Hollow In2O3 microcubes for sensitive and selective detection of NO2 gas

Herein, we report a facile approach for the synthesis of hollow Indium oxide (In2O3) microcubes (HIMC) by two step process which consist of hydrothermal method and followed by air annealing. Kirkendall effect has been employed to transform Indium hydroxide In(OH)3 microcubes (IHMC) to HIMCs. Particularly, the formation of HIMC was studied as function of annealing time. The evolution of hollowness was discussed through Kirkendall effect. Fabricated HIMC films were used to detect NO2 gas up to 100 ppm of concentration. We found that synthesized HIMC had a huge sensing response (S = 1401) towards 100 ppm NO2 gas, which demonstrates the effect of HIMC over simple microcubes. Response (Rs = 16s) and recovery (Rc = 165s) time of sensor were very short, which enables sensor to work rapidly. Also, HIMC sensor found selective for NO2 gas rather ammonia, acetone and carbon dioxide gases. NO2 sensing mechanism for the case of HIMC based sensor was described as per well known oxide based chemiresistive theory. From observations, it is found that the fabricated (HIMC)3hr based sensor is highly selective and sensitive towards NO2 gas at ppm level of concentration and could be undertaken for gas sensing application at various fields.