Abstract
To meet the requirements in air quality monitors for the public and industrial safety, sensors are required that can selectively detect the concentration of gaseous pollutants down to the parts per million (ppm) and ppb (parts per billion) levels. Herein, we report a remarkable NH
sensor using Ni-doped CeO
octahedral nanostructure which efficiently detects NH
as low as 45 ppb at room temperature. The Ni-doped CeO
sensor exhibits the maximum response of 42 towards 225 ppm NH
, which is ten-fold higher than pure CeO
. The improved sensing performance is caused by the enhancement of oxygen vacancy, bandgap narrowing, and redox property of CeO
caused by Ni doping. Density functional theory confirms that O vacancy with Ni at Ce site (V
Ni
) augments the sensing capabilities. The Bader charge analysis predicts the amount of charge transfer (0.04 e) between the Ni-CeO
surface and the NH
molecule. As well, the high negative adsorption energy (≈750 meV) and lowest distance (1.40 Å) of the NH
molecule from the sensor surface lowers the detection limit. The present work enlightens the fabrication of sensing elements through defect engineering for ultra-trace detection of NH
to be useful further in the field of sensor applications.