Graphene intrinsic carrier ambipolarity enables unique circuit functionalities that would otherwise require significantly more complex circuit topologies to achieve with conventional semiconductors. Yet, translating these properties into practical, wafer-scale electronic systems remains a significant challenge. Here, we present an experimental proof of concept of a reconfigurable frequency multiplier based on a single split-gate graphene field-effect transistor. The devices used for this demonstration were externally fabricated through a multi-project wafer tape-out of the 2D Experimental Pilot Line, an initiative aimed at providing a scalable platform service for the manufacturing of 2D-material-based devices and circuits. The split-gate architecture synthesizes a W-shaped transfer characteristic within a single device enabling electrically reconfigurable frequency multiplication by factors of × 2, × 3, and × 4 without requiring multiple transistors or fixed fabrication-dependent tuning mechanisms. Time-domain measurements and spectral analysis confirm harmonic reconfiguration, yielding spectral purities of 48% for the doubler, 69% for the tripler, and 19% for the quadrupler at an input frequency of 100 kHz. This constitutes the first demonstration of a reconfigurable circuit using devices from the multi-project wafer 2D-EPL platform, representing a step forward in the integration complexity achievable with wafer-scale graphene technology.
Graphene oxide (GO) is a class of chemically derived graphene materials widely used in diverse fields, ranging from electronics to environmental applications. Yet, its detailed structure remains an open question due to the effect of the different synthesis methods on the oxidation level. In this work, we compare our synchrotron radiation based soft X-ray spectroscopy and density functional theory (DFT) calculations to elucidate the relevance of functional groups on the structure and electronic properties of GO, synthesized by modified Hummers’ method. We demonstrate that the position of the hydroxyl groups strongly modulates the structure and local bonding environment. Our results indicate that it is energetically preferable to attach functional groups to only one side of the GO layer, which leads to a largely intact carbon network with 60% C-C regions. We observe that the presence of hydroxyl groups induces charge distortions while epoxide groups weaken the adjacent carbon bonds. Furthermore, our two-dimensional electron density map illustrates the detailed electron localization in various carbon sites within GO. This provides information on the interaction of functional groups, which is essential in order to tailor GO with specific properties for applications in energy storage, sensing, and next-generation electronic devices.
Two-dimensional (2D) van der Waals (vdWs) heterostructures offer a versatile platform where engineered interlayer coupling enables optical processes beyond those of individual materials. Their atomically sharp interfaces support charge-transfer states, directional carrier transport, and broadband light-matter interactions, making them promising for advanced optoelectronics. However, the role of interlayer charge-transfer states in mid-infrared (MIR) photodetection remains insufficiently understood. Here, we demonstrate that a vertically stacked SnS2/InSe vdWs heterostructure enables an interlayer charge-transfer process that extends the photodetection range to 2500 nm, surpassing the intrinsic absorption limits of the constituent layers. The device achieves a high responsivity of 281 A W-1 and an external quantum efficiency of 62,360.6% at 532 nm, representing enhancements of up to 104 compared to individual SnS2 and InSe devices. Density functional theory calculations reveal a reduced interlayer bandgap of 0.55 eV, which is consistent with the experimentally observed photoresponse measured up to 2500 nm. The device also exhibits polarization sensitivity, with a dichroic ratio of 1.35 at 1064 nm, and maintains stable operation under repeated 100th cycling. These results highlight the potential of SnS₂/InSe vdWs heterostructures for broadband and MIR photodetection driven by interlayer charge-transfer states.
Abstract Two-dimensional (2D) MBenes are the emerging members of the advanced 2D materials owing to their exceptional functional properties for applications such as energy storage. We report the fabrication of Mo₄/₃Y₂/₃B₂−x T z (T z = -O, -F, or -OH) i-MBene through the wet-chemical etching method using concentrated hydrofluoric (HF) acid. The structural, morphological, optical, and analytical results assured the successful etching of Al atoms and the synthesis of a stable structured i-MBene, and the consequent interlayer opening facilitates fast ion diffusion and enhanced storage capacity. The three-electrode system achieved the maximum gravimetric capacitance of 1112 Fg−1 with an outstanding energy density of 38 Wh kg−1 and power density of 250 W kg-1 at 1 Ag−1, which is the highest compared to the other recent 2D materials such as MXenes. Furthermore, the two-electrode system (device) exhibited the gravimetric capacitance of 90 Fg−1, energy density of 15 Wh kg−1, with a high power density of 800 W kg−1 at 1 Ag−1. Moreover, with 80% capacity retention yield over 5000 cycles at 10 Ag−1, i-MBene proved to be a new and notable performance active 2D material for electrochemical energy storage applications.
The development of boron-based two-dimensional materials has been constrained by the absence of scalable synthesis routes producing processable material beyond substrate-bound epitaxial films. Here we demonstrate a scalable top-down strategy for producing layered boron nanosheets from bulk crystalline boron. Our approach exploits a metallurgically derived LixB1-x alloy, which undergoes controlled chemical delithiation followed by liquid-phase exfoliation to yield amorphous layered boron nanosheets as a readily dispersible powder compatible with solution processing. Structural and chemical characterization demonstrates the conversion of bulk crystalline boron into a layered, amorphous nanosheet material with micrometer-scale lateral dimensions. These nanosheets can be assembled into continuous films by spray coating, enabling systematic investigation of thickness-dependent optical properties and the fabrication of stable coatings with high solar absorptivity for concentrated solar power applications. This work establishes a metallurgical pathway to processable B/O-rich boron nanosheets, providing a scalable pathway toward processable boron-based layered nanomaterials and expanding opportunities for their integration into energy and photonic technologies.
The integration of natural layered minerals into van der Waals heterostructures offers a scalable and earth-abundant route to high-performance 2D electronics. Here, we explore biotite, an ion-rich member of the mica family, as a multifunctional building block in ultrathin device architectures. Mechanically exfoliated biotite flakes are incorporated as gate dielectrics in monolayer MoS2 field-effect transistors, yielding low transfer hysteresis (20 mV) and field-effect mobilities around 10 cm2 V−1 s−1 in all-van der Waals configurations with graphite contacts. The same platform supports high-performance photodetection, with responsivities up to 392 AW−1 and rise times of ~20 ms. Biotite is also implemented as an active switching material in metal-insulator-metal memristors, where silver filament formation drives reproducible bipolar resistive switching across more than 104 cycles with memory windows of 102–104 Ω. By inverting the electrode bias configuration, the same device transitions from non-volatile to volatile threshold switching, which is especially relevant for neuromorphic device applications. Switching voltages scale with flake thickness, reaching below 0.5 V for 6 nm devices. Together, these findings reveal biotite as a promising natural layered 2D dielectric, unlocking new device functionalities in 2D transistors and memristors.
Nonvolatile control of electron spin using electric polarization offers a promising route toward energy-efficient spintronic devices. Early studies of conventional ferroelectrics, from GeTe to perovskite oxides, demonstrated that polarization switching can reversibly control spin textures and spin-to-charge conversion (SCC) in nonmagnetic materials. However, practical device implementation remains limited by polarization instabilities in ultrathin ferroelectrics and the modest efficiency of SCC. Recent advances in two-dimensional (2D) van der Waals (vdW) ferroelectrics provide new opportunities to overcome these challenges. In particular, sliding ferroelectricity enables polarization switching through interlayer displacement, offering ultralow switching barriers and reduced defect propagation while preserving the in-plane conductivity required for SCC and compatibility with atomically thin devices. In this Perspective, we discuss the evolution of ferroelectric control of spin-orbit phenomena from conventional bulk materials to emerging vdW ferroelectrics, bridging recent advances in 2D ferroelectricity with the field of spintronics. We examine polarization-controlled spin-orbit responses, including Rashba-Edelstein and spin Hall effects, and show how stacking, sliding, and twist—combined with strong spin-orbit coupling and persistent spin textures—expand the design space for ferroelectric spin-orbit (FESO) devices. Finally, we highlight opportunities offered by vdW ferroelectric altermagnets and identify the materials and device challenges that will be critical for realizing practical ferroelectric spintronic architectures.
Van der Waals heterostructures based on MXenes and transition metal dichalcogenides offer a versatile platform for engineering excitonic and optoelectronic properties. However, accurate prediction of their behavior is non-trivial; we highlight that reliance on standard 1 × 1 models of lattice-mismatched systems introduces artificial strain, creating a significant risk of misattributing computational artifacts to intrinsic interface physics. Here, we present a comprehensive first-principles investigation of Ti2CO2/MoS2 and Ti3C2O2/MoS2 heterostructures, employing many-body perturbation theory (GW-BSE) to benchmark the computationally efficient TD-HSE06 + Δ methodology for realistic, strain-relaxed Moiré supercells. Our analysis reveals a distinct “quasi-type-I” optoelectronic character for these systems. We show that advanced methods are indispensable for MXene/MoS2 heterostructures, as basic electronic structure predictions yield an incomplete picture: although the bands exhibit a type-II staggered alignment with the valence band maximum localized on the MoS2 and the conduction band minimum on the MXene, the theoretically lowest-energy interlayer transitions are rendered effectively dark due to negligible wavefunction overlap. Consequently, the optical landscape is dominated by bright intralayer excitons confined within the MXene layer. Therefore, while the type-II band alignment allows for subsequent non-radiative charge separation, the initial direct optical generation and radiative recombination of interlayer excitons are highly suppressed. This unique decoupling suggests these heterostructures can function as robust platforms where the bright optical transitions of the MXene are preserved, while still participating in ultrafast non-radiative interfacial charge dynamics.
Developing ultrathin, low-disorder gate-stacks for two-dimensional (2D) p-type field-effect transistors (pFETs) remains fundamentally challenging due to poor dielectric nucleation, interface defect formation, and uncontrolled threshold voltage (Vt) shifts. Here, we introduce a sacrificial oxidation–enabled gate-stack strategy that overcomes these limitations by employing a synthetic bilayer (SBL) WSe₂ approach, in which the top WSe2 layer is selectively oxidized to form an ultrathin WOₓ seed layer for high-κ dielectric integration while preserving an intact monolayer (ML) semiconductor channel. Fabrication of an SBL WSe2 by sequential transfer of ML WSe2 enables high-performance back-gate (BG) pFETs with low interface trap density (Dit) of (8–11) × 10¹¹ cm⁻² eV⁻¹, subthreshold swing values as low as 65 mV dec⁻¹, and an on/off current ratio exceeding 10⁷. Devices exhibit a median low-field hole mobility of 38 cm² V⁻¹ s⁻¹ with a maximum of 85 cm² V⁻¹ s⁻¹, and deliver record-high on-state currents of 108 μA μm⁻¹ at a technology-relevant overdrive voltage of 1 V, with peak drive currents reaching 690 μA μm⁻¹. Self-limiting plasma oxidation of the SBL WSe₂ selectively converts the sacrificial top layer into a WOₓ interfacial film, enabling uniform high-κ dielectric nucleation and fabrication of ML WSe₂ dual-gate (DG) FETs while preserving p-type channel behavior after gate-stack formation. In addition, Vt variability can be effectively minimized by selecting the appropriate plasma type. These results establish sacrificial layer–assisted gate-stack engineering as a viable pathway for scalable 2D p-channel transistor technologies.
Exfoliated transition metal dichalcogenide networks offer a scalable platform for engineering high-density catalytic interfaces with tunable electronic properties. Here, we systematically investigate the lateral size dependence of the hydrogen evolution reaction in liquid-phase exfoliated MoS2, WS2, and MoSe2 networks assembled on fluorine-doped tin oxide via electrophoretic deposition (EPD). Liquid cascade centrifugation (LCC) was employed to isolate nanosheet fractions with distinct lateral dimensions, edge-site densities, and electronic characteristics. Optical and electrochemical analyses reveal modified apparent band-edge energies and increased edge exposure with decreasing lateral size. Electrochemical measurements confirm that smaller flakes exhibit superior catalytic performance, including reduced overpotentials, lower charge-transfer resistance, higher double-layer capacitance, and increased exchange current density. Among the materials investigated, MoSe2 networks display the highest activity, consistent with favorable band-edge alignment and efficient charge transfer. Direct comparison of size-selected MoS2, WS2, and MoSe2 networks under identical fabrication conditions reveals material-dependent size–activity relationships that extend beyond edge-site density alone, reflecting the coupled influence of lateral size, layer number, and electronic structure. These findings establish LCC–EPD as a scalable platform for catalyst screening and rational electrode engineering.
Borophene has emerged as a promising two-dimensional material because of its tunable electronic properties, anisotropic structure, and highly reactive surface. This review highlights recent advances in borophene-based photocatalysts for hydrogen production and pollutant degradation under light irradiation. The relationships between borophene structure, charge-transfer behaviour, and photocatalytic activity are discussed, together with recent progress in synthesis, heterostructure engineering, current challenges, and future opportunities for sustainable energy and environmental applications.
Graphene field-effect transistors (GFETs) are attractive transducers for biosensing, but broader use is limited by fabrication complexity, device-to-device variability, stability concerns, and dependence on bulky external reference electrodes. Here, we report a wafer-scale, on-chip-gated GFET array platform that addresses these challenges through engineered passivation and array-level design. Across multiple fabrication runs, we benchmark monolayer-graphene arrays with three passivation schemes (Al2O3, SU-8, and Al2O3/SiNx) and quantify the effects of lithographic resist exposure and aging on the liquid-gated response. Using phosphate-buffered saline (PBS) as a model electrolyte, we statistically evaluate Dirac-voltage spread, hysteresis, gate leakage, and stability, identifying Al2O3/SiNx as the most robust configuration. By varying the ionic strength from PBS 0.001 × to 1 ×, we map the response across relevant Debye lengths. The platform is integrated with PDMS microfluidics and a portable PCB readout, and its intrinsic ionic transduction capability is assessed through proof-of-concept NaCl measurements in deionized water, yielding sensitivities of ~ 70 mV/dec and LoDs down to ~ 3 mM without ion-selective membranes. These results establish a compact, scalable, and electrically stable graphene transducer platform for future integration with portable biofunctionalized sensing assays.
Designing chemically robust photoanodes capable of efficient oxygen evolution reaction (OER) in neutral media remains a central challenge for practical photoelectrochemical (PEC) water splitting. By experiment and theory herein we report the PEC OER functionality of a durable and mechanistically well-defined 2D-SnSe2/mesoporous TiO2 heterostructure photoanode operating at pH 7. Highly crystalline 2D-SnSe2 nanosheets (1.8 ± 0.1 μm lateral size and 100 ± 5 nm thickness) were solvothermally grown over mesoporous TiO2 films, forming a layered 2D-SnSe2/TiO2 heterojunction, with efficient carrier transport and strong interfacial adhesion, solving the common delamination problem of 2D/TiO2 systems. Under solar illumination, the 2D-SnSe2/TiO2 photoanode delivers a 16-fold higher current density than its single counterparts (0.80 mA/cm2 at 1.7 V vs RHE), together with excellent operational stability ( < 3% decay over 3 × 16 h continuous irradiation). Combining Mott–Schottky, valence-band XPS, and optical bandgap measurements with density functional theory (DFT), we reconstruct a defect-driven S-scheme charge-transfer mechanism, where oxygen vacancies in (110) TiO2 shift band edges to promote selective electron–hole recombination at the interface. Finally, differential free adsorption energies calculations of the four OER intermediates over oxygen defective (110) TiO2, indicate the OH* → O* transition as the potential-determining step. These results establish 2D-SnSe2/TiO2 as a stable, visible-light-responsive S-scheme heterostructure for neutral-pH OER, broadening the OER applications of group-IV chalcogenides MX2 (M = Sn, Ge; X = S, Se)/TiO2 photoanodes in neutral electrolytes.
2D semiconductors such as MoS2 offer a promising pathway for future logic and analog transistors and memories. These materials feature scalable channel size, back-end of the line compatibility, and high mobility for relatively small channel thickness approaching few atomic monolayers. An open issue for the development of mature 2D-based digital technology is the availability of both n- and p-type transistors, as well as the ability to control the transistor type in a reconfigurable way. This work presents a novel MoS2-based transistor exhibiting reconfigurable n- or p-type characteristics, namely switching from n-type to p-type and vice versa, which is attributed to ion-assisted doping from the gate dielectric layer. Extensive characterization of the device shows repeatable switching with relatively low cycle-to-cycle (C2C) and device-to-device (D2D) variability. A reconfigurable p-n junction is demonstrated via a junction-less multi-gate MoS2-based transistor. We also demonstrate various reconfigurable logic gates, including a complementary metal-oxide-semiconductor (CMOS) inverter, a fully n-type inverter and an XNOR logic gate based on MoS2 transistors, showcasing the generality and flexibility of channel reconfiguration for logic circuit applications. These results underscore the strong potential of reconfigurable MoS2 transistors for ultra-scaled, reconfigurable logic circuits.
Graphene is predicted to be a potential heat spreader due to its high thermal conductivity. However, the material has not been explored or demonstrated yet for heat spreading applications. Graphene in its pristine form despite having high in-plane thermal conductivity is ineffective in spreading heat due to weak out-of-plane phonon coupling or low thermal boundary conductance (TBC) between graphene and metal. To address this issue, in this work, defect-engineering was carried-out on graphene and tracked the nanosecond time evolution of generated hotspots at metal-graphene interface using Thermoreflectance characterization technique. Furthermore, in this study extensive density functional theory simulations were carried out to gain atomistic insights into the underlying mechanisms and provide a theoretical framework that corroborates the experimental results. It is observed that defect-engineering at the interface enhances atomic orbital overlaps and phonon transmission which improves the out-of-plane phonon coupling and TBC at graphene-metal interface. In contrast to prior studies focused on graphene’s in-plane heat conduction, our work highlights interface engineering as a pathway to achieve more efficient out-of-plane thermal transport. The proposed solution reduces the generated hotspots thereby setting a new benchmark in overcoming interfacial limitations and underscoring graphene’s promise as a practical material for advanced thermal management applications.
In recent years, the integration of advanced material systems has shown remarkable potential for the development of high-performance motion sensors. Among them, only a limited number have demonstrated potential for integration into wearable electronics with energy-harvesting capabilities. Herein, a MoS2/BaTiO3 nanocomposite was developed and employed as a self-powered, standalone sensor node for a mechanical imparting sensing device. Specifically, the optical absorption of the MoS2/BaTiO3 nanocomposite was tuned by adjusting the concentration of BaTiO₃ nanoparticles. Notably, the nanocomposite not only improved charge separation but also reduced the band gap compared to the BaTiO3 nanoparticles. It proved ideal for converting mechanical energy into electrical energy, which was subsequently stored in a capacitor. Impressively, the sensor node is highly flexible and capable of detecting eye blinking with a high signal level (~2.26 V). This performance significantly exceeds that of traditional electrooculograms (~1 mV) and triboelectric nanogenerators (~750 mV) used in human–machine interfaces. Notably, the generated signals can trigger wireless communication and remotely control the movement of a robotic hand. The developed sensor demonstrates strong potential for application in communication interfaces for individuals with amyotrophic lateral sclerosis and in blink-triggered exoskeleton control.
Zr–Fe hydroxides exhibit diverse morphologies and compositions, and their synthesis outcomes vary significantly based on the Zr:Fe ratio. High-performance electrocatalysts require ultrathin Zr–Fe nanosheets with uniform Zr incorporation and stable surface chemistry, which are difficult to achieve using existing synthesis routes. In this regard, we synthesized Zr–Fe hydroxide nanosheets by systematically varying Zr:Fe ratios using a surfactant-assisted solution method and investigated their structural and compositional characteristics. The morphological and crystallographic features across different precursor ratios were studied using atomic force microscopy and electron microscopy, supported by surface and electronic state analyses. This multimodal characterization revealed that the formation of coordination disorder is strongly dependent on Zr content, with higher Zr proportions promoting vacancy generation. These coordination disorder play a key role in modulating charge transport and enhancing electrochemical activity. Our findings demonstrate that the precise control of the Zr:Fe ratio provides an effective approach for tailoring defect structures and optimizing the electrochemical performance of Zr–Fe hydroxide nanosheets.
Abstract The two-dimensional form of tellurium, named tellurene, holds intriguing properties for a broad range of applications. Here, the large area growth by molecular beam epitaxy of tellurium on Sb-passivated Si(111) is demonstrated. The influence of growth temperature and film thickness on the material properties was investigated. At optimized conditions, the two-dimensional growth of Te films as thin as 4 nm is established. The epilayers possess a (10 $$\bar{1}$$ 1 ¯ 0) surface orientation, with the Te chiral chains lying parallel to the surface plane. The van der Waals epitaxy occurs with the formation of a Sb2Te3 interlayer, as confirmed by transmission electron microscopy. Grazing incidence diffraction shows a discrete set of domains with in-plane rotation angles, which result in the alignment of Te lattice planes of neighbouring domains. The high hole mobility of epitaxial tellurium at room temperature is proven by Hall effect measurements. Optical spectroscopy measurements strongly support the electrical data. The thickness-dependent vibrational properties of the material were studied by Raman spectroscopy: by scaling down the film thickness, characteristic features of few-layer tellurium are observed. Hence, the present study opens the way for the integration of two-dimensional tellurium on silicon and the design of novel heterostructures of layered tellurides.
Abstract The integration of graphene with porous organic 2D crystals (O2DCs) represents an emerging class of van der Waals heterostructures in which the periodic pore structure of the O2DC can impose a well-defined structural superlattice on graphene. In this work, we investigate the structure-property relationships in graphene-O2DC (G-O2DC) heterostructures and the role of substrate interactions through computational studies. We demonstrate how O2DCs impose well-defined corrugation on graphene. The corrugation amplitude and superlattice periodicity are directly governed by O2DC pore dimensions and substrate, with larger pores and substrate interactions significantly enhancing the corrugation effect. Across all investigated configurations, the linear Dirac dispersion of graphene is preserved with no band flattening, while corrugation-induced band gaps of up to ~12 meV emerge at the Dirac point. Although these gap openings are below kBT at room temperature, they are of comparable magnitude to the remote-band gaps of magic-angle twisted bilayer graphene (TBG) and become significant at cryogenic temperatures. The underlying mechanism is corrugation-induced sublattice symmetry breaking together with a weak electrostatic perturbation from the O2DC layer, qualitatively distinct from the interlayer-hybridization mechanism responsible for the flat-band regime of magic-angle TBG. These findings establish G-O2DC heterostructures as a controllable platform for structural superlattice engineering of graphene and quantify the magnitude of the resulting electronic modification across a systematic series of pore geometries, laying the foundation for future studies exploiting chemical functionalization or through-pore interactions to enhance the electronic response.
