Two-dimensional Layered Materials Research Articles

Electrochemical production of two-dimensional atomic layer materials and their application for energy storage devices

Two-dimensional (2D) atomic layer materials have attracted a great deal of attention due to their superior chemical, physical, and electronic properties, and have demonstrated excellent performance in various applications such as energy storage devices, catalysts, sensors, and transistors. Nevertheless, the cost-effective and large-scale production of high-quality 2D materials is critical for practical applications and progressive development in the industry. Electrochemical exfoliation is a recently introduced technique for the facile, environmentally friendly, fast, large-scale production of 2D materials. In this review, we summarize recent advances in different types of electrochemical exfoliation methods for efficiently preparing 2D materials, along with the characteristics of each method, and then introduce their applications as electrode materials for energy storage devices. Finally, the remaining challenges and prospects for developing the electrochemical exfoliation process of 2D materials for energy storage devices are discussed.

Monolayer Iron Oxychloride with a Resonant Band Structure for Ultrasensitive Molecular Sensing.

Two-dimensional layered materials (2DLMs) are expected to be next-generation commercial sensors for surface-enhanced Raman scattering (SERS) sensing owing to their unique structural features and physicochemical properties. The low sensitivity and poor universality of 2DLMs are the dominant barriers toward their practical applications. Herein, we report that monolayer iron oxychloride (FeOCl) with a naturally suitable band structure is a promising candidate for ultrasensitive SERS sensing. The generally boosted Raman scattering cross section of different analyte-FeOCl systems benefits from the resonant photoinduced charge transfer processes and strong ground-state interactions. In addition, the strong adsorption ability of monolayer FeOCl is crucial for rapid detection in practical applications, which is proven to be much better than those of conventional SERS sensors. Consequently, monolayer FeOCl enables diverse SERS applications, including multicomponent analysis, chemical reaction monitoring, and indirect ion sensing.

A dye-sensitized solar cells with an efficiency of 10.01% based on the MoP/MoNiP2@Ti3C2 composite counter electrode

Transition metal phosphides are becoming a main study topic in new catalytic materials field due to their similar properties to transition metal nitrides and carbides as well as their excellent reaction activity and catalytic selectivity for deep hydrodesulfurization and hydrodenitrogenation. Mxene, a two-dimensional layered material with high specific surface area and electrical conductivity, plays an important role in accelerating catalytic reduction of triiodide ion in dye-sensitized solar cells (DSSCs). In this work, the MoP/MoNiP2 hybrid was synthesized while adopting Ti3C2 Mxene to realize the intercalation structure of composite with simple conditions, therefore enabling a formation of ‘pillared effect’ in Ti3C2 Mxene. The optimized MoP/MoNiP2@Ti3C2 composite was achieved by adjusting the doping ratio of the two. The DSSCs based on the MoP/MoNiP2@Ti3C2 catalyst with 80 wt% Ti3C2 doping reache an enhancement of power conversion efficiency of 10.01%, much higher than that of the platinum counter electrode (8.22%). Through a suite of morphological and electrochemical analyses, we summarize the reasons for the performance enhancement to the synergistic effect of the MoP/MoNiP2 hybrid and Ti3C2 Mxene, and especially, the unique intercalation structure of MoP/MoNiP2@Ti3C2 with ‘pillared effect’. The MoP/MoNiP2@Ti3C2 counter electrode with perfect electrochemical and photoelectrochemical properties is a promising alternative to the platinum electrode for DSSCs in the future.

Oriented adsorption and efficient sensing of NO2 on MoSe2 monolayer: a comparative study with WSe2 monolayer

Oriented adsorption is very rare on two-dimensional inorganic thin layers. Based on preliminary study, density functional theory (DFT) was used to explore the adsorption and sensing behavior of NO2 on MoSe2 perfect and defective monolayers including selenium vacancy (VSe), molybdenum vacancy (VMo), and antisite defect of selenium on molybdenum site (SeMo) by large-scale sampling. The adsorption energy can reach 0.29 eV with 0.182 e charge transfer on the perfect monolayer. The adsorption ability is improved largely on VSe, VMo, and SeMo monolayers (3.27, 0.93, and 1.20 eV) with considerable charge transfer (0.583, 0.152, and 0.139 e, respectively), demonstrating the potential of MoSe2 monolayers as NO2 sensing materials. Meanwhile, similar to WSe2 monolayer, oriented adsorption of NO2 is disclosed. NO2 molecule extends mainly along the Se–Mo–Se trough and the Se–Mo bond on all the four MoSe2 monolayers. Whereas, the oriented adsorption ability is weaker than the WSe2 monolayer, which can be confirmed by the relatively small proportion of oriented adsorption conformations. This kind of double oriented adsorption behavior (vertical adsorption and adsorption along specific direction of the two-dimensional material) was considered to be due to the good polarity match between molecule and monolayer. Molecular dipole moment and material bond population are believed to be two important parameters that determine the oriented adsorption capacity of molecular-material systems. The successive discovery of the unique oriented adsorption and the deepening of understanding provide chance for molecular design of oriented adsorption of inorganic small molecules on two-dimensional layered materials. The strong dissociation ability of the anionic vacancy monolayer to NO2 molecule indicates that MoSe2 monolayer has a very high adsorption, capture, and activation potential for nitrogen oxides. Comparative study proved that the Mo site activity was less than the W site activity on the perfect monolayer, and defects could help the Mo site activity overtake. These findings provide pivotal guidance for creating advanced surface regulated electronic systems, such as sensors.

A Review of the Structural Design of Anode Materials in Sodium-Ion Batteries Based on MXenes and Their Composites

The typical two-dimensional layered structure materials, MXenes, are widely used in energy conversion and storage due to their high conductivity, ion transport ability, and rich surface structures. Recently, MXenes and their composites have been widely employed in secondary batteries, especially sodium-ion batteries (SIBs), with obvious performance improvement. As anodic materials, MXenes, metal oxides, metal sulfides, and other materials contain certain advantages in Na+ storage, but they individually also suffer from some issues and challenges, such as low conductivity and serious volume change, as well as the associated low capacity and poor cyclability. By virtue of the advantages of MXenes, with their high conductivity and ultrathin two-dimensional structures, the construction of surface-functionalized MXenes and MXene-based composites could effectively improve the conductivity and mass-transport properties of composites, alleviate volume expansion, and, thus, enhance the capacity properties, rate performances, and cycle stability of SIBs. Herein, we review the latest research status of the structural design of MXenes and Mxene-based materials, as well as their applications in SIBs. We briefly introduce the research background and introduce MXenes and SIBs, and focus on their structural designs and corresponding applications in SIBs. Finally, the important challenges of MXene-based materials applied to SIBs are discussed, and the future prospects of MXene-based composite developments in SIBs are presented.

Ultrathin quantum light source with van der Waals NbOCl2 crystal.

Interlayer electronic coupling in two-dimensional materials enables tunable and emergent properties by stacking engineering. However, it also results in significant evolution of electronic structures and attenuation of excitonic effects in two-dimensional semiconductors as exemplified by quickly degrading excitonic photoluminescence and optical nonlinearities in transition metal dichalcogenides when monolayers are stacked into van der Waals structures. Here we report a van der Waals crystal, niobium oxide dichloride (NbOCl2), featuring vanishing interlayer electronic coupling and monolayer-like excitonic behaviour in the bulk form, along with a scalable second-harmonic generation intensity of up to three orders higher than that in monolayer WS2. Notably, the strong second-order nonlinearity enables correlated parametric photon pair generation, through a spontaneous parametric down-conversion (SPDC) process, in flakes as thin as about 46 nm. To our knowledge, this is the first SPDC source unambiguously demonstrated in two-dimensional layered materials, and the thinnest SPDC source ever reported. Our work opens an avenue towards developing van der Waals material-based ultracompact on-chip SPDC sources as well as high-performance photon modulators in both classical and quantum optical technologies1-4.

Advanced Stretchable Photodetectors: Strategies, Materials and Devices.

Past decades have witnessed the generation of new stretchable photodetectors in electronic eyes, health sensing, wearable devices, intelligent monitoring and other fields. Stretchable devices require not only outstanding performance but also excellent flexibility, adaptability and stability. Innovative strategies have been proposed to realize the stretchability of devices. In addition, novel functional materials including zero-dimensional nanomaterials, one-dimensional inorganic nanomaterials, two-dimensional layered materials, organic materials, and organic-inorganic composite materials with excellent properties are emerging to continuously improve the performance of devices. Here, the recent research progress of stretchable photodetectors in terms of both various design methods and functional materials is outlined. The optical performance and stretchable properties are also comprehensively reviewed. Finally, a summary and the challenges associated with the application of stretchable photodetectors are presented.

Recent progress of 2-dimensional layered thermoelectric materials

Nowadays, there are enormous amounts of energy wasted in the world, most of which is in the form of wasted heat. Thermoelectric effect, by converting heat energy into electricity without releasing dangerous substances, has aroused more and more interest from researchers. Since the discovery of graphene, more and more two-dimensional layered materials have been reported, which typically own superior electrical, optical and other physical properties over the bulk materials, and the development of the new theory and experimental technologies stimulates further research for them as well. In this work, first we introduce the measurement methods and techniques that are suitable for characterizing the thermoelectric properties of two-dimensional materials, and then discuss the relevant current challenging issues. Subsequently, graphene, transition metal disulfides, black phosphorus and other 2-dimensional materials in thermoelectric applications are introduced. Finally, we discuss the various strategies to improve the thermoelectric performance and the problems that need solving urgently.

Percolative proton transport in hexagonal boron nitride membranes with edge-functionalization.

Two-dimensional layered materials have been used as matrices to study the structure and dynamics of trapped water and ions. Here, we demonstrate unique features of proton transport in layered hexagonal boron nitride membranes with edge-functionalization subject to hydration. The hydration-independent interlayer spacing indicates the absence of water intercalation between the h-BN sheets. An 18-fold increase in water sorption is observed upon amine functionalization of h-BN sheet edges. A 7-orders of magnitude increase in proton conductivity is observed with less than 5% water loading attributable to edge-conduction channels. The extremely low percolation threshold and non-universal critical exponents (2.90 ≤ α ≤ 4.43), are clear signatures of transport along the functionalized edges. Anomalous thickness dependence of conductivity is observed and its plausible origin is discussed.

Li intercalation modulated photocurrent response in WS<sub>2</sub> optoelectronic devices

<sec>Transition metal dichalcogenides have emerged as a prominent class of two-dimensional layered material, capturing sustained attention from researchers due to their unique structures and properties. These distinctive characteristics render transition metal dichalcogenides highly versatile in numerous fields, including optoelectronics, nanoelectronics, energy storage devices, and electrocatalysis. In particular, the ability to modulate the doping characteristics of these materials plays a crucial role in improving the photoelectric response performance of devices, making it imperative to investigate and understand such effects.</sec><sec>In recent years, the electrochemical ion intercalation technique has emerged as a novel approach for precise doping control of two-dimensional materials. Building upon this advancement, this paper aims to demonstrate the effective doping control of transition metal dichalcogenides devices by utilizing the electrochemical ion intercalation method specifically on thick WS<sub>2</sub> layers. The results show that the conductivity is significantly improved, which is about 200 times higher than the original value, alongside the achievement of efficient and reversible control over the photoelectric response performance is effectively and reversibly controlled by manipulating the gate voltage. One of the key findings in this work is the successful demonstration of the reversible cyclic control of the photoelectric response in WS<sub>2</sub> devices through ion intercalation, regulated by the gate voltage. This dynamic control mechanism showcases the potential for finely tuning and tailoring the performance of photoelectric devices made from two-dimensional materials. The ability to achieve reversible control is especially significant as it allows for a versatile range of applications, enabling devices to be adjusted according to specific requirements and operating conditions.</sec><sec>The implications of this work extend beyond the immediate findings and present a foundation for future investigation into response control of photoelectric devices constructed by using two-dimensional materials through the utilization of the ion intercalation method. By establishing the feasibility and efficacy of this technique in achieving controlled doping and precise modulation of photoelectric response, researchers can explore its potential applications in various technological domains. Furthermore, this research serves as a stepping stone for developing the advanced doping strategies, enabling the design and fabrication of high-performance devices with enhanced functionalities.</sec><sec>In summary, this work showcases the significance of doping control in transition metal dichalcogenide devices and demonstrates the potential of the electrochemical ion intercalation method for achieving precise modulation of their photoelectric response performance. The observed enhancements in electrical conductivity and the ability to reversibly control the photoelectric response highlight the promising prospects of this technique. Ultimately, this work paves the way for future advancements in the field of two-dimensional materials and opens up new way for designing and optimizing photoelectric devices with improved functionality and performance.</sec>

Design and synthesis of novel pomegranate-like TiN@MXene microspheres as efficient sulfur hosts for advanced lithium sulfur batteries.

Lithium-sulfur (Li-S) batteries have the characteristics of low cost, environmental protection, and high theoretical energy density, and have broad application prospects in the new generation of electronic products. However, there are some problems that seriously hinder the Li-S batteries from going from the laboratory to the factory, such as poor stability caused by the large volume expansion of sulfur during charging and discharging, sluggish kinetics of the electrochemical reaction resulting from the low conductivity of the active materials, and loss of active materials arising from the dissolution and diffusion of the intermediate product lithium polysulfides (LiPSs). In this paper, the two-dimensional layered material MXene and TiN are firstly combined by spray drying method to prepare pomegranate-like TiN@MXene microspheres with both adsorption capacity and catalytic effect on LiPSs conversion. The interconnected skeleton composed of MXene not only solves the problem of easy stacking of MXene sheets but also ensures the uniform distribution of sulfur. Without affecting the excellent characteristics of MXene itself, the overall conductivity of the composite electrode material is improved. The TiN hollow nanospheres are coated with MXene layers to form a shell, catalyzing the adsorption of LiPSs and accelerating the transformation of high-order LiPSs to Li2S2/Li2S. As a result, the TiN@MXene cathode delivers a high initial discharge capacity of 1436 mA h g-1 at 0.1C, excellent rate performance of 636 mA h g-1 up to 3C, and an ultralong lifespan over 1000 cycles with a small capacity decay of 0.048% per cycle at the current density of 1.0C.

A versatile fluorescence sensor for DNA detection based on layered double hydroxides and exonuclease III

A versatile fluorescent sensor was constructed for DNA detection based on layered double hydroxides and exonuclease III.

Fast detection of Staphylococcus aureus using thiol-functionalized WS2 quantum dots and Bi2O2Se nanosheets hybrid through a fluorescence recovery mechanism.

Ultrafast and sensitive detection of Staphylococcus aureus (S. aureus), a harmful Gram-positive human pathogenic bacterium, by two-dimensional layered materials continues to be a challenge. Herein, we have studied the sensing of S. aureus using a tungsten disulfide (WS2) quantum dot (QD) and bismuth oxyselenide (Bi2O2Se) nanosheet (NS) hybrid through their unique optical functionalities. The WS2 QDs of a mean diameter of 2.5 nm were synthesized by liquid exfoliation. Due to the quantum confinement and functional groups, the WS2 QDs exhibit high fluorescence (FL) yield under UV excitation. The addition of Bi2O2Se NSs resulted in the adsorption of WS2 QDs on their surface, resulting in quenching of the FL emission due to nonfluorescent complex formation between the WS2 QDs and Bi2O2Se NSs. A specific sequencing single-standard DNA (ssDNA) aptamer, which identifies and explicitly binds with S. aureus, was attached to the defect sites of the WS2 QDs for selective detection. The thiol-modified ssDNA aptamers attach covalently to the WS2 QD defect sites, which was confirmed by Raman and X-ray photoelectron spectroscopy (XPS). The interaction of S. aureus with the aptamer functionalized WS2 QDs weakens the van der Waals interaction between the WS2 QDs and Bi2O2Se NSs, which results in the detachment of the WS2 QDs from the Bi2O2Se NS surface and restores the FL intensity of the WS2 QDs, thus allowing the efficient detection of S. aureus. Similar measurements with non-targeted bacteria show that the system is quite selective towards S. aureus. Our FL-based biosensor has a linear response in the range of 103-107 CFU mL-1 (colony formation unit mL-1) with a detection limit of 580 CFU mL-1. We have observed a fast response time of 15 minutes for sensing, which is superior to the previous reports. The proposed system was tested in human urine and can detect S. aureus in human urine samples selectively, proving its potential in real-life applications. The reported approach is versatile enough for sensing other biomolecules and metal ions by choosing suitable receptors.

Large Size Few-Layer Ambipolar MoS<sub>2</sub> Metal-Oxide-Semiconductor Field Effect Transistors by Nitrogen Plasma Doping

Molybdenum disulfide (MoS2), a typical two-dimensional layered semiconductor material, is widely studied due its excellent electronic properties in atomic scale. In this study, we achieved the growth of large size few-layer MoS2 films by using molybdenum boat with vertical shield at the end to carry MoO3 precursor in the chemical vapor deposition (CVD) system. The optical microscopy reveals the morphology and lateral size of as-grown films. The Raman spectrum testified that the synthesized films are few-layer MoS2 with defects. Metal-oxide-semiconductor field effect transistors (MOSFETs) based on CVD-grown MoS2 are fabricated, presenting n-type transportation with ION/IOFF ratio about 103. The transportation behaviour of MoS2 MOSFETs is changed from n-type to ambipolar by introducing nitrogen plasma into MoS2 films. The electron or hole transportation in MoS2 is controlled by gate-source voltage. The ambipolar MOSFETs show ION/IOFF ratio about 103.

Two dimensional MnPSe3 layer stacking composites with superior storage performance for alkali metal-ion batteries

Two-dimensional MnPSe3 Van der Waals stacked in an ABC sequence has abundant and low-cost Mn resources, but has yet to exhibit expected performance as an electrode material in battery devices. Here, we report a 2D/2D composite consisting of few layer MnPSe3 nanosheets and graphite through a high energy ball milling method for uses on the anodes alkali metal-ion batteries, including lithium ion battery (LIB) and potassium ion battery (PIB). These unique 2D/2D layer nanostructures, with MnPSe3 layers hierarchically stacked in graphite, can successfully overcome the severe aggregation due to restacking during charge/discharge cycles. Moreover, density functional theory (DFT) calculations show that the band gap of the MnPSe3/graphite hybrid is as low as 0.07 eV, confirming that the combination of MnPSe3 and graphite efficiently reduces the ion migration energy barrier. As a result, MnPSe3/graphite stacking composites achieve a discharge capacity of 488.1 mA h g−1 after 500 cycles at 2000 mA g−1 in LIB, and 236.7 mA h g−1 after 700 cycles at 250 mA g−1 in PIB. Moreover, the analysis of electrochemical, kinetics, reactions mechanism, DFT, and full cell applications were investigated deeply. This work strongly supports the possibility of MnPSe3/graphite hybrid as a promising candidate for alkali ion batteries, and makes important improvements for the application of two-dimensional MPCh3 layer materials in storage systems.

Structural defects in a Janus MoSSe monolayer: A density functional theory study

Two-dimensional layered materials with different anions on both faces of each layer, called Janus monolayers, have attracted significant interest due to their unique structural asymmetry perpendicular to the layer, which gives rise to an electric dipole moment that further diversifies the versatile properties of the transition-metal dichalcogenide materials class. However, the synthesis of a material such as MoSSe is prone to the introduction of various point defects, which could significantly modify the electric and optical properties as well as vibrational spectra. Using density functional theory, we provide an in-depth insight into the thermal stability of numerous point-vacancy and antisite defects in the Janus MoSSe monolayer. The structural changes are discussed in terms of the local strain induced by the modified atomic bonding around the defect sites. The electronic structure and linear optical response of Janus MoSSe monolayer with various point defects are studied, and possible fingerprints of electronic transitions due to defects are rationalized. First-principles calculations of phonons are carried out to spot the fingerprint of each point defect in the vibrational spectrum of the Janus MoSSe monolayer. Our systemic study will provide a broad picture of the roles the point defects could play in modifying and tuning the electronic and optical properties of two-dimensional Janus materials and thus help customizing them for certain applications.

Synthesis of Rhenium-Doped Molybdenum Sulfide by Atmospheric Pressure Chemical Vapor Deposition (CVD) for a High-Performance Photodetector.

Two-dimensional layered materials have attracted tremendous attention as photodetectors due to their fascinating features, including comprehensive coverage of band gaps, high potential in new-generation electronic devices, mechanical flexibility, and sensitive light-mass interaction. Currently, graphene and transition-metal dichalcogenides (TMDCs) are the most attractive active materials for constructing photodetectors. A growing number of emerging TMDCs applied in photodetectors bring up opportunities in the direct band gap independence with thickness. This study demonstrated for the first time a photodetector based on a few-layer Re x Mo1-x S2, which was grown by chemical vapor deposition (CVD) under atmospheric pressure. The detailed material characterizations were performed using Raman spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy (XPS) on an as-grown few-layer Re x Mo1-x S2. The results show that both MoS2 and ReS2 peaks appear in the Re x Mo1-x S2 Raman diagram. Re x Mo1-x S2 is observed to emit light at a wavelength of 716.8 nm. The electronic band structure of the few layers of Re x Mo1-x S2 calculated using the first-principles theory suggests that the band gap of Re x Mo1-x S2 is larger than that of ReS2 and smaller than that of MoS2, which is consistent with the photoluminescence results. The thermal stability of the few layers of Re x Mo1-x S2 was evaluated using Raman temperature measurements. It is found that the thermal stability of Re x Mo1-x S2 is close to those of pure ReS2 and MoS2. The fabricated Re x Mo1-x S2 photodetector shows a high response rate of 7.46 A W-1 under 365 nm illumination, offering a competitive performance to the devices based on TMDCs and graphenes. This study unambiguously distinguishes Re x Mo1-x S2 as a future candidate in electronics and optoelectronics.

Temperature-dependent friction coefficient on flat graphite plane

Investigating the frictional properties of two-dimensional layered materials with dynamic evolution of contact quality advances understanding the mechanism underlying puckering effects, offering a new pathway for the rational control of friction. In this letter, friction force microscopy (FFM) in ultra-high vacuum (UHV) conditions has been used to probe the nanoscale friction on a freshly cleaved flat graphite surface (0001) as a function of normal force and surface temperature. It is found that friction force shows a nonmonotonic change with the decrease of temperature with the maximum friction appeared around Tmax=140±5 K. Besides, coefficients of friction (COFs) defined as the slope of friction-normal force curves remains nearly constant before the friction peak while surprisingly change into negative values with the further decrease of temperature. The loading–unloading results reveal that, the abnormal COFs behavior originates from the temperature induced contact quality evolution which leads to the ripple formation at cryogenic temperatures in the front of scanning tip. The results reported here provide a deep insight into the effects of temperature on the frictional behaviors of graphite, which give a new thrust in the field of friction on lamellar materials.

High thermoelectric performance of intrinsic few-layers T-HfSe2

Due to their distinct electrical, mechanical, thermal, and optoelectronic properties, two-dimensional layered materials have drawn a lot of research and interest. This study employs first-principles calculations along with Boltzmann transport theory to precisely predict the thermoelectric properties of few-layer intrinsic (2 L, 3 L, and 4 L) T -HfSe 2 . The increase in layers causes band degeneracy, which greatly improves the Seebeck coefficient and power factor, we obtain an amazingly high power factor of 1.2 × 10 13 cm −3 at room temperature. Meanwhile, the lattice thermal conductivity of few-layer intrinsic T -HfSe 2 is found to be lower than that of monolayer caused by van der Waals interactions. Ultimately, a maximum p-type ZT value of ~0.53 can be reached at 300 K, which is close to the ZT value of ~0.6 for the latest work GeTe-based TE materials. Moreover, we obtai n n -type ZT of ∼1.3, which is amazingly high and close to Pb-doped SnSe ~1.2. The results indicate that layered HfSe 2 is quite an excellent thermoelectric material at room temperature. In summary, this work demonstrates the tremendous advantages of few-layered HfSe 2 in thermoelectric applications.

Accurate assignment of double resonant Raman bands in Janus MoSSe monolayer from first-principles calculations

• The double resonant Raman (DRR) spectra of Janus MoSSe monolayer is calculated within the first-principles framework. • Eleven DRR bands are assigned with combined modes compared quantitatively if one DRR band comprises more than one combined mode. • The rationality of the assignments has been verified by group theoretical analysis as well as the calculated DRR spectra under biaxial strains. Janus transition metal dichalcogenides (TMDs) structures, as a new type of two-dimensional layered materials, have drawn increasing research efforts mostly by the Raman characterization technique since their successful synthesis. First- and second-order resonant Raman spectra (RRS) have been reported by experiments. But, unlike much interest paid to the first-order RRS, there has been so far no much discussion dedicated to the second-order double resonant Raman (DRR) bands and band assignments of Janus TMDs, which nevertheless is indispensable but hampered by the difficulty of calculations. In this work, we calculate the DRR spectra of Janus MoSSe monolayer within the first-principles framework and succeed in achieving accurate assignments of the DRR bands. The assignments are in agreement with our group theoretical analysis. Moreover, taking advantage of its strain-sensitive feature, we calculate the DRR spectra under biaxial strain, and further verify the rationality of our assignments by analyzing strain-induced shift of the DRR bands. Our present study supplies an efficient strategy for quantitative understanding on the electron-phonon coupling in the Janus structures.