Substituted polythiophene-based sensor for detection of ammonia in gaseous and aqueous environment.

This manuscript presents the preparation of polymer layers based on polythiophene (PTh) and its 3-substituted derivatives (substituents 4-(CH3O)C6H4 and 4-(CF3)C6H4 marked as PThOCH3 and PThCF3, respectively) on platinum electrodes by cyclic voltammetry (CV). The polymerization process and the morphology of resulting layers were discussed analysing of CV-voltammograms and scanning electron microscopy (SEM), respectively. Subsequently, the prepared polymers were tested as active/sensitive media of two types of sensors: (i) electrochemical sensor detecting ammonia in aqueous environment, whose response was evaluated by electrochemical impedance spectroscopy (EIS); (ii) chemiresistor detecting NH3 in atmosphere, whose response was evaluated by measurement of resistance. It was found that both the physical (morphology, homogeneity, relative thickness) and receptor properties of the polymer layer deposited on electrode surface are significantly affected by the nature of substituent attached to the thiophene ring. The mutual context of ammonia detection in both environments is discussed. [ABSTRACT FROM AUTHOR]