Electrochemical sensors for detection of hydrogen in air: model of the non-Nernstian potentiometric response of platinum gas diffusion electrodes

The potentiometric response of three different platinum gas diffusion electrodes deposited on H3PO4 doped polybenzimidazole (PBI) was investigated under humidified atmospheres that contained H2 or mixtures of H2 and O2. Continuum modelling was used to analyse the response. It is shown that the non-Nernstian response under H2H2ON2 mixtures can be explained by a difference of water activity on both sides of the membrane. Under H2O2N2 mixtures, the oxygen mass transport parameters have a strong effect on the electrode sensitivity.