Sp2 Carbon Research Articles

Homo-Mannich Reaction of Cyclopropanols: A Versatile Tool for Natural Product Synthesis.

ConspectusThe Mannich reaction, involving the nucleophilic addition of an enol(ate) intermediate to an imine or iminium ion, is one of the most widely used synthetic methods for the synthesis of β-amino carbonyl compounds. Nevertheless, the homo-Mannich reaction, which utilizes a homoenolate intermediate as the nucleophilic partner and provides straightforward access to the valuable γ-amino carbonyl compounds, remains underexplored. This can be largely attributed to the difficulties in generation and manipulation of the homoenolate species, despite various homoenolate equivalents that have been developed. Among the homoenolate equivalents developed, cyclopropanol stands out due to its intriguing reactivities endowed by the highly strained cyclopropane. Upon activation by a metal, cyclopropyl alcohol is prone to undergo an endocyclic C(sp3)-C(sp3) bond cleavage to give a homoenolate intermediate or a β-keto radical intermediate, which sets the stage for a diverse range of transformations. This account outlines our recent progress in the development of homo-Mannich reaction of cyclopropanol and its applications in natural product total synthesis. This new methodology can be classified into two subtypes: 1) the homo-Mannich reaction of cyclopropanol with imines or iminium ions and 2) the homo-Mannich-type reaction of cyclopropanol with heteroarenes. Through different ways to generate imines or iminium ions, tandem or sequential reactions of C-H oxidation/homo-Mannich, Bischler-Napieralski/homo-Mannich, and asymmetric allylation/homo-Mannich have been developed, leading to the rapid assembly of core scaffolds of sarpagine, koumine, ibophyllidine, Aspidosperma, Melodinus, and Kopsia alkaloids. Besides the reactions with imines or iminium ions, cyclopropyl alcohol can undergo ring-opening addition to indole and pyrrole rings to deliver core scaffolds of schizozygane and indolizidine alkaloids. Based on these methodology advancements, we have accomplished the asymmetric synthesis of 29 alkaloids belonging to 8 families. In this Account, we present a complete picture of our works concerning synthetic design, method development, and applications in natural product total synthesis. It is anticipated that the development of new methodologies of cyclopropyl alcohol will find broad applications in the realm of natural product synthesis.

On-Surface Synthesis and Characterization of Pentadecacene and Its Gold Complexes.

Acenes are an important class of polycyclic aromatic hydrocarbons that have gained considerable attention from chemists, physicists, and material scientists, due to their exceptional potential for organic electronics. They serve as an ideal platform for studying the physical and chemical properties of sp2 carbon frameworks in the one-dimensional limit and also provide a fertile playground to explore magnetism in graphenic nanostructures due to their zigzag edge topology. While higher acenes up to tridecacene have been successfully generated by means of on-surface synthesis, it is imperative to extend their synthesis toward even longer homologues to comprehensively understand the evolution of their electronic ground state. Here, we demonstrate the on-surface synthesis of pentadecacene (15ac) from a trietheno-bridged precursor via the atom-manipulation-induced dissociation of protecting groups or the elimination of adatoms in a gold-pentadecacene complex. The generated 15ac was investigated by scanning tunneling microscopy (STM)/spectroscopy (STS) and noncontact atomic force microscopy (nc-AFM), in combination with first-principles spin-polarized density functional theory (DFT) calculations. We found that 15ac exhibits an open-shell singlet ground state with an experimental singlet-triplet gap of 124 meV and an STS transport gap of ∼1.12 eV. The formation of Au-pentadecacene complexes suggested a considerable contribution of polyradical character to the electronic ground state of 15ac. Our work contributes to a fundamental understanding of the electronic properties of long acenes and to the development of a versatile STM tip-assisted methodology for the synthesis of elusive compounds.

Sequential Conversion of Vinyl Triflates to 1,2-Disilanes via Technical Control of Magnesium and Calcium Reducibility Differences.

Reductive direct substitution of α-arylvinyl triflates on the sp2 carbon atom by magnesium in the presence of chlorosilane proceeded to give the corresponding α-silylstyrenes, which could not be reduced further, and the reaction completely stopped because the reduction potential of α-silylstyrenes lies out of the reducible field of magnesium. The subsequent reduction of α-silylstyrenes by calcium brought about the second introduction of another silyl group to the vicinal carbon atom to lead a selective and simple route to a variety of 1,2-disilanes from vinyl triflates by cooperative works of magnesium and calcium with different reduction potentiality.

Interrogation of Enantioselectivity in the Photomediated Ring Contractions of Saturated Heterocycles.

We recently reported a chiral phosphoric acid (CPA) catalyzed enantioselective photomediated ring contraction of piperidines and other saturated heterocycles. By extruding a single heteroatom from a ring, this transformation builds desirable C(sp3)-C(sp3) bonds in the ring contracted products; however, the origins of enantioselectivity remain poorly understood. In this work, enantioselectivity of the ring contraction has been explored across an expanded structurally diverse substrate scope, revealing a wide range of enantioselectivities (0-99%) using two distinct CPA catalysts. Mechanistic investigations support rate-determining excitation that generates short-lived achiral intermediates that are intercepted by the CPA in an enantiodetermining ring closure. The effects of competitive uncatalyzed reactivity and light-driven reversibility of the enantiodetermining ring closure on enantioselectivity have been elucidated. Statistical models were built by regressing the range of enantioselectivities from the substrate scope against key structural features of the products for both CPA catalysts. The resultant models suggested distinct factors that influence the enantioselectivity response for each catalyst and enabled rational modification of a pharmaceutically relevant target molecule to improve enantioselectivity. Finally, density functional theory (DFT)-based transition state analysis identified distinct noncovalent interactions with each catalyst that correlated with the unique selectivity-relevant features uncovered through statistical modeling. Our findings not only offer comprehensive insight into the origins of enantioselectivity in this system but should also aid future development of related photomediated CPA-catalyzed reactions.

Visualizing stepwise evolution of carbon hybridization from sp3 to sp2 and to sp

Regulating carbon hybridization states lies at the heart of engineering carbon materials with tailored properties but orchestrating the sequential transition across three states has remained elusive. Here, we visiualize stepwise evolution in carbon hybridizations from sp³ to sp² and to sp states via dehydrogenation and elimination reactions of methylcyano-functionalized molecules on surfaces. Utilizing scanning probing microscopy, we distinguish three distinct carbon-carbon bond types within polymers induced by annealing at elevated temperatures. Density-functional-theory calculations unveil the pivotal role of the electron-withdrawing cyano group in activating neighboring methylene to form C(sp3)–C(sp3) bonds, and in facilitating subsequent stepwise HCN eliminations to realize the transformation across three carbon-carbon bond types. We also demonstrate the applicability of this strategy on one-dimensional molecular wires and two-dimensional covalent organic framework on different substrates. Our work expands the scope of carbon hybridization evolution and serves as an advance in flexibly engineering carbon-material by employing cyanomethyl-substituted molecules.

3d-5d Orbital Hybridization in Nanoflower-Like High-Entropy Alloy for Highly Efficient Overall Water Splitting at High Current Density.

Exploring highlyefficient electrocatalysts for overall water splitting is a challenging butnecessary task for development of green and renewable energy. Herein, PtIrFeCoNi high-entropy alloy nanoflowers (HEA NFs) withstrong 3d-5d orbital hybridization were fabricated to achieve highly efficientoverall water splitting at high current density. The Pt26Ir7Fe13Co22Ni32 HEA NFs achieved a 57.52-fold higher than commercial IrO2 in turnoverfrequency (TOF) for oxygen evolution reaction (OER). Besides, its TOF value forhydrogen evolution reaction (HER) was 2.11-fold higher than that of commercialPt/C. The cell voltages based on Pt26Ir7Fe13Co22Ni32 HEA NFs for overall water splitting were only 1.594 V and 1.861 V at currentdensities of 100 mA cm-2 and 500 mA cm-2, which weresignificantly lower than those of Pt/C.

V‐/O‐Doping to Endow Ag2S‐based Bimetal Oxysulfide with Sulfur Vacancies and Heterovalent States for Rapid Reduction of Organic and Cr(VI) Pollutants in the Dark

AbstractA novel AgVOS oxysulfide catalyst for rapid catalytic reduction of toxic organic substances and Cr(VI) under dark is synthesized by a facile method. With the V/O co‐doping, the doped Ag2S catalyst has the effectively regulated electron transfer performance, the hydrazine‐driven V5+‐to‐V4+ reduction to disturb charge equilibrium, and the formed sulfur vacancy balanced by oxygen doping to maintain charge equilibrium. The formed sulfur vacancy acts as the active site for electrophilic nucleophilic reaction, while the orbital hybridization of O2p and S3p stabilizes the valence state of S2−. A suitable ratio of n(V4+/V5+) is regulated during the hydrazine‐driven synthesis to facilitate the electron transfer and enhance the V5+‐to‐V4+ reduction reaction. V/O co‐doped AgVOS‐3 prepared by a suitable hydrazine content exhibits super catalytic reduction performance of organic 4‐NP (4‐nitrophenol), MB (methyl blue), MO (methyl orange), and RhB (Rhodamine B, 20 ppm, 100 mL) dyes, which are completely reduced within 8, 8, 10, and 8 min, respectively. In comparison, Cr6+ (50 ppm, 100 mL) is also completely reduced within 6 min by AgVOS‐3, indicating its good catalytic reduction activity for organic and inorganic mixture pollutants. Furthermore, AgVOS‐3 has good stability after cyclic tests to maintain a reduction efficiency of 96.5%. Therefore, the AgVOS catalyst shows a promising application for industrial wastewater treatment.

Magnetic anisotropy of 4f atoms on a WSe2 monolayer: a DFT + U study

Inspired by recent advancements in the field of single-atom magnets, particularly those involving rare-earth (RE) elements, we present a theoretical exploration employing DFT+U calculations to investigate the magnetic properties of selected 4f atoms, specifically Eu, Gd, and Ho, on a monolayer of the transition-metal dichalcogenide WSe2 in the 1H-phase. This study comparatively examines RE with diverse 4f orbital fillings and valence chemistry, aiming to understand how different coverage densities atop WSe2 affect magnetocrystalline anisotropy. We observe that RE lacking 5d occupation exhibit larger magnetic anisotropy energies at high densities, while those with outer 5d electrons show larger anisotropies in dilute configurations. Additionally, even half-filled 4f shell atoms with small orbital magnetic moments can generate substantial energy barriers for magnetization rotation due to prominent orbital hybridizations with WSe2. Open 4f shell atoms further enhance anisotropy barriers through spin-orbit coupling effects. These aspects are crucial for realizing stable magnetic information units experimentally.

Nickel-Catalyzed Cross-Electrophile Coupling of Aryl Triflates with Alkyl Halides: Mechanism-Informed Design of More General Conditions.

Aryl triflates make up a class of aryl electrophiles that are available in a single step from the corresponding phenol. Despite the known reactivity of nickel complexes for aryl C-O bond activation of phenol derivatives, nickel-catalyzed cross-electrophile coupling using aryl triflates has proven challenging. Herein, we report a method to form C(sp2)-C(sp3) bonds by coupling aryl triflates with alkyl bromides and chlorides using phenanthroline (phen) or pyridine-2,6-bis(N-cyanocarboxamidine) (PyBCamCN)-ligated nickel catalysts. The scope of the reaction is demonstrated with 38 examples (61 ± 14% average yield). Mechanistic studies provide a rationale for the conditions used and a roadmap for further applications of cross-electrophile coupling. First, the rate of alkyl radical generation is controlled by maintaining the majority of alkyl halide as the alkyl chloride, which is unreactive, and utilizing a dynamic halide exchange process to adjust the concentration of reactive alkyl bromide or iodide. Second, the challenge of using electron-rich aryl triflates appears to be due to off-cycle transmetalation to form unproductive aryl zinc reagents. The optimal PyBCamCN ligand together with LiCl avoids this deleterious transmetalation step.

Swift heavy ion induced electronic structure modifications in ZnO thin films: X-ray absorption spectroscopy study

Abstract The ZnO is a potential material for electronic devices application due to its versatile semiconducting properties with a direct band gap of 3.3 eV.
This research represents a modification in the electronic structure of ZnO thin films (350 nm) irradiated with swift heavy ions (SHI) at different fluence. ZnO thin films were grown on silicon substrate (100) using radio-frequency (RF) magnetron sputtering which are highly oriented in single phase/plane (002). These deposited thin films were subjected to SHI of 100 MeV O-ion with fluence of 3$\times$10$^{12}$ ions/cm$^2$, 45 MeV Li-ion beams with fluence of 3$\times$10$^{12}$ ions/cm$^2$, and 120 MeV Au-ion with varying fluence from 1$\times$10$^{11}$ to 5$\times$10$^{12}$ ions/cm$^2$. {SRIM/TRIM software was utilized to studied theoretical effect of SHI like ion ranges, phonon energy, etc.} Modifications in the structure and the electrical properties of ZnO thin films were investigated using the high-resolution X-ray diffraction (HRXRD), {Atomic Force Microscopy (AFM)} and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the O K- and Zn L$_{3,2}$-edges. HRXRD revealed the structure, crystallinity and phase of the system whereas NEXAFS revealed the local atom bonding symmetry via the molecular orbital hybridization between Zn and O. Further, Density functional theory (DFT) based first principle FEFF9.6 software has been discussed for the understanding of the various parameter and cards for the good fitting of NEXAFS. Simulations were utilized to support the NEXAFS experimental data for the determination of various physical entity and their interpretations for diverse applications. NEXAFS measurements provide the deeper understanding of the effects of SHI for the promising applications through controlled fluence rate of ion beam irradiations.

Topochemical Synthesis and Electronic Structure of High-Crystallinity Infinite-Layer Nickelates on an Orthorhombic Substrate.

Superconductivity in infinite-layer nickelates has stirred much research interest, to which questions regarding the nature of superconductivity remain elusive. A critical leap forward to address these intricate questions is through the growth of high-crystallinity infinite-layer nickelates, including the "parent" phase. Here, we report the synthesis of a high-quality thin-film nickelate, NdNiO2. This is achieved through the growth of a perovskite precursor phase (NdNiO3) of superior crystallinity on the NdGaO3 substrate by off-axis RF magnetron sputtering and a low-temperature topochemical reduction using NaH. We observe a nonlinear Hall effect at low temperatures in this "non-doped" phase. We further study the electronic properties using advanced X-ray scattering and first-principles calculations. We observe spectroscopic indications of the enhanced two-dimensionality and a reduced hybridization of Nd 5d and Ni 3d orbitals. These findings unlock new pathways for preparing high-quality infinite-layer nickelates and provide new insights into the intrinsic features of these compounds.

Binding the Power of Cycloaddition and Cross-Coupling in a Single Mechanism: An Unexpected Bending Journey to Radical Chemistry of Butadiynyl with Conjugated Dienes.

What if an experiment could combine the power of cycloaddition and cross-coupling with the in situ formation of an aromatic molecule in a single collision? Crossed molecular beam experiments augmented with electronic structure and statistical calculations provided compelling evidence on a novel radical route involving 1,3-butadiynyl (HCCCC; X2∑+) radicals synthesizing (substituted) arylacetylenes in the gas phase upon reactions with 1,3-butadiene (CH2CHCHCH2; X1Ag) and 2-methyl-1,3-butadiene (isoprene; CH2C(CH3)CHCH2; X1A'). This elegant mechanism de facto merges two previously disconnected concepts of cross-coupling and cycloaddition-aromatization in a single collision event via the formation of two new C(sp2)-C(sp2) bonds and bending the 180° moiety of the linear 1,3-butadiynyl radical out of the ordinary by 60° to 120°. In addition to its importance to fundamental organic chemistry, this unconventional mechanism links two previously separated routes of gas-phase molecular mass growth processes of polyacetylenes and polycyclic aromatic hydrocarbons (PAHs), respectively, in low-temperature environments such as in cold molecular clouds like the Taurus Molecular Cloud (TMC-1) and in hydrocarbon-rich atmospheres of planets and their moons such as Titan, which revises the established understanding of low-temperature molecular mass growth processes in the Universe.

Effect of Alloying Metal Elements on the Valence Band of β-Ga2O3: A First-Principles Study.

β-Ga2O3 is a candidate semiconductor material for high-power electronics due to its ultrawide bandgap and high Baliga's figure of merit. However, its p-type doping is extremely difficult because of its low and flat band dispersion at its valence band maximum (VBM). A few reports have predicted that the VBM of β-Ga2O3 can be enhanced via alloying a specific metal (M), which enables p-type conduction. To fully understand the M regulation on the valence band of β-Ga2O3, 49 different M-alloyed β-Ga2O3 i.e., β-(M0.125Ga0.875)2O3, are investigated in this work through first-principles calculations. The alloys' configurations and electronic structures are found dependent more on the group number of M. The β-(M0.125Ga0.875)2O3 members with Ms in groups 3, 9, 13, and 15 and the Ms of Be, Cr, and Fe are semiconductors. The VBMs' energies are enhanced by more than 1 eV in the β-(M0.125Ga0.875)2O3 for the Ms of Rh, Ir, Sb, and Bi because these VBMs are newly formed by the orbital hybridization of the Ms and neighboring oxygen atoms. The band dispersions at VBMs generally become steeper, especially for Ms in groups 13 and 15. The average hole effective mass in β-(Al0.125Ga0.875)2O3 is only 3.43% of that in the β-Ga2O3. It is believed that the reduced hole effective mass and increased VBMs' energies make the p-type doping easier in these alloys and the applications of the alloys wider.

Ni-Catalyzed Regioselective Alkylarylation of Unactivated Alkenes in Amines Enabled by Cooperative Ligand Effects of Nitriles and Electron-Deficient Alkenes.

We report a Ni-catalyzed vicinal alkylarylation of unactivated alkenes in γ,δ- and δ,ε-alkenylamines with aryl halides and alkylzinc reagents. The reaction is enabled by amine coordination and can use all primary, secondary, and tertiary amines. The reaction constructs two new C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds and produces δ- and ε-arylamines with C(sp3)-branching at the γ- and δ-positions. A variety of aryl and heteroaryl iodides and both the primary and secondary alkylzinc reagents can be used as coupling carbon sources. Mechanistic studies suggest that the reaction is enabled by the cooperative effect of organic nitriles and electron-deficient alkenes (EDAs) as ligands.

F-p-d Orbital Hybridization Promotes Hydroxyl Intermediate Adsorption for Electrochemical Biomolecular Oxidation and Identification.

The rational design of efficient hydroxyl intermediate (*OH) adsorption catalysts for dopamine electrooxidation still faces a major challenge. To address this challenge, a CeO2-loaded CuO catalyst inspired by the f-p-d orbital hybridization strategy is designed to achieve efficient *OH adsorption and improve dopamine oxidation. The experimental results and theoretical calculations demonstrate that the f-p-d orbital hybridization regulates the electron distribution at the Ce-O-Cu interface, which facilitates electron transfer and optimizes the adsorption of *OH, thereby promoting dopamine oxidation. The designed electrochemical sensor exhibits excellent catalytic activity and sensitivity, reaching a limit of detection of 3.22 nM. This work provides a promising approach for designing highly active electrocatalysts with orbital hybridization for dopamine oxidation.

Assembling Gold Icosahedrons to Superatomic Molecules Mimicking the Bonding Rules in Molecules.

Icosahedral gold clusters with high-symmetry geometry and magic electronic shells are potential candidates for cluster-assembling, while their assembling rules are still awaiting further investigation. In this work, we use the all-metal icosahedral M@Au12 as a building block to assemble a series of bi-, tri-, tetra-, and penta-superatomic molecules with diverse superatomic bonding patterns via face-fusion, aiming to systemically explore the bonding rule of superatoms. Chemical bonding analyses indicate that these bi-, tri-, tetra-, and penta-superatomic molecules [M@Au12]n+/0 (M = Re, W, Ta, Ti, Hf, Ir, and Pt) can be considered electronic analogues to Cl2, O2, N2, CO, O3, CO2, NCl3, and CF4 molecules with single, double, triple, and multicenter bonds, respectively. In multi-superatomic molecules, the central superatom undergoes super S-P orbital hybridizations to form super σ bonds with each peripheral superatom, mimicking the bonding rules of molecules. Due to the large size of superatoms, superatomic molecules also present some distinct bonding characters in structure and relative energy compared to their analogues. This paper systemically investigated the superatomic bonding rules, giving references to further design and synthesis of superatom-assembled materials.

Theoretical study on the mechanisms of formation of primal carbon clusters and nanoparticles in space.

We present a theoretical study of assembling clusters and nanoparticles in space from primordial aggregations of unbound carbon atoms. Geometry optimization and SCC-DFTB dynamics methods are employed to predict carbon clusters, their time evolution and stability. The initial density of the aggregates is found to be of primary importance for the structure of the clusters. Aggregates with low initial density yield clusters with an approximately equal prevalence of sp and sp2 hybridization with almost missing sp3. Higher initial density results in sp2-dominant molecules, resembling the carbon skeleton of polycyclic aromatic hydrocarbons (PAHs). Larger initial aggregations result in sp2-dominant polymers. Such materials are highly porous and possess a similarity to laterally bound nanotubes. Some clusters resemble fullerene building blocks. We employed metadynamics to model the inter-fragment coupling of such structures and predict the formation of spheroid nanoparticles, closely resembling fullerenes. One such structure has the lowest binding energy per atom among the studied molecules. All zero-dimensional forms, obtained by the simulations, conform to the experimentally detected types of molecules in space. The theoretical IR spectrum of the nanoparticles closely resembles that of fullerene C70 and therefore such imperfect structures may be mistaken for known fullerenes in experimental infrared (IR) telescope studies.

A new carbon allotrope with high carrier mobility and optical absorption.

Carbon atom has different bonding modes, which provides the possibility for the existence of multilayer carbon allotropes. Among these bonding modes, the sp3 hybrid bonding mode often causes atoms to be noncoplanar. This provides the possibility for the emergence of two-dimensional (2D) multilayer materials. In this work, a new 2D multilayer carbon allotrope named trilaminar buckled T-graphene is proposed. Carbon atoms have sp2 and sp3 hybridization in this structure. It is nonmagnetic and has an indirect band gap of 1.70 eV. It has mechanical stability and dynamic stability, and formation energy calculations also prove that it is stable. Thermal stability calculations results indicate that it does not change the bonding pattern at 1000 K. It is an elastically soft material with a low value of elastic constants. This structure shows amazing electrical properties, which has a high hole mobility of close to 3071 cm2 V-1 s-1. Optical property calculations results show that it has an optical gap of 1.70 eV and an ultrahigh absorption in visible and near ultraviolet light. Considering all its properties, this structure has great application potential in high-speed electronic and optoelectronic devices, optical filters, modified substrates, and adsorption sensors.

Unique structure and high energy properties of lithium-nitrogen compound in the N-rich region

The structure and properties of the Li-N system in the nitrogen-rich region have been systematically studied at 50 GPa. We propose four stable novel phases: P1-LiN7, Pm-LiN8, P1-LiN9 and P1-LiN10. The polynitrogen polymeric structure in the P1-LiN10 phase is discovered for the first time: the N atoms exist in the form of nitrogen chains, which contain N5 rings, and every two the N5 rings are connected by five N atoms. The analysis of electrical properties shows that the P1-LiN7, Pm-LiN8 and P1-LiN9 phases are semiconductor, while the P1-LiN10 phase is a superconductor with 0.23 K at 50 GPa. The N atoms in the P1-LiN10 phase all exist in the sp3 hybrid form. The high energy density, and excellent detonation pressure, detonation velocity performance of the P1-LiN10 phase make it good candidate for high energy density materials.

Highly Efficient Electrode of Dirac Semimetal PtTe2 for MoS2-Based Field Effect Transistors.

Two-dimensional van der Waals (vdW) layered materials not only are an intriguing fundamental scientific research platform but also provide various applications to multifunctional quantum devices in the field-effect transistors (FET) thanks to their excellent physical properties. However, a metal-semiconductor (MS) interface with a large Schottky barrier causes serious problems for unleashing their intrinsic potentials toward the advancements in high-performance devices. Here, we show that exfoliated vdW Dirac semimetallic PtTe2 can be an excellent electrode for electrons in MoS2 FETs. High-performance FET characteristics reaching the FET mobility of 85 cm2 V-1 s-1 are observed with a negligibly small Schottky barrier height and large on-off current ratio over 108, which is among the highest performances in reported electrodes for MoS2. Discussions are had on the reason that exfoliated PtTe2 with Dirac states shows highly efficient electrode performances based on the comparisons with various other metal electrodes. The orbital hybrid effect between Dirac-semimetal PtTe2 and MoS2 was evidenced by the relative shift of Raman spectra peaks in the heterojunction, resulting in good ohmic contacts. These findings provide an important route to find high-performance electrodes for layered vdW materials and their related quantum devices.