Facile synthesis of In2O3 nanospheres with excellent sensitivity to trace explosive nitro-compounds

In2O3 nanospheres with excellent sensing ability to explosive nitro-compounds have been successfully synthesized via a two-step method including a mild solvothermal process and calcination at elevated temperature in air. The as-synthesized In2O3 nanospheres are of 200-300 nm in diameter and are composed of small nanoparticles with a size of around 5 nm. The structure, morphology and thermal stability are investigated by XRD, SEM, TEM, HRTEM, TG and XPS. At 140 °C, the responses of this sensor toward 100 ppm nitromethane, nitroethane and nitropropane are 163, 220 and 375, respectively. And what's more, the sensor also exhibits short response time of less than 1 s, good long-term stability, and low detection limits. The good sensing performance should be attributed to the strong electron-withdrawing effect of nitro group and low working temperature.