DOI: 10.1002/elan.201600509 Electrocatalysis of Chemical Warfare Agent Sulfur Mustard in Room Temperature Ionic Liquid Virendra V. Singh, [a] Pushpendra K. Sharma, [a] Bhavna Sikarwar, [a] Kumaran Ganesan, [a] Mannan Boopathi,* [a] and Beer Singh [a] 1 Introduction The use of room temperature ionic liquids (RTILs) as the electrolyte for electrochemical reactions has received a lot of attention during the past few decades owing to its extraordinary properties [1]. These electrolytes are being studied for application in batteries [2], dye-sensitized solar cells [3], electrochemical capacitors [4], membrane additives for fuel cells [2], electro-deposition of reactive metals [5], and nanomaterials [6], and in electrochemical sensors [7–9]. The properties such as nonvolatility, non flammability, good solvent characteristics, excellent ther- mal, chemical, electrochemical stability and the tenability [10,11] of RTILs make them attractive as electrolytes [12, 13]. Among them, nonflammability and negligible vapor pressure of RTILs make them ideal replacements for more toxic molecular solvents and importantly, over- come the problem of solvent evaporation that exists with the longterm use of volatile solvents in electrochemical applications. Moreover, RTILs usage as solvent in elec- trochemistry is not requiring any supporting electrolyte as RTILs themselves have lot of ions and they behave as solvent as well as supporting electrolyte. Due to the entire ionic composition, RTILs have been extensively used as an electrode film material in the construction of electrochemical biosensor [14–18] and have also been used in the development of stable electrochemical sensors for gaseous analytes such as H 2 O 2 ,O 2 , CO 2 , NH 3 and al- cohols [19–26]. In view of the above, RTILs have come to the forefront as important components of “Green Chemistry” [18] and they appear ready to replace classi- cal volatile organic solvents in many industrial applica- tions. Despite the greatly reduced threat of Cold War be- tween the nations, the threat of chemical, biological, radi- ological and nuclear attack remains serious and credible [27]. Among them, chemical warfare agents (CWAs) based threats are a growing concern to many countries. The uses of CWAs by terrorists organizations or even states is significant as they can be readily synthesized by simple chemical reactions and can be used to create ex- treme toxicity. Unfortunately, in the history there are many incidences of CWAs usage against humans by many countries. These chemicals were used on a large scale during the WW I and caused approximately 1.3 million casualties [28]. SM was used in 1980–1988 in the Iraq Iran conflict, being responsible for about 4 % of all casu- alties [28]. Due to the fatal effect of SM on human body and threat of attack from enemy nations there is an es- sential need to develop a reliable as well as potential method for the detection of SM. Among a variety of de- tection methodologies that have been developed for CWA, electrochemical detection offers the unrivaled merits of high sensitivity, lowcost, portablility and op- erational simplicity [29–33]. [a] V.V. Singh, P.K. Sharma, B. Sikarwar, K. Ganesan, M. Boopathi, B. Singh Defence Research and Development Establishment, DRDO, Gwalior-474002, India *e-mail: boopathi@drde.drdo.in Abstract : Room temperature ionic liquids (RTILs) have the potential for being ideal alternatives for organic sol- vents in chemical warfare agent (CWA) electrochemical reactions. In this paper, electrocatalysis of CWA sulfur mustard (SM) was achieved by exploring the potential ad- vantage of RTIL methyltrioctylammonium bis (trifluoro- methylsulfonyl) imide and further this methodology was used for the detection of CWA. The hydrophobicity of this RTIL offers the opportunity to use this methodology in field condition without environmental humidity effect. The diffusion coefficient calculated for SM in RTIL was 0.196  10 9 cm 2 /s. The electrochemical parameters de- duced from cyclic voltammetry such as electron transfer coefficient (a), electron transfer number (n) and hetero- genous rate constant were estimated 0.11, 2 and 4.41 s 1 , respectively. The electrocatalytic activity of the RTIL toward the electrochemical reduction and oxidation of CWA is evidenced, showing the potential of this novel ap- proach for the oxidation of other toxic CWAs. The new RTIL based strategy provides an opportunity to develop field deployable detection of CWA and could provide a new paradigm shift in CWA detection approach, ad- dressing the escalating threat of CWA. Keywords: chemical warfare agent · sulfur mustard · RTIL · Methyltrioctylammonium bis (trifluoromethylsulfonyl) imide · electrocatalysis www.electroanalysis.wiley-vch.de # 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electroanalysis 2016, 28, 1 – 7 &1& These are not the final page numbers! ÞÞ Full Paper