Enhanced photocatalytic degradation of methylene blue dye using CuS-CdS nanocomposite under visible light irradiation

The inorganic nanoparticles based semiconductor photocatalyst has attracted widespread attention for the practical applications in sustainable energy and environmental remediation due to its low cost, eco-friendly, high efficiency and ease of process. CuS, CdS and CuS-CdS nanocomposite photocatalysts have been successfully synthesized by a simple hydrothermal approach. The phase purity, composition and surface morphology of as synthesized nanomaterials were characterized using various analytical techniques. The photocatalytic activities of the as-prepared materials have been evaluated by the degradation of methylene blue (MB) dye in the presence of hydrogen peroxide (H2O2) which served as an oxidant under visible light irradiation. MB dye (10 ppm) was degraded by about 80%, 59% and 99.97% for CuS, CdS and CuS-CdS nanocomposite respectively at 10 min. The results demonstrate that CuS-CdS nanocomposite exhibited excellent photocatalytic activity as compared to the CuS and CdS is which mainly attributed to large surface area, narrow band gap, high adsorbing capacity of the dye and also low recombination of the photo-generated electrons and holes. Further, electrochemical impedance (EI) measurement revealed that as prepared CuS-CdS nanocomposite suggested that as compared to CuS and CdS, the CuS-CdS nanocomposite exhibits rapid migration of photo-induced charge carriers. In addition, the CuS-CdS nanocomposite demonstrated that good stability towards photocatalytic degradation even after repeated usage. Finally, a suitable photocatalytic reaction mechanism has been proposed to indicate the photocatalytic performance of the nanocomposite.