Breaking linear scaling relations by strain engineering on MXene for boosting N2 electroreduction

The development of N2 reduction reaction (NRR) electrocatalysts with excellent activity and selectivity is of great significance, but adsorption-energy linear scaling relations between reaction intermediates severely hamper the realization of this aspiration. Here, we propose an elegant strain engineering strategy to break the linear relations in NRR to promote catalytic activity and selectivity. Our results show that the N-N bond lengths of adsorbed N2 with side-on and end-on configurations exhibit opposite variations under strains, which is illuminated by establishing two different N2 activation mechanisms of "P-P" (Pull-Pull) and "E-E" (Electron-Electron). Then, we highlight that strain engineering can break the linear scaling relations in NRR, selectively optimizing the adsorption of key NH2NH2** and NH2* intermediates to realize a lower limiting potential (UL). Particularly, the catalytic activity-selectivity trade-off of NRR on MXene can be circumvented, resulting in a low UL of -0.25 V and high Faraday efficiency (FE), which is further elucidated to originate from the strain-modulated electronic structures. Last but not least, the catalytic sustainability of MXene under strain has been guaranteed. This work not only provides fundamental insights into the strain effect on catalysis but also pioneers a new avenue toward the rational design of superior NRR catalysts.

Tailoring Li Deposition by Regulating Structural Connectivity of Electrochemical Li Reservoir in Li-metal Batteries

Irregular Li deposition is the major reason for poor reversibility and cycle instability in Li metal batteries, even leading to safety hazards, the causes of which have been extensively explored. The structural disconnection induced by completely dissolving Li in the traditional testing protocol is a key factor accounting for irregular Li growth during the subsequent deposition process. Herein, the critical role played by the structural connectivity of electrochemical Li reservoir in subsequent Li deposition behaviors is elucidated and a morphology-performance correlation is established. The structural connection and resultant well-distributed morphology of the in situ electrochemical Li reservoir ensure efficient electron transfer and Li+ diffusion pathway, finally leading to homogenized Li nucleation and growth. Tailoring the geometry of Li reservoir can improve the coulombic efficiency and cyclability of anode-free Li metal batteries by optimizing Li deposition behavior.

Z-scheme Al2SeTe/GaSe and Al2SeTe/InS van der Waals heterostructures for photocatalytic water splitting

Designing Z-scheme van der Waals (vdW) heterostructured photocatalysts is a promising strategy for developing highly efficient overall water splitting. Herein, by employing density functional theory calculations, we systematically investigated the stability, electronic structures, photocatalytic and optical properties of Al2SeTe, GaSe, and InS monolayers and their corresponding vdW heterostructures. Interestingly, electronic structures show that all vdW heterostructures have direct band gaps, which is conducive to the transition of electrons from the valence band to the conduction band. Notably, Al2TeSe/GaSe and Al2TeSe/InS vdW heterostructures possess large overpotentials for Z-scheme photocatalytic water splitting, as proved by the results of band edge positions and band structure bending. Moreover, these vdW heterostructures exhibit good optical absorption in ultraviolet and visible light regions. We believe that our findings will open a new avenue for the modulation and development of Al2TeSe/GaSe and Al2TeSe/InS vdW heterostructures for photocatalytic water splitting.

2D Lateral Heterojunction Arrays with Tailored Interface Band Bending

Two-dimensional (2D) lateral heterojunction arrays, characterized by well-defined electronic interfaces, hold significant promise for advancing next-generation electronic devices. Despite this potential, the efficient synthesis of high-density lateral heterojunctions with tunable interfacial band alignment remains a challenging. Here, a novel strategy is reported for the fabrication of lateral heterojunction arrays between monolayer Si2 Te2 grown on Sb2 Te3 (ML-Si2 Te2 @Sb2 Te3 ) and one-quintuple-layer Sb2 Te3 grown on monolayer Si2 Te2 (1QL-Sb2 Te3 @ML-Si2 Te2 ) on a p-doped Sb2 Te3 substrate. The site-specific formation of numerous periodically arranged 2D ML-Si2 Te2 @Sb2 Te3 /1QL-Sb2 Te3 @ML-Si2 Te2 lateral heterojunctions is realized solely through three epitaxial growth steps of thick-Sb2 Te3 , ML-Si2 Te2 , and 1QL-Sb2 Te3 films, sequentially. More importantly, the precisely engineering of the interfacial band alignment is realized, by manipulating the substrate's p-doping effect with lateral spatial dependency, on each ML-Si2 Te2 @Sb2 Te3 /1QL-Sb2 Te3 @ML-Si2 Te2 junction. Atomically sharp interfaces of the junctions with continuous lattices are observed by scanning tunneling microscopy. Scanning tunneling spectroscopy measurements directly reveal the tailored type-II band bending at the interface. This reported strategy opens avenues for advancing lateral epitaxy technology, facilitating practical applications of 2D in-plane heterojunctions.

Experimental Realization of Monolayer α-Tellurene

2D materials emerge as a versatile platform for developing next-generation devices. The experimental realization of novel artificial 2D atomic crystals, which does not have bulk counterparts in nature, is still challenging and always requires new physical or chemical processes. Monolayer α-tellurene is predicted to be a stable 2D allotrope of tellurium (Te), which has great potential for applications in high-performance field-effect transistors. However, the synthesis of monolayer α-tellurene remains elusive because of its complex lattice configuration, in which the Te atoms are stacked in tri-layers in an octahedral fashion. Here, a self-assemble approach, using three atom-long Te chains derived from the dynamic non-equilibrium growth of an a-Si:Te alloy as building blocks, is reported for the epitaxial growth of monolayer α-tellurene on a Sb2 Te3 substrate. By combining scanning tunneling microscopy/spectroscopy with density functional theory calculations, the surface morphology and electronic structure of monolayer α-tellurene are revealed and the underlying growth mechanism is determined. The successful synthesis of monolayer α-tellurene opens up the possibility for the application of this new single-element 2D material in advanced electronic devices.

Design principles of heterointerfacial redox chemistry for highly reversible lithium metal anode

High electrochemical reversibility is required for the application of high-energy-density lithium (Li) metal batteries; however, inactive Li formation and SEI (solid electrolyte interface)-instability-induced electrolyte consumption cause low Coulombic efficiency (CE). The prior interfacial chemical designs in terms of alloying kinetics have been used to enhance the CE of Li metal anode; however, the role of its redox chemistry at heterointerfaces remains a mystery. Herein, the relationship between heterointerfacial redox chemistry and electrochemical transformation reversibility is investigated. It is demonstrated that the lower redox potential at heterointerface contributes to higher CE, and this enhancement in CE is primarily due to the regulation of redox chemistry to Li deposition behavior rather than the formation of SEI films. Low oxidation potential facilitates the formation of the surface with the highly electrochemical binding feature after Li stripping, and low reduction potential can maintain binding ability well during subsequent Li plating, both of which homogenize Li deposition and thus optimize CE. In particular, Mg hetero-metal with ultra-low redox potential enables Li metal anode with significantly improved CE (99.6%) and stable cycle life for 700 cycles at 3.0 mA cm-2. This work provides insight into the heterointerfacial design principle of next-generation negative electrodes for highly reversible metal batteries.

Contact engineering for 2D Janus MoSSe/metal junctions

The flourish of two-dimensional (2D) materials provides a versatile platform for building high-performance electronic devices in the atomic thickness regime. However, the presence of the high Schottky barrier at the interface between the metal electrode and the 2D semiconductors, which dominates the injection and transport efficiency of carriers, always limits their practical applications. Herein, we show that the Schottky barrier can be controllably lifted in the heterostructure consisting of Janus MoSSe and 2D vdW metals by different means. Based on density functional theory calculations and machine learning modelings, we studied the electrical contact between semiconducting monolayer MoSSe and various metallic 2D materials, where a crossover from Schottky to Ohmic/quasi-Ohmic contact is realized. We demonstrated that the band alignment at the interface of the investigated metal-semiconductor junctions (MSJs) deviates from the ideal Schottky-Mott limit because of the Fermi-level pinning effects induced by the interface dipoles. Besides, the effect of the thickness and applied biaxial strain of MoSSe on the electronic structure of the junctions are explored and found to be powerful tuning knobs for electrical contact engineering. It is highlighted that using the sure-independence-screening-and-sparsifying-operator machine learning method, a general descriptor WM3/exp(Dint) was developed, which enables the prediction of the Schottky barrier height for different MoSSe-based MSJ. These results provide valuable theoretical guidance for realizing ideal Ohmic contacts in electronic devices based on the Janus MoSSe semiconductors.

Magnetic-ferroelectric synergic control of multilevel conducting states in van der Waals multiferroic tunnel junctions towards in-memory computing

van der Waals (vdW) multiferroic tunnel junctions (MFTJs) based on two-dimensional materials have gained significant interest due to their potential applications in next-generation data storage and in-memory computing devices. In this study, we construct vdW MFTJs by employing monolayer Mn2Se3 as the spin-filter tunnel barrier, TiTe2 as the electrodes and In2S3 as the tunnel barrier to investigate the spin transport properties based on first-principles quantum transport calculations. It is highlighted that apparent tunneling magnetoresistance (TMR) and tunneling electroresistance (TER) effects with a maximum TMR ratio of 6237% and TER ratio of 1771% can be realized by using bilayer In2S3 as the tunnel barrier under finite bias. Furthermore, the physical origin of the distinguished TMR and TER effects is unraveled from the k||-resolved transmission spectra and spin-dependent projected local density of states analysis. Interestingly, four distinguishable conductance states reveal the implementation of four-state nonvolatile data storage using one MFTJ unit. More importantly, in-memory logic computing and multilevel data storage can be achieved at the same time by magnetic switching and electrical control, respectively. These results shed light on vdW MFTJs in the applications of in-memory computing as well as multilevel data storage devices.

Tailoring Broadband Nonlinear Optical Characteristics and Ultrafast Photocarrier Dynamics of Bi2 O2 S Nanosheets by Defect Engineering

Low-dimensional bismuth oxychalcogenides have shown promising potential in optoelectronics due to their high stability, photoresponse, and carrier mobility. However, the relevant studies on deep understanding for Bi2 O2 S is quite limited. Here, comprehensive experimental and computational investigations are conducted in the regulated band structure, nonlinear optical (NLO) characteristics, and carrier dynamics of Bi2 O2 S nanosheets via defect engineering, taking O vacancy (OV) and substitutional Se doping as examples. As the OV continuously increased to ≈35%, the optical bandgaps progressively narrow from ≈1.21 to ≈0.81 eV and NLO wavelengths are extended to near-infrared regions with enhanced saturable absorption. Simultaneously, the relaxation processes are effectively accelerated from tens of picoseconds to several picoseconds, as the generated defect energy levels can serve as both additional absorption cross-sections and fast relaxation channels supported by theoretical calculations. Furthermore, substitutional Se doping in Bi2 O2 S nanosheets also modulate their optical properties with the similar trends. As a proof-of-concept, passively mode-locked pulsed lasers in the ≈1.0 µm based on the defect-rich samples (≈35% OV and ≈50% Se-doping) exhibit excellent performance. This work deepens the insight of defect functions on optical properties of Bi2 O2 S nanosheets and provides new avenues for designing advanced photonic devices based on low-dimensional bismuth oxychalcogenides.

Enriching 2D transition metal borides via MB XMenes (M = Fe, Co, Ir): Strong correlation and magnetism

Recently, two-dimensional (2D) FeSe-like anti-MXenes (or XMenes), composed of late d-block transition metal M and p-block nonmetal X elements, have been both experimentally and theoretically investigated. Here, we select three 2D borides FeB, CoB and IrB for a deeper investigation by including strong correlation effects, as a fertile ground for understanding and applications. Using a combination of Hubbard corrected first-principles calculations and Monte Carlo simulations, FeB and CoB are found to be ferro- and anti-ferro magnetic, contrasting with the non-magnetic nature of IrB. The metallic FeB XMene monolayer, superior to most of the MXenes or MBenes, exhibits robust ferromagnetism, driven by intertwined direct-exchange and super-exchange interactions between adjacent Fe atoms. The predicted Curie temperature (TC) of the FeB monolayer via the Heisenberg model reaches an impressive 425 K, with the easy-axis oriented out-of-plane and high magnetic anisotropic energy (MAE). The asymmetry in the spin-resolved transmission spectrum induces a thermal spin current, providing an opportunity for spin filtration. This novel 2D FeB material is expected to hold great promise as an information storage medium and find applications in emerging spintronic devices.

Establishing theoretical landscapes for identifying basal plane active sites in MBene toward multifunctional HER, OER, and ORR catalysts

Exploring multifunctional electrocatalysts to realize efficient hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is urgently desired for developing novel renewable energy storage and conversion technologies. However, integrating these three merits in one single catalyst remains a big challenge due to the difficulty in balancing the adsorption strengths of multiple reaction intermediates. Herein, through first-principles calculations, we systematically investigated the electrocatalytic activity of M2B2, M3B4, and M4B6 type MBenes (M = Cr, Mn, Fe, Co, and Ni) for multifunctional HER, OER, and ORR. The results indicate that most of the investigated MBenes show outstanding catalytic activity for HER with hydrogen adsorption Gibbs free energy close to the optimal value (0 eV). Thereinto, Ni2B2 and Co3B4 MBenes can be promising multifunctional HER/OER/ORR electrocatalysts, and Fe3B4 MBene is expected to be a promising bifunctional electrocatalyst for HER/ORR. Especially, Ni2B2 MBene is even better than the benchmark RuO2 catalyst with ultralow low overpotentials of 0.26 and 0.30 V for OER and ORR, respectively. Then, we proposed that the overpotentials of OER/ORR can be well described by the varied ΔGOH* on MBene, which has been further illuminated through the d-band center and charge transfer analysis. Importantly, new scaling relations between the adsorption energies of OOH* and O* on MBenes have been established, where ΔGOOH* and ΔGO* possess different slopes versus ΔGOH*, allowing the significantly lower overpotentials of OER and ORR to be achieved. This work provides not only promising multifunctional HER/OER/ORR electrocatalysts but also new scaling relations to achieve the rational design of MBene-based electrocatalysts.

Crystal Engineering of BiVO4 for Photochemical Sensing of H2 S Gas at Ultra-low Concentration

We report a photochemical bismuth vanadate (BiVO4 ) sensing material, which possesses a large proportion of (110) and (011) facets combined with the additional (111) facets, for the selective detection of ultra-low concentration hydrogen sulfide (H2 S) driven by visible light. Specifically, the obtained octadecahedron BiVO4 (Octa-BiVO4 ) performs a high response value (67) and short response time (47.4 s) to 100 ppm H2 S with good stability for nearly 100 days, as well as undisturbedness by moist air. With the combination of experimental and theoretical calculation results, the adsorption and carrier transfer behaviors of H2 S molecules on the Octa-BiVO4 crystal surface are investigated. By adjusting the ratio of different crystal facets and controlling the facets with characteristic adsorption, we achieve improved anisotropic photoinduced carrier separation and high selectivity for a specific gas. Furthermore, this facial facet engineering can be extended to the synthesis of other sensing materials, offering huge opportunities for fundamental research and technological applications.

Predicted superconductivity in one-dimensional A3Hf2B3-type electrides

Inorganic electrides are considered potential superconductors due to the unique properties of their anionic electrons. However, most electrides require external high-pressure conditions to exhibit considerable superconducting transition temperatures (Tc). Therefore, searching for superconducting electrides under low or moderate external pressures is of significant research interest and importance. In this work, a series of A3Hf2B3-type compounds (A = Mg, Ca, Sr, Ba; B = Si, Ge, Sn, Pb) were constructed and systematically studied based on density functional theory calculations. According to the analysis of the electronic structures and phonon dispersion spectrums, stable one-dimensional electrides Ca3Hf2Ge3, Ca3Hf2Sn3, and Sr3Hf2Pb3, were screened out. Interestingly, the superconductivity of these electrides were predicted from electron phonon coupling calculations. It is highlighted that Sr3Hf2Pb3 showed the highest Tc, reaching 4.02 K, while the Tc values of Ca3Hf2Ge3 and Ca3Hf2Sn3 were 1.16 K and 1.04 K, respectively. Moreover, the Tc value of Ca3Hf2Ge3 can be increased to 1.96 K under 20 GPa due to the effect of phonon softening. This work enriches the types of superconducting electrides and has important guiding significance for the research on constructing electrides and related superconducting materials.

Unraveling the Emerging Photocatalytic, Thermoelectric, and Topological Properties of Intercalated Architecture MZX (M = Ga and In; Z = Si, Ge and Sn; X = S, Se, and Te) Monolayers

The continuous advancements in studying two-dimensional (2D) materials pave the way for groundbreaking innovations across various industries. In this study, by employing density functional theory calculations, we comprehensively elucidate the electronic structures of MZX (M = Ga and In; Z = Si, Ge, and Sn; X = S, Se, and Te) monolayers for their applications in photocatalytic, thermoelectric, and spintronic fields. Interestingly, GaSiS, GaSiSe, InSiS, and InSiSe monolayers are identified to be efficient photocatalysts for overall water splitting with band gaps close to 2.0 eV, suitable band edge positions, and excellent optical harvest ability. In addition, the InSiTe monolayer exhibits a ZT value of 1.87 at 700 K, making it highly appealing for applications in thermoelectric devices. It is further highlighted that GaSnTe, InSnS, and InSnSe monolayers are predicted to be 2D topological insulators (TIs) with bulk band gaps of 115, 54, and 152 meV, respectively. Current research expands the family of 2D GaGeTe materials and establishes a path toward the practical utilization of MZX monolayers in energy conversion and spintronic devices.

Artificial Post-Cycled Structure Modulation Towards Highly Stable Li-Rich Layered Cathode

High-capacity Li-rich layered oxides (LLOs) suffer from severe structure degradation due to the utilization of hybrid anion- and cation-redox activity. The native post-cycled structure, composed of progressively densified defective spinel layer (DSL) and intrinsic cations mixing, is deemed as the hindrance of the rapid and reversible de/intercalation of Li+ . Herein, the artificial post-cycled structure consisting of artificial DSL and inner cations mixing is in situ constructed, which would act as a shield against the irreversible oxygen emission and undesirable transition metal migration by suppressing anion redox activity and modulating cation mixing. Eventually, the modified DSL-2% Li-rich cathode demonstrates remarkable electrochemical properties with a high discharge capacity of 187 mAh g-1 after 500 cycles at 2 C, and improved voltage stability. Even under harsh operating conditions of 50 °C, DSL-2% can provide a high discharge capacity of 168 mAh g-1 after 250 cycles at 2 C, which is much higher than that of pristine LLO (92 mAh g-1 ). Furthermore, the artificial post-cycled structure provides a novel perspective on the role of native post-cycled structure in sustaining the lattice structure of the lithium-depleted region and also provides an insightful universal design principle for highly stable intercalated materials with anionic redox activity.

Synergism of Edge Effect and Interlayer Engineering of VS2 on CNFs for Rapid and Precise NO2 Detection

Although two-dimensional (2D) transition-metal dichalcogenides (TMDs) exhibit attractive prospects for gas-sensing applications, the rapid and precise sensing of TMDs at low loss remains challenging. Herein, a NO2 sensor based on an expanded VS2 (VS2-E)/carbon nanofibers (CNFs) composite (abbreviated as VS2-E-C) with ultrafast response/recovery at a low-loss state is reported. In particular, the impact of the CNF content on the NO2-sensing performance of VS2-E-C was thoroughly explored. Expanded VS2 nanosheets were grafted onto the surface of hollow CNFs, and the combination boosted the charge transport, exposing abundant active edges of VS2, which enhanced the adsorption of NO2 efficiently. The activity of the VS2 edge is further confirmed by stronger NO2 adsorption with a more negative adsorption energy (-3.42 eV) and greater than the basal VS2 surface (-1.26 eV). Moreover, the exposure of rich edges induced the emergence of the expanded interlayers, which promoted the adsorption/desorption of NO2 and the interaction of gas molecules within VS2-E-C. The synergism of edge effect and interlayer engineering confers the VS2-E-C3 sensor with ultrafast response/recovery speed (9/10 s) at 60 °C, high sensitivity (∼2.50 to 15 ppm NO2), good selectivity/stability, and a low detection limit of 23 ppb. The excellent "4S" functions indicate the promising prospect of the VS2-E-C3 sensor for fast and precise NO2 detection at low-loss condition.

Stable Harsh-Temperature Lithium Metal Batteries Enabled by Tailoring Solvation Structure in Ether Electrolytes

For lithium metal batteries (LMBs), the elevated operating temperature results in severe capacity fading and safety issues due to unstable electrode-electrolyte interphases and electrolyte solvation structures. Therefore, it is crucial to construct advanced electrolytes capable of tolerating harsh environments to ensure stable LMBs. Here, we proposed a stable localized high-concentration electrolyte (LHCE) by introducing the highly solvating power solvent diethylene glycol dimethyl ether (DGDME). Computational and experimental evidence discloses that the original DGDME-LHCE shows favorable features for high-temperature LMBs, including high Li+-binding stability, electro-oxidation resistance, thermal stability, and nonflammability. The tailored solvated sheath structure achieves the preferred decomposition of anions, inducing the stable (cathode and Li anode)/interphases simultaneously, which enables a homogeneous Li plating-stripping behavior on the anode side and a high-voltage tolerance on the cathode side. For the Li||Li cells coupled with DGDME-LHCE, they showcase outstanding reversibility (a long lifespan of exceeding 1900 h). We demonstrate exceptional cyclic stability (∼95.59%, 250 cycles), high Coulombic efficiency (>99.88%), and impressive high-voltage (4.5 V) and high-temperature (60 °C) performances in Li||NCM523 cells using DGDME-LHCE. Our advances shed light on an encouraging ether electrolyte tactic for the Li-metal batteries confronted with stringent high-temperature challenges.

Out-of-plane polarization modulated band alignments inβ-In2X3/α-In2X3(X = S and Se) vdW heterostructures

The construction of two-dimensional (2D) van der Waals (vdW) heterostructures is an effective strategy to overcome the intrinsic disadvantages of individual 2D materials. Herein, by employing first-principles calculations, the electronic structures and potential applications in the photovoltaic field of theβ-In2X3/α-In2X3(X = S and Se) vdW heterostructures have been systematically unraveled. Interestingly, the band alignments ofβ-In2S3/α-In2S3,β-In2Se3/α-In2Se3, andβ-In2Se3/α-In2S3heterostructures can be transformed from type-I to type-II by switching the polarization direction ofα-In2X3layers. It is highlighted that the light-harvesting ability of theβ-In2X3/α-In2X3vdW heterostructures is significantly higher than the corresponding monolayers in nearly the entire visible light region. Interestingly, type-IIβ-In2S3/α-In2Se3↓ heterostructure can achieve the power conversion efficiency of 17.9%, where theα-In2Se3layer acts as a donor and theβ-In2S3layer displays as the acceptor. The present research not only provides an in-depth understanding that the out-of-plane polarization ofα-In2X3monolayers can efficiently modulate the band edge alignment of theβ-In2X3/α-In2X3vdW heterostructures, but also paves the way for the application of these heterostructures in the field of photovoltaics and optoelectronics.

Enhanced Electrochemical Performance of a Ti-Cr-Doped LiMn1.5Ni0.5O4 Cathode Material for Lithium-Ion Batteries

Ti, Cr dual-element-doped LiMn_1.5Ni_0.5O₄ (LNMO) cathode materials (LTNMCO) were synthesized by a simple high-temperature solid-phase method. The obtained LTNMCO shows the standard structure of the Fd3®m space group, and the Ti and Cr doped ions may replace the Ni and Mn sites in LNMO, respectively. The effect of Ti-Cr doping and single-element doping on the structure of LNMO was studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) characteristics. The LTNMCO exhibited excellent electrochemical properties with a specific capacity of 135.1 mAh·g^-1 for the first discharge cycle and a capacity retention rate of 88.47% at 1C after 300 cycles. The LTNMCO also has high rate performance with a discharge capacity of 125.4 mAh·g^-1 at a 10C rate, 93.55% of that at 0.1C. In addition, the CIV and EIS results show that the LTNMCO showed the lowest charge transfer resistance and the highest diffusion coefficient of lithium ions. The enhanced electrochemical properties may be due to a more stable structure and an optimized Mn³⁺ content in LTNMCO through TiCr doping.

Regulation of Interfacial Lattice Oxygen Activity by Full-Surface Modification Engineering towards Long Cycling Stability for Co-Free Li-Rich Mn-Based Cathode

The construction of a protective layer for stabilizing anion redox reaction is the key to obtaining long cycling stability for Li-rich Mn-based cathode materials. However, the protection of the exposed surface/interface of the primary particles inside the secondary particles is usually ignored and difficult, let alone the investigation of the impact of the surface engineering of the internal primary particles on the cycling stability. In this work, an efficient method to regulate cycling stability is proposed by simply adjusting the distribution state of the boron nickel complexes coating layer. Theoretical calculation and experimental results display that the full-surface boron nickel complexes coating layer can not only passivate the activity of interface oxygen and improve its stability but also play the role of sharing voltage and protective layer to gradually activate the oxygen redox reaction during cycling. As a result, the elaborately designed cobalt-free Li-rich Mn-based cathode displays the highest discharge-specific capacity retentions of 91.1% after 400 cycles at 1 C and 94.3% even after 800 cycles at 5 C. In particular, the regulation strategy has well universality and is suitable for other high-capacity Li-rich cathode materials.

Promising M2CO2/MoX2 (M = Hf, Zr; X = S, Se, Te) Heterostructures for Multifunctional Solar Energy Applications

Two-dimensional van der Waals (vdW) heterostructures are potential candidates for clean energy conversion materials to address the global energy crisis and environmental issues. In this work, we have comprehensively studied the geometrical, electronic, and optical properties of M₂CO₂/MoX₂ (M = Hf, Zr; X = S, Se, Te) vdW heterostructures, as well as their applications in the fields of photocatalytic and photovoltaic using density functional theory calculations. The lattice dynamic and thermal stabilities of designed M₂CO₂/MoX₂ heterostructures are confirmed. Interestingly, all the M₂CO₂/MoX₂ heterostructures exhibit intrinsic type-II band structure features, which effectively inhibit the electron-hole pair recombination and enhance the photocatalytic performance. Furthermore, the internal built-in electric field and high anisotropic carrier mobility can separate the photo-generated carriers efficiently. It is noted that M₂CO₂/MoX₂ heterostructures exhibit suitable band gaps in comparison to the M₂CO₂ and MoX₂ monolayers, which enhance the optical-harvesting abilities in the visible and ultraviolet light zones. Zr₂CO₂/MoSe₂ and Hf₂CO₂/MoSe₂ heterostructures possess suitable band edge positions to provide the competent driving force for water splitting as photocatalysts. In addition, Hf₂CO₂/MoS₂ and Zr₂CO₂/MoS₂ heterostructures deliver a power conversion efficiency of 19.75% and 17.13% for solar cell applications, respectively. These results pave the way for exploring efficient MXenes/TMDCs vdW heterostructures as photocatalytic and photovoltaic materials.

Strain-Dependent Band Splitting and Spin-Flip Dynamics in Monolayer WS2

Triggered by the expanding demands of semiconductor devices, strain engineering of two-dimensional transition metal dichalcogenides (TMDs) has garnered considerable research interest. Through steady-state measurements, strain has been proved in terms of its modulation of electronic energy bands and optoelectronic properties in TMDs. However, the influence of strain on the spin-orbit coupling as well as its related valley excitonic dynamics remains elusive. Here, we demonstrate the effect of strain on the excitonic dynamics of monolayer WS₂ via steady-state fluorescence and transient absorption spectroscopy. Combined with theoretical calculations, we found that tensile strain can reduce the spin-splitting value of the conduction band and lead to transitions between different exciton states via spin-flip mechanism. Our findings suggest that the spin-flip process is strain-dependent, provides a reference for application of valleytronic devices, where tensile strain is usually existing during their design and fabrication.

How to Realize Ultrahigh Photochromic Performance for Real-Time Optical Recording in Transparent Ceramics

A combination of transparency and photochromic (PC) properties in ferroelectrics has promising application potential in smart windows and optical storage/imaging. Nonetheless, limited by understanding the underlying PC mechanism, a splendid PC performance is rarely achieved in transparent ferroelectrics. Here, a strategy to construct deep-lying traps by ion-doping induced defect engineering in (K_0.5Na_0.5)NbO₃-based ferroelectric ceramics is proposed. Based on the improved density functional theory simulations, a high concentration of vacancy defects can be realized by codoping 1 mol % Pr and 4 mol % Ba in (K_0.5Na_0.5)NbO₃, which helps achieving deep-lying traps and then superior PC performance. Through traditional pressureless sintering, highly transparent ceramics with designed optimal composition have been fabricated in a wide sintering temperature range (1170-1210 °C), exhibiting an ultrafast PC feature, i.e., 0.1 s response time (by illumination of 400 nm light), along with high PC efficiency (5.8 cm²·W^-1) and PC rate (7.1 s^-1), preeminent among reported inorganic PC transparent materials. Additionally, the ceramics have been utilized for real-time optical recording, displaying unambiguous patterning with long-time preservation (21 days). This research supplies a paradigm for designing high-performance PC transparent materials in optical applications and helps deepen the comprehensive understanding of the PC mechanism.

Ultrasensitive Detection for Lithium-Ion Battery Electrolyte Leakage by Rare-Earth Nd-Doped SnO2 Nanofibers

The problems of lithium-ion battery (LIB) failure have attracted growing attention since flammable and explosive electrolyte leakage might lead to serious consequences. However, due to the redox-neutral and volatile nature of main electrolyte components, such as dimethyl carbonate (DMC), trace leakages are difficult to detect. Therefore, research on LIB electrolyte sensors is urgent and lacking. Herein, sensors based on rare-earth Nd-doped SnO₂ nanofibers are reported for detecting DMC vapor in LIB. The excellent sensitivity (distinct response to 20 ppb DMC), high response (∼38.13-50 ppm DMC), and superior selectivity and stability of 3%Nd-SnO₂ suggest that it should be a promising candidate for LIB safety monitors. Meanwhile, it also shows clear and rapid response during the LIB-leakage real-time detection experiment. The doping of Nd endows SnO₂ with more oxygen vacancy defects. In addition, the highly active Nd sites greatly enhanced the adsorption energy of DMC on SnO₂. All of these features contribute to the improvement of DMC-sensing performances.

Dual-Functional Lithiophilic/Sulfiphilic Binary-Metal Selenide Quantum Dots Toward High-Performance Li-S Full Batteries

The commercial viability of lithium-sulfur batteries is still challenged by the notorious lithium polysulfides (LiPSs) shuttle effect on the sulfur cathode and uncontrollable Li dendrites growth on the Li anode. Herein, a bi-service host with Co-Fe binary-metal selenide quantum dots embedded in three-dimensional inverse opal structured nitrogen-doped carbon skeleton (3DIO FCSe-QDs@NC) is elaborately designed for both sulfur cathode and Li metal anode. The highly dispersed FCSe-QDs with superb adsorptive-catalytic properties can effectively immobilize the soluble LiPSs and improve diffusion-conversion kinetics to mitigate the polysulfide-shutting behaviors. Simultaneously, the 3D-ordered porous networks integrated with abundant lithophilic sites can accomplish uniform Li deposition and homogeneous Li-ion flux for suppressing the growth of dendrites. Taking advantage of these merits, the assembled Li-S full batteries with 3DIO FCSe-QDs@NC host exhibit excellent rate performance and stable cycling ability (a low decay rate of 0.014% over 2,000 cycles at 2C). Remarkably, a promising areal capacity of 8.41 mAh cm-2 can be achieved at the sulfur loading up to 8.50 mg cm-2 with an ultra-low electrolyte/sulfur ratio of 4.1 μL mg-1. This work paves the bi-serve host design from systematic experimental and theoretical analysis, which provides a viable avenue to solve the challenges of both sulfur and Li electrodes for practical Li-S full batteries.

Computational mining of GeH-based Janus III-VI van der Waals heterostructures for solar cell applications

The asymmetrical group III-VI monolayer Janus M₂XY (M = Al, Ga, In; X ≠ Y = S, Se, Te) have attracted widespread attention due to their significant optical absorption properties, which are the potential building blocks for van der Waals (vdW) heterostructure solar cells. In this study, we unraveled an In₂STe/GeH vdW heterostructure as a candidate for solar cells by screening the Janus M₂XY and GeH monolayers on lattice mismatches and electronic band structures based on first-principles calculations. The results highlight that the In₂STe/GeH vdW heterostructure exhibits a type-II band gap of 1.25 eV. The optical absorption curve of the In₂STe/GeH vdW heterostructure indicates that it possesses significant optical absorption properties in the visible and ultraviolet light areas. In addition, we demonstrate that the In₂STe/GeH vdW heterostructure shows high and directionally anisotropic carrier mobility and good stability. Furthermore, strain engineering improves the theoretical power conversion efficiency of the In₂STe/GeH vdW heterostructure up to 19.71%. Our present study will provide an idea for designing Janus M₂XY and GeH monolayer-based vdW heterostructures for solar cell applications.

Giant tunneling magnetoresistance in two-dimensional magnetic tunnel junctions based on double transition metal MXene ScCr2C2F2

Two-dimensional (2D) transition metal carbides (MXenes) with intrinsic magnetism and half-metallic features show great promising applications for spintronic and magnetic devices, for instance, achieving perfect spin-filtering in van der Waals (vdW) magnetic tunnel junctions (MTJs). Herein, combining density functional theory calculations and nonequilibrium Green's function simulations, we systematically investigated the spin-dependent transport properties of 2D double transition metal MXene ScCr₂C₂F₂-based vdW MTJs, where ScCr₂C₂F₂ acts as the spin-filter tunnel barriers, 1T-MoS₂ acts as the electrode and 2H-MoS₂ as the tunnel barrier. We found that the spin-up electrons in the parallel configuration state play a decisive role in the transmission behavior. We found that all the constructed MTJs could hold large tunnel magnetoresistance (TMR) ratios over 9 × 10⁵%. Especially, the maximum giant TMR ratio of 6.95 × 10⁶% can be found in the vdW MTJ with trilayer 2H-MoS₂ as the tunnel barrier. These results indicate the potential for spintronic applications of vdW MTJs based on 2D double transition metal MXene ScCr₂C₂F₂.

Influence of Al-O and Al-C Clusters on Defects in Graphene Nanosheets Derived from Coal-Tar Pitch via Al4C3 Precursor

By treating Al₄C₃ as the precursor and growth environment, graphene nanosheets (GNs) can efficiently be derived from coal-tar pitch, which has the advantages of simple preparation process, high product quality, green environmental protection, low equipment requirements and low preparation cost. However, the defects in the prepared GNs have not been well understood. In order to optimize the preparation process, based on density functional theory calculations, the influence mechanism of Al-O and Al-C clusters on defects in GNs derived from coal-tar pitch via Al₄C₃ precursor has been systematically investigated. With minute quantities of oxygen-containing defects, Al-O and Al-C clusters have been realized in the prepared GNs from X-ray photoelectron spectroscopy analysis. Therefore, the influences of Al-O and Al-C clusters on graphene with vacancy defects and oxygen-containing defects are systematically explored from theoretical energy, electron localization function and charge transfer analysis. It is noted that the remaining Al-O and Al-C clusters in GNs are inevitably from the thermodynamics point of view. On the other hand, the existence of defects is beneficial for the further adsorption of Al-O and Al-C clusters in GNs.

Adjustable Mixed Conductive Interphase for Dendrite-Free Lithium Metal Batteries

Lithium (Li) metal batteries with high energy density are of great promise for next-generation energy storage; however, they suffer from severe Li dendritic growth and an unstable solid electrolyte interphase. In this study, a mixed ionic and electronic conductive (MIEC) interphase layer with an adjustable ratio assembled by ZnO and Zn nanoparticles is developed. During the initial cycle, the in situ formed Li₂O with high ionic conductivity and a lithiophilic LiZn alloy with high electronic conductivity enable fast Li⁺ transportation in the interlayer and charge transfer at the ion/electron conductive junction, respectively. The optimized interface kinetics is achieved by balancing the ion migration and charge transfer in the MIEC Li₂O-LiZn interphase. As a result, the symmetric cell with MIEC interphase delivers superior cycling stability of over 1200 h. Also, Li||Zn-ZnO@PP||LFP (LFP = LiFePO₄) full cells exhibit long cyclic life for 2000 cycles with a very high capacity retention of 91.5% at a high rate of 5 C and stable cycling for 350 cycles at a high LFP loading mass of 13.27 mg cm^-2.

Strain-Enhanced Thermoelectric Performance in GeS2 Monolayer

Strain engineering has attracted extensive attention as a valid method to tune the physical and chemical properties of two-dimensional (2D) materials. Here, based on first-principles calculations and by solving the semi-classical Boltzmann transport equation, we reveal that the tensile strain can efficiently enhance the thermoelectric properties of the GeS₂ monolayer. It is highlighted that the GeS₂ monolayer has a suitable band gap of 1.50 eV to overcome the bipolar conduction effects in materials and can even maintain high stability under a 6% tensile strain. Interestingly, the band degeneracy in the GeS₂ monolayer can be effectually regulated through strain, thus improving the power factor. Moreover, the lattice thermal conductivity can be reduced from 3.89 to 0.48 W/mK at room temperature under 6% strain. More importantly, the optimal ZT value for the GeS₂ monolayer under 6% strain can reach 0.74 at room temperature and 0.92 at 700 K, which is twice its strain-free form. Our findings provide an exciting insight into regulating the thermoelectric performance of the GeS₂ monolayer by strain engineering.

Hybrid Chiral MoS2 Layers for Spin-Polarized Charge Transport and Spin-Dependent Electrocatalytic Applications

The chiral-induced spin selectivity effect enables the application of chiral organic materials for spintronics and spin-dependent electrochemical applications. It is demonstrated on various chiral monolayers, in which their conversion efficiency is limited. On the other hand, relatively high spin polarization (SP) is observed on bulk chiral materials; however, their poor electronic conductivities limit their application. Here, the design of chiral MoS₂ with a high SP and high conductivity is reported. Chirality is introduced to the MoS₂ layers through the intercalation of methylbenzylamine molecules. This design approach activates multiple tunneling channels in the chiral layers, which results in an SP as high as 75%. Furthermore, the spin selectivity suppresses the production of H₂ O₂ by-product and promotes the formation of ground state O₂ molecules during the oxygen evolution reaction. These potentially improve the catalytic activity of chiral MoS₂ . The synergistic effect is demonstrated as an interplay of the high SP and the high catalytic activity of the MoS₂ layer on the performance of the chiral MoS₂ for spin-dependent electrocatalysis. This novel approach employed here paves way for the development of other novel chiral systems for spintronics and spin-dependent electrochemical applications.

Computational design of double transition metal MXenes with intrinsic magnetic properties

Two-dimensional transition metal carbides (MXenes) have great potential to achieve intrinsic magnetism due to their available chemical and structural diversity. In this work, by spin-polarized density functional theory calculations, we designed and comprehensively investigated 50 double transition metal (DTM) MXenes MCr₂CT_x (T = H, O, F, OH, or bare) based on the chemical formula of M₂C (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Mo, W). We highlight that ferromagnetic half-metallicity, antiferromagnetic semiconduction, as well as antiferromagnetic half-metallicity have been achieved in the DTM MXenes. Herein, ferromagnetic half-metallic ScCr₂C₂, ScCr₂C₂H₂, ScCr₂C₂F₂, and YCr₂C₂H₂ are characterized with wide band gaps and high Curie temperatures. Very interestingly, the ScCr₂C₂-based magnetic tunnel junction presents a tunnel magnetoresistance ratio as high as 176 000%. In addition, the antiferromagnetic semiconducting TiCr₂C₂, ZrCr₂C₂, and ZrCr₂C₂(OH)₂, possessing moderate band gaps and high Néel temperatures, have been predicted. Especially, the Néel temperature of ZrCr₂C₂(OH)₂ can reach 425 K. Moreover, the Dirac cone-like band structure feature is highlighted in antiferromagnetic half-metallic ZrCr₂C₂H₂. Our study provides a new potential strategy for designing MXenes in spintronics.

Direct Z-scheme WTe2/InSe van der Waals heterostructure for overall water splitting

WTe2/InSe is a direct Z-scheme vdW heterostructure for water splitting. The Te-vacancy can effectively lower the energy of the HER, and the overall water splitting can proceed spontaneously on the surface of the WTe2/InSe heterostructure when pH > 7.

The interlayer coupling modulation of a g-C3N4/WTe2 heterostructure for solar cell applications

Constructing van der Waals (vdW) heterostructures has been proved to be an excellent strategy to design or modulate the physical and chemical properties of 2D materials. Here, we investigated the electronic structures and solar cell performances of the g-C₃N₄/WTe₂ heterostructure via first-principles calculations. It is highlighted that the g-C₃N₄/WTe₂ heterostructure presents a type-II band edge alignment with a band gap of 1.24 eV and a corresponding visible light absorption coefficient of ∼10⁶ cm⁻¹ scale. Interestingly, the band gap of the g-C₃N₄/WTe₂ heterostructure could increase to 1.44 eV by enlarging the vdW gap to harvest more visible light energy. It is worth noting that the decreased band alignment difference resulting from tuning the vdW gap, leads to a promotion of the power conversion efficiency up to 17.68%. This work may provide theoretical insights into g-C₃N₄/WTe₂ heterostructure-based next-generation solar cells, as well as a guide for tuning properties of vdW heterostructures.

g-C₃N₄/WTe₂ heterostructure with tunable vdW gap shows a favorable solar energy conversion performance.

Computational mining of endohedral C70 electrides: tri-metal alkali and alkaline-earth encapsulation

Based on the atoms in molecules analysis, electron localization functions, and nonlinear optical property analysis, M3@C70 (M = Li, Be, Mg, Ca) fullerenes are identified as electrides.

Comprehensive understanding of intrinsic mobility and sub-10 nm quantum transportation in Ga2SSe monolayer

Two-dimensional chalcogenides could play an important role to solve the short channel effect and extend the Moore's law in the post-Moore's era due to the excellent performances in the spintronics...

Layer-Tunable Nonlinear Optical Characteristics and Photocarrier Dynamics of 2D PdSe2 in Broadband Spectra

Layered 2D transition metal dichalcogenides (TMDCs) exhibited fascinating nonlinear optical (NLO) properties for constructing varied promising optoelectronics. However, exploring the desired 2D materials with both superior nonlinear absorption and ultrafast response in broadband spectra remain the key challenges to harvest their greatest potential. Here, based on synthesizing 2D PdSe₂ films with the controlled layer number, the authors systematically demonstrated the broadband giant NLO performance and ultrafast excited carrier dynamics of this emerging material under femtosecond visible-to-near-infrared laser-pulse excitation (400-1550 nm). Layer-dependent and wavelength-dependent evolution of optical bandgap, nonlinear absorption, and photocarrier dynamics in the obtained 2D PdSe₂ are clearly revealed. Specially, the transition from semiconducting to semimetallic PdSe₂ induced dramatic changes of their interband absorption-relaxation process. This work makes 2D PdSe₂ more competitive for future ultrafast photonics and also opens up a new avenue for the optical performance optimization of various 2D materials by rational design of these materials.

Computational discovery of PtS2/GaSe van der Waals heterostructure for solar energy applications

2D van der Waals (vdW) heterostructures as potential materials for solar energy-related applications have been brought to the forefront for researchers. Here, by employing first-principles calculations, we proposed that the PtS₂/GaSe vdW heterostructure is a distinguished candidate for photocatalytic water splitting and solar cells. It is shown that the PtS₂/GaSe heterostructure exhibits high thermal stability with an indirect band gap of 1.81 eV. We further highlighted the strain induced type-V to type-II band alignment transitions and band gap variations in PtS₂/GaSe heterostructures. More importantly, the outstanding absorption coefficients in the visible light region and high carrier mobility further guarantee the photo energy conversion efficiency of PtS₂/GaSe heterostructures. Interestingly, the natural type-V band alignments of PtS₂/GaSe heterostructures are appropriate for the redox potential of water. On the other hand, the power conversion efficiency of ZnO/(PtS₂/GaSe heterostructure)/CIGS (copper indium gallium diselenide) solar cells can achieve ∼17.4%, which can be further optimized up to ∼18.5% by increasing the CIGS thickness. Our present study paves the way for facilitating the potential application of vdW heterostructures as a promising photocatalyst for water splitting as well as the buffer layer for solar cells.

A Universal Strategy toward the Precise Regulation of Initial Coulombic Efficiency of Li-Rich Mn-Based Cathode Materials

Li-rich Mn-based cathode materials (LRMs) are potential cathode materials for high energy density lithium-ion batteries. However, low initial Coulombic efficiency (ICE) severely hinders the commercialization of LRM. Herein, a facile oleic acid-assisted interface engineering is put forward to precisely control the ICE, enhance reversible capacity and rate performance of LRM effectively. As a result, the ICE of LRM can be precisely adjusted from 84.1% to 100.7%, and a very high specific capacity of 330 mAh g^-1 at 0.1 C, as well as outstanding rate capability with a fascinating specific capacity of 250 mAh g^-1 at 5 C, are harvested. Theoretical calculations reveal that the introduced cation/anion double defects can reduce the diffusion barrier of Li⁺ ions, and in situ surface reconstruction layer can induce a self-built-in electric field to stabilize the surface lattice oxygen. Moreover, this facile interface engineering is universal and can enhance the ICEs of other kinds of LRM effectively. This work provides a valuable new idea for improving the comprehensive electrochemical performance of LRM through multistrategy collaborative interface engineering technology.

InSe/Te van der Waals Heterostructure as a High-Efficiency Solar Cell from Computational Screening

Designing the electronic structures of the van der Waals (vdW) heterostructures to obtain high-efficiency solar cells showed a fascinating prospect. In this work, we screened the potential of vdW heterostructures for solar cell application by combining the group III–VI MX_A (M = Al, Ga, In and X_A = S, Se, Te) and elementary group VI X_B (X_B = Se, Te) monolayers based on first-principle calculations. The results highlight that InSe/Te vdW heterostructure presents type-II electronic band structure feature with a band gap of 0.88 eV, where tellurene and InSe monolayer are as absorber and window layer, respectively. Interestingly, tellurene has a 1.14 eV direct band gap to produce the photoexcited electron easily. Furthermore, InSe/Te vdW heterostructure shows remarkably light absorption capacities and distinguished maximum power conversion efficiency (PCE) up to 13.39%. Our present study will inspire researchers to design vdW heterostructures for solar cell application in a purposeful way.

Structural, Electronic, and Nonlinear Optical Properties of C66H4 and C70Cl6 Encapsulating Li and F Atoms

Recently, nonclassical fullerene derivatives C66H4 and C70Cl6, which both contain two negatively curved moieties of heptagons, have been successfully synthesized. Inspired by these experimental achievements, the structural and electronic properties of C66H4, C70Cl6, Li@C66H4, F@C66H4, Li@C70Cl6, and F@C70Cl6 were systematical studied through density functional theory calculations in this work. Our results show that the reduction of the front molecular orbital gap of fullerene derivatives occurs with the introduction of Li and F atoms. After quantitative analysis of back-donations of charge between an encapsulated atom and an external carbon cage, it is found that C66H4 and C70Cl6 prefer to act as electron acceptors. It is interesting to note that the strong covalent nature of the interactions between a F atom and a carbon cage is observed, whereas the weak covalent and strong ionic interactions occur between a Li atom and a carbon cage. On the other hand, according to the first hyperpolarizability results, the encapsulation of the Li atom enhances the nonlinear optical response of fullerene derivatives. This work provides a strategy to improve nonlinear optical properties of C66H4 and C70Cl6, reveals the internal mechanism of the contribution from Li and F atoms to endohedral fullerene derivatives, and will contribute to the designation of endohedral fullerene derivative devices.

Multiscale Deficiency Integration by Na-Rich Engineering for High-Stability Li-Rich Layered Oxide Cathodes

Lithium-rich manganese-based (LRM) layered oxides are considered as one of the most promising cathode materials for next-generation high-energy-density lithium-ion batteries (LIBs) because of their high specific capacity (>250 mAh g^-1). However, they also go through severe capacity decay, serious voltage fading, and poor rate capability during cycling. Herein, a multiscale deficiency integration, including surface coating, subsurface defect construction, and bulk doping, is realized in a Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ cathode material by facile Na-rich engineering through a sol-gel method. This multiscale design can significantly improve the bulk and surface structural stability and diffusion rate of Li⁺ ions of electrode materials. Specifically, an outstanding specific capacity of 201 mAh g^-1 is delivered at 1C of the designed cathode material after 400 cycles, relating to a large capacity retention of 89.0%. Meanwhile, the average voltage is retained up to 3.13 V with a large voltage retention of 89.6% and the energy density is maintained at 627.4 Wh kg^-1. In situ X-ray diffraction (XRD), ex situ transmission electron microscopy (TEM) investigations, and density functional theory (DFT) calculations are conducted to explain the greatly enhanced electrochemical properties of a LRM cathode. We believe that this strategy would be a meaningful reference of LRM cathode materials for the research in the future.

Rapid and Large-Scale Quality Assessment of Two-Dimensional MoS2 Using Sulfur Particles with Optical Visualization

The efficient nondestructive assessment of quality and homogeneity for two-dimensional (2D) MoS₂ is critically important to advance their practical applications. Here, we presented a rapid and large-area assessment method for visually evaluating the quality and uniformity of chemical vapor deposition (CVD)-grown MoS₂ monolayers simply with conventional optical microscopes. This was achieved through one-pot adsorbing abundant sulfur particles selectively onto as-grown poorer-quality MoS₂ monolayers in a CVD system without any additional treatment. We further revealed that this favorable adsorption of sulfur particles on MoS₂ originated from their intrinsic higher-density sulfur vacancies. Based on unadsorbed MoS₂ monolayers, superior performance field effect transistors with a mobility of ∼49 cm² V^-1 s^-1 were constructed. Importantly, the assessment approach was noninvasive due to the all-vapor-phase and moderate adsorption-desorption process. Our work offers a new route for the performance and yield optimization of devices by quality assessment of 2D semiconductors prior to device fabrication.