Size Dependent Chemical Synthesis of Defective In₂O₃ Microcubes as NO₂ Sensor

Abstract

Indium oxide microcubes (IMCs) have been systematically synthesized by the hydrothermal method. The size of IMCs is systematically controlled by varying urea concentration (0.05–0.25 M) in the bath. The phase pure cubic indium oxide (In2O3) with preferred orientation along (222) direction is observed. The size of IMCs changes from 0.4 to 1.2 μm by varying urea concentrations. The urea concentration dependent plausible growth mechanism of IMCs is proposed. The defective IMCs have effectively used as NO2 sensors and have shown a gas response of 180 under the exposure of 80 ppm NO2 gas at low‐operating temperature (100 °C). However, IMCs exhibited shorter response (Rs = 4 s) and recovery time (Rc = 100 s) for 80 ppm NO2 gas. IMCs have shown selective to NO2 than NH3, CO2, and acetone.