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

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.

[1]  Xunyu Lu,et al.  Electrochemistry of room temperature protic ionic liquids: a critical assessment for use as electrolytes in electrochemical applications. , 2012, The journal of physical chemistry. B.

[2]  Xiangqun Zeng,et al.  In Situ EQCM Evaluation of the Reaction between Carbon Dioxide and Electrogenerated Superoxide in Ionic Liquids , 2013 .

[3]  Peter C. Hauser,et al.  Electrochemical Sensor for the Detection of SO2 in the Low-ppb Range , 1999 .

[4]  M. Casadei,et al.  Activation of Carbon Dioxide by Electrogenerated Superoxide Ion: A New Carboxylating Reagent , 1996 .

[5]  R. Compton,et al.  An electrochemical study of the oxidation of hydrogen at platinum electrodes in several room temperature ionic liquids. , 2007, The journal of physical chemistry. B.

[6]  Xuezhong He,et al.  Physical Properties of Ionic Liquids: Database and Evaluation , 2006 .

[7]  G. Wallace,et al.  Use of Ionic Liquids for π-Conjugated Polymer Electrochemical Devices , 2002, Science.

[8]  Hyman D. Gesser,et al.  The direct conversion of methane to methanol by controlled oxidation , 1985 .

[9]  Sheila N. Baker,et al.  The large scale synthesis of pure imidazolium and pyrrolidinium ionic liquids , 2007 .

[10]  J. Wadhawan,et al.  Voltammetry of oxygen in the room-temperature ionic liquids 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide and hexyltriethylammonium bis((trifluoromethyl)sulfonyl)imide: One-electron reduction to form superoxide. Steady-state and transient behavior in the same cyclic voltammogram re , 2003 .

[11]  Hui Jin,et al.  Physical properties of ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various anions and the bis(trifluoromethylsulfonyl)imide anion with various cations. , 2008, The journal of physical chemistry. B.

[12]  Q. Schiermeier.  Methane finding baffles scientists , 2006, Nature.

[13]  Xiangqun Zeng,et al.  Ionic liquids as electrolytes for the development of a robust amperometric oxygen sensor. , 2011, Analytical chemistry.

[14]  Sheila N. Baker,et al.  An analytical view of ionic liquids. , 2005, The Analyst.

[15]  S. Sotiropoulos,et al.  Hydrogen adsorption–desorption and oxide formation–reduction on polycrystalline platinum in unbuffered aqueous solutions , 1994 .

[16]  Joseph R. Stetter,et al.  Electrochemical NO2 gas sensors: Model and mechanism for the electroreduction of NO2 , 1990 .

[17]  Masaki Yamagata,et al.  Electrochemical Behavior of Oxygen/Superoxide Ion Couple in 1-Butyl-1-methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide Room-Temperature Molten Salt , 2005 .

[18]  M. Yoshikawa,et al.  Oxidation of NO into NO2 over active carbon fibers , 1994 .

[19]  Beat Müller,et al.  Determination of methane and other small hydrocarbons with a platinum–Nafion electrode by stripping voltammetry , 2001 .

[20]  Michael Stewart,et al.  Acidic ionic liquid/water solution as both medium and proton source for electrocatalytic H2 evolution by [Ni(P2N2)2]2+ complexes , 2012, Proceedings of the National Academy of Sciences.

[21]  Bruno Scrosati,et al.  Ionic-liquid materials for the electrochemical challenges of the future. , 2009, Nature materials.

[22]  I. Alnashef,et al.  Electrochemical Generation of Superoxide in Room-Temperature Ionic Liquids , 2001 .

[23]  Xiangqun Zeng,et al.  Dynamics of redox processes in ionic liquids and their interplay for discriminative electrochemical sensing. , 2012, Analytical chemistry.

[24]  Malcolm L. H. Green,et al.  Partial oxidation of methane to synthesis gas using carbon dioxide , 1991, Nature.

[25]  Tetsuya Tsuda,et al.  The Application of Room Temperature Molten Salt with Low Viscosity to the Electrolyte for Dye-Sensitized Solar Cell , 2001 .

[26]  Mingfang Yu,et al.  The physical properties of aqueous solution of room-temperature ionic liquids based on imidazolium: Database and evaluation , 2008 .

[27]  I. Alnashef,et al.  Superoxide Electrochemistry in an Ionic Liquid , 2002 .

[28]  S. Sundaresan,et al.  Oxygen transfer between metals and oxygen-ion conducting supports , 1988 .

[29]  Gino Bontempelli,et al.  Amperometric monitoring of ozone in gaseous media by gold electrodes supported on ion exchange membranes (solid polymer electrolytes) , 1990 .

[30]  David Thompson,et al.  Gold-catalysed oxidation of carbon monoxide , 2000 .

[31]  Oleksiy V. Klymenko,et al.  Kinetic Analysis of the Reaction between Electrogenerated Superoxide and Carbon Dioxide in the Room Temperature Ionic Liquids 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide and Hexyltriethylammonium Bis(trifluoromethylsulfonyl)imide , 2004 .

[32]  Andrew J. Mason,et al.  Methane Recognition and Quantification by Differential Capacitance at the Hydrophobic Ionic Liquid-Electrified Metal Electrode Interface , 2013 .

[33]  M. Flytzani-Stephanopoulos,et al.  Total Oxidation of Carbon-Monoxide and Methane over Transition Metal Fluorite Oxide Composite Catalysts: II. Catalyst Characterization and Reaction-Kinetics , 1995 .

[34]  Andrzej Czerwiński,et al.  Kinetics of carbon dioxide adsorption on a platinum electrode , 1974 .

[35]  T. Marks,et al.  Sulfur as a selective 'soft' oxidant for catalytic methane conversion probed by experiment and theory. , 2013, Nature chemistry.

[36]  D. Macfarlane,et al.  Pyrrolidinium Imides: A New Family of Molten Salts and Conductive Plastic Crystal Phases , 1999 .

[37]  Sheila N. Baker,et al.  Fluorescence studies of protein thermostability in ionic liquids. , 2004, Chemical communications.

[38]  R. G. Evans,et al.  Electroreduction of Oxygen in a Series of Room Temperature Ionic Liquids Composed of Group 15-Centered Cations and Anions , 2004 .

[39]  J. O'm. Bockris,et al.  The Mechanism of Oxygen Reduction at Platinum in Alkaline Solutions with Special Reference to H 2 O 2 , 1967 .

[40]  G. Olah,et al.  Anthropogenic chemical carbon cycle for a sustainable future. , 2011, Journal of the American Chemical Society.

[41]  P. Stonehart,et al.  Effect of poisons on kinetic parameters for platinum electrocatalyst sites , 1972 .

[42]  P. S. Wyckoff,et al.  On the Adequacy of Certain Experimental Observables as Measurements of Flame Burning Rate , 1998 .

[43]  P. Licence,et al.  Probing solvation in ionic liquids via the electrochemistry of the DPPH radical. , 2012, Journal of the American Chemical Society.

[44]  F. Endres,et al.  Air and water stable ionic liquids in physical chemistry. , 2006, Physical chemistry chemical physics : PCCP.

[45]  R. Adzic,et al.  Configuration and Site of O2 Adsorption on the Pt(111) Electrode Surface , 1998 .

[46]  N. Lawrence.  Analytical detection methodologies for methane and related hydrocarbons. , 2006, Talanta.

[47]  Prem K. Kilaru,et al.  Density and Surface Tension Measurements of Imidazolium-, Quaternary Phosphonium-, and Ammonium-Based Room-Temperature Ionic Liquids: Data and Correlations , 2007 .

[48]  Glenn David Fresch.  Neighbors and Natural Gas: Land Use Best Practices to Reduce Pipeline Risk , 2011 .

[49]  F. Hahn,et al.  Anodic oxidation of methane at noble metal electrodes: an ‘in situ’ surface enhanced infrared spectroelectrochemical study , 2001 .

[50]  Julian L. Roberts,et al.  Electrochemistry of oxygen and superoxide ion in dimethylsulfoxide at platinum, gold and mercury electrodes , 1966 .

[51]  Luís M. N. B. F. Santos,et al.  Mutual solubilities of water and hydrophobic ionic liquids. , 2007, The journal of physical chemistry. B.

[52]  Xingjiu Huang,et al.  Investigating the Mechanism and Electrode Kinetics of the Oxygen|Superoxide (O2|O2•−) Couple in Various Room-Temperature Ionic Liquids at Gold and Platinum Electrodes in the Temperature Range 298−318 K , 2009 .

[53]  Xiangqun Zeng,et al.  Bis(trifluoromethylsulfonyl)imide (NTf2)-Based Ionic Liquids for Facile Methane Electro-Oxidation on Pt , 2013 .

[54]  G. H. Lane.  Electrochemical reduction mechanisms and stabilities of some cation types used in ionic liquids and other organic salts , 2012 .

[55]  Amr Henni,et al.  Effect of cation on the solubility of carbon dioxide in three bis(fluorosulfonyl)imide low viscosity ([FSI]) ionic liquids , 2014 .

[56]  S. M. Lang,et al.  Methane activation and partial oxidation on free gold and palladium clusters: mechanistic insights into cooperative and highly selective cluster catalysis. , 2011, Faraday discussions.