Electrochimica Acta 88 (2013) 832–838 Contents lists available at SciVerse ScienceDirect Electrochimica Acta jou rn al h om epa ge: www.elsevier.com/locate/electacta Zero valent silver-based electrode for detection of 2,4,-dinitrotoluene in aqueous media Jonathan Mbah a,c,∗ , Kiara Moorer a,c , Leonardo Pacheco-Londo ˜ no b,c , Samuel Hernandez-Rivera b,c , Gabriel Cruz d a Department of Chemical Engineering, Tuskegee University, Tuskegee, AL 36088, USA b Department of Chemistry, University of Puerto Rico, Mayaguez, PR 00681, USA c Center for Chemical Sensor Development, University of Puerto Rico, Mayaguez, PR 00681, USA d Hewlett-Packard, Imaging and Printing Group (IPG), Technical Services Group, Aguadilla, PR 00603, USA a r t i c l e i n f o Article history: Received 13 September 2012 Received in revised form 16 October 2012 Accepted 17 October 2012 Available online 26 October 2012 Keywords: Electrode DNT detection and oxidation Cyclic voltammetry Ag/C Anode a b s t r a c t Detection of 2,4-dinitrotoluene (DNT), which is a common impurity in 2,4,6-trinitrotoluene (TNT)-based explosives is a point of focus in the fight against act of terrorism. In this study, the donor based electrode for the detection of DNT was synthesized by modifying the surface of carbon fiber material with zero valent silver (Ag) via chemical deposition. DNT detection was conducted electrochemically in aqueous media of pH 6.0. The cyclic voltammetric oxidation of DNT is diffusion controlled with detection sensi- tivity increasing with Ag loading of the electrode. Nevertheless, kinetic study given by Tafel slope and transfer coefficient (0.03 and 0.22 respectively) indicated slowly to moderate chemical reaction. The only oxidation product is benzoic acid, which suggests that the difference in performance of Ag/C electrode compared to other available materials is directly ascribable to the electrode fabricated in this study. Detection limit of DNT was 5 M with the electrode showing no signs of degradation after several cycles, and supported by surface behavior of characterized Ag/C electrode. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction The prevalent use of nitro-aromatic materials including, 2,4,6- trinitrotoluene (TNT) for explosive devices has made their detection crucial in the fight against act of terrorism and detection of military explosives. But rather than attempting to detect TNT, researchers focus on detecting 2,4-dinitrotoluene (DNT) which is a common impurity in TNT-based explosive [1–4]. DNT has a higher vapor pressure than TNT, allowing for more sensitivity and easy detection. In the production of munitions and explosives, DNT is used as a gelatinizing and waterproofing agent. Furthermore, it can be found in landmines, contaminated water, waste sites, and a variety of other locations. It is also used as intermediate in the man- ufacture of dyes, and as a purified form, in smokeless gunpowder. DNT has been detected in the soil, surface water, and groundwater of hazardous waste sites that contain buried munitions wastes. Several methods of DNT detection have been reported in lit- erature which includes optical or electrochemical sensors [5,6] – optical sensors work a luminescence that is quenched in the ∗ Corresponding author at: Tuskegee University, Chemical Engineering Depart- ment, Luther H. Foster Hall, Suite 513, Tuskegee Institute, AL 36088, USA. Tel.: +1 334 727 8972; fax: +1 334724 4188. E-mail addresses: mbahj@tuskegee.edu, mbahj@mytu.tuskegee.edu (J. Mbah). presence of DNT, while electrochemical sensors take advantage of the redox activity of the nitro groups that are a part of many explosives [7–11], electrochemical impedance detection [12], and detection by combining capillary electrophoresis and electrochem- ical detection with a porous-carbon-modified electrode [13]. Recent activity in various laboratories has led to the develop- ment of novel electrode materials, submersible remote sensors, and electrochemical detectors for on-site electrochemical detection of explosive substances. The attractive behavior of these electrochem- ical monitoring systems make them very promising for addressing major security and environmental problems. The reactivity of particulate zero-valent metals in solution is affected not only by particle size (nano vs. micro), surface con- ditions (passivation by coatings of oxides), solution conditions (including the type and concentration of oxidants) but also by the metal type. Silver nanoparticles have unique optical, electrical, and thermal properties and are being incorporated into products that range from photovoltaics to biological and chemical sensors. More- over, of the three metals (Ag, Au, Cu) that display plasmon reso- nances in the visible spectrum, Ag exhibits the highest efficiency of plasmon excitation [14]. When nanoparticles are in solution, molecules associate with the nanoparticle surface to establish a double layer of charge that stabilizes the particles and prevents aggregation [15,16]. Additionally, Ag nanoparticles have high elec- trical conductivity, stability, and low sintering temperatures. 0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2012.10.068