Room temperature ammonia sensing of α-MoO3 nanorods grown on glass substrates

Abstract We report the fabrication of ammonia gas sensors operating at room temperature using aligned one-dimensional orthorhombic molybdenum trioxide (α-MoO3) nanorods. α-MoO3 nanorods were fabricated on glass substrates by thermal evaporation under vacuum condition and subsequent annealing at ambient air. The selectivity of fabricated sensors was performed with different test gases viz. ammonia, xylene, acetone, toluene, isopropanol, 2-methoxyethanol, n-butanol, methanol, and ethanol. Highest sensitivity for ammonia gas at room temperature (28°C, 35% relative humidity) for a concentration of 100 ppm, was achieved. The sensors annealed at 400 °C showed response to lower concentrations of ammonia (1 ppm) with high repeatability. The sensing response dropped only less than 1% after one year of stable performance. The change in morphology and the structural modifications of α-MoO3 nanorods with annealing had improved the sensing response.