A highly-sensitive
ammonia (NH3) gas sensor based on
molybdenum trioxide nanoribbons was developed in this study. α-MoO3 nanoribbons (MoO3 NRs) were successfully synthesized
via a hydrothermal method and systematically characterized using various
advanced technologies. Following a simple drop-cast process, a high-performance
chemiresistive NH3 sensor was fabricated through the deposition
of a MoO3 NR sensing film onto Au interdigitated electrodes.
At an optimal operation temperature of 450 °C, the MoO3 nanoribbon-based sensor exhibited an excellent sensitivity (0.72)
at NH3 concentration as low as 50 ppb, a fast response
time of 21 s, good stability and reproducibility, and impressive selectivity
against the interfering gases such as H2, NO2, and O2. More importantly, the sensor represents a remarkable
limit of detection of 280 ppt (calculated based on a signal-to-noise
ratio of 3), which makes the as-prepared MoO3 NR sensor
the most sensitive NH3 sensor in the literature. Moreover,
density functional theory (DFT) simulations were employed to understand
the adsorption energetics and electronic structures and thus shed
light on the fundamentals of sensing performance. The enhanced sensitivity
for NH3 is explicitly discussed and explained by the remarkable
band structure modification because of the NH3 adsorption
at the oxygen vacancy site on α-MoO3 nanoribbons.
These results verify that hydrothermally grown MoO3 nanoribbons
are a promising sensing material for enhanced NH3 gas monitoring.
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