Electrochimica Acta 54 (2009) 7294–7298 Contents lists available at ScienceDirect Electrochimica Acta journal homepage: www.elsevier.com/locate/electacta Preparation and characterization of a 1,10-phenanthroline-modified glassy carbon electrode Yasemin Oztekin ∗ , Zafer Yazicigil Selcuk University, Faculty of Science, Department of Chemistry, Konya, Turkey article info Article history: Received 12 April 2009 Received in revised form 13 July 2009 Accepted 17 July 2009 Available online 24 July 2009 Keywords: 1,10-Phenanthroline Metal sensor Surface modification Glassy carbon abstract This paper describes the grafting of 1,10-phenanthroline (P) molecules on the surface of a glassy carbon (GC) electrode. This modification was carried out in both aqueous and non-aqueous media. Britton Robin- son (BR) was used in aqueous experiments at different pHs and tetrabutylammonium tetrafluoroborate (TBATFB), 0.1 M in acetonitrile (ACN) was used in non-aqueous experiments. Surface modification exper- iments were performed in the +1.2–2.7 V potential range with a scan rate of 100 mV/s and 30 cycles. The presence of P at the GC surface was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), contact angle measurement (CAM) and ellipsometry. The ability of the complex to modify surfaces was investigated with differential pulse voltammetry (DPV). Crown Copyright © 2009 Published by Elsevier Ltd. All rights reserved. 1. Introduction Modification of electrode surfaces is an important area of research in electrochemistry and materials science. In recent years, covalently modified electrodes for catalytic, analytical and biotech- nological applications have garnered interest. A recent electrode modification approach has involved self-assembled monolayers (SAMs) of thiol derivatives on metal surfaces [1]. The advantage of this approach is that well ordered and closely packed SAMs can be covalently formed by immersing an electrode in a solution con- taining thiol derivatives. Thus, the thiol SAMs allow construction of a wide variety of functional layers on metal surfaces [2–4]. Sev- eral chemical pretreatment procedures have been proposed for modifying the surface of carbon electrodes [5]. To enhance the chemical functionalities of the carbon surface, oxidizing procedures that generate oxygenated functional groups (carboxylic, hydroxylic, quinone, and other ketonic groups) have been employed. These methods include strong oxidation processes, such as treatment in a hot oxidizing acid solution, O 2 plasma radiation, or heating in air at high temperature. The resulting functional layer is not uniform and the electrode surface can be roughened or damaged during these modifying processes. In the past decade, electrochemi- cally assisted covalent modification of carbon electrode surfaces [6] has been developed. This simple modification process can be per- formed under relatively mild experimental condition, which leads to improved functional layers compared to those formed by the ∗ Corresponding author. Tel.: +90 332 2231263; fax: +90 332 2410106. E-mail address: yoztekin@gmail.com (Y. Oztekin). oxidizing procedures. In general, these methods are based on elec- trochemical oxidation or reduction of organic functional groups; for example the oxidation of amines, alcohols, carboxylates, and hydrazides, or the reduction of aryl diazonium salts. Thus, modifi- cations of carbon electrodes by a wide variety of organic compounds have been reported, and the modified electrode characteristics have been studied. The covalent modification of aryl diazonium salts was first developed by Pinson’s group [7]. The one-electron reduction of aryl diazonium salt at a carbon electrode results in the forma- tion of covalent bonds between the aryl groups and the carbon atoms at the electrode surface. As reviewed by Downard [6], this method has been applied to modification of various carbon elec- trodes including GC [8], highly oriented pyrolytic graphite (HOPG) [9], carbon fiber [10], and porous graphite carbon sphere [11]. Recently, the functionalization of bulk single-walled carbon nan- otubes (SWCNTs) [12] and individual SWCNTs [13] was reported. The modification procedure is simple, and the modified electrodes have long-term stability, so various types of electrochemical sen- sors have been developed by the electrochemical reduction of aryl diazonium salts. These electrodes have led to the development of an amperometric glucose sensor [7], flow detectors [14], voltam- metric differentiation of dopamine and ascorbic acid [15], and an application for the detection of alkaline phosphatase [16]. Although 1,10-phenanthroline is one of the most widely used chelating ligands in coordination chemistry, it has not been thoroughly stud- ied electrochemically in non-aqueous media. The ligand and its complexes have found applications in different areas including molecular catalysis, solar energy conversion, colorimetric analy- sis, herbicides, molecular recognition, self assembly, antineoplastic agents, nucleic acid probes and the development of luminescence 0013-4686/$ – see front matter. Crown Copyright © 2009 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.electacta.2009.07.050