Temperature-dependent dual selectivity of hierarchical porous In2O3 nanospheres for sensing ethanol and TEA

Realizing dual gas selectivity on a sensor based on metal oxide semiconductor (MOS) is a meaningful work, but still remains a challenge. In this paper, we reported the synthesis of In2O3 hierarchical porous nanospheres (HPNSs) that showed high sensitivity and dual selectivity to ethanol and trimethylamine (TEA) by controlling the operating temperature. Uniform In(OH)3 nanospheres that assembled with solid nanocubes were prepared in advance via a facile hydrothermal route and then used as precursor for In2O3 by calcinating at different temperatures. At an optimized calcination temperature of 500 °C, In2O3 HPNSs with uniform diameter of about 100 nm, unique micro- and mesoporous structure, and high content of oxygen vacancy (Ov: 45.2 %) were successfully prepared. At the operating temperatures of 240 and 320 °C, the sensor based on as-prepared In2O3 HPNSs (IO-500) showed high sensitivity and excellent selectivity to ethanol and TEA, respectively. Moreover, when the IO-500 sensor was used to detect ethanol and TEA, it also showed some other impressive characteristics, such as fast response speed, perfect response linearity, and good repeatability and stability. The temperature-dependent dual selectivity of the In2O3 HPNSs for ethanol and TEA was discussed.