MoS₂ Defect Healing for High-Performance Chemical Sensing of Polycyclic Aromatic Hydrocarbons

Abstract

The increasing population and industrial development are responsible for environmental pollution. Among toxic chemicals, polycyclic aromatic hydrocarbons (PAHs) are highly carcinogenic contaminants resulting from the incomplete combustion of organic materials. Twodimensional materials, such as transition metal dichalcogenides (TMDCs), are ideal sensory scaffolds, combining high surface-to-volume ratio with physical and chemical properties that are strongly susceptible to environmental changes. TMDCs can be integrated in field-effect transistors (FETs), which can operate as high-performance chemical detectors of (non)covalent interaction with small molecules. Here, we have developed MoS 2 -based FETs as platforms for PAHs sensing, relying on the affinity of the planar polyaromatic molecules for the basal plane of MoS 2 and the structural defects in its lattice. X-ray photoelectron spectroscopy analysis, photoluminescence measurements, and transfer characteristics showed a notable reduction in the defectiveness of MoS 2 and a p-type doping upon exposure to PAHs solutions, with a magnitude determined by the correlation between the ionization energies (E I ) of the PAH and that of MoS 2 . Naphthalene, endowed with the higher E I among the studied PAHs, exhibited the highest output. We observed a log−log correlation between MoS 2 doping and naphthalene concentration in water in a wide range (10 −9 −10 −6 M), as well as a reversible response to the analyte. Naphthalene concentrations as low as 0.128 ppb were detected, being below the limits imposed by health regulations for drinking water. Furthermore, our MoS 2 devices can reversibly detect vapors of naphthalene with both an electrical and optical readout, confirming that our architecture could operate as a dual sensing platform.

Two-Dimensional Tunneling Memtransistor with Thin-Film Heterostructure for Low-Power Logic-in-Memory Complementary Metal-Oxide Semiconductor

“…We performed high-resolution X-ray photoelectron spectroscopy (XPS) to investigate the quality of the exfoliated WSe 2 nanoflakes. The overall defect was explored by fitting the peak in Figure g to the Se 2p XPS spectra. − WSe 2 nanoflakes had a higher defect density of ∼9.42%, which can influence the electronic properties of WSe 2 , resulting in the memtransistor characteristics. Specifically, depending on their type, defects can form holes or electron traps by introducing occupied or empty electronic states, respectively, within the band gap (Figure h). ,, Previous studies revealed that V Se and V 2Se can cause electron traps below the CBM, whereas V W and W ad can generate hole traps above the VBM.…”

High Selectivity and Sensitivity in Chemiresistive Sensing of Co(II) Ions with Liquid‐Phase Exfoliated Functionalized MoS2: A Supramolecular Approach

“…The high-resolution spectra of the S2p peak for the pristine and complex-functionalized film (Figure 1e,f) feature two main sulfur peaks at ≈162.3 and ≈163.5 eV, which are ascribed to the S2p 3/2 and S2p 1/2 components, respectively, and a broad component at ≈161.2 eV that emerges from the defects of crystal structure. [24,25,32] The decrease of the relative area of the defect peak from 8.7% in the pristine film to 6.7% in complex-treated one bears witness to the efficient defect healing and thus chemical functionalization of MoS 2 nanosheets. Additionally, XPS provided evidence for the complete Zn(II) ion removal upon HCl treatment (Figures S5 and S6, Supporting Information).…”

“…Conversely, less attention has been paid to 2D transition metal dichalcogenides (TMDs) for multireadout sensing of a wide library of analytes. [ 24 ] In its pristine form, molybdenum disulfide (MoS 2 ) has been employed for the sensing of heavy metals, such as mercury (II) cations, [ 24 ] and polycyclic aromatic hydrocarbons, [ 25 ] in devices with electrical readout. Indeed, the semiconducting nature of MoS 2 makes it susceptible to subtle electronic variations during the sensing process, resulting from doping effect induced by the interaction with analytes.…”

2D Materials in Flexible Electronics: Recent Advances and Future Prospectives

“…In addition, defect sites in grown films could be healed by treating the 2D materials surface with specific chemical molecules having high chemical affinity to the exposed atoms at the defect sites, thus mitigating the defect’s impact. Organic or inorganic species containing chalcogens (e.g., sulfur, selenium, tellurium) or halogens (e.g., fluorine, chlorine, bromine, iodine) could potentially be used for passivating defects in TMDs. − For example, bis­(trifluoromethane)­sulfonimide (TFSI) passivation has been demonstrated to significantly improve the photoluminescence quantum yield (PLQY) by suppressing the effect of defects in MOCVD-grown MoS 2 film (Figure d) …”