Synthesis and characterization of a core–shell BiVO4@g-C3N4 photo-catalyst with enhanced photocatalytic activity under visible light irradiation

Abstract

Novel core–shell structured ellipsoid-like BiVO₄@g-C₃N₄ composites, with different amounts of g-C₃N₄, have been successfully prepared by a simple hydrothermal-chemisorption method. Their performance as photocatalysts was systematically evaluated during RhB degradation under visible light irradiation. The composite with 7 wt% g-C₃N₄ was found to be 7 times more efficient as a photocatalyst than pristine BiVO₄. Its core–shell structure and activity were also found to be highly stable after it was used for 5 times in RhB degradation. The new composites were examined by various characterization techniques. The core–shell structure enhanced the contact area between the BiVO₄ core and g-C₃N₄ nano-sheet shell, which provided more active sites and strengthened the chemical band interaction. The thin g-C₃N₄ nano-sheets reduced the charge carrier transfer distance, which further suppressed the recombination of the photo-induced electron–hole pairs and therefore enhanced the photocatalytic activity of the composites. A reaction mechanism of the photocatalytic RhB degradation was proposed and discussed in detail.