Visible-light photocatalytic activity of Ag@MIL-125(Ti) microspheres

Ag nanoparticle (NP)-decorated MIL-125(Ti) microspheres (Ag@MIL-125(Ti)) were firstly fabricated via a facile hydrothermal and following photo-reduction method. The photocatalysts were characterized using X-ray diffraction, scanning and transmission electron microscopies, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy. The characterization results indicated that Ag NPs were dispersed on the surface of MIL-125(Ti) microspheres, and the Ag NPs had a uniform diameter of about 40nm. The composites exhibited excellent visible-light absorption, due to the modification with the Ag NPs. The photocatalytic activity for the visible-light-promoted degradation of Rhodamine B was improved through the optimization of the amount of Ag loaded as a co-catalyst, this amount being determined as 3wt%. Additionally, studies performed using radical scavengers indicated that O-2(-) and e(-) served as the main reactive species. The catalyst can be reused at least five times without significant loss of its catalytic activity. Furthermore, a photocatalytic mechanism for degradation of organics over Ag@MIL-125(Ti) is also proposed. Copyright (c) 2015 John Wiley & Sons, Ltd.