Microstructural engineering of ZIF-8/In2O3 core-shell nanocomposites for superior ppb-level NO2 gas sensing performance

The enhanced sensitivity and selectivity of NO 2 gas sensors are crucial for atmospheric environmental monitoring. In this study, a novel NO 2 gas sensor based on small-sized ZIF-8/In 2 O 3 core-shell nanocube has been developed through a simple solvothermal method along with in situ modification. The ZIF-8 coating significantly increased the specific surface area of the In 2 O 3 nanocubes from 60.64 m 2 /g to 140.84 m 2 /g, while also boosting the adsorption of oxygen ions on the surface. Gas-sensing tests revealed that the ZIF-8/In 2 O 3 composites exhibited a response of 56.3 to 1 ppm of NO 2 , with an exceptionally low detection limit of 1 ppb. Notably, the sensor demonstrated outstanding selectivity for NO 2 over other potential interfering gases. The remarkable NO 2 sensing performance of the ZIF-8/In 2 O 3 composites can be attributed to the grain boundary effects in the In 2 O 3 nanocubes (with side lengths of approximately 40–50 nm), as well as the sensitizing and filtering effects of the ZIF-8 layer. This work holds significant promise for the rapid detection of low-concentration NO 2 gases in various applications.