Quantum Confinement Research Articles

Effect of ball milling on bulk MoS2 and the development of Al–MoS2 nanocomposites by powder metallurgy route

Abstract The present study provides an in-depth investigation of the exfoliation of molybdenum disulfide (MoS2) using high-energy ball milling and the subsequent development of aluminum‒molybdenum disulfide (Al–MoS2) nanocomposites via a powder metallurgy (PM) route. X-ray diffraction confirmed that the commercially available bulk MoS2 did not develop new phases after intense ball milling for up to 30 h. The effects of ball milling on the thermal stability and morphological changes in MoS2 powder have also been reported. The milling action caused a shift in the band gap of MoS2, from 1.2 to 1.44 eV due to quantum confinement phenomena confirmed by UV–visible absorption spectroscopy. The impacts of ball milling on the specific surface area and mean pore diameter of MoS2 were determined by the Brunauer–Emmett–Teller surface area analysis technique. Additionally, the investigation through Fourier transform infrared spectroscopy verifies the presence of functional groups, such as hydroxyl (O–H), alkane (C–H), and ether (C–O), on the MoS2 surface. The milling resulted in a significant reduction in particle size from an initial mean size of 1.2 µm–480 nm. Field emission scanning electron microscopy micrographs of the exfoliated MoS2 revealed a thin, cracked, and flake-like morphology. High-resolution transmission electron microscopy images revealed that the high-energy ball milling resulted in few-layered MoS2 nanoplatelets after 30 h of ball milling. Subsequently, the investigation extended its focus to the development of Al–MoS2 nanocomposites using the PM route, incorporating MoS2 into the Al matrix at different weight percentages (1, 2, 3, and 5 wt.%). Al-5 wt.% MoS2 nanocomposite showed the highest relative density of 93.09 %, the maximum hardness of 743.6 MPa, and the best wear performance among all the Al–MoS2 nanocomposites. The hardness of Al-5 wt.% MoS2 nanocomposite was 109.11 % higher than that of the pure Al sample developed similarly. A maximum compressive strength (σ max) of 494.67 MPa was observed in Al-5 wt.% MoS2 nanocomposite, which was 1.84 times the value of σ max obtained from sintered pure Al sample.

A simple approach for integrating quantum confinement effects into TCAD simulations of tunnel field-effect transistors

A simple approach for integrating quantum confinement effects into TCAD simulations of tunnel field-effect transistors

Interface Engineering: Enhanced Catalysis Through Precise Control of Metal Nanocluster Transformation.

Atomically precise metal nanoclusters (NCs) have garnered significant interest due to their unique atomic stacking structures, the effect of quantum confinement, and enriched active sites but suffer from thermal- or light-induced poor instability and self-aggregation, together with in situ self-conversion to conventional metal nanoparticles (NPs). How to effectively harness the generic detrimental self-transformation property of metal NCs has so far not garnered immense attention within the realm of catalysis. In this work, we develop a layer-by-layer assembly technology to accurately anchor metal NCs to the metal oxide matrix. Then, the anchoring of metal NCs to metal NPs is triggered by a simple thermal treatment that enables precise control over the interface structure, resulting in a hollow core-shell heterostructure with a metal core (Au, Ag) encapsulated by a metal oxide (CeO2, Fe2O3, SnO2) shell. Benefiting from the synergistic interplay between metal NPs and the metal oxide substrate, such self-assembled metal NPs@metal oxide heterostructures display excellent catalytic activities and stability in the reduction of aromatic nitro compounds. The detailed catalytic mechanism is elucidated. Our work offers fresh impetus for the judicious utilization of the inherent instability of metal NCs for catalytic selective organic transformation.

Synergizing internal electric field and quantum-confined stark effect for customized carrier dynamics in two-dimensional heterostructures

The customized transport of carriers within two-dimensional (2D) heterostructures (HSs) is instrumental in enhancing the electronic and optoelectronic functionalities. Internal electric field (IEF) has opened potential pathways for manipulating carrier migration behaviors, unlocking diverse applications such as photocatalysts, solar cells, photodetectors, and other photoelectrochemical (PEC) devices. While it is intuitively understood that the orientation of IEF governs the direction of carrier transport, there are notable discrepancies between theoretical predictions and experimental results concerning the dynamics of photogenerated carriers. In this work, based on several polar HSs with tunable IEF, we unveiled the role of IEF in the carrier dynamics within these HSs. Our findings show that IEF not only regulates the band alignment of the HSs but also manipulates the electron–phonon (e-ph) coupling. The synergistic interplay of IEF and the quantum-confined Stark effect determines the dynamics of photoexcited carriers, facilitating the transition between type-Ⅱ and Z-scheme. These insights offer prospective strategies for tailoring interlayer charge carrier migration pathways and the photocatalytic activity of HSs.

Twin boundary formation in Pb thin film under conditions of the quantum confinement effect

Twin boundary formation in Pb thin film under conditions of the quantum confinement effect

Mo6X6 nanowires enhance the catalytic and cycling performance of non-aqueous Li-O2 batteries

Lithium-air batteries are considered one of the most promising energy storage technologies due to their extremely high theoretical energy density. However, low catalytic efficiency of the cathode catalyst limits its practical application. Here, we systematically studied the ORR/OER performance of Mo6X6 (X = S, Se, Te) nanowires as cathode catalysts for Li-O2 batteries using first-principles calculations. The results indicate that quantum confinement effect induces Mo6S6 and Mo6Se6 nanowires to exhibit metallic properties and high electronic conductivity. Furthermore, Mo6S6 nanowire exhibits the lowest overpotentials for ORR and OER, demonstrating excellent electrochemical performance. Meanwhile, we considered the solvent effect and found that Mo6X6 exhibits excellent structural stability in both DMSO and TEGDME without causing decomposition of the solvent molecules. More interestingly, Molecular dynamics simulations show that the surface of Mo6S6-NWs is more prone to the formation of an amorphous Li2O2 film, which can significantly reduce the interface contact resistance. This leads to rapid decomposition of the film-like Li2O2 and results in lower overpotential and good cycling performance. Nudged elastic band (NEB) calculation indicates that O2 has difficulty displacing the non-metallic elements in Mo6X6 nanowires, demonstrating their excellent structural stability. Our work provides important references for efficiently screening and developing cathode catalysts for Li-O2 batteries.

Sodium doped CsPbI3-PMMA composite electrospun fibrous membranes for aqueous photocatalyst and LED

All-inorganic CsPbI3 halide perovskite nanocrystals exhibit excellent photoluminescent properties, but their ambient instability presents a challenge. Adding dopants has been an effective way to improve stability. However, very few work was done for CsPbI3, which is relevant for optoelectronic and photovoltaic applications. Here sodium doped CsPbI3 nanocrystals were precipitated in situ in PMMA polymer matrix at room temperature using an electrospinning technique. It was found that the sodium doping improved the photoluminescence intensity and stability of Na-doped CsPbI3@PMMA electrospun fibrous membranes (EFMs) both in air and in water with an optimal concentration of Na/Pb = 0.75. It is speculated that sodium doping creates a core–shell structure with the sodium passivates the shell while the emission wavelength of the core blue-shifts due to the quantum confinement effect. Furthermore, EFMs can be used as photocatalysts to degrade methyl orange and to create white-LED with CIE of (0.2935, 0.3304) and color temperature of 7227 k.

Engineered Polymeric Carbon Nitride for Photocatalytic Diverse Functionalization of Electronic‐Rich Alkenes

Engineered polymeric carbon nitride represents a promising class of metal‐free semiconductor photocatalysts for organic synthesis. Herein, we utilized engineered polymeric carbon nitride nanosheets, which exhibit an increased specific surface area and bandgap due to enhanced quantum confinement from vacancy enrichment. These nanosheets serve as a heterogeneous organic semiconductor photocatalyst to facilitate diverse functionalizations of electron‐rich alkenes, including arylsulfonylation, aminodifluoroalkylation, and oxytrifluoromethylation. This catalytic system operates under mild conditions, offering excellent functional group compatibility and high yields. Additionally, CNNs‐3 demonstrates outstanding recyclability and efficiency in flow reactors, highlighting its significant potential for industrial applications.

Engineered Polymeric Carbon Nitride for Photocatalytic Diverse Functionalization of Electronic-Rich Alkenes.

Engineered polymeric carbon nitride represents a promising class of metal-free semiconductor photocatalysts for organic synthesis. Herein, we utilized engineered polymeric carbon nitride nanosheets, which exhibit an increased specific surface area and bandgap due to enhanced quantum confinement from vacancy enrichment. These nanosheets serve as a heterogeneous organic semiconductor photocatalyst to facilitate diverse functionalizations of electron-rich alkenes, including arylsulfonylation, aminodifluoroalkylation, and oxytrifluoromethylation. This catalytic system operates under mild conditions, offering excellent functional group compatibility and high yields. Additionally, CNNs-3 demonstrates outstanding recyclability and efficiency in flow reactors, highlighting its significant potential for industrial applications.

Blow‐up for a nonlocal semilinear pseudo‐parabolic p$$ p $$‐Laplacian type equation

In this paper, a nonlocal semilinear pseudo‐parabolic ‐Laplacian type equation is considered, and finite time blow‐up of solution with different initial energy is proved. More precisely, the upper bound for the blow‐up time of solution with subcritical initial energy is established by potential well method and concavity argument. When the initial energy is supercritical, we prove the finite time blow‐up of solution and obtain the upper bound for the blow‐up time by different invariant set and concavity inequality. Moreover, by constructing a new control functional and providing careful estimates, the lower bound for the blow‐up time of solution is given.

Physics-based, data-driven production forecasting in the Utica and Point Pleasant Formation

We introduce a robust, data-driven and physics-based method to forecast the estimated ultimate recovery (EUR) of gas and condensates from the Utica-Point Pleasant Formation. By categorizing 3,410 horizontal wells into eight static cohorts based on the initial gas-oil ratios (GOR) and completion dates, we construct generalized extreme value (GEV) distributions of annual reservoir fluid mass production for each cohort. We use the expected values (means) to build historical, statistical well prototypes for each cohort. These prototypes account for hydraulic fracture deterioration, pressure interference between neighboring fractures, well interference, and advancements in completion technology. We extrapolate mass production of the reservoir fluids for several decades by fitting the scaling parameters of our physics-based model to the statistical well prototypes. A key innovation in this approach is using GEV statistics to generate a time series for each cohort’s GOR and condensate-gas ratio (CGR). We replace the individual production rates from all existing wells with their corresponding extended well prototypes and convert mass to volumetric rates. We sum up the latter rates and provide a base forecast of total reservoir fluid rates and cumulative production, closely matching the historical field production. Our base forecasts predict approximately 23 trillion scf of gas and 200 million barrels of condensate by 2035.The Utica-Point Pleasant Formation is divided into core and noncore areas, each further subdivided into regions based on fluid types. We analyze the future infill potential per square mile in each of these regions, proposing two drilling schedules and four potential future drilling scenarios. We identify approximately 35,847 potential future wells: 12,476 in the core area and 23,371 in the noncore area. The core wells can contribute about 157 trillion scf of natural gas and 0.9 billion barrels of condensate.This study marks the first integrated evaluation of the future production from the Utica-Point Pleasant Formation by combining GEV statistics, physics-based modeling, big-data analysis, geology, proposed drilling programs, and economics. It provides a comprehensive understanding of the Utica-Point Pleasant Formation’s significance in future U.S. shale production.

Doping- and capacitor-less 1T-DRAM cell using reconfigurable feedback mechanism

In this paper, we propose a doping- and capacitor-less 1T-DRAM cell, which achieved virtual doping by leveraging charge plasma and bias-induced electrostatic doping (bias-ED) techniques in a 5 nm-thick intrinsic silicon body, thereby eliminating doping processes. Platinum was in contact with the drain, while aluminum was in contact with the source, enabling virtual doping of the silicon body into ap*-i-n* configuration via the charge-plasma technique. Two coupled polarity gates and one control gate are positioned above the intrinsic channel region. The intrinsic channel region is virtually doped through the bias-ED by applying voltages to the gates, forming potential wells inside the channel. The voltage applied to the two coupled polarity gates determines whether the device operates in thep- orn-channel mode, whereas the control gate governs the flow of charge carriers. Charge carriers are stored and released in the potential wells inside the channel by adjusting the gate, effectively replacing the capacitor. In this device, the placement of polarity gates on either side of the control gate enables the observation of the reconfigurable characteristics. Moreover, the proposed device utilizes a feedback mechanism, enabling excellent memory characteristics such as a high on/off current ratio of ∼109, steep switching behavior of ∼0.2µV dec-1, short write time of 10 ns, long hold retention of over 100 s, and long read retention of over 600 s.

Prominence of copper in AuCu alloy towards enhance surface plasmon resonance-driven water oxidation

To fully harness the potential of surface plasmon resonance (SPR) in augmenting photocatalytic water oxidation, a comprehensive exploration of structure-activity relationship of metal nanoparticles is essential. This work presents a wrap-bake-peel (WBP) strategy designed to stabilize AuCu/TiO2 nanostructures while preserving SPR absorption and refining the metal-semiconductor interfaces. Through strategically incorporating trace Cu into Au (Cu/Au = 0.06), we achieved a 2.6-fold enhancement of SPR-induced oxygen evolution reaction (OER) performance compared to pristine Au/TiO2. This enhancement is due to the synergistic effect of SPR and a well-defined Schottky barrier, which improves plasmonic hot carrier charge separation, as verified by detailed spectroscopic analyses. The incorporation of copper plays a critical role, acting as an electron shuttle that facilitates the transfer of hot electrons from photoexcited gold to the AuCu NP surface, thereby reducing recombination. This process, driven by SPR-induced hot electrons from Au, also extends electron-phonon (τ0e-ph), interactions by 138 %, significantly prolonging hot carrier lifetimes. Mechanistic insights reveal that d-band onset potentials (Ed-AuCu∼-0.9 V/ Ed-Au∼-1.2 V) and increased hot hole d-band occupancy in AuCu further enhance the overall SPR-induced water oxidation performance. Simulated electron distributions and quantum confinement in AuCu vs. Au critically dictate SPR characteristics, enabling precise modulation of plasmonic responses. These findings underscore the crucial role of Cu in fine-tuning the properties of plasmonic photocatalysts, demonstrating a significant advancement in the rational design of efficient solar-to-fuel conversion systems.

Preferential graphitic-nitrogen formation in pyridine-extended graphene nanoribbons

Graphene nanoribbons (GNRs), nanometer-wide strips of graphene, have garnered significant attention due to their tunable electronic and magnetic properties arising from quantum confinement. A promising approach to manipulate their electronic characteristics involves substituting carbon with heteroatoms, such as nitrogen, with different effects predicted depending on their position. In this study, we present the extension of the edges of 7-atom-wide armchair graphene nanoribbons (7-AGNRs) with pyridine rings, achieved on a Au(111) surface via on-surface synthesis. High-resolution structural characterization confirms the targeted structure, showcasing the predominant formation of carbon-nitrogen (C-N) bonds (over 90% of the units) during growth. This favored bond formation pathway is elucidated and confirmed through density functional theory (DFT) simulations. Furthermore, an analysis of the electronic properties reveals metallic behavior due to charge transfer to the Au(111) substrate accompanied by the presence of nitrogen-localized states. Our results underscore the successful formation of C-N bonds on the metal surface, providing insights for designing new GNRs that incorporate substitutional nitrogen atoms to precisely control their electronic properties.

Unraveling Ion Migration Mechanisms under Operating Conditions in Perovskite Solar Cells by Variable-Load Transient Photoelectric Technique.

Ion migration in perovskite solar cells (PSCs) significantly impacts their photoelectric performance and physicochemical stability. Existing research has predominantly focused on inhibiting ion migration through chemical strategies or observing it under open-circuit or short-circuit conditions. This focus has led to a limited theoretical understanding and control of ion migration under practical conditions, constraining advances in long-term stability. In this study, we introduce a novel variable-load transient photoelectric technique (VL-TPT) to investigate ion migration dynamics in PSCs under practical operating conditions. Results show that ion accumulation correlates with photogenerated carrier concentration under open-circuit conditions. During operation, ion accumulation decreases with reduced load, because charge is transferred to the external circuit, leading to a reduction in carrier concentration within the device. An unusual increase in interface ions is observed at low loads due to interactions between charges accumulated in the potential well and ions. Introducing FA+ in MA0.75FA0.25PbI3 devices suppresses ion migration in the open-circuit state but accelerates interface ion buildup under operating conditions. These findings provide valuable insights for enhancing device stability and performance.

Differential Cross-Sections for the Vibrationally Excited H + HOD(vOH = 1-4) → H2 + OD Reactions.

Using the time-dependent wave-packet approach, we calculate the first fully converged state-to-state differential cross-sections for the H + HOD(vOH = 1-4) → H2 + OD reactions on a highly accurate neural network PES. It is found that, unlike the loss of memory effect observed in the product distributions for low vibrational excitation reactions, high initial OH vibrational excitation significantly influences not only the product vibrational distribution but also the angular distribution. Furthermore, for the H + HOD(vOH = 3,4) reactions, the total integral cross-sections maintain the pronounced oscillatory structures in the J = 0 probabilities at low collision energies, which originate from the prereactive van der Waals resonances. Notably, the product angular distributions exhibit forward-backward peaked behavior at these energies, akin to those observed in the complex-forming system with deep potential wells. This is attributed to the much longer lifetimes of these resonances compared to those of conventional transition state resonances.

Генерация незатухающих тепловых волн и их влияние на удаленные и экранированные мишени дейтерированного титана

The paper experimentally studies and theoretically substantiates the conditions and features of generation of undamped thermal waves during water cavitation, which are associated with the features of the relaxation processes of such waves in the air. The minimum frequency of such waves at normal pressure and air temperature corresponds to 70-80 MHz. It is shown that the interaction of a traveling thermal wave in the air with the front surface of a metal screen leads to the formation of strong acoustic waves in its volume. In the experiments, samples of deuterated titanium removed and shielded by a metal plate, in which the concentration of deuterium was 1.5 times higher than the concentration of basic titanium nuclei, were exposed to high-frequency thermal waves. The states of deuterium nuclei located in a potential well in the titanium lattice as a result of this impact were studied.

Titanium Oxysulfate‐Derived 1D Lepidocrocite Titanate Nanostructures

AbstractNanostructured titania, TiO2, holds significant importance in various scientific fields and technologies for their distinctive properties and multipurpose characteristics. In this article, the facile, economical, and scalable synthesis of 1D lepidocrocite, 1DL, titania nanostructures derived from a water‐soluble Ti precursor, titanium oxysulfate (with oxidation of Ti+4) at temperature <100 °C under atmospheric pressure is discussed. Titanium oxysulfate with tetramethyl ammonium hydroxide, TMAH, is simply reacted to yield individual lepidocrocite titania‐based chain‐forming nanofilaments, NFs, 6 × 6 Å2 in minimal cross‐section and aspect ratios of ≈20 1DLs. If only ethanol is used for washing, the 1DL self‐assemble into ≈10 µm, porous mesostructured particles, PMPs. If water is used, quasi‐2D sheets form instead. Characterization of the resulting powders showed them to be quite similar to those derived from TiB2, and other water‐insoluble Ti precursors. The 1DL bandgap energies are ≈4 eV, due to quantum confinement. They adsorbed rhodamine 6G. The latter also sensitized the 1DLs and allowed for dye degradation using only visible light. Used as electrodes in supercapacitors, the 1DLs can be cycled over 1.6 V and result in high power densities (300 W kg−1). Stronger birefringence started to appear in samples with concentrations >15 gL−1 indicating the formation of a liquid crystal phase. This new synthesis protocol enables the cheaper scalable production of 1DLs with significant implications across various fields.

Synthesis of tetraphenylphosphonium/polysulfide hybrids and their temperature-induced switchable WORM/flash electrical memory behavior

The development of innovative non-volatile storage materials is essential for the progression of next-generation high-performance storage devices. In this study, a hybrid material (Ph4P)2S7 was synthesized, and single crystal structure analysis demonstrated that the organic tetraphenylphosphonium cation (Ph)4P+ adopts a regular tetrahedral conformation and forms one-dimensional chains through CH···π interactions. The (S7)2- anion, characterized by quasi-bicentric symmetry and a right-handed helical cluster, is confined within the one-dimensional quantum well established by the (Ph)4P+ cation chain in the organic matrix. A device composed of FTO/(Ph4P)2S7/Ag was fabricated through spin-coating, demonstrating remarkable temperature-induced switchable binary write-once-read-many-times (WORM)/Flash electrical memory behavior. At room temperature, the material demonstrated nonvolatile binary WORM-type resistance switching behavior with a switching ratio of 1.95 × 103 and an onset voltage of 1.01 V. Conversely, at 150 °C, it transits into binary Flash-type resistance switching behavior characterized by current ratio of 3.34 × 102 and onset/reset voltages of 1.05/−1.99 V. The mechanism underlying binary resistive switching is identified as spatial charge-limited charge capture. Furthermore, the observed reversible transition between WORM- and Flash- type electrical memory behavior at elevated temperatures can be attributed to lattice expansion of the (Ph)4P+ cations at high temperatures, resulting in denser packing of organic molecules and deeper trapping potential wells for electrons within the active layer. This study provides theoretical insights into developing novel high-performance information storage materials.

Introducing boron gallium nitride as carriers’ source layer for efficient near-ultraviolet microLED

Abstract This study explored the impact of boron gallium nitride (BGaN) in buffer layer and hole source layer. We employed B0.05Ga0.95N which reduced the lattice mismatch as well as the electric field. BGaN not only minimized the number of electrons leaking out of quantum wells (QWs) but also improved the hole injection. It is evident from our simulations that internal quantum efficiency (IQE) is enhanced significantly as more carriers are available for radiative recombination in multiple quantum wells (MQWs). Along with the increase in IQE, droop is also reduced in BGaN ultraviolet light-emitting diodes. Significantly high luminous power and emission intensity were observed along with slight blueshift because of minimized quantum confinement stark effect (QCSE).