture for optimizing photoabsorption, energy band levels and charge separation, thereby promoting the photo-oxidation and molecular oxygen activation performance. BiOCl0.5I0.5/Bi5O7I shows a core-shell-like structure with BiOCl0.5I0.5 thin nanoflakes (∼3 to 8 layers) homogeneously vertical coating on the surface of Bi5O7I strips. The photo-responsive range of BiOCl0.5I0.5/Bi5O7I can be orderly tuned from 450nm to 650nm by increasing the BiOCl0.5I0.5 content. Regardless of visible light (λ>420nm) or UV light (365nm) irradiation, BiOCl0.5I0.5/Bi5O7I casts highly promoted photocatalytic activity in decomposing methyl orange (MO) compared to the BiOCl0.5I0.5 and Bi5O7I. This enhancement on full-spectrum photoreactivity is attributable to the facilitated charge separation derived from BiOCl0.5I0.5/Bi5O7I heterojunction with intimate interfacial interaction, which is approved by transient photocurrent response under visible and UV-vis light. To probe the photocatalytic mechanism, active species trapping tests are performed over BiOCl0.5I0.5, Bi5O7I and BiOCl0.5I0.5/Bi5O7I, which reveal superoxide radical (O2-) and hole (h+) take dominant roles in photo-oxidation reaction. BiOCl0.5I0.5/Bi5O7I was also found possessing a stronger ability in molecular oxygen activation with a O2- production rate of 2.22×10-7molL-1h-1, which far outperforms Bi5O7I (1.35×10-7molL-1h-1) and BiOCl0.5I0.5 (1.54×10-7molL-1h-1). It further corroborates the efficient band charge transfer between BiOCl0.5I0.5 and Bi5O7I. This work may furnish a new concept on smart design of high-performance photocatalytic materials via manipulating multiple strategies.