High-Performance UV-Assisted NO₂ Sensor Based on Chemical Vapor Deposition Graphene at Room Temperature

Abstract

Nitrogen dioxide (NO 2 ) is one of the most dangerous air pollutants that can affect human health even at the ppb (part per billion) level. Thus, the superior sensing performance of nitrogen dioxide gas sensors is an imperative for real-time environmental monitoring. Traditional solid-state sensors based on metal-oxide transistors have the drawbacks of high power consumption, high operating temperature, poor selectivity, and difficult integration with other electronics. In that respect, graphene-based gas sensors have been extensively studied as potential replacements. However, their advantages of high sensing efficiency, low power consumption, and simple electronic integration have been countered by their slow response and poor repeatability. Here, we report the fabrication of high-performance ultraviolet (UV)-assisted room temperature NO 2 sensors based on chemical vapor deposition-grown graphene. UV irradiation improves the response of the sensor sevenfold with respect to the dark condition attaining 26% change in resistance at 100 ppm NO 2 concentration with a practical detection limit below 1 ppm (42.18 ppb). In addition, the recovery time was shortened fivefold to a few minutes and the excellent repeatability. This work may provide a promising and practical method to mass produce room-temperature NO 2 gas sensors for real-time environment monitoring due to its simple fabrication process, low cost, and practicality.

Defect-Induced Gas-Sensing Properties of a Flexible SnS Sensor under UV Illumination at Room Temperature

“…Therefore, it can be further improved to integrate into portable and wearable devices. For comparison, the NO 2 sensing performances of some reported flexible sensors are summarized in Table 4 [ 39 , 40 , 41 , 42 , 43 , 44 ]. The SnS thin-film sensor reveals relatively short response/recovery times compared to others.…”

Room-Temperature Gas Sensors Under Photoactivation: From Metal Oxides to 2D Materials

“…Ma and co-workers studied the effects of thermal and optical energy on gas sensing characteristics of graphene via fabricating graphene sensor array (Fig. 9 a) [ 87 ]. They observed that transferred CVD grown graphene-based gas sensor exhibited deterioration in sensitivity to NO 2 gas with increased temperature (25–100 °C).…”

“…10a), which helped to enhance the sensitivity of graphene sensor with a detection limit of 0.5 ppb NO 2 at RT under laser illumination. Figure 10b, c clearly illustrates the concave region at PS bead/ graphene interface and upon NO 2 exposure, two static forces, one from the bead and another from graphene drag more number of gas molecules which results in enhanced gas [87]. Copyright 2019, American Chemical Society response in PS decorated graphene than that of the pristine graphene sensor.…”

Vertically aligned carbon nanotubes, MoS2–rGo based optoelectronic hybrids for NO2 gas sensing

“…Atomic thickness and high surface-to-volume ratio of two-dimensional (2d) materials make them good candidates for gas sensing applications because their electronic transport properties are highly dependent on the surrounding atmosphere [4][5][6] . Despite the introduction of many new 2d materials, graphene as the first material discovered, is still used in many ongoing sensing studies thanks to its high electrical conductivity, large detection surface area, and high sensitivity potentials 7,8 . However, the desorption of the adsorbed molecules onto the surface of the graphene in the sensor channel does not occur easily resulting in a loss of sensitivity, poor response, and incomplete recovery of the sensor at room temperature 9 .…”

“…Although, increasing the operating temperature up to 200 °C is associated with an improvement of the sensor performance, higher energy consumption and safety concerns limit their practical usages 7 . As an alternative suggestion, the required energy can be provided by light irradiation 8,9 . In fact, in situ exposure to light during gas detection process results in the photo-generated carriers within the channel of the optical-sensitive device.…”