Novel Multifunctional Graphene Sheets with Encased Au/Ag Nanoparticles for Advanced Electrochemical Analysis of Organic Compounds

• Published in: Chemphyschem Vol. 13; no. 16; pp. 3632 - 3639
• Main Authors: Pruneanu, Stela, Biris, Alexandru R., Pogacean, Florina, Lazar, Diana Mihaela, Ardelean, Stefania, Watanabe, Fumyia, Dervishi, Enkeleda, Biris, Alexandru S.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 12-11-2012; WILEY‐VCH Verlag; Wiley
• Subjects: Anticonvulsants - analysis; Carbamazepine - analysis; Catalysis; Chemistry; Colloidal state and disperse state; Electrochemical Techniques; Electrochemistry; Exact sciences and technology; General and physical chemistry; gold; Gold - chemistry; graphene; Graphite - chemistry; Kinetics and mechanism of reactions; nanoparticles; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Physical and chemical studies. Granulometry. Electrokinetic phenomena; silver; Silver - chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Methane; High resolution; Support; Stacking; Nanoparticle; Voltammetry; Potential; Electrodes; Electrocatalysis; Synthesis; nanoparticles; Platinum; Oxidation; Organic compounds; Drug; Gold; Catalytic reaction; Magnesium oxide; Transition element compounds; Transition metal; Nanostructure; Electron microscopy; Chemical vapor deposition; Carbamazepine; Substrate; Silver; Heterogeneous catalysis; Graphene; Morphology; Electrochemistry; Nanostructured materials
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201200424

This work is the first presentation of the synthesis of few‐layer graphene decorated with gold and silver nanoparticles (Gr–Au–Ag) by chemical vapor deposition over a catalytic system formed of bimetallic Au–Ag nanoclusters supported on MgO and with methane used as the source of carbon. The sheetlike morphology of the graphene nanostructures, with mean sizes in the range of hundreds of nanometers, was observed by high‐resolution electron microscopy. The distinctive feature found in all the samples was the regular rectangular or square shapes. This multi‐component organic–inorganic nanomaterial was used to modify a platinum substrate and subsequently employed for the detection of carbamazepine, an anti‐convulsion drug. UV/Vis spectroscopy revealed that a strong hypochromism occurred over time, after mixing solutions of graphene–Au–Ag with carbamazepine. This can be attributed to π–π stacking between the aromatic groups of the two compounds. Linear sweep voltammetry (LCV) provided evidence that the modified platinum substrate presented a significant electrocatalytic reaction toward the oxidation of carbamazepine. The intensity of the current was found to increase by up to 2.5 times, and the oxidation potential shifted from +1.5 to +1.35 V(Ag/AgCl) in comparison with the unmodified electrode. Electrochemical impedance spectroscopy (EIS) was further used to thoroughly assess the activity of the platinum electrode that was modified by the deposition of the Gr‐Au‐Ag composites in the presence of various concentrations of carbamazepine. The experimental EIS records were used for the generation of an equivalent electrical circuit, based on the charge‐transfer resistance (Rct), Warburg impedance (ZD), solution resistance (Rs), and a constant phase element (CPE) that characterizes the non‐ideal interface capacitive responses.
Sensitive nanomaterials: The synthesis of multicomponent nanostructural materials based on Au/Ag nanoparticles and graphene layers is discussed. These nanocomposites are used for the high‐sensitivity detection of carbamazepine, a model organic molecule.