Carbonized electrode materials were prepared from carbonization of graphene nanoribbon (GNR) / coal tar pitch (CTP) composite (m% of GNR: 1%, 3%, 5% and 10%). The carbonized materials were denoted as follows: CTP-GNR1, CTP-GNR2, CTP-GNR3 and CTP-GNR4. Characterization included cyclic voltammetry (CV), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). CTP-GNR1 was obtained as the nanocoil structure via SEM. Electrocatalytic activity for some redox probes, such as ferrocene and ferric/ferrous (K3Fe(CN)6 and K4Fe(CN)6) probe on the CTP-GNR1 modified glassy carbon (GC/CTP-GNR1) was found to be greater than others. The nanocoil material (CTP-GNR1) was used in the determination of dopamine (DA) and uric acid (UA) by differential pulse voltammetry (DPV). The electrode exhibits linear responses to DA and UA in the ranges of 2 μM–20 μM in the presence of 300 μM of L-ascorbic acid (AA). The detection limits (S/N = 3) for DA and UA are 3 nM and 6 nM, respectively.

A new electrode was prepared by the electrooxidation of orto-, meta-, and para-substituted nitro phenols on glassy carbon electrode. Electrochemical modification of the electrodes was carried out in 0.01 M HCl using cyclic voltammetry (CV). Then nitro groups in the covalently grafted nitro phenol derivatives on GC electrode were reduced to amine groups in 0.01 M HCl. The electrochemical behavior of the modified electrodes was studied in the presence of electroactive redox probes such as ferrocene and ferricyanide by CV and electrochemical impedance spectroscopy (EIS). X-ray photoelectron spectroscopy (XPS) was employed to characterize the surface structure and composition of the modified substrates. Thickness of the films was measured by using an ellipsometer. Surface topography of the nanofilms and bare GC was characterized via AFM. Graphene oxide (GO) was covalently attached on 4-aminophenyl involved surface through EDC. Simple immersing of the GO covered nanoplatform into a sample solution led to the chemical deposition by means of the interaction with Cd 2+ and Pb 2+ ions, simultaneously. Various analysis parameters that affect the simultaneous analysis of the ions such as deposition time, pH factor and deposition temperature, were optimized. Calibration curve for the GO grafted electrode surface with Square-wave anodic stripping voltammetry (SWASV) were obtained in the concentration range between 1 × 10 −8 M and 1 × 10 −12 M for Pb 2+ and Cd 2+ . The detection limits of the modified electrode for Pb 2+ and Cd 2+ ions were determined to be about 3.2 (± 0.1) × 10 −13 M and 2.4 (± 0.2) × 10 −13 M, respectively.

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