Ethylene gas sensor from electrochemically synthesized polyaniline/tin oxide/ multiwall carbon nanotube composites

Abstract

This research proposed four steps to fabricate and improve sensor for ethylene gas detection based on polyaniline (PANi) and/or PANi composites. The effects of amount of PANi, acid dopant of PANi (i.e., hydrochloric acid (HCl), sulfuric acid (H2SO4), phosphoric acid (H3PO4), p-toluene sulfonic acid (TSA), and dodecyl benzene sulfonic acid (DBSA) at each different concentration of 0.1, 0.075, 0.05, 0.025, and 0.01 M), multiwall carbon nanotubes (MWCNTs at 0.2, 0.4, and 0.8% wt) and tin oxide nanoparticles (Sn2O NPs at different deposit times of 60, 90, 120, and 150 second) were used to study the sensing property against ethylene gas. The nanofibril structure of PANi film was easily obtained under applying continuous potential cycle ranging from -0.3-1.0 V with scanning rate 10 mV/s at 10 scans of cyclic voltammetry. The type and concentration of acid dopant had marked influences on the sensing properties against ethylene gas. The sensitivity of PANi with different acid dopants decreased in the order of H2SO4> H3PO4> TSA> DBSA>HCl. After aging for 3 months, the doping PANi with 0.1 M H2SO4 can detect ethylene gas at 10 ppm with sensing magnitudes of 2.94 %. The addition of 0.2 % wt. MWCNT into PANi resulted in an improve sensitivity of PANi against 10 ppm ethylene gas from 2.94% to 4.39% after aging for three months. Multilayer composites of PANi/ MWCNT / SnO2 NPs were synthesized by electrophoretic deposition of SnO2 NPs and then chronoamperometric deposition of the PANi/MWCNT. The level of deposition SnO2 NPs at 60 second in MWCNT/PANi composites exhibited the highest sensitivity for the detection ethylene gas at 10 ppm but its sensitivity decreased with increasing SnO2 NPs.