Frontiers of graphene and 2D material-based gas sensors for environmental monitoring

Abstract

The World Health Organization reported that 4.2 million deaths every year were a direct result of exposure to ambient air pollution (NO 2 , SO 2 , NH 3 , CO 2 , CO, CH 4 ). There is a well-demonstrated global need for high sensitivity, low cost and low energy consumption miniaturised gas sensors to be deployed in a dense network and to be used in an attempt to pinpoint and avoid high pollution hot spots. The high sensitivity of graphene to the local environment has shown to be highly advantageous in sensing applications, where ultralow concentrations of adsorbed molecules induce a significant response on the electronic properties of graphene. This is commonly attributed to the π electrons of graphene, being directly exposed to the surrounding environment. The unique electronic structure makes graphene the 'ultimate' sensing material for applications in environmental monitoring and air quality. In this review, we present the frontiers of graphene-based sensors considering both electrical and optical methods of detection and discuss the topical progress in an attempt to establish whether graphene can be considered as the ideal sensing material. We pay special attention to the optimization of the sensor performance, using various graphene hybrids and doping mechanisms. Furthermore, we present the recent developments in other 2D material-based sensors that have followed in the wake of graphene. We discuss the benchmarked parameters of graphene sensors, such as sensitivity, selectivity, response/recovery time and detection limit, and compare them with other 2D materials as well as existing state-of-the-art sensors currently being used in the field. We also perform a brief market analyses for the environmental sensing industry as well as provide a Strengths-Weaknesses-Opportunities-Threats analysis of graphene technology for environmental sensing.

Nanoelectromechanical Sensors Based on Suspended 2D Materials

“…2D material gas sensors can be used for environmental monitoring [ 12 ]. These are generally based on the adsorption of analytes such as NH 3 , CO 2 , H 2 O, and NO 2 on the sensor surface [ 1 , 150 , 226 – 228 ].…”

“…An overview of graphene-based nanoelectromechanical resonators was provided in a 2013 review paper [ 9 ], and the utilization of graphene and carbon nanotubes in NEMS was briefly summarized by Zang et al [ 10 ]. However, it has recently become clear that graphene has potential for enabling a much wider range of NEMS sensors, with transition metal dichalcogenide (TMD) and 2D semiconductor materials also emerging in this application space [ 6 , 11 , 12 ].…”

Graphene on SiC Substrate as Biosensor: Theoretical Background, Preparation, and Characterization

“…After appearing in a previous paper [ 1 ], where it was shown that using graphene as a substrate makes it possible to detect a single gas molecule, a great interest in the performance of graphene-based gas sensors [ 2 , 3 , 4 ] and biosensors [ 4 , 5 , 6 , 7 , 8 , 9 ] arose. To fulfill this program, corresponding adsorption theory is needed (see, for example, [ 10 , 11 , 12 , 13 ] and references on the earlier papers therein).…”

Functionalized epitaxial graphene as versatile platform for air quality sensors

“…Moreover, the detection of NO2 at these very low concentrations is of interest as a marker for the production of ultra-fine particles [138]. Buckley et al give a comprehensive overview about the sensor performances of graphene based chemiresistors and, depending on the functionalization, LODs ranging from single ppt up to tens of ppm are observed for NO2 [139].…”