Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

• Ethanol gas sensors based on Pd:NiFe2O4 nanoparticle thin film were fabricated.
• Pd incorporation in NiFe2O4 matrix inhibits grain growth.
• The sensors were more selective to ethanol gas.
• Sensors exhibited fast response and recovery when doped with palladium.
• Pd:NiFe2O4 thin film sensor displays excellent long–term stability.

In this work, Pd:NiFe2O4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe2O4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost.