Recent Development of Gas Sensing Platforms Based on 2D Atomic Crystals

Abstract

Sensors, capable of detecting trace amounts of gas molecules or volatile organic compounds (VOCs), are in great demand for environmental monitoring, food safety, health diagnostics, and national defense. In the era of the Internet of Things (IoT) and big data, the requirements on gas sensors, in addition to sensitivity and selectivity, have been increasingly placed on sensor simplicity, room temperature operation, ease for integration, and flexibility. The key to meet these requirements is the development of high-performance gas sensing materials. Two-dimensional (2D) atomic crystals, emerged after graphene, have demonstrated a number of attractive properties that are beneficial to gas sensing, such as the versatile and tunable electronic/optoelectronic properties of metal chalcogenides (MCs), the rich surface chemistry and good conductivity of MXenes, and the anisotropic structural and electronic properties of black phosphorus (BP). While most gas sensors based on 2D atomic crystals have been incorporated in the setup of a chemiresistor, field-effect transistor (FET), quartz crystal microbalance (QCM), or optical fiber, their working principles that involve gas adsorption, charge transfer, surface reaction, mass loading, and/or change of the refractive index vary from material to material. Understanding the gas-solid interaction and the subsequent signal transduction pathways is essential not only for improving the performance of existing sensing materials but also for searching new and advanced ones. In this review, we aim to provide an overview of the recent development of gas sensors based on various 2D atomic crystals from both the experimental and theoretical investigations. We will particularly focus on the sensing mechanisms and working principles of the related sensors, as well as approaches to enhance their sensing performances. Finally, we summarize the whole article and provide future perspectives for the development of gas sensors with 2D materials.

Detection of Carbon, Sulfur, and Nitrogen Dioxide Pollutants with a 2D Ca12O12 Nanostructured Material

“…Overall, the studied surfaces adsorbed NO 2 preferentially when compared to other counterparts. 14 NO 2 , SO 2 , and CO 2 are important ambient air pollutants and are highly intense in confined spaces, causing global challenges, which contribute to global warming, and they are toxic pollutant gases with pungent smell. Exposure to them might likely cause severe injury and perhaps result in death, depending on the degree of exposure.…”

“…Only minimal changes in adsorption characteristics were observed for the different studied gases regardless of significant changes in the electronic structure and properties orchestrated by band gap variations. Overall, the studied surfaces adsorbed NO 2 preferentially when compared to other counterparts …”

Realization of Oriented and Nanoporous Bismuth Chalcogenide Layers via Topochemical Heteroepitaxy for Flexible Gas Sensors

“…Note that the edges of Bi 2 Se 3 layers, i.e., the (110) and (100) facets are particularly more effective in NO 2 adsorption and charge transfer compared to those on the (001) basal plane (Figure 5(b)). Indeed, the nanoporous The improved sensing ability can also be attributed, in part, to the formation of a p-n junction at the epitaxial interface between BiOCl and Bi 2 Se 3 (Figure S14), where the interdiffusion of electrons and holes across the interface created a charge depletion region along with a built-in potential barrier [61][62][63][64]. The height of the energy barrier was mainly determined by the hole concentration in BiOCl because of the much wider bandgap of BiOCl than that of Bi 2 Se 3 [65,66].…”

Selectivity in trace gas sensing: recent developments, challenges, and future perspectives

“…Recent experimental and theoretical demonstrations show that high sensitivity and high-quality factor can be achieved by using different PhC sensor configurations/sensors 209,210 e.g. , PhC waveguide, 211,212 PhC nanoresonator, 213,214 PhC cavity, 215,216 polymeric PhC, 217 1-D PhC, 218,219 2-D PhC, 83,220 3-D PhC, 221 plasmonic PhC, 222 MEMS PhC, 223 porous PhC, 224 and PhC fiber. 164,225,226…”

“…, sensing performance) of existing MOS materials so that it is possible to selectively resolute every constituent gas. Several researchers have discussed in recent review 4,10,26–28,114,220 about the possible strategies to improve the sensing performance of MOS-based gas sensors – (i) Exposer of high-energy crystal facets : High energy crystal facets of MOS materials have higher surface energy and more defect sites (leads to more active physicochemical properties) as evident by experiments and first-principles calculations. 241–243 It is beneficial for gas sensing owing to two factors – gas adsorption and electron transport.…”