LAUSR

Abstract The large-scale synthesis of ultra-small NiCo2O4 nanoparticles (20 nm) was developed using a facile hydrothermal technique without post-annealing process. A powder X-ray diffraction (XRD) and Transmission electron micrograph analysis were used to obtain the cubic structure and well crystalline spherical uniform NiCo2O4 nanoparticles. The N2 adsorption-desorption study shows that the NiCo2O4 nanoparticles BET surface area is estimated at 88.5 m2/g, and the distribution of the pore size is about 20 nm. The gas sensing characteristics of the modified fiber optic gas sensor NiCo2O4 are exposed to varying concentrations of ethanol and acetone gases (0−500 ppm). Results indicate that the NiCo2O4 sensor displayed exceptional sensing response to acetone gas, such as high sensitivity (72 × 10−3k/P), rapid response (20 s) and recovery time (26 s). More detailed discussion is also given on the theoretical sensing mechanism for the proposed sensor.