Extension to Acid-Base Active Gases

The above treated gases were redox-active gases, i.e., gases whose interactions with electrons are the relevant one. Yet, the characteristic interaction of many complex gases such as NH3, H2O, CO2 is the interaction with ions, i.e., they are acid-base active through 

A detection of these gases via a redox change, may be possible, but would involve low selectivity. Let us expUcitly follow Ref. and systematically construct the analogues to the 3 modes discussed above, in terms of add-base interactions. 

This is achieved in the electrochemical CO2 sensor to be described now. The gas sensitive electrode in the emf sensors for CO2 detection is based on an alkahne or alkahne earth carbonate.If NazCOs is to be used, Na- p -alumina or Nasicon (Part 1 ) are suitable electrolytes. A thermodynamically well-defined sensor is obtained by using a mixture of a binary and a ternary oxide such as  

Owing to the electrolytic nature of the electrolyte A// 3. is zero, while Afi represents the cell voltage.) As CO2 does not interact 

Na2C03 + M02 Na2M03 + C02 or in the more precise electrochemical equilibrium formulation 

The chemical diffusion coefficient, D =/ (c, c, c (which can be calculated just as done for Dq =f (c, c, in Part 1), reads for negligible trapping effects as 

Schonherr, and J. Maier, Solid State Ionics 70/71 (1994) 278-284. Copyright 1994 with permission from Elsevier. 

This is achieved in the electrochemical CO2 sensor to be described now. The gas sensitive electrode in the emf sensors for CO2 

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