Room Temperature Ammonia Gas Sensing Using Polyaniline/Indium Oxide/Onion-Like Carbon Composite

Abstract

The modification of onion-like carbons (OLCs) and conducting polymer composites with semiconductor metal oxides could enhance sensing performance at room temperature. The present study compared two microwave-assisted solution-phase methods for the synthesis of indium oxides. The first method produced indium hydroxide $(\text{In} (\text{OH})_{3})$ followed by its conversion to $\text{In}2\mathrm{O}_{3}$ through annealing at 400 $^{\circ}{\mathrm{C}}$ , and the second method used a one-step method where ethanol was used as a solvent instead of water. A flexible room temperature ammonia $(\text{NH}_{3})$ gas sensor was developed using a sensing layer composed of indium oxide $(\text{In}_{2}\mathrm{O}_{3})$ /OLCs)/polyaniline (PANI) composite at relative humidity of 45%. The results showed that $\text{In}_{2}\mathrm{O}_{3}$ materials can be successfully applied in room temperature gas sensing and further enhance the sensing response of OLC/PANI composite.