Improved selectivity of borophene sensor towards NO2 gas with PEI-ZIF-8 overlayer

Stable and selective gas sensing is essential to detect toxic gases and avoid gas leak accidents. Two-dimensional (2D) materials are potential sensing materials for making gas sensors because of their high surface-to-volume ratios, broad surface activity, and defect sites. In this work, a recent 2D material, borophene, is used as the NO2 gas-sensing material. Polyetherimide (PEI) incorporated with the Zeolitic imidazole framework (ZIF-8) with different loading (mixed matrix membrane, MMM) is used as a selective gas separation membrane for its solu-bility (imide, isopropylidene and ether groups on PEI) and diffusion (porosity) properties. The MMM was se-lective to NO2 gas as ZIF-8 is selective towards NO2 gas, and PEI is resistant to substances like hydrocarbons, alcohols, and halogenated solvents. A slight variation in borophene's gas sensing response (0.6%) was observed for 25 ppm NO2 at 25 degrees C and 35% relative humidity (RH) with and without the PEI-ZIF-8 filter, showing the MMM filter is not affecting the sensing response highly. As ZIF-8 is hydrophobic, the borophene sensor showed higher stability at higher RH conditions. These findings suggest that fabricated sensors can detect NO2 gas at varying concentrations for environmental and human safety.

Automated summary

Stable and selective gas sensing is crucial for detecting toxic gases and preventing gas leak accidents. In this study, borophene is identified as a potential material for NO2 gas sensing, while a polyetherimide-zeolitic imidazole framework mixed matrix membrane is used as a selective gas separation membrane. Experimental results demonstrate that the fabricated sensors exhibit stable and reliable detection performance for NO2 gas at varying concentrations.