Graphene Decorated with Silver Nanoparticles as a Low-Temperature Methane Gas Sensor

Abstract

This paper is devoted to an investigation on the methane sensing properties of graphene (G), decorated with silver nanoparticles (AgNPs), under ambient conditions. To do so, we first present an effective modification in the standard manner of decorating graphene by AgNPs. From structural analysis of the product (AgNPs/G), it is concluded that graphene is indeed decorated by AgNPs of a mean size 29.3 nm, free of aggregation, with a uniform distribution. The so-produced material is then used, as a resistivity-based sensor, to examine its response to the presence of methane gas. Our measurements are performed at relatively low temperatures, for various silver-to-graphene mass ratios (SGMRs) and methane concentrations. To account for the effects of humidity, we have made the measurements, at room temperature, for different levels of humidity. Our results demonstrate that an increase in the SGMR enhances the response of AgNPs/G to methane with an optimum value of SGMR ≅ 12%. It is also illustrated that for methane concentrations less than 2000 ppm, the maximal response increases linearly and rapidly, even at room temperature. Moreover, we demonstrate that AgNPs/G is of low limit of detection, highly stable, selective, reversible, repeatable, and sensor-to-sensor reproducible, for methane sensing. The results thus promise a low-cost and simple-to-fabricate methane sensing device.

A Langasite Crystal Microbalance Coated with Graphene Oxide-Platinum Nanocomposite as a Volatile Organic Compound Sensor: Detection and Discrimination Characteristics

“…The D + D' band is a combination mode that is also sensitive to the disorder in the crystal lattice [23]. The broadened 2D and D + D' bands with relatively low intensities imply irregular stacking of multilayer graphene nanosheets and presence of intentional defects in the sample [12,23,24]. The VOC concentration (V ratio ) for V carrier values of 15, 30 and 60 sccm correspond to 2.73%, 5.45%, and 10.91%, respectively.…”

“…This causes the formation of ionized oxygen and depletion of electrons (accumulation of holes) in the graphene layer leading to the p-type behaviour of GO. The decoration of GO with Pt nanostructures is to further enhance the p-type characteristic and catalyze the oxidation of adsorbed VOC molecules [12]. The work function of Pt is higher than that of graphene [17].…”

“…However, graphene in its pristine state has inferior molecular sensing performance due to its relatively inert surface [11]. Decoration of pristine graphene with noble metal nanoparticles, organic functional groups, and heteroatoms has been shown to improve the sensing performance of graphene-based VOC sensors [12,13]. Graphene oxide (GO), graphene with attached organic functional groups, presents an enormous prospect for enhanced VOC sensing performance owing to its tunable semiconductive character in contrast to the intrinsic conductive nature of pristine graphene [14,15].…”

“…Graphene oxide (GO), graphene with attached organic functional groups, presents an enormous prospect for enhanced VOC sensing performance owing to its tunable semiconductive character in contrast to the intrinsic conductive nature of pristine graphene [14,15]. Deposition of precious metal nanoparticles including silver, gold, and platinum on GO surface has been reported to promote RT molecular sensing by catalyzing the interactions between the adsorption sites and the target molecules [12,16,17]. Thus, GO in combination with noble metal nanoparticles offers an excellent sensing material for molecular detection.…”

“…It is essential to note that most of the graphene-based gas sensors reported in the literature have utilized sensor architectures in the form of a transistor or chemiresistor [8,12,16,17]. Gas sensors based on graphene in combination with a piezoelectric microbalance, are however, scarcely reported.…”