Electrochemical Behaviour of Organic Explosive Compounds in Ionic Liquids: Towards Discriminate Electrochemical Sensing

Abstract

AbstractThe electrochemical reduction of four organic explosive compounds, 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX), 1,3,5‐trinitro‐1,3,5‐triazinane (RDX), pentaerythritol tetranitrate (PETN) and 2,4,6‐trinitrophenylmethylnitramine (tetryl), is studied in eight room temperature ionic liquids (RTILs). In all RTILs, the reduction peaks were highly complicated, but much better resolved than in previous studies in conventional solvents. HMX typically showed broad overlapping peaks in RTILs with distinctly different voltammetric wave shapes. The voltammetry of RDX also varied dramatically, ranging from one to four reductive peaks with broad features. PETN showed one large reduction peak owing to the overlapping reduction processes for all the nitro‐ groups. Tetryl produced the most complex voltammetry with the largest number of cathodic peaks, likely due to the structure that contains both nitramine and nitroaromatic groups. For all explosives, an electrogenerated product was oxidized on the reverse scan. The reduction potentials and voltammetric wave shapes were found to vary significantly in the different RTILs, allowing the possibility to ‘fingerprint’ the different explosives using their distinct signatures, suggesting that discriminative sensing may be possible by careful tuning of the RTIL structure. Exploring the electrochemical behaviour of these explosives is a first step towards utilising RTILs as favourable solvents for the electrochemical detection of such compounds.