Noncovalent functionalization of graphene by CdS nanohybrids for electrochemical applications

• A simple noncovalent approach to synthesize graphene–CdS (GR–CdS) nanocomposites
• Direct electrochemistry of glucose oxidase based on synergistic effect of GR–CdS
• A sensitive glucose biosensor was fabricated based on the GR–CdS hybrids.

Graphene–CdS (GR–CdS) nanocomposites were synthesized via a noncovalent functionalization process. To retain the intrinsic electronic and mechanical properties of graphene, the pristine graphene was firstly modified with 1-aminopyrene based on a strong π–π bond between the pyrenyl groups and the carbon rings of the graphene. Then the CdS nanocrystals were uniformly grown on the amino-graphene. The GR–CdS nanocomposites were characterized by UV–vis spectroscopy and scanning electron microscopy. A glucose biosensor was then fabricated based on the as-prepared GR–CdS nanocomposite by immobilizing glucose oxidase (GOD) in a chitosan thin film on a glassy carbon electrode. Direct electron transfer between GOD and the electrode was achieved and the biosensor showed good electrocatalytic activity with glucose ranging from 0.5 to 7.5 mM and a sensitivity of 45.4 μA mM− 1 cm− 2. This work provided a simple and nondestructive functionalization strategy to fabricate graphene-based hybrid nanomaterials and it is expected that this composite film may find more potential applications in biosensors and biocatalysis.