Nano-zero-valent iron and MnOx selective deposition on BiVO4 decahedron superstructures for promoted spatial charge separation and exceptional catalytic activity in visible-light-driven photocatalysis-Fenton coupling system.

Abstract

Novel nano-zero-valent iron (Fe0)/MnOx/BiVO4 ternary magnetic assemblies are fabricated through hydrothermal and photo-deposition strategy. The assemblies are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Fe0 as a reduction cocatalyst are deposited on surface of monoclinic BiVO4 decahedron supersturcture. Meanwhile, MnOx as an oxidation cocatalyst is selectively anchored on oxidative {110} facet of BiVO4 by photodeposition. The photogenerated electrons and holes can be transmitted to Fe0 and MnOx, respectively, which favors the spatial charge separation. The adjunction of Fe0 significantly enhances light absorption, and forms a photocatalysis-Fenton coupling system simultaneously. The assemblies with narrow band gap of 2.10 eV display an exceptional photocatalytic activity, and the visible-light-driven photocatalytic degradation ratio of 2,4-dichlorophenol and Bisphenol A are up to 95.4 and 91.4%, respectively, which are several times higher than that of pristine BiVO4. This is ascribed to the selective decoration of Fe0 and MnOx favoring the spatial charge separation, and the photocatalysis-Fenton coupling system enhancing degradation. Moreover, the superior magnetic property due to Fe0 decoration realizes magnetic separation of catalysts, which is favorable in practical applications.