Preparing ZnWO4–CdS composite with excellent visible light photocatalytic activity under mild conditions

Abstract

ZnWO4–CdS composite was designed and synthesized via a surface functionalized route under mild conditions. In this composite, CdS nanoparticle was successfully anchored on ZnWO4 nanorod with addition of citric acid. The formed composite was characterized by X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller, photoluminescence and transient photocurrent response. Besides, a possible nucleation-growth mechanism was proposed. To explore the photocatalytic performance of as-prepared ZnWO4–CdS composite, methylene blue and ciprofloxacin were chosen as the representative to systematically assess the degradation ability of as-prepared composite under visible light irradiation. The obtained results indicate that the ZnWO4–CdS3 composite photocatalyst is more efficient to methylene blue and ciprofloxacin than others under same conditions. The greatly enhanced photocatalytic performance of ZnWO4–CdS composite can be attributed to larger specific surface area, wider photo adsorption range and higher photo-induced carriers separation efficiency. A reasonable mechanism of the enhanced photocatalytic activity was confirmed and demonstrated by a series of characterization methods. The formation of n-n heterojunction between ZnWO4 and CdS can effectively promote the separation and transfer efficiency of photo-generated carriers and enhance the photocatalytic performance of composite.