Detection of NH3 gas using CrVO4 nanoparticles

Nanostructured chromium orthovanadate with an average particle size of 65nm was prepared by the co-precipitation technique for the chemiresistive sensor. The morphology and particle size distribution of CrVO4 nanoparticles were examined by SEM and TEM. According to XRD, most of the prepared CrVO4 material (crystallites) has a monoclinic structure belonging to the space group C2/m. XPS and UV-Vis absorbance measurements provided additional information on the main phase and the surface. The material has shown reasonable selectivity towards the NH3 gas. The as-prepared CrVO4 nanostructures exhibit a maximum relative response of 32% to 50 ppm NH3. The identical dynamic response profiles during the sequential injections of 50 ppm NH3 evinced the repeatability of the sensor. The limit of detection (LOD) value of the sensor was estimated ca 0.7 ppm using relative response values towards a wide range of NH3 concentrations from 10 ppm to 100 ppm. The sensing mechanism was expressed in terms of the surface band bending phenomenon caused by the adsorption and desorption of the ammonia. The best sensor performance was achieved at 330 °C, where the effects of humidity and moisture can be neglected. The results confirmed that the CrVO4 nanomaterial has the potential to fabricate an affordable, easy-to-make, and reliable gas sensor for NH3 gas.