Synergistic effects of multi-active sites in silver modified Bi°-BiVO4 toward efficient reduction of aromatic nitrobenzene.

Graphical abstract Highlights • Ag/Bi°-BiVO 4 catalysts with multi-active sites were fabricated toward high-efficient reduction of aromatic nitrobenzene. • The catalysts presented excellent catalytic activity and good stability to 4-NP reduction. • The BiVO 4 , Bi° and Ag offered multi-active sites to synergistically act on the reduction of nitrophenol. Abstract In this work, we report on the preparation of silver nanoparticles modified bismuth/bismuth vanadate (Bi°-BiVO 4) catalyst with multi-active sites toward efficient reduction of aromatic nitrobenzene, aiming to tailor the synergistic effects of multi-active sites and specify the underlying catalytic mechanism. The as-prepared catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray and X-ray photoelectron spectroscopy. It is observed that Ag nanoparticles with diameter of ˜30 nm were anchored evenly on the surface of rod-shaped BiVO 4 , which offered multi-active sites to contact with the reactants effectively and transfer interfacial electron to 4-nitrophenol (4-NP) rapidly. The activity factor k of Ag/Bi°-BiVO 4 for 4-NP reduction is estimated to ˜3933.4 min−1 g−1, which is much higher than that obtained from pristine BiVO 4 catalyst, Bi° and noble metal Ag nanoparticles. According to the experimental results, the reaction mechanism and reaction path of 4-NP reduction for BiVO 4 , Bi and Ag were studied through the density functional theory (DFT) theoretical calculation, which suggested that they exhibit synergistic catalytic effect in the reaction process. This work may provide a feasible foundation for the mechanism research of semiconductor reduction to 4-nitrophenol. [ABSTRACT FROM AUTHOR]