Hydrogen sensing in automobile application is the need of the hour as fuel cell based hybrid electric vehicle is developing at a faster pace. Nickel ferrite (NiFe₂O₄) nanoparticles embedded reduced graphene oxide (rGO) prepared by a facile hydrothermal thermal process was employed as a chemiresistive sensor for the detection of H₂ gas. To study the morphological and structural features the synthesized samples were characterized by transmission electron microscopy (TEM), X-Ray diffraction and Raman Spectroscopy. 50 nm cube shaped NiFe₂O₄ nanoparticles were found to be distributed on few layered rGO nanosheets. The electrical conductivity of pristine n type NiFe₂O₄ and NiFe₂O₄/rGO were tested at various operating temperatures. Hydrogen sensing characteristics were measured by forming a thick film of the synthesized nanocomposite paste on an alumina substrate. Sensing results showed that NiFe₂O₄/ 1% rGO showed the maximum response at an optimum temperature of 80 ºC towards 200 ppm of hydrogen gas among four variants. Integration of NiFe₂O₄ nanoparticles on rGO nanosheets has markedly enhanced the conductivity of the nanocomposite. The sensor showed a lower detection limit of 8 ppm with two linear ranges from 30-90 ppm and 100 to 700 ppm. Further the sensor was tested for its selectivity and stability.

Keywords: Hydrogen sensor, Nanoparticles, Chemiresistive, Electric Vehicles