Selective Electronic NO₂ Sensors Using a Polydimethylsiloxane Filter on WSe₂ Devices

Abstract

Atomically thin two-dimensional (2D) materials are ideal gas sensing materials with ultrahigh sensitivity due to the high surface-to-volume ratio, low electronic noise, and tunable Fermi level alignment. However, obtaining selectivity to a target analyte in the presence of other confounding gases in the environment remains an issue preventing selective gas sensing using 2D materials. In the present work, we fabricate a selective nitrogen dioxide (NO2) sensor using WSe2 by adding a simple oil layer as a filter. For this proof of concept study, we used polydimethylsiloxane (PDMS) due to its dipole moment being similar to NO2 (∼0.3 D). This PDMS layer helps selectively detect NO2 and filter out both more polar gases, such as ammonia (NH3) and hydrogen sulfide (H2S), as well as nonpolar gases, such as carbon monoxide (CO), that are likely to be present in the background environment. Not only did we obtain a selective response for single components but also we observed an improved sensing response (around 200%) when NO2 is mixed with other gases compared to the intrinsic WSe2 device without modification. The obtained results were found to be reproducible and reversible. The charge transfer effect of different gases to WSe2 devices was characterized by an atomic force microscope (AFM) through phase imaging techniques.

Highly efficient metalloporphyrin-based nanosensors for NO detection

“…Remarkably, the average K for NO, K [NO], reaches 15 and 25 compared to CO and CO 2 for the Au–CrPor–Au junction. The obtained K for our considered molecular sensor is comparable to 2D NbS 2 nanosheets, 53 WSe 2 coated by PDMS, 54 and CNFs/CoS 2 /MoS 2 55 composites. The CrPor sensor gives sensitivity at dilute concentration and remains approximately unchanged upon voltage changes.…”

Room-Temperature NO2 Detection by MoS2–Nanoflake-Decorated AuPt/SnO2 Nanotubes

“…The polarity of the gas molecules also plays a role in adsorption. The relatively small dipole moment (μ) is conducive to the physisorption of gas molecules on the chalcogenide surface, which could explain the higher response of the MAPS device toward NO 2 gas (μ = 0.29 D) compared with NH 3 (μ = 1.47 D), CO (μ = 0.11 D), C 2 H 6 O (μ = 1.69 D), C 3 H 8 O (μ = 1.66 D), and C 3 H 6 O (μ = 2.88 D) gases. − Similarly, the response to NH 3 or CO gas was also higher than that to C 2 H 6 O, IPA, and C 3 H 6 O gases. NO 2 molecules have both smaller dipole moments and dynamic diameters than the other gas molecules, and these characteristics are suitable for NO 2 penetrating nanopores of porous composites and being adsorbed.…”