Characteristics of point defects on the room temperature ferromagnetic and highly NO2 selectivity gas sensing of p-type Mn3O4 nanorods

Abstract This study investigates the room temperature (RT) gas-sensing and ferromagnetic behavior of p-type materials based on a comparison of NiO, Mn 3 O 4 , and CuO nanostructures prepared using a hydrothermal method. The Mn 3 O 4 nanorods based sensor exhibited high sensitivity and responses to 40 ppm NO 2 and a selectivity to NO 2 over the interference of CO, NH 3 , CH 4 , C 6 H 6 , C 7 H 8 and C 3 H 6 O gases at 23 °C. The observed response and selectivity to 40 ppm NO 2 are ascribed to the vastly gas accessibility induced by ample porosity, high surface area and point defects of Mn 3 O 4 . This is justified by a clear correlation of point defects with the ferromagnetic and gas-sensing properties. The linear behavior observed for the response versus gas concentration (adj R 2  = 0.98519), signified that the Mn 3 O 4 -based sensor is suitable for NO 2 detection at 23 °C. A model of the gas-sensing mechanism and the influence of point defects were presented to further illustrate the sensing performance.