Polyaniline emeraldine salt as an ammonia gas sensor - Comparison of quantum-based simulation with experiment

Abstract

Abstract Polyaniline as a conducting polymer is proposed to react with gas molecules and thus change its electrical conductivity. In this paper, a polyaniline molecule, in the form of emeraldine salt, and its electrical conductivity in or without the presence of NH3 were studied using numerical modeling (Synopsys QuantumATK [1]). From the I-V characteristic of emeraldine salt molecule in the presence and without the presence of ammonia molecule, the effective resistance (R − R0)/R0 was computed and compared with experimental data from [2] and from [3]. Because of only one molecule computation, I-V characteristics comes to saturation (limited amount of charge carriers). The resistance is computed for pure polyaniline (PANI) and PANI with adsorbed ammonia molecule corresponding to approximative ammonia gas concentration of 3 ppm. The relative resistance increase was compared with experimental data and it was shown to be consistent with the measured values. From the results, PANI in the form of emeraldine salt is suitable as a sensing element in NH3 gas sensors.