Energy-efficient gas sensors based on nanocrystalline indium oxide

The effect of the nanocrystal size on the sensitivity of nanocrystalline indium oxide In$_{2}$O$_{3}$ with an extremely small size of nanocrystals (from 7 to 40 nm) synthesized by the sol-gel method to nitrogen dioxide with low concentrations is investigated at room temperature under ultraviolet (UV) illumination and without it. It is found that the greatest response to nitrogen dioxide is demonstrated by a sample with an intermediate nanocrystal size. The possibility of using nanocrystalline In$_{2}$O$_{3}$ for fabricating sensors for detecting NO$_2$ in air at room temperature under conditions of additional UV illumination is demonstrated. It is shown that such a sensor can also operate under conditions of pulsed illumination, which significantly reduces its power consumption.