A facile route for the synthesis of ZnS rods with excellent photocatalytic activity

A simple wet chemistry method was employed for the synthesis of ZnS rods using thioglycollic acid as a capping agent under reflux condition. The obtained products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR) and UV-vis absorption spectroscopy (UV). The amount of thioglycollic acid was systematically varied, and it was found that the thioglycollic acid content played an important role in the formation of ZnS rods. Under optimized conditions, highly crystalline ZnS rods about 1 mu m in length and 260 nm in diameter were obtained, and a possible growth mechanism was proposed. The as-synthesized ZnS samples were used as photocatalysts for the degradation of methyl orange (MO) and 2, 4-dinitrophenol (2, 4-NP) under UV irradiation. The ZnS rods obtained using 5 mL thioglycollic acid showed the highest photocatalytic activity with nearly 95% of MO and 54% of 2, 4-NP degraded after irradiation for 20 min, respectively, which clearly outperformed commercial Degussa TiO2 under the same conditions. The excellent photocatalytic activity of the ZnS rods can be ascribed to large specific surface area, high hydrophilicity, unique morphology and excellent adsorption ability. With the help of various radical scavengers, O-center dot(2)- and h(+) were proved to be the main reactive species for the degradation of MO and 2, 4-NP. (C) 2013 Elsevier B.V. All rights reserved.