Solvothermal synthesis of CdS QDs/MWCNTs nanocomposites with high efficient photocatalytic activity under visible light irradiation

Abstract

Cadmium sulphide (CdS) quantum dots (QDs) deposited multi-walled carbon nanotubes (MWCNTs) photocatalysts were synthesized via a facile one-pot solvothermal process. The as-prepared samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), Fourier transform infrared spectra (FT-IR) and photoluminescence (PL). The CdS QDs with the size at range of 5–8 nm were immobilized on the surface of MWCNTs. The photocatalytic activity of the CdS QDs/MWCNTs nanocomposites were evaluated by the decomposition of malachite green (MG) under visible light irradiation. All CdS QDs/MWCNTs photocatalysts possessed higher photocatalytic activity than pure MWCNTs. It could be found that MG was photodegraded with the highest degradation efficiency of 94.5% by 2.5-CdS QDs/MWCNTs photocatalysts under visible light irradiation. This enhanced photocatalytic performance was attributed to an efficient electron–hole separation of photogenerated electron–hole pairs of CdS. Moreover, the photocatalytic mechanism of CdS QDs/MWCNTs nanocomposites was also discussed.