Oxygen and carbon monoxide role on the electrical response of a non-Nemstian potentiometric gas sensor; proposition of a model

The sensor used for the study was obtained from a solid electrolyte fitted with two metal electrodes (gold and platinum, respectively) located in the same gas mixture and was made using the screen printing technology. A kinetic model able to account for the electrical responses obtained in the presence of oxygen and carbon monoxide is proposed. This model is mainly based on the existence of several oxygen species adsorbed on the surface of the device and on the ideally polarizable properties of the electrodes. Action of carbon monoxide is assumed to occur according to a Langmuir-Hinshelwood model, which involves the consumption of oxygen species considered as a weakly metal-bonded particle. The simulations reveal that such a model is able to account for the complex influence of carbon monoxide, the oxygen pressure and the temperature on the electrical sensor's response. (C) 2003 Elsevier B.V. All rights reserved.