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

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.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…Generally, the preparation methods can be classified into top‐down and bottom‐up methods, such as mechanical exfoliation,72, 92, 116 solvothermal method,97, 129, 140, 141 vapor deposition,69, 76, 118, 142 atomic layer deposition,126, 143 and so on. In the following context, we will focus on four methods.…”

“…Most employed solvothermal methods for synthesizing GIVMCs can summarized by the following procedure: Sn‐halogenides (Cl used mostly) + varied chalcogenide precursors, as shown in Figure 3 a 97, 117, 119, 140, 141, 144, 145, 146, 147. Usually the selection of chalcogenides and the combination of ligands can play crucial roles in determining the morphology, sizes, yield and crystal phases of the as‐synthesis products.…”

A 3D Chemically Modified Graphene Hydrogel for Fast, Highly Sensitive, and Selective Gas Sensor

“…For example, NO 2 gas acts as a source of acid rain and contributes to the formation of ozone (O 3 ), which is the major cause of photochemical smog 5, 6. NO 2 at a concentration higher than 1 ppm can also cause serious diseases to people's respiratory system 2, 6, 7. Furthermore, ammonia (NH 3 ) is a toxic and colorless gas with permissible exposure limit of 50 ppm over 8 h per working day or 40 h per working week 8.…”

2D SnS2—A Material for Impedance-Based Low Temperature NOx Sensing?

“…In this work a new material class based on 2D transition metal dichalcogenides (TMD) is discussed as sensing materials for NOx sensors [6,7]. Due to the special structure of SnS2, the charge transfer between physisorbed NO2 gas molecules and the 2D SnS2 material allows for NO2 sensing with high NO2 sensitivity and selectivity at low operating temperatures.…”

“…Due to the special structure of SnS2, the charge transfer between physisorbed NO2 gas molecules and the 2D SnS2 material allows for NO2 sensing with high NO2 sensitivity and selectivity at low operating temperatures. In [6], the NO2 sensor response of SnS2 is described at 120 °C. In the present work, tin disulfide (SnS2) flakes are investigated as functional materials for NOx sensing at 130 °C with focus on the NO sensing performance of SnS2.…”