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

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.