Selective ppb-level NO2 gas sensor based on SnO2-boron nitride nanotubes

This paper demonstrated a hybrid SnO2-BNNTs (SnO2 decorated boron nitride nanotubes) for trace ppb-level sensing towards NO2. A facile way is utilized for the synthesis of SnO2-BNNTs in which BNNTs are consistently coated with SnO2 nanoparticles (NPs). The existence of SnO2 NPs onto BNNTs was confirmed by XRD, XPS, FESEM, and TEM. Sensing characteristics of SnO2-BNNTs sensor, including the sensor response, repeatability, long-term stability, and response-recovery times were studied by exposure to several NO2 gas concentrations varying from 250 ppb to 5 ppm at different operating temperatures form 25 degrees C-300 degrees C. As a result, the SnO2-BNNTs sensor showed an extremely low detection limit (DL) of 250 ppb, as well as a better sensor response as compared to the SnO2 sensor. The maximum sensor response of SnO2-BNNTs sensor was similar to 2610 towards 5 ppm NO2 gas at low operating temperature (100 degrees C). Expanded variation of space charge depleted regions was created at p-n heterojunction which promoted tunneling effect caused by entrapment of NO2 gas molecule and offered conducting channels (CCs) through BNNTs for charge carriers towards an improved sensor response of SnO2-BNNTs sensor.

Automated summary

This paper demonstrated a hybrid SnO2-BNNTs sensor for trace ppb-level NO2 detection, with a low detection limit and better sensor response than the SnO2 sensor. The sensing characteristics of the sensor were studied, including response, repeatability, stability, and response-recovery time. The increased space charge depleted regions at the p-n heterojunction promoted a tunneling effect and provided conducting channels through BNNTs for an improved sensor response.