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

Abstract

In this work, we report on the preparation of silver nanoparticles modified bismuth/bismuth vanadate (Bi°-BiVO4) 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 BiVO4, 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°-BiVO4 for 4-NP reduction is estimated to ˜3933.4 min-1 g-1, which is much higher than that obtained from pristine BiVO4 catalyst, Bi° and noble metal Ag nanoparticles. According to the experimental results, the reaction mechanism and reaction path of 4-NP reduction for BiVO4, 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.