The development of new microelectrode gas sensors: an odyssey. Part 2. O2 and CO2 reduction at membrane-covered gold microdisc electrodes

CO2 Gas Sensing at Microelectrodes in Nonaqueous Solvents

“…However, their calculation of a limiting current of 800 nA, using the saturated CO 2 concentration of Albery of 84 mM [26] and n 2, uses a diffusion coef®cient of 6.15610 À6 cm 2 s À1 which is probably too low, given that it is calculated from the Sand equation using a saturated concentration of 128 mM [27] which is higher than values reported in later studies [24,26]. Hahn et al, took fast potential scans at 3.4 mm and 10 mm diameter gold microdisk electrodes [30,31], to produce current plateaus proportional to the concentrations of both 10±30 vol. % O 2 (monitored at À1.0 V (Ag wire quasireference)) and 3±15 vol.…”

The development of new microelectrode gas sensors: An odyssey

“…Over the last decade or so, the electrochemical measurement of oxygen, carbon dioxide and nitrous oxide has typically utilised aprotic solvents such as dimethyl sulfoxide (DMSO) [12][13][14][15][16][17][18][19] found in previous studies [12][13][14][15][16][17][18], including earlier odyssey chapters [15][16][17][18]. We do however summarize the proposed mechanisms briefly below, see Eqs.…”

“…As described previously [12][13][14][15][16]18,19], significant complications arise for the simultaneous electrochemical detection of oxygen and carbon dioxide in non-aqueous solvent since oxygen is more readily reduced than carbon dioxide. The superoxide radical anion species, generated electrochemically at lower potentials compared to carbon dioxide reduction, attacks the carbon dioxide species in a nucleophilic addition reaction leading to the formation of the peroxydicarbonate anion [9][10][11].…”

“…The ability to determine both respiratory gases, such as oxygen and carbon dioxide as well as inspired anaesthetic agents that include nitrous oxide, enflurane, isoflurane and sevoflurane accurately has been the focus of recent scientific interest [1][2][3][4][5][6][7][8][12][13][14][15][16][17][18][19]. Much of this work has centred on the development of an electrochemical sensor that can simultaneously measure mixtures of these gases and agents using cheaper technologies than those currently employed.…”

Electrochemical Detection for Gaseous Vinyl Chloride with a Sputtered Au/Porous Alumina Substrate/Pt Electrode Assembly

“…Furthermore, the gaseous electroactive species, hydrogen and oxygen, were dissolved into the organic medium and analyzed [4,5]. Hahn and co-workers [6,7] used a gold microdisk electrode to investigate the detection of O 2 and CO 2 in gaseous phase by using solvent of dimethyl sulfoxide (DMSO), containing supporting electrolyte of 0.1 M Bu 4 NClO 4 . The organic medium indeed provided a suitable sensing condition for the reduction of O 2 and CO 2 with a low background current.…”