Low-cost ultra-sensitive SnO2-based ammonia sensor synthesized by hydrothermal method

Abstract

Tin oxide (SnO2) and 2 mol% Ce-doped SnO2 nanoparticles synthesized by the hydrothermal method to detect ammonia vapors at room temperature. X-ray diffraction investigations have been confirmed that the synthesized nanoparticles are polycrystalline in nature with tetragonal rutile phase. The particle size is determined using Scherrer’s formula and it is found to increase with the “Ce” dopant. Scanning electron microscopy observations reveal that these samples have spherical morphology composed of fine crystallites. The EDX spectra reveal the dominant presence of Sn and O in the case of pure SnO2 nanoparticles. Whereas in the case of doped sample, the EDX reveals the existence of Ce in lesser percentage in comparison with the Sn and O. Atomic force microscopy studies reveals that the root mean square roughness of the nanoparticles is increased from 4.4 nm to 15.3 nm due to the Ce dopant in the SnO2 matrix. Optical bandgap is calculated with the Tauc plot and it is increased with the doping of cerium atoms and it is due to the Burstein–Moss effect. Gas-sensing characterization has been performed using static liquid distribution technique against various volatile organic compounds (VOCs) such as ammonia, ethanol, methanol and toluene in the range of 1 to 25ppm at room temperature.