C₆₀Br₂₄/SWCNT: A Highly Sensitive Medium to Detect H₂S via Inhomogeneous Carrier Doping

Abstract

H 2 S is a toxic and corrosive gas, whose accurate detection at sub-ppm concentrations is of high practical importance in environmental, industrial, and health safety applications. Herein, we propose a chemiresistive sensor device that applies a composite of single-walled carbon nanotubes (SWCNTs) and brominated fullerene (C 60 Br 24 ) as a sensing component, which is capable of detecting 50 ppb H 2 S even at room temperature with an excellent response of 1.75% in a selective manner. In contrast, a poor gas response of pristine C 60 -based composites was found in control measurements. The experimental results are complemented by density functional theory calculations showing that C 60 Br 24 in contact with SWCNTs induces localized hole doping in the nanotubes, which is increased further when H 2 S adsorbs on C 60 Br 24 but decreases in the regions, where direct adsorption of H 2 S on the nanotubes takes place due to electron doping from the analyte. Accordingly, the heterogeneous chemical environment in the composite results in spatial fluctuations of hole density upon gas adsorption, hence influencing carrier transport and thus giving rise to chemiresistive sensing.

An ultra-sensitive NH3 gas sensor enabled by an ion-in-conjugated polycroconaine/Ti3C2Tx core–shell composite

“…Such behavior may be explained via the Langmuir adsorption model similar to those observed for other sensors. 39,40 Accordingly, the calculated highest sensitivity appears at the lowest applied analyte concentration (i.e. at 500 ppb NH 3 ) having a value of 2.8%/ppm, which is significantly better than those published for pristine Ti 3 C 2 T x (inset of Fig.…”

Wearable Nano-Based Gas Sensors for Environmental Monitoring and Encountered Challenges in Optimization

“…In the case of chemiresistive gas sensing, providing a chemically heterogeneous nanocomposite can affect the hole density of the fullerenes and, consequently, increase the gas adsorption. In another study, a chemiresistive sensing composite of brominated fullerene and single-walled carbon nanotubes (C 60 Br 24 /SWCNT) was proposed [34]. While SWCNTs bring about a conductive composite, Br atoms make it capable of bonding with H atoms of gas molecules through medium-strength halogen bonds.…”

“…Based on results and DFT calculations, the best sensing performance was demonstrated by halogenated C 60 composites mixed with SWCNT (10 wt%) compared to pristine fullerene composites (Figure 1). At RT, a trace amount (50 ppb) of H 2 S was selectively detected in the presence of CO or NO with a superb response of 1.75% [34].…”

“…As it is the first and most sensitive unfunctionalized carbon-nanomaterialbased gas sensor operating at RT, it can offer valuable knowledge for constructing the next generation of CNT-based gas sensors [37]. Images reused from [34], with no changes. CC-BY 4.0 licence (https://creativecommons.org/licenses/by/4.0/, accessed on 8 October 2023).…”

Identification of Material Dimensionality Based on Force Constant Analysis

“…Materials that are easily cleaved in one or more dimensions, such as graphite and other layered materials, have been studied for centuries, , but identification and synthesis of the constituent atomic-scale units started with zero-dimensional (0D) Buckminsterfullerene (C 60 ) in the 1980s, one-dimensional (1D) carbon nanotubes (CNT) in the 1990s, and two-dimensional (2D) graphene in 2004 and have since attracted a great deal of attention. After the potential of these systems was realized, the amount of research dedicated to finding new low- and mixed-dimensional materials with unique electronic, − optical, − magnetic, − and topological − properties has remarkably increased. In this context, the “dimensionality” of the material means that the atomic structure consists of units (sheets, clusters, and/or chains) with strong bonds within the unit but weak interactions between the units.…”