In2O3-decorated ordered mesoporous NiO for enhanced NO2 sensing at room temperature

In this work, ordered mesoporous structures of In2O3-decorated NiO were prepared by a two-step process, comprising of the synthesis of ordered mesoporous NiO followed by injection of In3+ into their pores. The pore size distribution of the as prepared samples was between 4.1 and 21.1 nm. Furthermore, their sensing performances toward NO2 were tested systematically. The results showed the highest response about 3 towards 15 ppm NO2 sensing at room temperature for 5.0 at.% In2O3-decorated NiO compared to other decorated and pure samples. Moreover, the sensor displayed excellent selectivity towards NO2 in the presence of other interfering gases, such as carbon monoxide, ammonia, ethanol, methanol, formaldehyde, toluene, acetone. The exceptional NO2 sensing performance of the In2O3-decorated mesoporous NiO may be attributed to their high specific surface area and the formation of p-n junction with modified carrier concentration caused by In3+ doping. This method can act as an effective strategy for enhancement of gas-sensing properties of pure metal oxides.