Novel electrode materials for electrochemical sensors

Electrode materials are the key components for electrochemical sensors, which can be used for determination of gaseous and dissolved species. The sensitivity as well as the selectivity are mainly influenced by the kind and the structure of sensitive electrode material. In this paper two kinds of materials are described. Screen printed carbon electrodes can be modified by thin layers of conducting polymers like Poly(3,4-ethylendioxythiophene) (PEDOT). By means of differential pulse (DPV) and square wave voltammetry (SWV) it is possible to determine biogene amine like dopamine in liquids of human bodies and explosives in ground water in the μM und ppb level, respectively. Polyaniline (PANI) can be used not only at room temperature but also in high temperature sensors. For the first time we could show that zirconia sensors with Nb₂O₅ or FeCl₃ and Co(NO₃)₂ embedded PANI electrodes are suitable for the hydrogen and hydrocarbons sensing in oxygen containing atmospheres at 450 °C. The sensitivities of such electrodes are much higher than those of the usual applied oxide systems like Nb₂O₅ or La_0.75Ca_0.25Mn_0.5Ni_0.5O_3-δ. Due to the availability and compactness of electronic devices electrochemical sensors with modified electrodes can be applied in stationary (potentiometric) and non-stationary (SWV or DPV) mode in field application.