Fast Responding Amperometric CO2 Microsensor with Ionic Liquid-Aprotic Solvent Electrolytes

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Knowledge about the microscale distribution of CO2 is essential in many environmental and technical settings, and electrochemical CO2 sensing may be optimized to yield such information. The performance of a Clark-type CO2 sensor was greatly improved by adding 20% dimethylformamide (DMF) to the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide (EMIM-DCA) previously used as an electrolyte. The addition of DMF resulted in a much faster response to increasing (95% response of about 100 s) or decreasing CO2 concentration, a negligible interference from low concentrations of N2O, and a signal temperature dependence similar to that of O2 microsensors. The use of 80% EMIM-DCA/20% DMF as an electrolyte leads to CO2 reduction at -0.72 V (vs standard hydrogen electrode), reducing the overpotential by 0.2 V as compared to the use of 100% EMIM-DCA. The CO2 microsensor has a calculated limit of detection of 0.5 Pa CO2, and sensors optimized for high sensitivity exhibited a linear response within the range of 0-4.6 kPa (0-1.7 mM) CO2. A set of four sensors exhibited no noticeable change of zero current and CO2 sensitivity during 4 months of continuous polarization.

OriginalsprogEngelsk
TidsskriftACS Sensors
Vol/bind5
Nummer8
Sider (fra-til)2604-2610
Antal sider7
ISSN2379-3694
DOI
StatusUdgivet - aug. 2020

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