CO2 sensor based on a solid state oxygen concentration cell

A potentiometric CO2 sensor based on a solid-state oxygen concentration cell is described, which comprises yttria stabilized zirconia (YSZ) as solid electrolyte and sodium carbonate as CO2 sensitive phase. The necessary transformation of the sodium chemical potential into the corresponding oxygen potential is achieved by employing a gas-tight membrane of an electronically short-circuited phase mixture of Na-(β+β″)–Al2O3 as an interlayer between zirconia and sodium carbonate. The sensor signal is stable and reproducible during long-term operation. Further improvement of the sensor behaviour appears to be feasible by maximizing the buffer capacity of the Na-β/Na-β″–Al2O3 phase equilibrium.