MOF-derived In2O3 nanotubes/Cr2O3 nanoparticles composites for superior ethanol gas-sensing performance at room temperature

Semiconductor metal oxide gas sensors have been frequently used for real-time monitoring of various gases in different applications. However, the working temperature is usually high (>150 degrees C), which limits their appli-cation. In this work, the composites of In2O3 nanotubes derived from metal-organic framework (MOF) and Cr2O3 nanoparticles were successfully prepared via solvothermal and impregnation method. The structure, surface morphology and elementary of In2O3/Cr2O3 composites were characterized. Due to the synergistic effects of unique hollow tube structure, large specific surface area and p-n heterojunctions, the In2O3/Cr2O3 composites sensor exhibits excellent ethanol sensing performance at room temperature, including high response under low concentration (less than 5 ppm), excellent selectivity, good repeatability, fast response/recovery time, and long-term stability. The sensing mechanism was discussed in detail. This work provides a feasible synthesis strategy to prepare metal oxide-based hybrid composites, which could be used for fabrication of gas sensor with low energy consumption and high response.