Preparation of sulfonic-functionalized graphene oxide as ion-exchange material and its application into electrochemiluminescence analysis

Graphene oxide (GO) obtained from chemical oxidation of flake graphite was derivatized with sulfonic groups to form sulfonic-functionalized GO (GO-SO3-) through four sulfonation routes: through amide formation between the carboxylic group of GO and amine of sulfanilic acid (AA-GO-SO3-), aryl diazonium reaction of sulfanilic acid (AD-GO-SO3-), amide formation between the carboxylic group of GO and amine of cysteamine and oxidation by H2O2 (CA-GO-SO3-), and alkyl diazonium reaction of cysteamine and oxidation by H2O2 (CD-GO-SO3-). Results of Fourier transform infrared spectroscopy and X-ray photoelectrospectrocopy showed that -SO3- groups were attached onto GO. Thermo gravimetric analysis showed that derivatization with sulfonic groups improved thermo stability of GO. X-ray diffraction results indicated that GO-SO3- had more ordered Tr-Tr stacking structure than the original GO. GO-SO3- and cationic polyelectrote, poly (diallyldimethylammoniumchloride) (PDDA) were adsorbed at indium tin oxide (ITO) glass surface through layer-by-layer assembling to form (GO-SO3-/PDDA)(n)/ITO multilayers. After tris-(2,2'-bipyridyl) ruthenium (II) dichloride (Ru(bpy)(3)(2+)) was incorporated into the multilayers, the obtained Ru(bpy)(3)(2+)/(GO-SO3- /PDDA)(n)/ITO electrodes can be used as electrochemiluminescence sensors for detection of organic amine with high sensitivity (limit of detection of 1 nM) and stability. (C) 2010 Elsevier B.V. All rights reserved.