In-situ synthesized Sn-doped In2O3 nanorods for low-temperature NO2 sensing with high response

As a key air pollutant, the efficient detection of nitrogen dioxide (NO 2 ) is of great significance for environmental monitoring. In this study, In 2 O 3 nanorods with different Sn doping concentrations (0–10 mol.%) were in-situ synthesized on Al 2 O 3 ceramic tubes via a one-step hydrothermal method combined with an annealing process. The structure, morphology, and NO 2 gas-sensing properties of the as-prepared materials were systematically investigated. Gas-sensing results demonstrate that 5 mol.% Sn-doped In 2 O 3 nanorods exhibit a high response (227.6) to 50 ppm NO 2 at 100 °C, which is 31 times that of pure In 2 O 3 (7.3). They also feature rapid response/recovery times (22 s/21 s), excellent selectivity, and long-term stability (response fluctuation <15 % over 30 days). Characterization results reveal that Sn 4 + is successfully incorporated into the In 2 O 3 lattice, leading to lattice contraction and an increase in oxygen vacancy content (oxygen vacancy ratio of 44.96 %). The gas-sensing mechanism, combining the adsorbed oxygen model with density functional theory (DFT) calculations, demonstrates that Sn doping enhances the adsorption energy and charge transfer between NO 2 and the sensing material.