Rapid and accurate detection of highly toxic NO2 gas based on catkins biomass-derived porous In2O3 microtubes at low temperature

Development of In2O3-based gas sensors has recently attracted widespread attention, however, how to shorten the response and recovery time for sub-ppm level NO2 detection remains challenging. In this work, biomorphic In2O3 sensing material (In2O3-600) was successfully prepared through simple indium chloride solution immersion and air calcination at 600 ? with waste catkins template. This hierarchical structure is cross-linked by uniform spherical nanoparticles with good crystallinity. Its multi-stage pores and 1-D microtube structure are conducive to promoting the rapid diffusion and desorption of target gas, and the existence of oxygen vacancy defects can also effectively increase the conductivity, active sites and the content of surface adsorbed oxygen species. Their synergism significantly improves the rapid response and recovery speed of sensor to trace NO2 under low energy consumption. At 92 degrees C, the response value of In2O3-600 sensor towards 10 ppm NO2 is up to 193 with rapid response and recovery times (56 and 14 s), even 1 ppm for 64 and 32 s, which is significantly shorter than most reported In2O3-based sensors. In addition, the sensor also has a wide linear detection range, low detection limit, good selectivity, and satisfactory reproducibility, moisture resistance and long-term stability. Therefore, the biomorphic porous In2O3-600 microtubes are available as candidate for detecting sub-ppm level NO2 gas at low temperature.

Automated summary

In this study, a biomorphic In2O3 sensing material (In2O3-600) was successfully prepared, which showed improved response and recovery time for sub-ppm level NO2 detection. The hierarchical structure of the material, along with its multi-stage pores and 1-D microtube structure, promoted rapid diffusion and desorption of the target gas. The material also exhibited good conductivity, active sites, and surface adsorbed oxygen species, leading to enhanced sensor performance.