Highly selective ammonia gas sensor using Ga2O3/MoO3 nanocomposite at ambient atmospheric conditions

The β-Ga 2 O 3 and MoO 3 nanocomposite with varying concentration of MoO 3 at 2.5 %, 5 % and 7.5 % were synthesized through hydrothermal method followed by physical mixing. Obtained nanocomposites were characterized to study its morphological, structural and optical properties through XRD, SEM, EDAX, TEM, XPS and UV–Visible spectroscopy. Surface area analysis was done using BET analysis method. Ammonia (NH 3 ) sensing studies were conducted at room temperature for synthesized composites. Nanocomposite with increased MoO 3 concentration showed increase in the response towards ammonia detection and highest response of 420.12 % for 100 ppm NH 3 at relative humidity (RH) of 69 % with response and recovery time of 53.75 s and 27.44 s respectively. Studies on humidity dependent sensing have been conducted for the same synthesized nanocomposites. The enhanced sensing of NH 3 in room temperature is attributed to sensing mechanism mediated by the adsorbed humidity and oxygen on the surface of the sensing material in addition to the chemical and electronic sensitization effects. • A chemiresistive NH 3 gas sensor of Ga 2 O 3 /MoO 3 composite with varying concentrations of MoO 3 was developed by the hydrothermal method. • The Ga 2 O 3 /MoO 3 composite exhibits a good response towards NH3 gas at room temperature under humid conditions. • The composite with 7.5 wt% MoO 3 showed the highest response of 420.12 % for 100 ppm NH 3 at a relative humidity (RH) of 69 % with response and recovery times of 53.75 s and 27.44 s, respectively. • Sensing mechanism is mediated by the adsorbed humidity and oxygen on the surface of the sensing material, in addition to the chemical and electronic sensitization effects.