Charge Stability Research Articles

Charge Stability and Charge-State-Based Spin Readout of Shallow Nitrogen-Vacancy Centers in Diamond.

Spin-based applications of the negatively charged nitrogen-vacancy (NV) center in diamonds require an efficient spin readout. One approach is the spin-to-charge conversion (SCC), relying on mapping the spin states onto the neutral (NV0) and negative (NV-) charge states followed by a subsequent charge readout. With high charge-state stability, SCC enables extended measurement times, increasing precision and minimizing noise in the readout compared to the commonly used fluorescence detection. Nanoscale sensing applications, however, require shallow NV centers within a few nanometers distance from the surface where surface related effects might degrade the NV charge state. In this article, we investigate the charge state initialization and stability of single NV centers implanted ≈5 nm below the surface of a flat diamond plate. We demonstrate the SCC protocol on four shallow NV centers suitable for nanoscale sensing, obtaining a reduced readout noise of 5-6 times the spin-projection noise limit. We investigate the general applicability of the SCC for shallow NV centers and observe a correlation between the NV charge-state stability and readout noise. Coating the diamond with glycerol improves both the charge initialization and stability. Our results reveal the influence of the surface-related charge environment on the NV charge properties and motivate further investigations to functionalize the diamond surface with glycerol or other materials for charge-state stabilization and efficient spin-state readout of shallow NV centers suitable for nanoscale sensing.

Exploring the antiviral potency of γ-FP and PA compounds: Electronic characterization, non-covalent interaction analysis and docking profiling with emphasis on QTAIM aspects

As focuses on a set of pertinent compounds that incorporate a γ-substituted halophenol linkage with pentanamide (PA). The properties of these compounds were comprehensively assessed through various analytical techniques, including density functional theory (DFT) calculations, offering insights into their geometry and electronic energy gap characteristics. Charge delocalization and stability were explored via natural bond orbital (NBO) analysis. The chemical reactivity was further scrutinized by evaluating NBO, Molecular Electrostatic Potential (MEP), Hirshfeld surface analysis and Fukui functions. The compounds were found to exhibit stability attributed to a robust hydrogen bonding network, which was corroborated by Interaction Region Indicator (IRI) and Electron Density (ED) assessments. Additionally, pharmacological properties were predicted using the PASS (Prediction of Activity Spectra for Substances) server. Molecular docking studies suggested potential antiviral and antioxidant properties, particularly concerning carbonic anhydrase. The overall results imply that these compounds possess favorable drug-like characteristics and show promise for biological efficacy. The study also includes a 2D interaction profile image of the four most interacted proteins and a Ramachandran plot to elucidate the stereochemistry of a selected protein. Furthermore, the activities of 6FDM were investigated following a comprehensive literature survey, with detailed findings presented.

Shallow Silicon Vacancy Centers with Lifetime-Limited Optical Linewidths in Diamond Nanostructures.

The negatively charged silicon vacancy center (SiV-) in diamond is a promising, yet underexplored candidate for single-spin quantum sensing at sub-kelvin temperatures and tesla-range magnetic fields. A key ingredient for such applications is the ability to perform all-optical, coherent addressing of the electronic spin of near-surface SiV- centers. We present a robust and scalable approach for creating individual, ∼50 nm deep SiV- with lifetime-limited optical linewidths in diamond nanopillars through an easy-to-realize and persistent optical charge-stabilization scheme. The latter is based on single, prolonged 445 nm laser illumination that enables continuous photoluminescence excitation spectroscopy without the need for any further charge stabilization or repumping. Our results constitute a key step toward the use of near-surface, optically coherent SiV- for sensing under extreme conditions, and offer a powerful approach for stabilizing the charge-environment of diamond color centers for quantum technology applications.

Influence of Above Burden Probes in Blast Furnace on Centre Coke Charging and Subsequent Operational Stability

Influence of Above Burden Probes in Blast Furnace on Centre Coke Charging and Subsequent Operational Stability

Spin-Stabilization by Coulomb Blockade in a Vanadium Dimer in WSe2.

Charged dopants in 2D transition metal dichalcogenides (TMDs) have been associated with the formation of hydrogenic bound states, defect-bound trions, and gate-controlled magnetism. Charge-transfer at the TMD-substrate interface and the proximity to other charged defects can be used to regulate the occupation of the dopant's energy levels. In this study, we examine vanadium-doped WSe2 monolayers on quasi-freestanding epitaxial graphene, by high-resolution scanning probe microscopy and ab initio calculations. Vanadium atoms substitute W atoms and adopt a negative charge state through charge donation from the graphene substrate. VW-1 dopants exhibit a series of occupied p-type defect states, accompanied by an intriguing electronic fine-structure that we attribute to hydrogenic states bound to the charged impurity. We systematically studied the hybridization in V dimers with different separations. For large dimer separations, the 2e- charge state prevails, and the magnetic moment is quenched. However, the Coulomb blockade in the nearest-neighbor dimer configuration stabilizes a 1e- charge state. The nearest-neighbor V-dimer exhibits an open-shell character for the frontier defect orbital, giving rise to a paramagnetic ground state. Our findings provide microscopic insights into the charge stabilization and many-body effects of single dopants and dopant pairs in a TMD host material.

3D-Printed Piezoelectret Based on Foamed Polylactic Acid for Energy-Harvesting and Sensing Applications.

Poly(lactic) acid (PLA) is a bio-compatible polymer widely used in additive manufacturing, and in the form of cellular foam it shows excellent mechanical and piezoelectric properties. This type of structure can be easily 3D-printed by Fusion Deposition Modelling (FDM) with commercially available composite filaments. In this work, we present mechanical and electrical investigations on 3D-printed low-cost and eco-friendly foamed PLA. The cellular microstructure and the foaming degree were tuned by varying extrusion temperature and flowrate. The maximum surface potential and charge stability of disk samples were found in correspondence of extrusion temperature between 230 and 240 °C with a flowrate of 53-44% when charging on a heated bed at 85 °C. The cells' morphology and correlated mechanical properties were analyzed and the measured piezoelectric d33 coefficient was found to be 212 pC/N. These findings show the importance of printing parameters and thermal treatment during the charging process in order to obtain the highest charge storage, stability and material flexibility. These results suggest that 3D-printed cellular PLA is a promising sustainable material for sensing and energy-harvesting applications.

Stearate and hindered amine light stabilizers coordinate to boost charge storage performance of water electret melt-blown nonwovens

Water electret (WE) technology is a current research hotspot in the field of high-efficiency and low-resistance melt-blown filter materials. The electret is an important factor affecting the filtration performance and durability of WE melt-blown nonwovens. In this paper, WE melt-blown nonwovens were prepared with stearate compounded with hindered amine light stabilizer (HALS) as the electret additives, which exhibited excellent performance and the filtering efficiency of DEHS oily particles exceeding 99%. The charge formation and storage mechanism of WE melt-blown nonwoven were also elucidated by using the thermally stimulated discharge technique. Benefiting from the inherent amino group of HALS and the synergistic effect with stearate, positively charged hydrated protons were attracted and migrated to the interior of the fiber to form durable space charges, which led to a significant enhancement of the filtration/charge storage performance of melt-blown nonwoven. The charge stability performance of WE melt-blown nonwoven was also investigated under the treatment of solvents such as constant temperature and humidity, high-temperature hot water, alcohol, and isopropyl alcohol. These studies help to improve the product quality of WE melt-blown nonwovens, as well as provide a systematic guide to an in-depth understanding of the electret mechanism of WE technology.

Optical, magnetic, and electrochemical properties of a fluorite-perovskite Ce0.9Gd0.1O2-∂ - La0.6Sr0.4FeO3-∂ nanocomposite synthesized by one pot sol-gel auto-combustion route

Gadolinium-doped cerium oxide (Ce0.9Gd0.1O2-∂; CGO) and strontium-doped lanthanum ferrite (La0.6Sr0.4FeO3; LSF) are well-known compounds for their application in solid oxide fuel cells, dense oxygen permeable membrane, and high-temperature ceramic reactor. The superior electro-catalytic performance of these two individual oxides or their composites is well established as it originates from multivalent cations (Ce3+/4+ and Fe2+/3+/4+) and doping-induced defects like electrons, holes, and oxygen vacancies. This work focuses on synthesizing and characterizing composite taking CGO and LSF in different weight ratios, i.e., 10:90, 30:70, 50:50, 70:30, and 90:10 by sol-gel auto-combustion process. End members CGO and LSF were also synthesized for comparison purposes. All synthesized nanopowders (single phases and their composites) were characterized with X-ray diffraction (XRD) for phase identification and Scanning electron microscopy (SEM) for elemental composition analysis. XRD and SEM results established the formation of the required phase and targeted composition. The optical properties of the materials were evaluated with the help of ultraviolet–visible Diffuse Reflectance Spectroscopy (UV–Vis DRS). Tauc's approximation measured band gap energies, and all the composites showed a very high band gap in the 4.85–5 eV range. Magnetic properties such as saturation magnetization (Ms), remanence (Mr), and coercive force (Hc) were calculated from a magnetic hysteresis loop obtained from the Vibrating-sample magnetometer (VSM) experiment at room temperature. Furthermore, the law of approach to saturation (LAS) model was applied to more precisely calculate Ms and other essential parameters. In magnetic characterization, the LSF phase fraction controls the overall magnetic property of the composites. Electrochemical behavior, such as the composites' charge storage ability and stability were tested by cyclic voltammetry and chronopotentiometry method. All the samples exhibited good stability, and the highest specific capacitance of 26 F/gm was obtained for the composite sample (CL91) when only 10 % LSF phase was incorporated in the nanocomposite.

Low-temperature plasma-induced porous Sb2WO6 microspheres with rich oxygen vacancies to promote high-performance photocatalytic activity

The escalating issue of water pollution has sparked significant attention among researchers in the field of photocatalysis. Consequently, it holds immense significance to develop photocatalysts that exhibit high charge separation efficiency and stability for effectively degrading pollutants in water. In this study, OV-Sb2WO6-X photocatalyst was synthesized by incorporating oxygen vacancies into pristine Sb2WO6. The introduction of oxygen vacancies significantly enhanced the charge separation efficiency, resulting in a substantial improvement in the photocatalytic activity. The content of oxygen vacancies was controlled by plasma treatment time, processed for 10, 20 and 30 min, and electron paramagnetic resonance (EPR) test demonstrated the introduction of oxygen vacancies successfully. Furthermore, X-ray photoelectron spectroscopy (XPS) characterized the internal electron flow direction of the photocatalyst. OV-Sb2WO6-20 showed the degradation rate of Rhodamine B (RhB) that nine times of the Sb2WO6, while the Tetracyclines (TC) degradation rate showed 3.5 times that of Sb2WO6. Moreover, OV-Sb2WO6-20 exhibited superior stability in terms of recycling activity and material structural integrity. Additionally, free radical trapping experiments and electron spin-resonance spectroscopy characterization demonstrated that h+ played a crucial role as the reactive species during the degradation process. This research presents a viable approach for the modification of Sb2WO6-based materials, enabling effective treatment of dye wastewater and achieving successful purification.

Ti3C2Tx constrained Sb2S3 composite biomass-derived carbon ribbon film achieves stable sodium storage for flexible quasi-solid full-battery

Optimizing electrode structure, reducing the proportion of inactive substances, and fabricating a flexible free-standing electrode without fluid collection are desirable to enhance the energy density, fast charging, and cycling stability of flexible batteries. In this study, we utilized the biological characteristics of Aspergillus niger to synthesize one-dimensional (1D) Sb2S3 nanoparticle composite N-doped C ribbons. Subsequently, vacuum filtration was employed to blend and assemble these 1D composite C ribbons with Ti3C2Tx nanosheets into a free-standing flexible anode for Sodium-ion batteries (SIBs). Using 1D C ribbons can effectively inhibit the stacking of 2D MXenes, thereby facilitating the penetration of Na+ into Sb2S3@NCR through the interlamellar pores. Ex-situ X-ray photoelectron spectroscopy analyses indicated that the MXene layers were not only physically confined but also effectively suppressed polysulfide diffusion through chemical confinement. Consequently, the energy density and cycling stability of the Sb2S3@NCR composite electrode were enhanced. The Sb2S3@NCR/MXene||CGPFE||NVP@CNF full battery, consisting of an Sb2S3@NCR/MXene anode, free standing NVP@CNF cathode, and PVDF-HFP fiber quasi-solid-state polymer electrolyte prepared via electrospinning, achieved 1,000 stable cycles at a current density of 1 Ag−1. Additionally, the flexible quasi-solid-state bag-type battery could power an LED lamp at a bending angle of 0°–180°.

The Potential Game‐Changer: A Concept‐to‐Proof Study on D:A Heterojunction‐Free Organic Photovoltaics†

Comprehensive SummarySince 1986, the donor‐acceptor (D:A) heterojunction has been regarded a necessity for high‐efficiency organic photovoltaics (OPVs), due to its unique advantage in compensating the intrinsic limitations of organic semiconductors, such as high exciton binding energy and poor ambipolar charge mobility. While this adversely causes tremendous non‐radiative charge recombination and instability issues, which currently become the most critical limits for commercialization of OPVs. Here, we present a concept‐to‐proof study on the potential of D:A heterojunction free OPV by taking advantage of recent progress of non‐fullerene acceptors. First, we demonstrate that the “free carriers” can be spontaneously generated upon illumination in an NFA, i.e., the 6TIC‐4F single layer. Second, the 6TIC‐4F layer also exhibits good ambipolar charge transporting property. These exceptional characteristics distinguish it from the traditional organic semiconductors, and relieve it from the reliance of D:A heterojunction to independently work as active layer. As a result, the subsequent OPV by simply sandwiching the 6TIC‐4F layer between the cathode and anode yields a considerably high power conversion efficiency ~1%. Moreover, we find the D:A heterojunction free device exhibits two order of magnitude higher electroluminescence quantum efficiency and significantly reduced VOC loss by 0.16 eV compared to those of the D:A BHJ structure, validating its promise for higher efficiency in the future. Therefore, our work demonstrates the possibility of using D:A heterojunction‐free device structure for high performance, that can potentially become the next game changer of OPV.

Copper nanoparticles/polyaniline/molybdenum disulfide composite as a nonenzymatic electrochemical glucose sensor

A Cu@Pani/MoS2 nanocomposite was successfully synthesized via combined in-situ oxidative polymerization and hydrothermal reaction and applied to an electrochemical nonenzymatic glucose sensor. The morphology of the prepared Cu@Pani/MoS2 nanocomposite was characterized using FE-SEM and Cs-STEM, and electrochemical analysis was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry techniques. Electrostatic interaction between Cu@Pani and MoS2 greatly enhanced the charge dispersion, electrical conductivity, and stability, resulting in excellent electrochemical performance. The Cu@Pani/MoS2 was used as an electrocatalyst to detect glucose in an alkaline medium. The proposed glucose sensor exhibited a sensitivity, detection limit, and wide linear range of 69.82 μAmM−1cm−2, 1.78 μM, and 0.1–11 mM, respectively. The stability and selectivity of the Cu@Pani/MoS2 composite for glucose compared to that of the potential interfering species, as well as its ability to determine the glucose concentration in diluted human serum samples at a high recovery percentage, demonstrated its viability as a nonenzymatic glucose sensor.

Sulfobetaine methacrylate-coated reduced graphene oxide-IR780 hybrid nanosystems for effective cancer photothermal-photodynamic therapy

Nanomaterials with near infrared light absorption can mediate an antitumoral photothermal-photodynamic response that is weakly affected by cancer cells’ resistance mechanisms. Such nanosystems are commonly prepared by loading photosensitizers into nanomaterials displaying photothermal capacity, followed by functionalization to achieve biological compatibility. However, the translation of these multifunctional nanomaterials has been limited by the fact that many of the photosensitizers are not responsive to near infrared light. Furthermore, the reliance on poly(ethylene glycol) for functionalizing the nanomaterials is also not ideal due to some immunogenicity reports. Herein, a novel photoeffective near infrared light-responsive nanosystem for cancer photothermal-photodynamic therapy was assembled. For such, dopamine-reduced graphene oxide was, for the first time, functionalized with sulfobetaine methacrylate-brushes, and then loaded with IR780 (IR780/SB/DOPA-rGO). This hybrid system revealed a nanometric size distribution, optimal surface charge and colloidal stability. The interaction of IR780/SB/DOPA-rGO with near infrared light prompted a temperature increase (photothermal effect) and production of singlet oxygen (photodynamic effect). In in vitro studies, the IR780/SB/DOPA-rGO per se did not elicit cytotoxicity (viability > 78 %). In contrast, the combination of IR780/SB/DOPA-rGO with near infrared light decreased breast cancer cells’ viability to just 21 %, at a very low nanomaterial dose, highlighting its potential for cancer photothermal-photodynamic therapy.

Improved charge density and stability in PDMS ferroelectrets using PDMS/PTFE composite materials

A ferroelectret is a flexible cellular polymer structure that generates electrical power under mechanical force. It behaves like a piezoelectric material in that a voltage is generated when the ferroelectret deforms. Its electrical output significantly depends on the surface charge density of the material used. Previous ferroelectrets fabricated from polydimethylsiloxane (PDMS) benefit from the soft, stretchable mechanical properties of the PDMS but the ability of this material to trap charge at its surface is poor. This paper presents approaches to enhance the surface charge density and stability of a PDMS based ferroelectret device by adding Polytetrafluoroethylene (PTFE) to the PDMS. This PDMS/PTFE composite has been evaluated when used to fabricate the ferroelectret device and when used as an additional coating the internal void surfaces of an otherwise plain PDMS ferroelectret. As the proportion of PTFE increases, the surface charge density on the void surfaces increases resulting in a corresponding increase in the piezoelectric properties of the ferroelectret. A weight ratio of PTFE powder and PDMS of 1:3 was found to achieve improved piezoelectric performance with an initial effective piezoelectric coefficient, d33e, of around 700 pC/N which decayed initially and reached a steady state value of around 365 pC/N measured after 4 months after poling. This presents a considerable improvement in performance when compared with the effective d33e of pure PDMS which has an initial value of around 110 pC/N and drops to below 8 pC/N after 4 months. The energy harvester potential of the ferroelectret was explored by cyclically compressing the PDMS/PTFE composite layer ferroelectret structure with a force of 500 N applied at 1 Hz. The output of the ferroelectret was found to charge a 10 μF capacitor to 0.12 V after 40 s. Maximum output power occurs at a load resistance of 15 MΩ, with a peak power of 4 μW. A fabricated PDMS/PTFE composite layer ferroelectret sample (weight ratio of PTFE powder and PDMS of 1:3) was also tested as a pressure sensor range from 0 to 500 N and achieved a sensitivity of 9.9 mV/N. The nonlinearity error of the proposed sensor was 1.7%.

Flexible fiber optoelectrodes integrating Perovskite-Nafion-ITO layers for efficient photoelectrocatalytic water purification

Photoelectrocatalytic processes (PECs) combine photocatalysis and electrochemical principles to enhance charge carrier generation and stability within nanomaterials (NMs). Nano-enabled PECs can be used for water purification or hydrogen production. While most PEC studies focus on nanomaterial discovery to improve charge carriers generation and separation, PEC reactor design is important to maximize energy efficiency of light delivery to activate photocatalysts. Current designs face challenges due to low energy efficiencies because most reactor designs orientate light sources perpendicular to flat photocatalyst-coated electrode surfaces, and light must pass through glass materials plus water. We developed a low-cost, physically flexible catalytic polymeric optical fiber (POF) architecture, called optoelectrode fibers, embedded with electrically-conductive indium tin oxide (ITO) nanomaterials (NMs) plus TAB3Bi2Br7I2 perovskite (ABI) visible-photocatalysts in Nafion-PVDF polymers surface layer. The PEC-POF architecture achieves > 6000% larger surface area than flat glass electrodes, > 90% organic pollutant removal in water, and > 300% better incident photon-to-current than the same ABI-NM deposited on a conventional ITO-coated flat glass-plate under low energy irradiation. POFs are useful because are agonistic to the type of NM, facilitating deposition of NMs tunable to specific wavelengths using LED or polychromatic light sources. Bundling large numbers of POF optoelectrodes together achieves reactors with orders of magnitude higher packing geometries (m2 of catalyst surface per m3 of reactor volume) than flat-electrode PEC reactors, enabling the optoelectrode fiber to address environmental problems.

A Theoretical Study on the Unique Site Preference and Atomic Ordering of Hexagonal CoSn‐type Ternary Intermetallic Compound Co3Ge2Sn

AbstractThe inclusion of Ge in hexagonal B35 type CoSn leads to the formation of a new ternary substituted ordered variant Co3Ge2Sn. The experimentally reported crystallographic site‐occupancy pattern of this compound has been fundamentally addressed by the PBE‐GGA density functional theory‐based Mulliken population analysis. The site preference of Ge in the structure of Co3Ge2Sn is governed by the rule of ‘topological charge stabilization’. It turns out that the covalent inter‐layer heteroatomic Co−Ge bonds play a profound impact on the formation and stability of the compound. The structure of Co3Ge2Sn is decided by a combined factor of site energy and bond energy.

Design and Implementation of High-Misalignment Tolerance WPT System for Underwater Vehicles Based on a Variable Inductor

Wireless charging for autonomous underwater vehicles (AUVs) has been widely explored recently by the merit of safety and convenience. However, due to the misalignment between charging coils in the horizontal and vertical directions, the system may not maintain constant current (CC) or constant voltage (CV) output. Therefore, this article proposes a mistuned IPT system structure and corresponding design methods to improve misalignment tolerance. The proposed IPT system adopts series-series compensation and includes a variable inductor (VI) on the secondary side. A general design method based on the established mathematical model is proposed. The worst scenarios (i.e., the maximum value of misalignment) are used for the optimization of the system parameters. The control strategy for VI without any communication link to the primary side is established. Finally, a 1 kW IPT system for tolerance of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> of 0.15-0.5 and output voltage of 74-150 V variation is set up. The experimental results show that the horizontal and vertical direction misalignment ranges reach ±47% and +140%, respectively, and the maximum system efficiency exceeds 96% for full power output. The proposed system improves the freedom and stability of charging in the harsh underwater environment.

Study of the nitrocellulose gunpowder regeneration process using hydrogen peroxide

World experience in storing ammunition shows that during long-term storage, pyroxylin gunpowders used in ammunition are capable of arbitrarily undergoing various physical and chemical transformations, which negatively affects the ballistic characteristics of ammunition. In some countries, ammunition is in use with a shelf life of 30–35 years or more.&#x0D; Factors influencing the physicochemical stability of gunpowder charges during long-term storage have been identified.&#x0D; An analysis of the chemical processes occurring in nitrocellulose gunpowders (NCP) during long-term storage is carried out, and the possibility of regenerating NCP by treatment with hydrogen peroxide is substantiated.&#x0D; It is indicated that there are no methods for regenerating gunpowder charges with long shelf life. It has been shown that one of the ways to increase the ballistic and energy characteristics of long-term storage ammunition can be the regeneration of nitrocellulose gunpowder charges.&#x0D; Data are presented on an experimental study to determine the characteristics of NCP after regeneration. It has been shown that when regenerating nitrocellulose gunpowder charges with hydrogen peroxide, the calorific value of the starting material increases.&#x0D; Based on the results obtained, an approach to assessing the feasibility of using regeneration technology is proposed. This approach is based on the effect of mass replenishment during the regeneration process due to ongoing chemical processes and heat and mass transfer.&#x0D; The ways for further research on the use of nitrocellulose as a high-calorie fuel are presented

A Tetrathiafulvalene-based Bimetal–Organic Framework for a Hybrid Lithium-Ion Capacitor: The Role of Bimetallic Centers in Charge Storage and Stability

A Tetrathiafulvalene-based Bimetal–Organic Framework for a Hybrid Lithium-Ion Capacitor: The Role of Bimetallic Centers in Charge Storage and Stability

Self-Discharge Processes in Symmetrical Supercapacitors with Activated Carbon Electrodes.

The self-discharge of an electric double-layer capacitor with composite activated carbon electrodes and aqueous electrolyte (1 M MgSO4) was studied in detail. Under a long-term potentiostatic charge (stabilization), a decrease in the discharge capacity was observed in the region of voltages exceeding 0.8 V. The self-discharge process consists of two phases. In the initial phase, the cell voltage drop is due to the charge redistribution inside electrodes. During the main phase, the charge transfer between the electrodes determines the voltage drop. The optimal stabilization time of the self-discharge was found to be 50 min at 1.4 V. Hydrophilization of the negative electrode occurred during long-term polarization due to the formation of epoxy functional groups.