Magnetic composite microspheres with exposed {001} faceted TiO2 shells: a highly active and selective visible-light photocatalyst

Abstract

We have demonstrated a sandwich-structured Fe₃O₄/SiO₂/Au/TiO₂ photocatalyst, which shows magnetic separability, selective absorption and photocatalysis activity, and high efficiency, in catalyzing the decomposition of organic compounds under illumination of visible-light and simulated sunlight. The structural design of the photocatalyst takes advantage of the dense, homogeneous structure and the AuNPs content (ca. 4 nm, 1.63 wt%), which is prepared by a simple method. It possesses high efficiency visible-light photocatalytic activity due to the stable from nonmetal-doping and the plasmonic metal decoration, which enhances light harvesting and charge separation, and the small grain size of the anatase nanocrystals, which reduces the exciton recombination rate. More importantly, the catalyst is synthesized by a combination of plasmonic metal decoration of TiO₂ nanocrystals with exposed {001} facets, and the selective adsorption and photocatalytic decomposition of azo dyes is accomplished by design of the surface chemistry. Additionally, these sandwich-structured photocatalysts can be applied to other catalytic system such as dye decoloration, water decomposition, hydrogen generation, and so on.