Reactivity and Mechanistic Insight into Visible-Light-Induced Anerobic Selective Reaction by Ag/Brookite Titania

摘要

Ag-loaded brookite titania (Ag/TiO_2(B)) nanocomposites were prepared via photochemical reduction using silver acetate and pure TiO_2(B) as precursor. The samples were characterized by X-ray diffraction spectrometry (XRD), ultraviolet-visible diffuse reflectance spectrometry (UV-vis DRS), transmission electron microscopy (TEM) and photoluminescence spectra (PL). Photocatalytic degradation of Rhodamine B (Rh B) and photocatalytic oxidation of benzyl alcohol served as a probe reaction to evaluate the photocatalytic activity of the as-prepared nanocomposites under visible light irradiation (λ > 400 nm). The results indicate different Ag loading amount influence the activity of the samples, among which Ag/TiO_2(B) with 2.5 wt% Ag content exhibited the best photodegradation activity of Rh B as well as the highest selectivity for photocatalytic oxidation of benzyl alcohol. The effect of Ag loading and reaction substrates on the performance of Ag/TiO_2(B) is investigated in detail. Based on the characterization results and frontier electron density theory (FED) calculation, possible mechanism of the photocatalytic oxidation of benzyl alcohol by photo-generated holes is discussed.