Study of CO₂ electrodes in open devices of potentiometric sensors

Joel Ramirez-Salgado (1) , Pierre Fabry (1)

1 LEPMI - Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces

Potentiometric CO₂ sensors in open devices with NASICON as solid electrolyte were tested in the temperature range 150–500 °C and at partial pressures between 10⁻⁶ and 0.1 atm in air. The sensors were built with sodium titanate and La_1−xSr_XMnO_3±δ (LSM) mixtures as oxygen reference electrode and Na₂CO₃–BaCO₃ or Na₂CO₃–SrCO₃ mixed with gold as measuring electrodes. The CO₂ electrode reaction is based on an electrochemical mechanism with a fast electron transfer and an adsorption–diffusion phenomenon. In sensor devices, the system with Na₂CO₃–BaCO₃ deviates from Nernst law in all the pressure ranges whatever the device (pellet or coplanar devices) is. The system with Na₂CO₃–SrCO₃ obeys a Nernst behaviour for the highest CO₂ pressures. The observed responses are very fast. A discussion is engaged to explain the subnernstian behaviour from the thermodynamic stability of Na₂CO₃ and a mixed voltage phenomenon.

Mots clés: Carbon dioxide; Potentiometric sensor; NASICON; Sodium titanate; LSM; Mixed voltage

Domaines: Matériaux

Joel Ramirez-Salgado, Pierre Fabry. Study of CO₂ electrodes in open devices of potentiometric sensors. Solid State Ionics, 2003, 158 (3-4), pp. 297-308. ⟨10.1016/S0167-2738(02)00775-0⟩. ⟨hal-00418065⟩