Characterization of mesoporous Zn doped NiCo2O4 rods produced by hydrothermal method for NOx gas sensing application

We report the characterization and NOx gas sensing properties of Zn doped NiCo2O4 mesoporous rods obtained through a simple hydrothermal approach. X-ray powder diffraction confirms the spinel structure with cell parameter (a) of 8.110 Å. X-ray photoelectron spectroscopy studies reveal the oxidation states of metal oxides. N2-adsorption-desorption analysis and electron microscopic studies show the mesoporous nature of the sample. The specific surface area is found to be 76 m2 g−1 with an average pore diameter of 21 nm. The thick film of Zn doped NiCo2O4 mesoporous rods exhibit good gas sensing characteristics towards NOx. Gas response of the sensor increases with concentration of NOx from 2 ppm to 200 ppm. It has a response time of 28 s and recovery time of 30 s towards 10 ppm NOx gas at 200 °C. The NOx gas concentration dependent responses and cyclic tests of the sensor demonstrate better reliability and reproducibility with regards to NOx gas sensing.