Transition Metals Ni2+, Fe3+ Incorporated Modified ZnO Thick Film Sensors to Monitor the Environmental and Industrial Pollutant Gases

Abstract

Zinc oxide is known as multifaceted material due to its special physical and chemical properties. Present research deals with the fabrication of undopedZnO, 1.5% Fe3+ doped ZnO, and 1.5% Ni2+ doped ZnOnanoparticles by low-cost co-precipitation method. These prepared materials were utilized to prepare thick film sensorsby employing a screen printing technique.The structuralconfirmations of these materials wereperformed by various nano-characterization techniques. The structural properties were investigated by XRD to confirm the nanoscaleZnO as well as the average crystal dimensions. The surface morphological properties of undoped and modified ZnO wereanalyzedby SEM and TEM methods. The average volume pores over prepared materials and surface area were concluded from the N2 adsorption-desorption experiment (BET analysis). The Fe3+ doped ZnO has the highest surface area among all the prepared sensors i.e. 23.55 m²/g. The Fe3+ doped ZnO and Ni2+ZnOnanomaterials were observed to show declined band gaps in comparison to the undoped ZnO material. All the prepared sensors were employed for the gas sensing study of gases like NH3, LPG, formaldehyde vapors, toluene vapors, CO, CO2, and NO2. The CO2 and NH3vapors found to be very sensitive towards Fe3+ doped ZnO with 76.62% and 76.58% sensitivity respectively. TheNi2+ doped ZnO sensor sensitivity for CO2 and NH3was recorded as71.20% and 70.23% respectively. The LPG, CH2O, and toluene vapors' sensitivity was also studied for the modified ZnO sensor. Besides, modified ZnO utilized as a relative humidity sensor with an RH variation of 10-90%. The impedance versus humidity curves recorded for all sensors.The Fe3+ doped ZnOnanomaterial at 10Hz was found to be an effective humidity sensor. Theresponse and recovery were found to be very rapid in Fe3+ doped ZnO for NH3, CO2, NO2, and LPGvapors.