Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification

Abstract

Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample matrix and allows for the elimination of several types of random and systematic errors in the detection. We have also validated this IL-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single- and double-potential step chronoamperometry.

In Situ Generated Platinum Catalyst for Methanol Oxidation via Electrochemical Oxidation of Bis(trifluoromethylsulfonyl)imide Anion in Ionic Liquids at Anaerobic Condition

“…Higher concentrations of oxygen can facilitate the oxidation of the Pt surface to form Pt–O which could hinder the oxidation of NTf 2 − and obstruct the formation of Pt–NTf 2 · radicals. 38 In contrast, NTf 2 − anions are well-known for their high electrochemical stability in atmosphere condition; 14 the anaerobic environment provided an extreme condition that decreased their electrochemical stability.…”

2,4-Toluene diisocyanate detection in liquid and gas environments through electrochemical oxidation in an ionic liquid

“…Thus, utilization of [C 4 mpy][NTf 2 ] was validated to be suitable for electrochemical detection of 2,4-TDI, as has been done by our group for various different analyte targets. 28, 30, 31, 33, 39 In [C 4 mpy][NTf 2 ], the oxidation peak current of 2,4-TDI was approximately seven times larger than that of the reduction peak, as shown in Figure 1A . Therefore, it is also clear that the oxidation process is capable of providing better sensitivity for the detection of 2,4-TDI ( Figure 1B ) and can be used for further quantifications.…”

Electrode–Electrolyte Interfacial Processes in Ionic Liquids and Sensor Applications

“…We have shown redox chemistry that occurs only in ILs and can be exploited to enhance sensor performance [202]. As shown in Fig.…”

“…The coupled reactions facilitate the complete oxidation of methane to CO 2 and water in [C 4 mPy][NTf 2 ] and the in situ generated CO 2 was used as an internal standard for oxygen detection which addresses the fundamental limitations to accuracy and the long-term stability and reliability in chemical analysis. We have validated this ionic liquid-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single-and double-potential step chronoamperometry and the analytical parameters [202]. , as methane concentration is increased and oxygen concentration is decreased.…”