Charge Flow Research Articles

Field Testing of an Affordable Zero-Liquid-Discharge Arsenic-Removal Technology for a Small-Community Drinking Water System in Rural California

Arsenic contamination in groundwater threatens public health, particularly in small, low-income communities lacking affordable treatment solutions. This study investigated the field implementation of novel air cathode assisted iron electrocoagulation (ACAIE) technology for arsenic removal in Allensworth, California, where groundwater arsenic concentrations exceeded 250 µg/L. Over four months, a pilot-scale ACAIE system, operating at 600 L/h, consistently reduced arsenic levels to below the EPA’s maximum contaminant level of 10 µg/L. Laboratory experiments informed the optimization of charge dosage and flow rates, which were validated during field testing of the ACAIE 600 L/h system. The in-situ generation of hydrogen peroxide at the cathode speeded up the reaction kinetics, ensuring high arsenic removal efficiency while allowing high throughput, even with a compact reactor size. An economic analysis demonstrated a treatment cost of USD 0.02/L excluding labor, highlighting the system’s affordability compared to conventional methods. Adding labor costs increased the treatment cost to USD 0.09/L. The regeneration of air cathodes extended their operational life, addressing a key maintenance challenge, thus reducing the costs slightly. Intermittent challenges were encountered with filtration and secondary contaminant removal; these issues highlight opportunities for further operational improvements. Despite these challenges, ACAIE’s low operational complexity, scalability, and cost-effectiveness make it a promising solution for underserved small communities. These findings provide critical insights into deploying sustainable arsenic remediation technologies that are tailored to the needs of rural, low-resource communities.

EVALUATION SUBSTATION PROTECTION SYSTEM FROM LIGHTNING STRIKES AT 150KV JATIGEDE SUBSTATION

Grounding serves a crucial role in the field lightning protection, electric power, and electric power communications networks. The grounding system's purpose is to guide the flow of electrical charges to the ground mass as rapidly as feasible. The goal of this study is to analyze the grounding system utilized to ensure the continuity of electrical energy production and delivery. In this study, quantitative methods are used to calculate lightning parameters, substation protection by earthing wires and protection towers, earthing system, mesh voltages, touch voltages and step voltages. According to IEEE 80-2013 (latest revision) standards, an ideal earthing application should have a resistance value of 1Ω. The results of the analysis and calculation of the grounding system using the grid grounding type obtained a value of 0.28276 Ω (1Ω), and mesh voltage 0,851314 kV. The protection system which consists of a 103.47288 M ground wire and a 55.27325 M protection tower, is capable of protecting the substation from lightning strikes with a peak current of 51.32913 kA. The touch voltage for humans weighing 50kg and 70kg is 133.39304 V and 180.54060 V, and the step voltage results in 185.5770 V and 251.1690 V. When the grounding current at touch and step voltages is considered, the values become 442.87730 kV and 616.17712 kV. Both exceed the allowed levels of 626 and 2,216 V.

Surfactant-based interface capture towards the development of 2D-printed photonic structures.

This study focuses on fabricating photonic crystals (PCs) by surfactant-based particle capture at the gas-liquid interface of evaporating sessile droplets. The captured particles form interfacial films, resulting in ordered monolayer depositions manifesting iridescent structural colors. The particle dynamics behind the ordered arrangement is delineated. This arrangement is influenced by the alteration in particles' hydrophobicity, charge, and internal flow introduced by the surfactant addition. The influence of surfactant and particle concentrations on the phenomenon is also investigated. The work demonstrates a drop-by-drop technique to scale up the formation of PCs. Furthermore, the work is extended towards demonstrating the utilization of this mechanism to fabricate arbitrary PCs efficiently by direct writing technique. The particle coverage in directly written patterns is influenced by printing speed and particle concentration, which are adjusted to achieve covert photonic patterns. Finally, the replication of colloidal PC onto a flexible polymer with minimal colloid transfer is demonstrated using soft lithography.

Tracking and controlling ultrafast charge and energy flow in graphene-semiconductor heterostructures

Tracking and controlling ultrafast charge and energy flow in graphene-semiconductor heterostructures

Construction of organic heterojunctions as metal-free photocatalysts for enhancing water splitting and phenol degradation by regulating charge flow.

Metal-free photocatalysts derived from earth-abundant elements have drawn significant attention owing to their ample supply for potential large-scale applications. However, it is still challenging to achieve highly efficient photocatalytic performance owing to their sluggish charge separation and lack of active catalytic sites. Herein, we designed and constructed a series of covalently bonded organic semiconductors to enhance water splitting and phenol degradation. Experimental and theoretical results revealed that the charge transfer mechanism transformed from type II in the physical mixture to a Z-scheme in the covalently bonded composite, resulting from the interfacial electric field formed at the interface between a β-ketoenamine-linked covalent organic framework (TP-COF) and a urea linked perylene diimide (PDI) semiconductor (UP) linked by amide bonds. The Z-scheme charge transfer route not only improved charge separation but also preserved the high redox ability of both semiconductors. Moreover, more active catalytic sites were created owing to the net charge transfer from the UP to TP-COFs with the amide bonds, contributing to improved photocatalytic performance. As a result, high HER, OER and phenol degradation rates of 613.30 μmol g-1 h-1, 1169.36 μmol g-1 h-1, and 0.81 h-1 were achieved, respectively. This work provides a new strategy to develop metal-free photocatalysts with simultaneously improved charge separation efficiency and catalytic site activity.

Short Review on Plasma–Aerosol Interactions

ABSTRACTSystems where cold atmospheric plasma interacts with liquid aerosols provide information on unexplored physico‐chemical phenomena and yield multiple advantages. Plasma‐activated aerosols show high chemical reactivity within small liquid microdroplet volumes, making them suitable for various applications and industrial processes. Plasma–aerosol interactions present complex interdisciplinary challenges that demand detailed investigations of the underlying physical, chemical, and transport mechanisms. This short review focuses on the key challenges in understanding plasma–aerosol interactions and the diagnostic hurdles in elucidating the physical and chemical mechanisms governing microdroplet interactions with plasma discharges. The scalability of plasma–aerosol systems, including high‐throughput charged water flows, are analyzed. Some “niche” applications of plasma–aerosols are identified, especially in decontamination, nitrogen fixation, and agriculture. The controversies in the field are also introduced and critically discussed. The review concludes with a proposed path and outlook for the development of plasma–aerosol technology.

Lattice atom-bridged chemical bond interface facilitates charge transfer for boosted photoelectric response

ABSTRACT The construction of chemical bonds at heterojunction interfaces currently presents a promising avenue for enhancing photogenerated carrier interfacial transfer. However, the deliberate modulation of these interfacial chemical bonds remains a significant challenge. In this study, we successfully established a p-n junction composed of atomic-level Pt-doped CeO2 and 2D metalloporphyrins metal-organic framework nanosheets (Pt-CeO2/CuTCPP(Fe)), which enables the realization of photoelectric enhancement by regulating the interfacial Fe–O bond and optimizing the built-in electric field. Atomic-level Pt doping in CeO2 leads to an increased density of oxygen vacancies and lattice mutation, which induces a transition in interfacial Fe–O bonds from adsorbed oxygen (Fe–OA) to lattice oxygen (Fe–OL). This transition changes the interfacial charge flow pathway from Fe–OA–Ce to Fe–OL, effectively reducing the carrier transport distance along the atomic-level charge transport highway. This results in a 2.5-fold enhancement in photoelectric performance compared with the CeO2/CuTCPP(Fe). Furthermore, leveraging the peroxidase-like activity of the p-n junction, we employed this functional heterojunction interface to develop a photoelectrochemical immunoassay for the sensitive detection of prostate-specific antigens.

Exploring p-Type Contact for Monolayer WS2 FETs Using Halogen Doping and Intermediate Layers.

This work presents a density functional theory (DFT) study of substitutional and adsorption-based halogen (I or F) doping of WS2-based transistors to enhance their contact properties. Substitutional doping of the WS2 monolayer with halogens results in n-type behavior, while halogen adsorption on the surface of the WS2 monolayer induces p-type behavior. This is attributed to differing directions of charge flow, as supported by the Mulliken analysis. However, due to Fermi-level pinning (FLP) at the WS2-metal interface, the p-type behavior resulting from halogen adsorption is not very prominent. To achieve better p-type contact, intermediate layers of graphene and h-BN are used to mitigate the FLP effect, showing significant improvement. The F-adsorbed WS2-graphene-Pt interface demonstrates excellent p-type contact with a substantial reduction in the hole Schottky barrier height, making it ideal for efficient WS2-based p-type MOS transistors in CMOS technology.

P-Type Vertical FETs Realized by Using Fermi-Level Pinning-Free 2D Metallic Electrodes.

In two-dimensional (2D) nanomaterial electronics, vertical field-effect transistors (VFETs), where charges flow perpendicular to the channel materials, hold promise due to the ease of forming ultrashort channel lengths by utilizing the thinness of 2D materials. However, the poor performance of p-type VFET arises from the lack of a gate-field-penetrating electrode with suitable work functions, which is essential for VFET operation. This motivated us to replace graphene (work function of ∼4.5 eV) with a high-work-function electrode to achieve the desired VFET characteristics. In this study, we demonstrate that WSe2-based p-type VFETs with a high on/off ratio of ∼105 can be realized using van-der-Waals contacts formed with high-work-function 2D metals (i.e., 2H-TaS2, NbSe2, and NbS2), which form a p-type ohmic contact to the WSe2 channel by suppressing Fermi-level pinning. Furthermore, we successfully fabricate a 2D metal-incorporating pseudocomplementary FET structure, demonstrating a great potential to significantly reduce the scaling factor by dense structure and vertical operation.

Computational studies molecular structure investigation and experimental characterization of Bis(2-aminothiazolium): quantum chemical analysis, electronic transitions, interaction mechanisms, and molecular dynamics

Bis(2-aminothiazolium) succinate succinic acid (ATSA), was synthesized and evaluated using standard spectroscopic studies. Density Functional studies were employed for the theoretical investigation of the substance, aiding in the determination of the chemical molecule’s structure and form. The molecule’s structural stability and the flow of charges within and between molecules were explored using natural bond orbital calculations. The primary binding sites and subtle interactions of the molecule were identified through topological analyses analysis endorse the ultimate charge transfer (CT) within the molecule. In the calculation of a chemical’s potential as a therapeutic candidate, pharmacological research is undertaken. This assessment encompasses molecule’s drug-likeness, pharmaceutical profile, and environmentally friendly toxicity contemplations. A molecular docking technique was used toward ligand spanning different antimicrobial targets, and the associated characteristics were imparted. When likened with positive controls and other pathogens, studies on antimicrobial activity expose that the compounds linked to Enterococcus faecalis, Staphylococcus aureus, Rhizopus stolonifer, and Penicillium notatum exhibit notable antimicrobial efficacy.

Origins of background signal effects in all-metallic non-local spin valves

The non-local spin valve (NLSV) is a useful device for studying spin transport at nanoscopic dimensions, with potential technological applications. Despite this appeal, background signals, unrelated to spin diffusion, often hinder the interpretation of spin signals in NLSVs and could compromise performance in future devices. In this paper, we comprehensively investigate these background signals in all-metallic NLSVs fabricated from a variety of ferromagnetic (FM; Ni80Fe20, Fe, Co) and nonmagnetic (NM; Al, Cu) metals. We demonstrate that a background signal emerges in AC measurements, with contributions from both current spreading and thermoelectric effects, with a complex dependence on both temperature and FM injector-detector separation. Despite the complexity of these dependencies, we demonstrate excellent agreement with three-dimensional finite-element modelling that accounts for current-spreading and thermoelectric effects, across a wide range of temperatures, FM separations, and FM/NM pairings. This approach additionally offers a means to estimate the Seebeck coefficients for the tested FM/NM pairings, providing further insight into the charge and heat flow in such nanoscopic spintronic devices. Published by the American Physical Society 2024

Dirac Theory, Relativistic Fluid Dynamics & Fisher Information

Abstract In previous papers we have shown how Schrödinger equations which include an electromagnetic field interaction can be deduced from a fluid dynamical Lagrangian of a charged potential flow that interacts with an electromagnetic field. The quantum behaviour was derived from Fisher information terms which were added to the classical Lagrangian. It was thus shown that a quantum mechanical system is drived by information and not only electromagnetic fields. This program was applied also to Pauli’s equations by removing the restriction of potential flow and using the Clebsch formalism. Although the analysis was quite successful there were still terms that did not admit interpretation, some of them can be easily traced to the relativistic Dirac theory. It is thus suggested to repeat the analysis for a relativistic flow, relating it to the Dirac theory by adding invariant four dimensional Fisher information terms. It is shown that while the classical parts of a classical fluid and a Dirac fluid can be mapped, the Fisher information term of Dirac theory is non-trivial. L Quantum = L Classical Fluid + L Fisher Information

An Innovative Laser Decal transfer of ZnO Ceramic in LIG for advanced Hybrid Nanogenerator applications

An Innovative Laser Decal transfer of ZnO Ceramic in LIG for advanced Hybrid Nanogenerator applications

Thermal Vacuum Synthesis: Physical Processes in Nanomaterial Production

The thermovacuum process offers an efficient and cost-effective method for producing nanomaterials by ensuring the continuous flow of dispersed material inside a spiral heating element. This is achieved by introducing the material into the heating element's cavity along with air, forming a two-phase gas-solid particle system. The material moves upward through the heated space, where pressure gradually decreases. Experimental studies on materials like carbon, brown coal, and zirconium dioxide indicate specific conditions are necessary for the system's continuous operation. One key requirement is that the mass of solid particles should not exceed 1.0 to 1.2 grams per liter of air entering the heating element. This limit ensures that nanodispersed and finely dispersed particles can move freely, avoiding collisions and allowing faster-moving particles to overtake slower ones. These particles increase in velocity and temperature as they pass through the heating element, with changes in heat capacity and particle motion contributing to wave motion and pulsed heat loads. The velocity at which the material particles travel depends on the thermal radiation from the heater walls and the energy generated by local pulse steam explosions, which create shock waves. Higher explosion energy results in increased particle velocity, greater impact angles against the heater walls, and higher environmental temperatures. These conditions lead to accelerated electron, proton, and other charged particle flows, forming plasma clots and neutrino clouds. The nanoparticles take various forms, including nanotubes, fullerenes, thin films, and crystals, reaching velocities up to a thousand kilometers per second and heating temperatures of up to 17 million degrees during pulses. This process consistently subjects the material to force, heat, deformation, and ionization, expediting the creation of nanodispersed materials with enhanced physicochemical and mechanical properties. The thermovacuum process not only improves the efficiency of thermotechnological equipment but also reduces energy consumption, production time, and costs. The research findings support its use in the continuous and effective production of high-quality nanomaterials.

Bismuth sensitized iron oxide on exfoliated graphene oxide (Bi–Fe2O3@GO) for oxygen evaluation reaction

Electrochemical water splitting is a promising approach towards a sustainable and renewable energy source. However, the demand for high anodic potential and sluggish kinetics of oxygen evolution reaction (OER) restrict the efficiency and feasibility of the water-splitting process. In this quest, transition metal oxides and alloys are considered potential candidates owing to their natural occurrence and high redox potential for OER. However, many associated challenges in their use are still there to be addressed. Here, we designed a new class of bismuth-doped iron oxide on exfoliated graphene oxide by optimizing the metal loading on the conductive support to facilitate the flow of charge during catalysis. The catalytic ability of the synthesized Bi-doped nanocomposites was evaluated in activating the OER under extreme alkaline conditions (1 MKOH). On screening different combinations, 20Bi–Fe2O3@GO was identified as the most efficient and sustainable electrocatalyst even under harsh operating conditions, with an onset potential of 1.48 V and a Tafel slope of 65 mV/dec. The current study offers a new class of Bi-doped electrocatalysts, where the precise doping of Bi and the optimized loading of metal was found the key to achieving low onset potential and high current density to initiate OER.Graphical abstract

Enhancing Stability of Glass Fiber Separators in Lithium-Ion Batteries through Sol-Gel Hybrid Coatings

Lithium ion batteries are largely divided into an anode, a cathode, and a separator impregnated with an electrolyte. It is well known that the battery separator is an important element in all batteries, as it physically separates the anode and cathode to prevent the direct flow of electrons, and allows the flow of charge through the movement of ions. Polyolefin-based separators, which are widely used in existing batteries, are vulnerable to rapid environmental changes, drastically reducing battery performance. Additionally, the thermal contraction and expansion that leads to a short circuit significantly reduces the stability of the battery. To overcome stability in such extreme environments, glass fiber separators are emerging as an alternative. To overcome stability in such extreme environments, glass fiber separators are emerging as an alternative. Glass fiber has excellent mechanical properties, electrical insulation, heat resistance, and chemical resistance, so it can drastically improve the stability of the battery. It can also improve electrolyte impregnation by controlling porosity to improve battery performance.In this study, a sol-gel hybrid coating solution was synthesized and coated on a glass fiber separator to enhance the ionic conductivity and stability. The coating on glass fiber was performed using a dip coating method. The optimization of the hybrid solution and coating conditions led to a reduction in the porosity and enhancement of the flexibility of the glass fiber separators. The adhesion of the coating was evaluated by measuring the hardness of the coating using pencil hardness, and the results showed that the tensile strength of the coated glass fiber separator was improved by about two times compared to before coating. Finally, as a result of evaluating the electrical performance according to the coating, the battery performance was similar at room temperature. On the other hand, it was confirmed that the operating voltage and discharge time at low temperatures were increased by the sol-gel hybrid coating. These results suggest that the coated glass fiber separators are promising candidates for overcoming the stability of battery operation in extreme environments.

In Situ Formed Metal-p-n Heterojunction for Ultrahigh Energy Density Supercapattery: Decelerates Ion Diffusion to Sustain Slow Discharge

Supercapatteries combine both diffusion-controlled and capacitive charge storage mechanisms to simultaneously deliver exceptional power density and energy density. Though developing materials that combine both charge storage mechanisms for use as supercapattery electrodes is difficult, one solution has been to modify a material that inherently has one of these mechanisms so that it also exhibits the other form of charge storage. In the present study, we modulate the electrochemical reconstruction of a W5N4 electrode to modify its charge storage from pure battery-type to pseudocapacitive. This modulation was carried out by embedding Co in W5N4 (Co-W5N4), leading to the formation of W-doped CoOOH as an active phase. The incorporation of a thin layer of TiO2 (Co-W5N4/TiO2) through atomic layer deposition minimized tungsten dissolution during reconstruction, thus generating in-situ a dynamic metal–p-n junction heterostructure (Co-W5N4||CoOOH||TiO2) that modulated the charge flow, achieving high-rate capability (retaining 53.1% at 50 A g−1 compared to 2 A g−1)and cyclic stability (82.8% after 100,000 cycles at a high current density of 40 A g−1). As illustrated by operando electrochemical impedance spectroscopy and physicochemical analysis, the dynamic response of metal–p-n junction sustains the pseudocapacitive charge storage mechanism at high current rate. This p-n junction modulated the diffusion speed of OH− ions due to a decrease and an increase in the width of the depletion layer under charging and discharging, respectively. The solid-state supercapattery device assembled with a positive CoWN/TiO2 electrode and a negative NiMo2S4/Fe2O3 electrode attained an impressive energy density of 259.5 Wh kg− 1 at a power density of 2550 W kg− 1 and operated in a stable manner over 25,000 cycles. Our study thus highlights the importance of the band structure and its dynamic response to the operating conditions, and our approach can be extended to the design of a variety of energy-storage electrodes and energy-conversion catalysts.

Geometrical features and chemical adsorptions of (Ag3Sn)n clusters

Geometrical features and chemical adsorptions of (Ag3Sn)n clusters

Activated CdS/ sulfur doped g-C3N4 photocatalyst for dye and antibiotic degradation: Experimental and DFT verification of S-scheme heterojunction

To alleviate situation caused by azo dyestuff and antibiotics, a series of CdS/sulfur doped carbon nitride (GCNS) S-scheme heterojunction photocatalysts have been successfully fabricated by a pretty facile solid-state diffusion (SSD) method,. Under visible light, the optimal sample called CdS/GCNS-1:2 presented the best photodegradation rate of nearly 100% over methyl orange (MO), of which the reaction constant k was about 9.67 and 5.39 times higher than that of pure GCNS and CdS, respectively. Degradation rate of 91% over tetracycline hydrochloride (TCH) was achieved within 60min as well. The DFT calculations, XPS and charge flow tracking tests clarified the surge of C-S linkages and the construction of interfacial S-scheme heterojunction. The former promoted the fixation and conversion of adsorbed oxygen, while the latter accelerated the separation/transport of charge carriers. These tuning eventually collaborates on the promotion of •O2- reactive species, which confirmed as the predominant role of photoreaction. Furthermore, the plausible degradation pathways of MO/TCH and photocatalytic optimization mechanism were thoroughly elucidated.

Néel Vector Auto-Oscillations and Reorientations Induced by Spin-Polarized Electric Currents in Antiferromagnetic Mn2Au Nanolayer

The electrical excitation of spin dynamics in antiferromagnets is important for the development of high-speed spintronic devices with a low power consumption. Here, we present a theoretical study of the spin dynamics generated in the Ni/Cu/Mn2Au/Cu/Ni nanostructure by a perpendicular-to-plane electric current. Our investigation includes atomistic simulations of spin reorientations in a few monolayer antiferromagnetic Mn2Au film and numerical calculations of nonequilibrium spin accumulation in the nanostructure comprising ferromagnetic Ni polarizers with antiparallel magnetizations. This combined approach enables us to quantify the dynamics of Mn magnetic moments induced by the spin-transfer torque created by the spin-polarized charge flow. The calculations show that the direct electric current with the density exceeding some temperature-dependent threshold value gives rise to steady-state auto-oscillations of the Néel vector in the [Formula: see text]-oriented Mn2Au nanolayer. As the precession of Mn magnetic moments occurs around an out-of-plane direction strongly deflected from their initial in-plane orientations, the emergence of auto-oscillations should be regarded as the realization of a dynamic spin reorientation transition in the antiferromagnetic crystal. Remarkably, the precession frequency rises with increasing current density J and exceeds 1[Formula: see text]THz at [Formula: see text][Formula: see text]A[Formula: see text]m[Formula: see text], which makes the described antiferromagnetic spin transfer nano-oscillator attractive for device applications. Furthermore, our simulations demonstrate that a picosecond current pulse injected into the Ni/Cu/Mn2Au/Cu/Ni nanostructure can induce a precessional switching of the Néel vector. Depending on the current density and pulse duration, the Néel vector rotates by either 90° or 180° and attains stable orientation along the corresponding [Formula: see text] easy axis in the plane of the Mn2Au nanolayer. This feature shows that the Ni/Cu/Mn2Au/Cu/Ni nanostructure could be used as a nonvolatile memory cell with the electrical writing and readout.