Targeted thiolation of graphene oxide and its utilization as precursor for graphene/silver nanoparticles composites

We describe a route to graphene/silver nanoparticles composites based on the targeted chemical thiolation of graphene oxide (GO), followed by a chemical reduction in the presence of Ag+ cations. The carboxylic groups on the GO surface were selectively modified with cysteamine (CA) through amide bonds, and the free thiol groups remaining in CA were further used as capping agent for silver nanoparticles, preventing particle aggregation in the preparation of graphene/silver nanoparticles composites. Characterizations were carried out by infrared and Raman spectroscopy, thermogravimetric analysis, X-ray diffraction and transmission electron microscopy, confirming both the targeted chemical modification and the composite formation. Results show that increasing functionalization of GO with CA give smaller and more homogenous silver nanoparticles, with mean diameter of ∼5 nm. Therefore, the modified GO has potential in size controlling the silver nanoparticles, essential for the design of novel composites with promising applications in catalysis, surface enhanced Raman scattering and bactericide activity.