Preparation, Characterization and Photocatalytic Performance of Ag/BiOX (X=Cl, Br, I) Composite Photocatalysts

A series of novel bismuth oxyhalide Ag/BiOX (X=Cl, Br, I) composite photocatalysts were synthesized by a solution-based photodeposited method at room temperature. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) emission spectroscopy, UV-Vis diffuse reflectance spectroscopy (DRS), and N-2 physical adsorption. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II under visible light (420 nm<660 nm) irradiation. Analysis by N-2 physical adsorption showed that deposition of Ag decreased the specific surface area of the catalyst. UV-Vis DRS analysis indicated that the presence of Ag could result in surface plasmon absorption, effectively increasing the visible light absorption ability of BiOCl and BiOBr. Furthermore, PL analysis indicated that Ag could effectively suppress the recombination of photogenerated electron (e(-))-hole (h(+)) pairs of Ag/BiOX. Activity testing indicated that the deposition of an optimal amount of 1%-2% (w, mass fraction) Ag brought about 10, 13, and 2 fold increases in the photocatalytic activity of BiOCl, BiOBr, and BiOI, respectively. The high photocatalytic performance of the composite photocatalysts could be attributed to the strong visible light absorption, silver plasmon photocatalysis role and the recombination restraint of the e(-)/h(+) pairs resulting from the presence of metal silver particles.