Improving Electrochemical Pb²⁺ Detection Using a Vertically Aligned 2D MoS₂ Nanofilm

Abstract

Recent advancements in MoS 2 nanofilms have aided in the development for important water-related environmental applications. However, a MoS 2 nanofilm-coated sensor has yet to have been applied for heavy metal detection in water-related environmental samples. In this study, a novel vertically aligned two-dimensional (2D) MoS 2 (edge exposed) nanofilm was applied for in situ lead ion (Pb 2+ ) detection. The developed sensor showed an excellent linear relationship toward Pb 2+ between 0 and 20 ppb at −0.45 V vs Ag/AgCl using square wave anodic stripping voltammetry (SWASV) with the improved limit of detection (LOD) of 0.3 ppb in a tap water environment. The vertically aligned 2D MoS 2 sensor exhibited improved detection sensitivity (2.8 folds greater than a previous metallic [Bi] composite electrode) with lower relative standard deviation for repetitive measurements (n = 11), indicating enhanced reproducibility for Pb 2+ detection. The vertically aligned 2D MoS 2 layers exhibited 2.6 times higher sensitivity than horizontally aligned 2D MoS 2 (basal plane exposed). Density functional theory calculations demonstrated that adsorption energy of Pb on the MoS 2 side edge was much higher (4.11 eV) than those on the basal plane (0.36 and 0.07 eV). In addition, the band gap center of vertical MoS 2 was found to be higher than the Pb 2+ → Pb reduction potential level and capable of reducing Pb 2+ . Overall, the newly developed vertically aligned 2D MoS 2 sensor showed excellent performance for detecting Pb 2+ in a real drinking water environment with good reliability.

Magnetic Enhancement for Hydrogen Evolution Reaction on Ferromagnetic MoS2 Catalyst

“…As shown in Figure c, compared with the reference bilayer structure, for the bowl-like MoS 2 structure, the total potential of the top ring layers lifts up and the potential barrier along the layer-normal direction in bowl-like MoS 2 has reduced. The calculated results of the total electrostatic potential are in good agreement with the other theoretical calculations. , As shown in Figure d, electrons in the ferromagnetic bowl-like MoS 2 could be more sensitive to the external magnetic field and obtain extra energy MH compared to those in nonmagnetic bilayer MoS 2 under external vertical magnetic field H . The electrons in the bowl-like MoS 2 structure are easier to transport due to possessing a higher energy than those in bilayer MoS 2 .…”

Automated Assembly of Wafer-Scale 2D TMD Heterostructures of Arbitrary Layer Orientation and Stacking Sequence Using Water Dissoluble Salt Substrates

“…This challenge has been the major limiting factor in terms of fully exploring technological opportunities of VA 2D-TMD layers beyond their growth substrate-bound forms. In general, VA 2D-TMD layers exhibit unparalleled chemical reactivity and physisorption properties owing to their surface-exposed rich dangling bonds, suggesting great implications for high-performance electrochemical and/or molecular sensing applications. , Such unprecedented opportunities can be realized even in flexible and/or stretchable forms as far as they are deterministically and stably integrated on mechanically reconfigurable yet functional substrates retaining their original structural integrity. Figure c illustrates schematics of our manufacturing strategy, which overcomes this limitation and can be generalized to 2D TMD layers of any layer orientation.…”

Novel Three‐dimensional Sensor for Rapid Detection of Pb(II) and Cd(II) in Edible Mushrooms

“…Besides, MoS 2 showed excellent adsorption performance for HMIs owing to the high binding affinity between divalent ions and its sulfur sites. Also, MoS 2 (molybdenum disulfide) was applied as an available adsorbing material and promoted the reduction of some ions into elements [15]. Gan [16] et al reported electrochemical sensor for Cd(II) detection based on MoS 2 nanosheets synthesized by liquid-phase exfoliation, the prepared sensor acquired high sensitivity and selectivity for Cd(II) detection.…”

“…Besides, MoS 2 showed excellent adsorption performance for HMIs owing to the high binding affinity between divalent ions and its sulfur sites. Also, MoS 2 (molybdenum disulfide) was applied as an available adsorbing material and promoted the reduction of some ions into elements [15]. Gan [16] et al.…”