Few-layer Molybdenum Disulfide Research Articles

Enhanced Raman Scattering in CVD-Grown MoS2/Ag Nanoparticle Hybrids.

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful, non-destructive technique for enhancing molecular spectra, first discovered in 1974. This study investigates the enhancement of Raman signals from single- and few-layer molybdenum disulfide (MoS2) when interacting with silver nanoparticles. We synthesized a MoS2 membrane primarily consisting of monolayers and bilayers through a wet chemical vapor deposition method using metal salts. The silver nanoparticles were either directly grown on the MoS2 membrane or placed beneath it. Raman measurements revealed a significant increase in signal intensity from the MoS2 membrane on the silver nanoparticles, attributed to localized surface plasmon resonances that facilitate SERS. Our results indicate that dichalcogenide/plasmonic systems have promising applications in the semiconductor industry.

Room-Temperature Geometrical Circular Photocurrent in Few-Layer MoS2.

Valleytronics, i.e., the manipulation of the valley degree of freedom, offers a promising path for energy-efficient electronics. One of the key milestones in this field is the room-temperature manipulation of the valley information in thick-layered material. Using scanning photocurrent microscopy, we achieve this milestone by observing a geometrically dependent circular photocurrent in a few-layer molybdenum disulfide (MoS2) under normal incidence. Such an observation shows that the system symmetry is lower than that of bulk MoS2 material, preserving the optical chirality-valley correspondence. Moreover, the circular photocurrent polarity can be reversed by applying electrical bias. We propose a model where the observed photocurrent results from the symmetry breaking and the built-in field at the electrode-sample interface. Our results show that the valley information is still retained even in thick-layered MoS2 at room temperature and opens up new opportunities for exploiting the valley index through interface engineering in multilayer valleytronics devices.

A Dual-Channel MoS2-Based Selective Gas Sensor for Volatile Organic Compounds.

Significant progress has been made in two-dimensional material-based sensing devices over the past decade. Organic vapor sensors, particularly those using graphene and transition metal dichalcogenides as key components, have demonstrated excellent sensitivity. These sensors are highly active because all the atoms in the ultra-thin layers are exposed to volatile compounds. However, their selectivity needs improvement. We propose a novel gas-sensing device that addresses this challenge. It consists of two side-by-side sensors fabricated from the same active material, few-layer molybdenum disulfide (MoS₂), for detecting volatile organic compounds like alcohol, acetone, and toluene. To create a dual-channel sensor, we introduce a simple step into the conventional 2D material sensor fabrication process. This step involves treating one-half of the few-layer MoS₂ using ultraviolet-ozone (UV-O3) treatment. The responses of pristine few-layer MoS₂ sensors to 3000 ppm of ethanol, acetone, and toluene gases are 18%, 3.5%, and 49%, respectively. The UV-O3-treated few-layer MoS₂-based sensors show responses of 13.4%, 3.1%, and 6.7%, respectively. This dual-channel sensing device demonstrates a 7-fold improvement in selectivity for toluene gas against ethanol and acetone. Our work sheds light on understanding surface processes and interaction mechanisms at the interface between transition metal dichalcogenides and volatile organic compounds, leading to enhanced sensitivity and selectivity.

Constructing a hierarchical MoS2/MXene heterostructure for efficient capacitive deionization of saline water

Well-dispersed and few-layered molybdenum disulfide (MoS2) has been considered as a suitable electrode material for pseudocapacitive capacitive deionization (CDI) due to its lamellar structure, flexible interlayer intercalation, and high theoretical capacity. However, the serious aggregation, low electrical conductivity and poor hydrophilicity of MoS2 have limited its desalination application. To address these issues, few-layered MXene is used as a conductive and hydrophilic skeleton to support MoS2 nanosheets. In this study, a hierarchical MoS2/MXene heterostructure is fabricated for highly efficient CDI of saline water. The designed heterostructure effectively inhibits the agglomeration of MoS2 and MXene nanosheets, exposes more active electrochemical sites, and improves the wettability, thereby enhancing ion/charge transport. The MoS2/MXene heterostructure electrode exhibits low electrical resistance (3.2 Ω), along with a high specific capacitance of 171.8 F·g-1 at 2 A·g-1. Furthermore, the MoS2/MXene-based CDI electrode demonstrates an excellent desalination capacity of 55.8 mg·g-1 and a fast desalination rate of 13 mg·g-1·min-1. This study paves the way for novel applications in the CDI field.

Wafer-Scale epitaxial molybdenum disulfide ultrathin film on sapphire prepared by low-energy reactive magnetron sputtering

Molybdenum disulfide, a two-dimensional semiconductor, has found broad applications in various functional devices. Currently, developing a reliable method for growing wafer-scale monolayer molybdenum disulfide presents a significant challenge in its integration into the contemporary semiconductor industry. This study employed low-energy reactive magnetron sputtering with hydrogen disulfide gas to deposit wafer-scale epitaxial few-layer and monolayer molybdenum disulfide on c-sapphire substrates. The epitaxial molybdenum disulfide nano-thin film was examined using scanning nano-probe X-ray diffraction technique, revealing a single grain size of no less than 50 × 50 μm2. Furthermore, the growth of monolayer molybdenum disulfide on both c-sapphire and thermal silicon oxide substrates was verified through Raman microscope. Measurements of photoluminescence and X-ray photoelectron spectroscopy also confirmed the monolayer state of the sputtered nano-thin films. This study suggests that reactive magnetron sputtering with hydrogen disulfide gas offers a cost-effective, scalable method for growing large-area molybdenum disulfide nano-thin films, thereby holding significant potential for practical semiconductor industrial applications.

Hydrogen evolution mediated by sulfur vacancies and substitutional Mn in few-layered molybdenum disulfide

MoS2 is widely praised as a promising replacement for Pt as an electrocatalyst for the hydrogen evolution reaction (HER), but even today, it still suffers from low performance. This issue is tackled by using Mn3+ as a surface modifier to trigger sulfur vacancy formation and enhance electron transport in few-layered 2H MoS2. Only 10% of Mn is sufficient to transform the semiconductive MoS2 into an active HER electrocatalyst. The insertion of Mn reduces both HER onset potential and Tafel slope which allows reaching 100 mA/cm2 at an overpotential of 206 mV, ten times larger of what undoped MoS2 can achieve. The enhanced activity arises because Mn3+ introduces electronic states near the conduction band, promotes sulfur vacancies, and increases the hydrogen adsorption. In addition to its facile production and extended shelf-life, Mn–MoS2 exhibits an efficiency of 73% at 800 mA/cm2 and 2.0 V when used in proton exchange membrane water electrolyzers.

Probing Polymorphic Stacking Domains in Mechanically Exfoliated Two-Dimensional Nanosheets Using Atomic Force Microscopy and Ultralow-Frequency Raman Spectroscopy.

As one of the key features of two-dimensional (2D) layered materials, stacking order has been found to play an important role in modulating the interlayer interactions of 2D materials, potentially affecting their electronic and other properties as a consequence. In this work, ultralow-frequency (ULF) Raman spectroscopy, electrostatic force microscopy (EFM), and high-resolution atomic force microscopy (HR-AFM) were used to systematically study the effect of stacking order on the interlayer interactions as well as electrostatic screening of few-layer polymorphic molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) nanosheets. The stacking order difference was first confirmed by measuring the ULF Raman spectrum of the nanosheets with polymorphic stacking domains. The atomic lattice arrangement revealed using HR-AFM also clearly showed a stacking order difference. In addition, EFM phase imaging clearly presented the distribution of the stacking domains in the mechanically exfoliated nanosheets, which could have arisen from electrostatic screening. The results indicate that EFM in combination with ULF Raman spectroscopy could be a simple, fast, and high-resolution method for probing the distribution of polymorphic stacking domains in 2D transition metal dichalcogenide materials. Our work might be promising for correlating the interlayer interactions of TMDC nanosheets with stacking order, a topic of great interest with regard to modulating their optoelectronic properties.

Promotion of Sulfur Vacancies and Mn Substitution in Few-Layered Molybdenum Disulfide Towards Superior Hydrogen Evolution in Acid

The superior features of hydrogen as an energy source with high energy density (120 MJ kg-1) and zero CO2 emission, makes it a strong candidate for replacing fossil fuels. Recently the European Commission has pledged to invest €470 billion in renewable hydrogen technologies by 2050, with a significant portion of this investment expected to be allocated for the deployment of renewable hydrogen electrolyzers by 2030. Water electrolysis via Proton Exchange Membrane (PEM) with Pt/Pd-based noble metals as a cathode, is currently the most effective method for hydrogen production, but alternatives are highly needed due to the scarcity and the higher cost of these metals. One of the promising classes of electrocatalysts for hydrogen evolution reaction (HER) is transition metal dichalcogenides (TMDs), and among them molybdenum disulfide (MoS2) has shown promising properties as an electrocatalyst for hydrogen production. MoS2 has different phases of 1T, 2H, and 3R with 2H-MoS2 being the most promising electrocatalyst for hydrogen production due to its semiconductive behavior and long-term stability. However, the poor conductivity, large band gap and no active basal plane towards HER limits the applications of 2H-MoS2 for water electrolysis in PEM cells. Strategies such as introduction of defects, S-vacancies, edge engineering and doping can result in enhanced HER activity of 2H-MoS2. Incorporating different transition metals (Ni, Co, Mn, Fe) into MoS2 lattice can increase the number of active sites and improve charge transfer during the electrocatalytic reaction. Based on Density Functional Theory (DFT) studies, insertion of Mn into MoS2 layer can decrease the bandgap to zero, resulting in large number of available electronic states around the Fermi level. In this work we introduce Mn doped MoS2 produced via a cost-effective microwave-assisted solid-state approach to explore the potential of few-layered MoS2, doped with different levels of manganese (5%, 10% and 15% at.) for HER in acidic media. The electrocatalytic activity towards HER reveals that 10% at. Mn incorporation into MoS2 lattice, reduces the overpotential (η10) from 210 mV for pristine MoS2 to 148 mV for 10%Mn-MoS2, respectively. In addition, Tafel slope analysis has confirmed a faster kinetics of 10%Mn-MoS2 (53 mV dec-1) compared to MoS2 (75 mV dec-1) revealing the Volmer–Heyrovsky mechanism as the rate determining step (rds). Further characterization by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and DFT studies show that Mn substitution promotes the creation of sulfur vacancies, which in turn enhances the catalytic activity towards HER. Additionally, the 10% Mn-doped MoS2 demonstrates remarkable activity in a single-cell PEM electrolyzer with long-term durability. This study highlights the potential of Mn doped MoS2 as an efficient, low-cost electrocatalyst for hydrogen production, with implications for the development of a sustainable hydrogen economy. Figure 1

Exceptionally high-rate production of few-layer MoS2 by a scalable and cost-effective gas-driven shear exfoliation method and its application for supercapacitors

Two-dimensional (2D) few-layer molybdenum disulfide (MoS2) is a versatile future electronic material with fascinating unique properties, but the commercialization of its’ applications is still hampered by high-rate production of few-layer MoS2 flakes on low-cost. Herein, we present a simple, scalable and cost-effective gas-driven shear exfoliation method for producing high-aspect-ratio few-layer MoS2 flakes with exceptionally high production rate. The gas-driven exfoliated MoS2 flakes, with an average thickness of 3 nm, show a reasonable large lateral dimension, with more than 10% of the flakes >1.0 μm and ∼73 % of the flakes in the range of 0.3–1.0 μm. In a lab-scale setup, the production rate reaches an impressive high value of 1.23 g/h, while the exfoliation energy consumption is as low as 0.175 kW⋅h/g. At an industrial level, the production rate can exceed 3 kg/h, marking a significant advancement towards the mass production of few-layer MoS2 on low-cost. As a proof-of-concept, the as-exfoliated few-layer MoS2 was employed as an active material for supercapacitor, which exhibited a good electrochemical performance with the specific capacity of 101.8 mAh/g. After 5000 cycles, the capacitance retention sustained at a high level of 92.9%.

Piezoelectric polarization induced by dual piezoelectric materials ZnO nanosheets/MoS2 heterostructure for enhancing photoelectrochemical water splitting

Zinc oxide (ZnO) has a broad range of applications in piezo-photoelectrochemical water splitting. However, the narrow light absorption range and high photogenerated carrier recombination efficiency make ZnO somewhat limited in applying piezo-photoelectrochemical water splitting. Heterogeneous structure construction is a superior handle to these two drawbacks. Herein, few-layer molybdenum disulfide (MoS2) nanospheres are compounded on ZnO nanosheets (NSs) to form a dual-piezoelectric-material heterojunction of ZnO NSs/MoS2. The photocurrent density of ZnO NSs/MoS2 reaches 0.68 mA/cm2 at 1.23 V vs. RHE under ultrasonic vibrations. It is 2.4 times higher than that of ZnO NSs under ultrasonic vibrations. The efficient piezo-photoelectrochemical performance is attributed to increased absorption range and polarization field. On the one hand, the narrow band gap of the few-layer MoS2 widens the light absorption range of ZnO. On the other hand, compared to pure ZnO NSs, ZnO NSs/MoS2 has an enhanced polarization field under ultrasonic vibrations due to the piezoelectric properties of dual piezoelectric materials, which dramatically accelerates the electron transfer and suppresses the recombination of between electrons and holes. This work provides a new approach to constructing photoelectrodes with effective piezoelectric photocatalytic properties.

Towards Low-Temperature CVD Synthesis and Characterization of Mono- or Few-Layer Molybdenum Disulfide.

Molybdenum disulfide (MoS2) transistors are a promising alternative for the semiconductor industry due to their large on/off current ratio (>1010), immunity to short-channel effects, and unique switching characteristics. MoS2 has drawn considerable interest due to its intriguing electrical, optical, sensing, and catalytic properties. Monolayer MoS2 is a semiconducting material with a direct band gap of ~1.9 eV, which can be tuned. Commercially, the aim of synthesizing a novel material is to grow high-quality samples over a large area and at a low cost. Although chemical vapor deposition (CVD) growth techniques are associated with a low-cost pathway and large-area material growth, a drawback concerns meeting the high crystalline quality required for nanoelectronic and optoelectronic applications. This research presents a lower-temperature CVD for the repeatable synthesis of large-size mono- or few-layer MoS2 using the direct vapor phase sulfurization of MoO3. The samples grown on Si/SiO2 substrates demonstrate a uniform single-crystalline quality in Raman spectroscopy, photoluminescence (PL), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy. These characterization techniques were targeted to confirm the uniform thickness, stoichiometry, and lattice spacing of the MoS2 layers. The MoS2 crystals were deposited over the entire surface of the sample substrate. With a detailed discussion of the CVD setup and an explanation of the process parameters that influence nucleation and growth, this work opens a new platform for the repeatable synthesis of highly crystalline mono- or few-layer MoS2 suitable for optoelectronic application.

Spectroscopic visualization of intermediate phases during CVD synthesis of MoS2

Chemical vapor deposition (CVD) is the broadly used technique in the synthesis of 2D materials for various electronic and optoelectronic devices. In this study, we aim to understand the precise phase transition of molybdenum trioxide (MoO3), the most commonly used transition metal precursor, under the influence of sulfur in a CVD process that ultimately leads to the growth of mono-to few-layer molybdenum disulfide (MoS2) with varying morphologies. For this, we employed a space-confined growth method and carried out a methodical spectroscopic analysis to understand the step-by-step reduction of MoO3 under reaction with sulfur vapors and its subsequent transformation to MoS2 on a SiO2 substrate. The sulfur-promoted reduction of MoO3 forming molybdenum dioxide (MoO2), followed by molybdenum oxysulfide (MoOS2) to MoOS2/MoS2 hybrid crystals, and finally monolayer (few layer) triangle (hexagonal) MoS2 crystals, is discussed. The results show that the nucleation presumably initiated by oxy-chalcogenide micro-particles that serve as heterogeneous monolayer nucleation sites. We validate our findings with optical and scanning electron microscope images, micro-Raman, photoluminescence (PL), and x-ray photoelectron spectroscopy (XPS) studies. Our findings can contribute to a better understanding of the growth processes of sequential sulfurization reactions.

Chemically Engineered Sulfur Vacancies on Few-Layered Molybdenum Disulfide Nanosheets for Remarkable Surface-Enhanced Raman Scattering Activity

In recent years, molybdenum disulfide nanosheets (MoS2 NSs) with sulfur surface defects have been used for surface-enhanced Raman scattering (SERS). However, methods to generate sulfur defects on the MoS2 NS surface are sophisticated and expensive. In this study, we present a relatively straightforward approach to quickly creating sulfur defects on MoS2 NSs by chemical treatment with NaBH4. Few-layered MoS2 NSs (FL-MoS2 NSs) were formed by exfoliating bulk-MoS2 in isopropanol. By oxidation–reduction reactions of FL-MoS2 NSs mixed with a suitable concentration of NaBH4, the resulting MoS2 NSs with abundant sulfur defects (SV-FL-MoS2 NSs) can be obtained. Spectroscopic and electron microscopic methods are used to demonstrate sulfur defects in SV-FL-MoS2 NSs. Rhodamine (R6G) and rhodamine-B (RhB) were used as Raman analytes to evaluate the SERS efficiency of SV-FL-MoS2 NSs. The developed SERS substrate provided detection limits of 1 × 10–8 M for both R6G and RhB, with enhancement factors of 2.21 × 106 and 4.02 × 106, respectively. Our measurements of SV-FL-MoS2 NSs’ energy band gap and R6G/RhB confirmed that charge transfer (CT) and tight molecular contacts are responsible for their excellent SERS sensitivity. With the development of new, low-cost semiconductor-based SERS materials, this discovery could impact materials science and biosensing platforms.

The interplay of intra- and inter-layer interactions in bending rigidity of ultrathin 2D materials

Continuum mechanics break down in bending stiffness calculations of mono- and few-layered two-dimensional (2D) van der Waals crystal sheets, because their layered atomistic structures are uniquely characterized by strong in-plane bonding coupled with weak interlayer interactions. Here, we elucidate how the bending rigidities of pristine mono- and few-layered molybdenum disulfide (MoS2), graphene, and hexagonal boron nitride (hBN) are governed by their structural geometry and intra- and inter-layer bonding interactions. Atomic force microscopy experiments on the self-folded conformations of these 2D materials on flat substrates show that the bending rigidity of MoS2 significantly exceeds those of graphene or hBN of comparable layers, despite its much lower tensile modulus. Even on a per-thickness basis, MoS2 is found to possess similar bending stiffness to hBN and is much stiffer than graphene. Density functional theory calculations suggest that this high bending rigidity of MoS2 is due to its large interlayer thickness and strong interlayer shear, which prevail over its weak in-plane bonding.

Electron transmission and mean free path in molybdenum disulfide at electron-volt energies

In van der Waals (vdW) materials, the electron mean free path (MFP) is largely influenced by the discrete states in the unoccupied band structure. So far, the influence of these states has only been measured in graphene, while all measurements on other vdW materials lack energy resolution. Here, we present reflection and transmission spectra of freestanding, few-layered molybdenum disulfide $(\mathrm{Mo}{\mathrm{S}}_{2})$ samples in the $0--55$ eV electron range. Our measurements reveal states of enhanced electron transmissivity above the vacuum level, that correspond to the (unoccupied) density of states. We also show a full quantum-mechanical calculation that confirms a good understanding of the elastic scattering in $\mathrm{Mo}{\mathrm{S}}_{2}$. A model is developed to extract the inelastic MFP spectrum, which is a measure of the inelastic scattering cross section. As $\mathrm{Mo}{\mathrm{S}}_{2}$ is a complicated system of different atomic planes, we expect that our methods generalize well to other van der Waals materials and heterostacks thereof.

Decoupling Effects of Electrostatic Gating on Electronic Transport and Interfacial Charge-Transfer Kinetics at Few-Layer Molybdenum Disulfide.

The electronic properties of electrode materials play a crucial role in defining their electrochemical behavior in energy conversion and storage devices. The assembly of van der Waals heterostructures and fabrication into mesoscopic devices enable the dependence of an electrochemical response on electronic properties to be systematically interrogated. Here, we evaluate the effect of charge carrier concentration on heterogeneous electron transfer at few-layer MoS2 electrodes by combining spatially resolved electrochemical measurements with field-effect electrostatic manipulation of band alignment. Steady-state cyclic voltammograms and finite-element simulations reveal a strong modulation of the measured electrochemical response for outer-sphere charge transfer at the electrostatic gate voltage. In addition, spatially resolved voltammetric responses, obtained at a series of locations at the surface of few-layer MoS2, reveal the governing role of in-plane charge transport on the electrochemical behavior of 2D electrodes, especially under conditions of low carrier densities.

Atomic-level understanding on progressive lithiation of few-layer MoS2 with surface vacancies

Vacancy engineering is a powerful modification strategy to elevate the electrochemical performance of electrode materials. In this work, the impacts of various surface vacancies in few-layer molybdenum disulfide (MoS2) on Li adsorption/intercalation and diffusion at both MoS2 surface and interlayers are systematically investigated to advance the material performance using first-principles calculations. The results show that the surface vacancy in few-layer MoS2 is easier to form than internal ones, and surface single S vacancy (VS) is the most stable. All seven surface vacancies can promote Li adsorption and intercalation at MoS2 surface and interlayer, and have a much more beneficial role on Li surface adsorption than interlayer intercalation. Surface single Mo vacancy (VMo) can upgrade the diffusion rate of Li at the few-layer MoS2 surface and nearby interlayer, and VS has a neglected impact on the rate capability. VMo is found to be the most propitious vacancy type for Li binding and diffusion at the few-layer MoS2. This theoretical exploration can help the comprehension of the impact of vacancies on the Li adsorption, intercalation, and transportation at the surface and interlayers of the dichalcogenides as high-performance electrode materials for rechargeable batteries.

Interfacial stress transfer in monolayer and few-layer MoS2 nanosheets in model nanocomposites

Understanding the stress transfer mechanisms from a polymer matrix to two-dimensional (2D) reinforcements is essential for the preparation of high performance nanocomposites. In this study, the interfacial stress transfer from a flexible polymer substrate to monolayer and few-layer molybdenum disulfide (MoS2) under tension has been investigated. Layer-dependent and strain-dependent photoluminescence (PL) spectroscopy were used to examine the stress transfer efficiency. The interlayer stress transfer efficiency of MoS2 was determined to be in the range of 0.76–0.86, higher than that of graphene. The transfer of strain from the polymer substrate to the flakes was derived through strain-dependent band shifts. With progressive loading, the strain distribution in monolayer MoS2 can be described by the shear-lag, partial-debonding and total-debonding models. The interfacial shear and frictional stresses were calculated to quantify the strength of the MoS2/polymer interface. It was found that the strength of the interface is similar to the strength of a graphene-polymer interface. Strain mapping was performed at different strain levels and it was found that the strain distribution in bilayer MoS2 is similar to the case of a monolayer sample. The interfacial shear strength remains almost unaffected, while the stress transfer length increases with increasing layer number.

P-type electrical contacts for 2D transition-metal dichalcogenides.

Digital logic circuits are based on complementary pairs of n- and p-type field effect transistors (FETs) via complementary metal oxide semiconductor technology. In three-dimensional (3D) or bulk semiconductors, substitutional doping of acceptor or donor impurities is used to achieve p- and n-type FETs. However, the controllable p-type doping of low-dimensional semiconductors such as two-dimensional (2D) transition-metal dichalcogenides (TMDs) has proved to be challenging. Although it is possible to achieve high-quality, low-resistance n-type van der Waals (vdW) contacts on 2D TMDs1-5, obtaining p-type devices by evaporating high-work-function metals onto 2D TMDs has not been realized so far. Here we report high-performance p-type devices on single- and few-layered molybdenum disulfide and tungsten diselenide based on industry-compatible electron beam evaporation of high-work-function metals such as palladium and platinum. Using atomic resolution imaging and spectroscopy, we demonstrate near-ideal vdW interfaces without chemical interactions between the 2D TMDs and 3D metals. Electronic transport measurements reveal that the Fermi level is unpinned and p-type FETs based on vdW contacts exhibit low contact resistance of 3.3 kΩ µm, high mobility values of approximately 190 cm2 V-1 s-1 at room temperature, saturation currents in excess of 10-5 A μm-1 and an on/off ratio of 107. We also demonstrate an ultra-thin photovoltaic cell based on n- and p-type vdW contacts with an open circuit voltage of 0.6 V and a power conversion efficiency of 0.82%.

New insight to piezocatalytic peroxymonosulfate activation: The critical role of dissolved oxygen in mediating radical and nonradical pathways

This study leverages piezocatalysis to accelerate redox reactions in heterogeneous peroxymonosulfate (PMS) activation. We syntheized few-layered molybdenum disulfide (MoS2) nanosheets as the piezoelectric catalyst for ultrasonic vibration (US)-coupled PMS system toward enhanced pollutant abatement. Scavenger tests, dissolved oxygen (DO) exclusion experiment and electron paramagnetic resonance (EPR) identify that sulfate radical (SO4•−) and singlet oxygen (1O2) are the primary ROS in the US/MoS2/PMS system. Particularly, O2•− is a vital intermediate for 1O2 generation, and multiple formation pathways of 1O2 were proposed in the US/MoS2/PMS system. With the assistance of DO and ultrasound, the utilization efficiency and activity of PMS will be remarkably increased because the majority of PMS evolves into more reactive SO4•− and 1O2 for pollutant degradation. This work not only provides mechanistic insights into the interconnected regimes of piezocatalysis and heterogeneous Fenton-like reactions, but also achieves high chemical efficiency for sustainable water remediation.