Search Results (617)

Electric-field-sensitive dielectrics play a crucial role in electric field induction sensing and related capacitive conversion, with interfacial polarization and charge accumulation largely determining the signal output. This paper introduces graphene/transition metal dichalcogenide (TMD) (MoSe₂, MoS₂, and WS₂) heterojunctions as functional fillers to enhance the dielectric response and electric-field-induced voltage output of flexible polydimethylsiloxane (PDMS) composites. Density functional theory (DFT) calculations were used to evaluate the stability of the heterojunctions and interfacial electronic modulation, including binding behavior, charge redistribution, and Fermi level-referenced band structure/total density of states (TDOS) characteristics. The calculations show that the graphene/TMD interface is primarily controlled by van der Waals forces, exhibiting negative binding energy and significant interfacial charge rearrangement. Based on these theoretical results, graphene/TMD heterojunction powders were synthesized and incorporated into polydimethylsiloxane (PDMS). Structural characterization confirmed the presence of face-to-face interfacial contacts and consistent elemental co-localization within the heterojunction filler. Dielectric spectroscopy analysis revealed an overall improvement in the dielectric constant of the composite materials while maintaining a stable loss trend within the studied frequency range. More importantly, calibrated electric field induction tests (based on pure PDMS) showed a significant enhancement in the voltage response of all heterojunction composite materials, with the WS₂-G/PDMS system exhibiting the best performance, exhibiting an electric-field-induced voltage amplitude 7.607% higher than that of pure PDMS. This work establishes a microscopic-to-macroscopic correlation between interfacial electronic modulation and electric-field-sensitive dielectric properties, providing a feasible interface engineering strategy for high-performance flexible dielectric sensing materials. Full article

Nanoparticle-mediated photothermal conversion exploits the unique light-to-heat transduction properties of engineered nanomaterials to address challenges in energy, water, and healthcare. This review first examines fundamental mechanisms—localized surface plasmon resonance (LSPR) in plasmonic metals and broadband interband transitions in semiconductors—demonstrating how tailored nanoparticle compositions can achieve >96% absorption across 250–2500 nm and photothermal efficiencies exceeding 98% under one-sun illumination (1000 W·m⁻², AM 1.5G). Next, we highlight advances in solar steam generation and desalination: floating photothermal receivers on carbonized wood or hydrogels reach >95% efficiency in solar-to-vapor conversion and >2 kg·m⁻²·h⁻¹ evaporation rates; three-dimensional architectures recapture diffuse flux and ambient heat; and full-spectrum nanofluids (LaB₆, Au colloids) extend photothermal harvesting into portable, scalable designs. We then survey photothermal-enhanced thermal energy storage: metal-oxide–paraffin composites, core–shell phase-change material (PCM) nanocapsules, and MXene– polyethylene glycol—PEG—aerogels deliver >85% solar charging efficiencies, reduce supercooling, and improve thermal conductivity. In biomedicine, gold nanoshells, nanorods, and transition-metal dichalcogenide (TMDC) nanosheets enable deep-tissue photothermal therapy (PTT) with imaging guidance, achieving >94% tumor ablation in preclinical and pilot clinical studies. Multifunctional constructs combine PTT with chemotherapy, immunotherapy, or gene regulation, yielding synergistic tumor eradication and durable immune responses. Finally, we explore emerging opto-thermal nanobiosystems—light-triggered gene silencing in microalgae and poly(N-isopropylacrylamide) (PNIPAM)–gold nanoparticle (AuNP) membranes for microfluidic photothermal filtration and control—demonstrating how nanoscale heating enables remote, reversible biological and fluidic functions. We conclude by discussing challenges in scalable nanoparticle synthesis, stability, and integration, and outline future directions: multicomponent high-entropy alloys, modular photothermal–PCM devices, and opto-thermal control in synthetic biology. These interdisciplinary innovations promise sustainable solutions for global energy, water, and healthcare demands. Full article

Characterized by their atomic thickness and exceptional mechanical properties, two-dimensional (2D) materials offer a compelling platform for developing flexible optoelectronic devices that maintain performance stability under mechanical deformation such as bending and stretching. This review systematically summarizes and critically discusses the recent advancements in applying three prominent 2D material categories—graphene, transition metal dichalcogenides (TMDs, e.g., MoS₂ and WS₂), and MXenes—in flexible optoelectronics. We focus on their specific applications in flexible photodetectors, light-emitting devices, optical modulators, solar cells, and gas sensors. A particular emphasis is placed on analyzing the unique physicochemical properties of these materials and elucidating the underlying mechanisms that enable bandgap stability and efficient optoelectronic conversion under mechanical strain. The potential of these devices demonstrated here underscores their broad application prospects in wearable systems and self-powered electronic platforms. Finally, we conclude by discussing the challenges and future prospects in the field of flexible optoelectronic devices based on two-dimensional materials. Full article

Transition-metal dichalcogenides have emerged as promising non-noble-metal electrocatalysts for efficient hydrogen production through the hydrogen evolution reaction (HER). In this work, we fabricated the graphitic carbon nitride-decorated cobalt diselenide (gC₃N₄-CoSe₂) nanocomposites via the facile hydrothermal method. The prepared gC₃N₄-CoSe₂ nanocomposites displayed an interconnected and aggregated morphology of gC₃N₄-decorated CoSe₂ nanoparticles with offering large surface area of 82 m²/g. The gC₃N₄-CoSe₂ nanocomposites exhibited excellent HER activity with a low overpotential (141 mV) and tiny Tafel slope (62 mV/dec) with excellent durability for 100 h at 10 mA/cm² in an alkaline electrolyte. These outstanding HER performances of gC₃N₄-CoSe₂ can be ascribed to the synergistic interaction between the electrochemically active porous CoSe₂ nanoparticles and the highly conductive gC₃N₄ nanosheets. These results indicate that the gC₃N₄-CoSe₂ nanocomposites hold promising and efficient HER electrocatalysts for sustainable green hydrogen production. Full article

Optoelectronic synapses based on transition metal dichalcogenides have received much attention as artificial synapses due to their good stability in the air and excellent photoelectric properties; however, they suffer from ultraviolet light-triggered synapses due to the ultraviolet insensitivity of transition metal dichalcogenides. In this paper, an ultraviolet-enhanced artificial synapse was achieved on WSe₂ combined with SrAl₂O₄: 6% Eu²⁺, 4% Dy³⁺ phosphor. The strong ultraviolet absorption of SrAl₂O₄: 6% Eu²⁺, 4% Dy³⁺ phosphor and radiation reabsorption are responsible for the ultraviolet-enhanced response of the WSe₂-SrAl₂O₄ synapse. The excitatory post-synaptic current of the WSe₂-SrAl₂O₄ synapse triggered by a single pulse at 365 nm was enhanced 4 times more than that from 2D WSe₂, while the decay time of the post-synaptic current was 9.7 times longer than those from the WSe₂ device. The excellent ultraviolet sensitivity and decay time promoted the good regulation of the synaptic plasticity of the WSe₂-SrAl₂O₄ device in terms of power densities, pulse widths, pulse intervals, and pulse numbers. Furthermore, outstanding learning behavior was simulated successfully with a forgetting time of 25 s. Handwritten digit recognition was realized with 96.39% accuracy, based on the synaptic weight of the WSe₂-SrAl₂O₄ synapse. This work provides a new pathway for ultraviolet photoelectric synapse and brain-inspired computing. Full article

Gold-assisted exfoliation is an effective approach to obtain clean and large-area monolayers of transition metal dichalcogenides, yet the microscopic evolution of interfacial adhesion remains poorly understood. Here, we investigate temperature-controlled exfoliation of MoS₂ between 30 and 170 °C. Based on optical microscopy image analysis, mild heating slightly improves the exfoliation yield, which is associated with the release of interfacial contaminants and trapped gases—these substances enhance the adhesion between gold and molybdenum disulfide (Au-MoS₂). Unexpectedly, as revealed by AFM, SEM-EDS, and Raman analyses, parts of the Au film start to peel off from the underlying Ti adhesion layer at approximately 100 °C. This Au film detachment, resulting from the surprisingly weak Au-Ti adhesion, serves as a unique probe for interfacial strength: it preferentially occurs at the boundaries of MoS₂ flakes, indicating that the reinforcement of the Au-MoS₂ interaction originates at the edges rather than being uniformly distributed. At higher temperatures (>130 °C), Au detachment expands to larger areas, indicating that boundary-localized adhesion progressively extends across the entire interface. Additional STM/STS measurements further confirm that thermal annealing improves local Au-MoS₂ contact by removing interfacial species and enabling surface reconstruction. These findings establish a microscopic picture of temperature-assisted exfoliation, highlighting the dual roles of interfacial contaminant release and boundary effects, and offering guidance for more reproducible fabrication of high-quality 2D monolayers. Full article

Rapid progress on the fabrication of lead halide perovskite has led to the development of high performance optoelectronic devices, particularly in the field of solar cell technologies. This initial success has subsequently inspired investigations into layered 2D-halide perovskite structures, motivated in part by their good environmental stability, but more significantly by their intriguing fundamental photo-physics. They have recently been used to improve the photoresponsivity of monolayer transition metal dichalcogenides in hybrid heterostructures. In this paper, we report on the synthesis of the (PEA)₂(MA)_n−1Pb_nI_3n+1 series (with n = 1, 2, 3) of 2D-halide perovskites, in order to develop a platform that provides ultra-thin layers for the fabrication of hybrid heterostructures. The crystal synthesis method and its basic structural and optical characterization are shown, highlighting the differences in the crystal synthesis processes. Furthermore, we explore the preparation of 2D halide perovskite ultra-thin flakes using the mechanical exfoliation method, and few-layer-areas of n = 1 member of the series are identified using atomic force microscopy. Finally, we study the deposition of thin and ultra-thin films using the spin coating technique to provide an alternative process to the exfoliation. Full article

Over the past few years, two-dimensional transition metal dichalcogenides (TMDCs) have garnered substantial attention in the field of two-dimensional materials research, owing to their exceptional physicochemical properties. Notably, V-WSe₂ distinguishes itself by reducing the Schottky barrier at the interface between the material and metal electrodes, thus exhibiting remarkable potential for applications in optoelectronic devices. Our work explores the synthesis of monolayer V-WSe₂ through halide-assisted atmospheric-pressure chemical vapor deposition (APCVD), with an emphasis on the effects of various halide types on the growth mechanism. In addition, we investigate the impact of vanadium (V) content on the performance of WSe₂. Comprehensive optical and structural characterizations of the synthesized material were systematically performed. The findings indicate that incorporating halide salts effectively reduces the volatilization temperature of tungsten trioxide (WO₃), thereby markedly enhancing reaction controllability and material crystallinity. Among the tested halide salts, KCl, NaCl, and KI, KI demonstrated the capability to achieve the lowest growth temperature. Varying the V content in the V-WSe₂ structure significantly influences the optical properties, with higher vanadium concentrations reducing the material’s optical bandgap and Raman frequency. This study highlights the critical role of halides and vanadium content in the material growth process, providing valuable insights for the controlled synthesis of two-dimensional TMDC materials and how varying vanadium concentrations also affect the material’s performance. Full article

We report the fabrication of nanoscale MoS₂ (nMoS₂) via laser ablation in liquid and its application in electrochemical sensing. The laser ablation process fragments microscale MoS₂ sheets into ~5 nm dots with stable aqueous dispersibility. Electrochemical analysis reveals that nMoS₂ possesses multiple reversible redox states, enabling it to participate in redox cycling reactions that can amplify electrochemical signals. When the nMoS₂ is embedded in an electrochemically inert matrix, a chitosan layer, and subsequently incorporated within a nanostructured Au electrode, the nMoS₂-participating redox cycling reactions are further enhanced by the nanoconfinement effect, leading to synergistic signal amplification. As a model system, this hybrid nMoS₂-in-nanoporous Au electrode demonstrates a 9-fold increase in sensitivity for detecting pyocyanin, a biomarker of Pseudomonas aeruginosa infection, compared with a flat electrode without nMoS₂ loading. This study not only elucidates the redox characteristics of laser-fabricated zero-dimensional transition metal dichalcogenides but also presents a strategy to integrate semiconducting nanomaterials with metallic nanostructures for high-performance electrochemical sensing. Full article

Phase engineering has emerged as a powerful method for manipulating the structural and electrical characteristics of nanomaterials, resulting in significant enhancements in their electrochemical performance. This paper examines the correlation among morphology, crystal phase, and electrochemical performance of nanomaterials engineered for high-performance batteries and supercapacitors. The discourse starts with phase engineering methodologies in metal-based nanomaterials, including the direct synthesis of atypical phases and phase transformation mechanisms that provide metastable or mixed-phase structures. Special emphasis is placed on the impact of these synthetic processes on morphology and surface properties, which subsequently regulate charge transport and ion diffusion during electrochemical reactions. Additionally, the investigation of phase engineering in transition metal dichalcogenide (TMD) nanomaterials highlights how regulated phase transitions and heterophase structures improve active sites and conductivity. The optimized phase-engineered ZnCo₂O₄@Ti₃C₂ composite exhibited a high specific capacitance of 1013.5 F g⁻¹, a reversible capacity of 732.5 mAh g⁻¹, and excellent cycling stability, with over 85% retention after 10,000 cycles. These results confirm that phase and morphological control can substantially enhance charge transport and electrochemical durability, offering promising strategies for next-generation batteries and supercapacitors. The paper concludes by summarizing current advancements in phase-engineered nanomaterials for lithium-ion, sodium-ion, and lithium-sulfur batteries, along with supercapacitors, emphasizing the significant relationship between phase state, morphology, and energy storage efficacy. This study offers a comprehensive understanding of the optimal integration of phase and morphological control in designing enhanced electrode materials for next-generation electrochemical energy storage systems. Full article

Bilayer transition metal dichalcogenides (TMDs) are promising materials for next-generation field-effect transistors (FETs) due to their atomically thin structure and favorable transport properties. In this study, we employ density functional theory (DFT) to compute the electronic band structures and phonon dispersions of bilayer WS₂, WSe₂, and MoS₂, and the electron-phonon scattering rates using the EPW (electron-phonon Wannier) method. Carrier transport is then investigated within a semiclassical full-band Monte Carlo framework, explicitly including intrinsic electron-phonon scattering, dielectric screening, scattering with hybrid plasmon–phonon interface excitations (IPPs), and scattering with ionized impurities. Freestanding bilayers exhibit the highest mobilities, with hole mobilities reaching 2300 cm²/V·s in WS₂ and 1300 cm²/V·s in WSe₂. Using hBN as the top gate dielectric preserves or slightly enhances mobility, whereas HfO₂ significantly reduces transport due to stronger IPP and remote phonon scattering. Device-level simulations of double-gate FETs indicate that series resistance strongly limits performance, with optimized WSe₂ pFETs achieving ON currents of 820 A/m, and a 10% enhancement when hBN replaces HfO₂. These results show the direct impact of first-principles electronic structure and scattering physics on device-level transport, underscoring the importance of material properties and the dielectric environment in bilayer TMDs. Full article

The global transition toward renewable energy sources has intensified in response to escalating environmental challenges. Nevertheless, the inherent intermittency and instability of renewable energy necessitate the development of reliable energy storage technologies. Supercapacitors are particularly notable for their high specific capacitance, rapid charge and discharge capability, and exceptional cycling stability. Concurrently, the increasing demand for efficient and sustainable energy storage systems has stimulated interest in multifunctional electrode materials that integrate electrocatalytic activity with electrochemical energy storage. Two-dimensional transition metal dichalcogenides (TMDs), owing to their distinctive layered structures, large surface areas, phase state, energy band structure, and intrinsic electrocatalytic properties, have emerged as promising candidates to achieve dual functionality in electrocatalysis and electrochemical energy storage for asymmetric supercapacitors (ASCs). Specifically, their unique electronic properties and catalytic characteristics promote reversible Faradaic reactions and accelerate charge transfer kinetics, thus markedly enhancing charge storage efficiency and energy density. This review highlights recent advances in TMD-based multifunctional electrodes. It elucidates mechanistic correlations between intrinsic electronic properties and electrocatalytic reactions that influence charge storage processes, guiding the rational design of high-performance ASC systems. Full article

Due to their high carrier mobility, thermal conductivity, and exceptional foldability, transition metal dichalcogenides (TMDs) present promising prospects in the realm of flexible semiconductor devices. Concurrently, tunneling field-effect transistors (TFETs) have garnered significant attention owing to their low energy consumption. This study investigates a TMD van der Waals heterojunction (VdWH) TFET, specifically by fabricating MoS₂ field-effect transistors (FETs), WSe₂ FETs, and MoS₂/WSe₂ VdWH TFETs. The N-type characteristics of the MoS₂ and P-type characteristics of WSe₂ are established through an analysis of the electrical characteristics of the respective FETs. Finally, we analyze the energy band and electrical characteristics of the MoS₂/WSe₂ VdWH TFET, which exhibits a drain current switching ratio of 10⁵. This study provides valuable insights for the development of novel low-power devices. Full article

Two-dimensional (2D) nanomaterials have attracted growing attention in the field of oral medicine due to their unique physicochemical properties, including high surface area, adjustable surface chemistry, and exceptional biocompatibility. In recent years, a variety of 2D materials, including graphene-based nanomaterials, black phosphorus nanosheets, MXenes, layered double hydroxides (LDHs), transition metal dichalcogenides (TMDs), 2D metal–organic frameworks (MOFs), and polymer-based nanosheets, have been extensively explored for the treatment of oral diseases. These functional materials demonstrate multiple therapeutic capabilities, such as antibacterial activity, reactive oxygen species (ROS) scavenging, anti-inflammatory modulation, and promotion of tissue regeneration. In this review, we systematically summarize the recent advances of 2D nanomaterials in the treatment of common oral diseases such as dental caries, periodontitis, oral cancer and peri-implantitis. The underlying therapeutic mechanisms are also summarized. Challenges for clinical translation of these nanomaterials and the possible solutions are discussed as well. Full article

Understanding the non-equilibrium dynamical processes in two-dimensional (2D) transition metal dichalcogenide (TMDC) heterostructures is essential for elucidating their photoelectric behaviors. In this work, we investigate the electronic structure, electric field modulation, and transient optical performance of the MoSe₂/WSe₂ heterostructure using first principles and nonadiabatic molecular dynamics (NAMD) methods. Applying an external electric field effectively modulates the bandgap and band arrangement of MoSe₂/WSe₂ heterostructure, along with a transition from indirect to direct bandgap during which the type-II band alignment can be maintained. Specifically, the ultrafast interlayer photogenerated electron transfer time is 72 fs, and the interlayer electron-hole recombination time can be as long as 357 ns, which is longer than that of the intralayer recombination in the constituent monolayers (110 ns for MoSe₂ and 288 ns for WSe₂), yielding an ultrahigh charge separation efficiency of up to 99.99%. The significant time difference in the processes of photoinduced charge transfer and recombination can be attributed to the corresponding different nonadiabatic coupling averaged values, mainly determined by the electron–phonon coupling and energy difference. The carrier dynamics mechanism revealed in the MoSe₂/WSe₂ heterostructure is conducive to the development of 2D ultrafast optoelectronic devices. Full article