The development of new microelectrode gas sensors: an odyssey. Part 1. O₂ and CO₂ reduction at unshielded gold microdisc electrodes

In this paper we describe the reduction of O₂ and CO₂, when both molecules are always present and the balance gas is N₂, at unshielded gold microdisc electrodes in dimethyl sulphoxide (DMSO) in a standard reaction cell. We show that both gases can be reduced in the presence of each other, in the range 3-15 vol.% CO₂ and 10-30 vol.% O₂, with minimal cross-interference from "feedforward" and "feedback" reaction products from the individual O₂ and CO₂ reduction processes. Well-separated O₂ and CO₂ reduction processes were obtained with gold microdisc electrodes when the polarizing voltage was swept typically at 0.1-0.5 V s^-1, and steady state limiting currents were measured which were proportional to the O₂ and CO₂ concentrations.