Abstract
Two-dimensional (2D) nanomaterials have attracted a large amount of attention regarding gas sensing applications, because of their high surface-to-volume ratio and unique chemical or physical gas adsorption capabilities. As an important research method, theoretical calculations have been massively applied in predicting the potentially excellent gas sensing properties of these 2D nanomaterials. In this review, we discuss the contributions of theoretical calculations in the study of the gas sensing properties of 2D nanomaterials. Firstly, we elaborate on the gas sensing mechanisms of 2D layered nanomaterials, such as the traditional charge transfer mechanism, and a standard for distinguishing between physical and chemical adsorption, from the perspective of theoretical calculations. Then, we describe how to conduct a theoretical analysis to explain or predict the gas sensing properties of 2D nanomaterials. Thirdly, we discuss three important methods that have been applied in order to improve the gas sensing properties, that is, defect functionalization (vacancy, edge, grain boundary, and doping), heterojunctions, and electric fields. Among these strategies, theoretical calculations play a very important role in explaining the mechanisms underlying the enhanced gas sensing properties. Finally, we summarize both the advantages and limitations of the theoretical calculations, and present perspectives for further research on the 2D nanomaterials-based gas sensors.
Highlights
Gas sensors are devices used for detecting the composition and concentration of gases, which are applied in many fields, including in resident life, industry, military, and medical treatment [1,2]
Various materials have been investigated for gas sensing, including semiconducting metal oxides [3,4,5], conducting polymers [6], carbon nanotubes (CNTs) [7,8,9], and so on [10]
There have been some attempts looking at the possibility of using metal oxides at room temperature or nearly room temperature, or using light activation instead of heating [13]
Summary
Gas sensors are devices used for detecting the composition and concentration of gases, which are applied in many fields, including in resident life, industry, military, and medical treatment [1,2]. Various materials have been investigated for gas sensing, including semiconducting metal oxides [3,4,5], conducting polymers [6], carbon nanotubes (CNTs) [7,8,9], and so on [10]. Among these sensing materials, metal oxides have been extensively investigated in the past few decades, because of their high sensitivity and low cost [11]. Theoretical studies of the interactions between gas molecules and 2D sensing materials provided both a theoretical basis, as well as design ideas for developing novel gas-sensing materials with an enhanced gas-sensing performance
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