Noncovalent functionalization of graphene by CdS nanohybrids for electrochemical applications

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 pi-pi 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 mu A 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. (C) 2014 Elsevier B.V. All rights reserved.