Boosting the photocatalytic activity of BiOX under solar light via the selective crystal facet growth
The selective crystal facet growth of BiOX (X = Cl, Br, I) is very significant due to each facet possessing different physicochemical properties. In this work, polyvinylpyrrolidone (PVP), a structure directing agent, was unprecedentedly introduced to modulate crystal facet growth of BiOX to obtain BiOX/PVP with more (110) active facet exposure for the first time. The exposure of the (110) crystal surface of BiOX due to the introduction of PVP is comprehensively explained from the molecular level. A possible application is dye wastewater photodegradation, such as rhodamine B (RhB), as more hydroxyl radicals are generated compared to the standard under identical visible light irradiation conditions. By First-Principles calculations, the (110) crystal face has a higher hole density allowing it to generate holes more easily. In comparison with pure BiOCl, a higher (110) active facet exposure for BiOCl/PVP prolonged the lifetimes of photoinduced carries and enhanced the photocatalytic activity. Here, the enhancement mechanism of photoactivity was explained via various experiments and theoretical calculation in detail.