Nitrogen doped In₂O₃-ZnO nanocomposite mesoporous thin film based highly sensitive and selective ethanol sensors

Nanocomposite metal oxide thin films exhibit promising qualities in the field of gas sensors due to the opportunities provided by the heterointerface formation. In this work, we present the synthesis of nitrogen doped mesoporous In₂O₃-ZnO nanocomposite thin films by a simple wet chemical method using urea as the nitrogen precursor. SEM investigation suggests the formation of mesoporous nanocomposite thin films, where the uniformity of the surface pore distribution depends on the relative proportion of In₂O₃ and ZnO in the composites. HRTEM investigation suggests the formation of sharp interfaces between N-In₂O₃ and N-ZnO grains in the nanocomposite thin films. The nanocomposite thin films have been tested for their ethanol sensing performance over an extensive range of temperatures, ethanol vapor concentrations and relative humidities. Nitrogen doped nanocomposite thin films with an equal proportion of In₂O₃ and ZnO exhibit excellent ethanol sensing performance at a reasonable operating temperature (∼94% at 200 °C for 50 ppm of ethanol), fast response time (∼two seconds), stability over time, enhanced resilience against humidity and selectivity to ethanol over various other volatile organic compounds. All the results indicated that nitrogen doped In₂O₃/ZnO nanocomposite thin films portray great possibilities in designing improved performance ethanol sensors.