Novel noble metal (Rh, Pd, Pt)/BiOX(Cl, Br, I) composite photocatalysts with enhanced photocatalytic performance in dye degradation

Novel noble metal (Rh, Pd, Pt)/BiOX(Cl, Br, I) composite photocatalysts were prepared and well characterized by nitrogen-physical adsorption, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) emission spectroscopy. The effects of noble metals deposition on the optical and photocatalytic performance of BiOX in degradation of the acid orange II dye under both UV and visible light irradiation were systematically investigated. Results show that noble metal depositions enhance their visible light absorption and photocatalytic performance. However, catalytic activity is controlled by the species and concentration of noble metal. Over BiOCl, the noble metals, abilities to promote activity are in the orders Pt > Pd > Rh and Rh > Pt > Pd under UV light and visible light irradiation, respectively. Over different BiOX with optimal noble metal content, the best UV light activities are in the order Pd(0.5%)/BiOBr > Pt(1%)/BiOCl > Pd(2%)/BiOCl. Under visible light illumination, the best activities change to Pd(4%)/BiOBr > Pd(0.5%)/BiOI > Rh(1%)/BiOCl. The enhanced photocatalytic efficiency could be attributed to the promoted separation rate of photo-generated e−/h+ pairs and the role of plasmon photocatalysis caused by deposited noble metal nanoparticles.