Facile synthesis of Au/CdS core-shell nanocomposites using laser ablation technique

Metallic nanoparticles within a semiconductor have the potential for many important optoelectronic applications. Here we report a strategy for the synthesis of Au-CdS core-shell structure using laser assisted method. We performed laser ablation of bulk gold within the colloidal CdS solution which resulted in the formation of the Au core with an average particle size of 8.8 nm surrounded by a shell coating of CdS with average diameter 5.8 nm. The average size of as prepared nanocomposites is of the order of 15-45 nm. We consider this as a versatile method that can be extended to synthesize other core-shell NPs that can find potential in sensing, imaging, photocatalysis, and energy harvesting applications. The optical properties of these nanocomposites were investigated. We also studied the sunlight mediated photodegradation of methylene blue (MB) and observed an increase in the degradation rate for the Au/CdS core shell structures as compared to CdS. The enhanced photocatalytic activity of Au/CdS nanocomposites can be attributed to the efficient suppression in the recombination of photogenerated charge carriers in CdS due to the electron scavenging activity of the Au core.