Humidity-Insensitive NO2 Sensors Based on SnO2/rGO Composites

Abstract

This study reported a novel humidity-insensitive nitrogen dioxide (NO2) gas sensor based on tin dioxide (SnO2)/reduced graphene oxide (rGO) composites through the sol-gel method. The sensor demonstrated ppb-level NO2 detection in p-type sensing behaviors (13.6% response to 750 ppb). Because of the synergistic effect on SnO2/rGO p-n heterojunction, the sensing performance was greatly enhanced compared to that of bare rGO. The limit of detection of sensors was as low as 6.7 ppb under dry air. Moreover, benefited from the formed superhydrophobic structure of the SnO2/rGO composites (contact angle: 149.0°), the humidity showed a negligible influence on the dynamic response (Sg) of the sensor to different concentration of NO2 when increasing the relative humidity (RH) from 0 to 70% at 116°C. The relative conductivity of the sensor to 83% relative humidity was 0.11%. In addition, the response ratio (Sg/SRH) between 750 ppb NO2 and 83% RH was 649.0, indicating the negligible impaction of high-level ambient humidity on the sensor. The as-fabricated humidity-insensitive gas sensor can promise NO2 detection in real-world applications such as safety alarm, chemical engineering, and so on.

Sub PPM Detection of NO2 Using Strontium Doped Bismuth Ferrite Nanostructures

“…The surface-adsorbed atomic oxygen species reacts with the high-affinity NO 2 gas which reduces the electron concentration near the surface, giving rise to recombination with the holes, resulting in the resistance to increase. A plausible reason could be that NO 2 gas diffuses onto the surface of the BSFO crystal grains, and oxygen ions react with NO 2 in the following reversible process (4), (5), (6), and (7), forming a depletion region [ 48 , 49 ]. …”

SnO2 Nanoparticle-Reduced Graphene Oxide Hybrids for Highly Selective and Sensitive NO2 Sensors Fabricated Using a Component Combinatorial Approach

“…The LOD is a crucial parameter for practical use as even short-term exposure to a few hundred ppb concentration of NO 2 is detrimental to human health. 38 The SnO 2 −rGO device exhibits a low response time (5.6 s) and recovery time (14.1 s) in the presence of 80 ppm of NO 2 gas, which is appreciable for a room-temperature NO 2 sensor (Figure 5c). The device exhibits a repeatable response for 80 ppm NO 2 gas with an RSD of 10.6% (Figure 5d).…”

“…The plot of logarithmic increase in NO 2 gas concentration for response ( I g – I a / I a ) resulted in a linear slope ( R 2 = 0.97), and the limit of detection (LOD) was calculated to be 209 ppb. The LOD is a crucial parameter for practical use as even short-term exposure to a few hundred ppb concentration of NO 2 is detrimental to human health . The SnO 2 –rGO device exhibits a low response time (5.6 s) and recovery time (14.1 s) in the presence of 80 ppm of NO 2 gas, which is appreciable for a room-temperature NO 2 sensor (Figure c).…”

Phenylalanine Dipeptide-Regulated Ag/In2O3 Nanocomposites for Enhanced NO2 Gas Sensing at Room Temperature with UV Illumination

“…Here, the response and recovery time are defined as the time spent by a sensor to reach 90% of the total resistance change in the adsorption/desorption stage, respectively. We obtained the minimum detection limit of 53 ppb by theoretical calculation. − The specific calculation process can be found in Section S3. Figure e reveals good repeatability for the sensors exposed to 20 ppm NO 2 four times.…”