Physisorption-Based Charge Transfer in Two-Dimensional SnS₂ for Selective and Reversible NO₂ Gas Sensing

TLDR

Nitrogen dioxide is a key industrial, agricultural, and healthcare pollutant, yet low‑limit sensing remains difficult, especially amid interfering gases, and current technologies trade off selectivity, sensitivity, reversibility, and cost. The study aims to develop a selective and reversible NO₂ sensor by demonstrating an economical platform. The platform operates via charge transfer between physisorbed NO₂ molecules and two‑dimensional tin disulfide flakes at low temperatures. The resulting sensor achieves high sensitivity and superior selectivity at temperatures below 160 °C, exhibits excellent reversibility rarely seen in 2D materials, and its performance stems from the planar morphology and favorable electronic band positions of SnS₂, offering a low‑cost solution for NO₂ detection.

Abstract

Nitrogen dioxide (NO2) is a gas species that plays an important role in certain industrial, farming, and healthcare sectors. However, there are still significant challenges for NO2 sensing at low detection limits, especially in the presence of other interfering gases. The NO2 selectivity of current gas-sensing technologies is significantly traded-off with their sensitivity and reversibility as well as fabrication and operating costs. In this work, we present an important progress for selective and reversible NO2 sensing by demonstrating an economical sensing platform based on the charge transfer between physisorbed NO2 gas molecules and two-dimensional (2D) tin disulfide (SnS2) flakes at low operating temperatures. The device shows high sensitivity and superior selectivity to NO2 at operating temperatures of less than 160 °C, which are well below those of chemisorptive and ion conductive NO2 sensors with much poorer selectivity. At the same time, excellent reversibility of the sensor is demonstrated, which has rarely been observed in other 2D material counterparts. Such impressive features originate from the planar morphology of 2D SnS2 as well as unique physical affinity and favorable electronic band positions of this material that facilitate the NO2 physisorption and charge transfer at parts per billion levels. The 2D SnS2-based sensor provides a real solution for low-cost and selective NO2 gas sensing.