CO2 gas sensing at microelectrodes in nonaqueous solvents

The reduction of CO2 has been examined at gold and platinum microelectrodes in solutions of 0.1 M tetraethylammonium perchlorate (TEAP) in dimethyl su lfoxide (DMSO), acetonitrile (MeCN) and mixed solvent systems. The gold mic roelectrode in 90% MeCN/10% DMSO produced currents 4 times larger than in p ure DMSO while still showing a large potential window over which reduction currents can be measured. Films of polyaniline were insoluble in MeCN and a cted as a diffusional barrier for CO2 reduction. Polyaniline was soluble in DMSO solutions, but the adsorbates which remained following polyaniline di ssolution helped to lower the CO2 reduction overpotential, producing a broa d current plateau of 500 mV for the measurement of CO2 concentrations.