Increase In Current Density Research Articles

Effect of bidirectional electromigration rehabilitation on corroded reinforcement and surrounding concrete in chloride contaminated concrete

Chlorides in marine environment are the major factors induced durability issues of concrete structures. Electrochemical methods are reported to efficiently solve these problems due to the intrusion of chloride salts. In this study, an electric field of different durations and different current densities were applied between the rebar cathode and the external anode to migrate the triethylenetetramine (TETA) corrosion inhibitor into the specimens. The linear polarization method was used to measure the corrosion condition of steel bars. Electrochemical impedance spectroscopy (EIS) was used to measure the impedance changes in reinforced concrete specimens. The concentrations of corrosion inhibitors and chloride ions were measured for different depths of the concrete cover. The scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) were used to determine concrete morphology and pore structure, respectively. The results showed that the bidirectional electromigration treatment increased the resistance of the concrete cover and recovered the corrosion potential of the steel bars to a lower level. With the increase in treatment time or current density, the chloride content in the concrete cover decreased, whereas the concentration of corrosion inhibitor in the specimen rose. The porosity evolved from micropores (0.001–0.1 μm) to mesopores (0.1–1 μm) in the concrete cover. Rehabilitation resulted in the hydration products being decomposed at the cathode and aggregated at the anode.

Electromechanical response of smart ultra-high-performance concrete under uniaxial load: Experimental investigation and electric field analysis

This study explores the electromechanical response of smart ultra-high-performance concrete (S-UHPC) under uniaxial tension and compression using both attached and embedded electrodes with direct current. Within the linear elastic region, the response of S-UHPC was influenced by the type of electrode due to the deformation of the silver paste used in the attached electrodes. Furthermore, although the electromechanical response of S-UHPC beyond the linear elastic region showed minimal variation between different electrode types, their self-sensing capabilities were significantly affected by the choice of electrode. Under uniaxial tension, the electrical resistivity of S-UHPC decreased marginally up to the limit of proportionality and then more substantially beyond it, primarily owing to the formation of matrix cracks. This reduction in electrical resistivity associated with crack formation was corroborated through electrical field analysis performed using COMSOL MultiphysicsⓇ. A key finding was that the decrease in electrical resistivity (from 0.1788 to 0.0286 kΩ·cm, -84.0 %) in the tensile strain-hardening region could be attributed to an increase in electrical current density within steel fibers; specifically, the current density increased from 0.2417 to 0.7047 A/mm2 as the number of matrix cracks increased from zero to seven.

Characterization of graphene–TiO2-deposited semi-organic solar cell

High energy supply is critical, particularly in developing countries, to maintain lifestyles as the world's population and technological-economic metropolis grow. Solar photovoltaic cells have been used as an alternative to generate renewable, sustainable, and green energy for the past two decades. In general, the materials employed in the photoanode part are critical to manufacturing high-efficiency solar cells with 14–18% efficiency. A simple and successful method has been discovered for creating a film composed of graphene sheets and 99.8% pure anatase titanium oxide (TiO2) nanoparticles. After sensitization, the films were tested as photoelectrodes for dye-sensitized solar cells. The experimental results show that using an optimized graphene material considerably improves the power conversion efficiency of the cells, resulting in a 45% increase in short-circuit current density ( JSC). This study uses capsician as a bonding agent to enhance the current density of a graphene–TiO2 based semi-organic solar cell. The mechanical and electrical properties of the cell are investigated using a scanning electron microscope, energy dispersive X-ray, and Corescan.

37‐2: Impact of Thermal Factors on Carrier Density in OLED under Low‐Voltage Condition

In this paper, we explored the underlying mechanism behind the intriguing increase in current density at low voltage with a corresponding rise in temperature. We identified key parameters associated with this phenomenon and developed a suitable equation for quantitative prediction. Subsequently, we demonstrated that the injection of current into emission layer in the module can be accurately pre‐evaluated based on TEG device measurements. Our research results not only establish a theoretical framework for evaluating performance from TEG device development to the module state but also present the physical cause of temperature sensitivity in OLEDs.

Sensitivities of critical operating conditions on proton exchange membrane fuel cell performance: an experimental study

Abstract The performance of the Proton Exchange Membrane Fuel Cell (PEMFC) is subject to substantial influence from operating conditions. In this paper, the impact of various operating conditions on the polarization curves is examined through single-variable polarization curve tests. Notably, it is observed that the polarization curves intersected within the range of 1.0 A/cm2 to 1.5 A/cm2 under varying cathode inlet humidity and working pressure conditions. Expanding upon this observation, an orthogonal experiment is designed and executed to evaluate the sensitivity of PEMFC performance to diverse operating conditions under two distinct current densities of 1.0 A/cm2 and 2.0 A/cm2. Consequently, it is revealed that the output voltage, charge transfer impedance, and mass transfer impedance are most significantly influenced by three specific operating conditions: temperature, cathode inlet humidity, and stoichiometric ratio. Furthermore, as the current density increases, the dominant factors governing PEMFC performance have evolved from temperature-dominated charge transfer impedance to cathode stoichiometric ratio-dominated mass transfer impedance.

Study on corrosion behavior of 40Cr steel in 3.5 % NaCl solution under the synergistic effect of UV illumination and strain

The corrosion behavior of 40Cr steel under the synergistic effect of plastic tensile strain and UV was investigated. The results show that the corrosion current density increases under the synergistic effect of strain and illumination. Before the formation of the complete rust layer, it is mainly attributed to the variation of the electric double layer, and the strain can enhance the effect of illumination on the electric double layer. After the formation of the complete rust layer, the increase in corrosion current density was mainly related to the change in the inner rust layer composition. Data availabilityThe data that has been used is confidential.

Study on electrochemical corrosion dynamics of cathode dic shield in concrete crack

Abstract Corrosion of steel reinforcement is a primary factor that negatively impacts the service life and safety of bridges made of concrete. Cathodic protection techniques are widely used to protect reinforcing bars in concrete against corrosion. However, it is inevitable that corrosion cracks will develop in the concrete during long-term operation, which will significantly shorten the cathodic current protection distance and increase the degree of corrosion of the rebar within the cracks. Therefore, electrochemical experiments and characterization of corrosion forms were carried out based on the company’s design of a rectangular connection device, we studied HRB500 steel in 3 wt.% corrosion behavior in rectangular joints under different CP current densities in NaCl solution. The results showed that with increasing experimental time, the corrosion in the crevice transitioned from activation corrosion to oxygen concentration corrosion, with the open-pore potential of the HRB500 steel inside the crevice appearing as a positive shift and the open-pore potential outside the crevice shifting from positive to negative. When implementing cathodic protection, the corrosion of HRB500 steel within the crevice is activated, while the corrosion outside the crevice changes from anodic to mixed controlled corrosion and from full to pitting corrosion. With the increase of CP current density, the corrosion process of HRB500 steel outside the gap is mainly dominated by cathode control, then gradually weakens, and the corrosion form changes from pitting to comprehensive corrosion.

Boosting photoelectrochemical performance through appling magnetic field in manganese-doped cobalt ferrite photoanodes

An efficient photoelectrochemical water-splitting process is of paramount importance as it provides a sustainable and clean method for generating hydrogen fuel, which is crucial for addressing the world’s growing energy needs while mitigating environmental concerns. Herein, the effects of applying a magnetic field on the photoelectrochemical performance of photoanodes composed of Cobalt ferrite (CoFe2O4) and Manganese (Mn)-doped CoFe2O4 are investigated. The CoMnxFe2-xO4 nanoparticles were synthesized using a sol–gel method, with varying values of x (0.0, 0.1, 0.3, and 0.5). X-ray diffraction analysis consistently reveals a singular cubic spinel structure for all four samples. Magnetic analyses demonstrate an enhancement in magnetic characteristics, including saturation magnetization, coercivity, and anisotropy field in the CoMn0.3Fe1.7O4 sample compared to the other three samples. Photoelectrochemical (PEC) measurements indicate that the photocurrent increases in all four samples when a static magnetic field is applied. However, the CoMn0.3Fe1.7O4 sample shows a more pronounced enhancement. Specifically, the dark current density increases by more than 115 % when a magnetic field of 190 ± 20 mT is applied. Additionally, it rises by 387 % under light illumination with the magnetic field. This enhancement in PEC performance is attributed to electron spin polarization adjusted through the external magnetic field.

Unprecedented and laborless polymer film of azorubin S for electrocatalytic sensing of nicotine in human serum and saliva

AbstractAn accurate, disposable and cost‐effective determination, and monitoring of nicotine in human bodily fluids such as serum and saliva is significant due to the deleterious effects on humankind. In this paper, it was reported an electrocatalytic sensing platform for nicotine determination with poly azorubin s film modified pencil graphite electrode qualified by electroanalytical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy, electron beam based technique of scanning electron microscopy, and X‐ray based techniques including photoelectron spectroscopy and energy dispersive spectroscopy. The developed platform exhibited a 410 % signal increase compared to the bare pencil graphite electrode (280 % increase in current density over aPGE) for nicotine detection due to the improved charge transfer and conductivity characteristics of the polymer film. The oxidation peak at 700 mV was employed for nicotine detection with a good detection sensitivity of , a remarkable detection limit of 89 nM, and wide linear ranges of 0.25–3 μM and 5–100 μM. Furthermore, the electrochemical sensor showcases superb stability, selectivity and accuracy for the determination of nicotine in real samples of human serum and saliva.

Boosting the visible-light-driven photocatalytic efficiency in porous Cu/TiO2 ceramic coatings

In this study, we examined how current density, sodium phosphate concentration, and the addition of copper sulfate to the supporting electrolyte affect PEO coatings on pure titanium. The chemical composition, morphology, and optical behavior of PEO coatings were extensively analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV–Vis diffuse reflectance spectroscopy (DRS). With an increase in current density from 6 to 18 A/dm2, the coating's pore size enlarges and the rutile phase content within the coatings increases. The coating created at 12 A/dm2 shows the highest photocatalytic activity and triggers a unique three-stage behavior in the voltage-time diagram. Adding 4 g/l of CuSO4 to the electrolyte resulted in the formation of an unwanted Cu-based precipitates, causing electrolyte instability. To stabilize it, potassium hydroxide was removed, and the base electrolyte concentration was adjusted. To address this issue, potassium hydroxide was eliminated from the supporting electrolyte. Subsequently, the concentration of the base electrolyte was optimized. Also, the synergistic influence of CuSO4 addition (4 g/l) to the supporting electrolyte at different concentrations of 5, 10, and, 15 g/l of trisodium phosphate on PA was investigated. The superior photocatalytic performance of the optimum coating created in the electrolyte containing 5 g/l trisodium phosphate and 4 g/l CuSO4 is attributed to its enhanced porous structure, along with the heterojunction between the anatase and rutile phases. These features significantly boost the available surface area and facilitate the efficient separation and transfer of photogenerated charge carriers. Ultimately, a mechanism for MB photodegradation was proposed based on the findings from Mott-Schottky analysis and DRS.

In Situ Characterizations of the Dynamics of Cathode Electrolyte Interfaces at Different Current Densities.

LiNi0.8Mn0.1Co0.1O2 with high nickel content plays a critical role in enabling lithium metal batteries (LMBs) to achieve high specific energy density, making them a prominent choice for electric vehicles (EVs). However, ensuring the long-term cycling stability of the cathode electrolyte interfaces (CEIs), particularly at fast-charge conditions, remains an unsolved challenge. The decay mechanism associated with CEIs and electrolytes in LMB at high current densities is still not fully understood. To address this issue, in situ Fourier transform infrared (FTIR) is employed to observe the dynamic process of formation/disappearance/regeneration of CEIs during charge and discharge cycles. These dynamic processes further exacerbate the instability of CEIs as current density increases, leading to rupture and dissolution of CEIs and subsequent deterioration in battery performance because of continuous electrolyte reactions. Additionally, the dynamic changes occurring within individual components of CEIs at different cycling stages and various current densities are also discussed. The results demonstrate that excellent capacity retention at small current density is attributed to enrichment of inorganic compounds (Li2CO3, LiF, etc.) and rendering better stability and smaller expansion of CEIs. The key to achieving excellent electrochemical performance at high current densities lies on protecting CEIs, mainly inorganic components.

Retaining the self-released chalcogenate at reconstructed cobalt sites by self-transformed carbonate regulation for boosted oxygen evolution

The in-situ generated oxyanions at electrochemically reconstructed catalysts from metal-based non-oxide compounds have been proven to significantly accelerate oxygen evolution reaction (OER) kinetics. However, it remains a challenge to retain these self-released oxyanions at reconstructed catalysts, hindering its utilization as a tool to develop efficient OER catalysts. Here, we demonstrate a versatile self-transformed carbonate regulation strategy to efficiently retain the self-released chalcogenate at Co oxyhydroxides reconstructed from carbon-incorporated Co selenides under OER conditions. These self-transformed CO32− can induce electron accumulation and narrow d bond at Co sites to facilitate the Co 3d–O 2p orbital hybridization between Co sites and SeOx2− for enhanced SeOx2− retention, which can accelerate the rate-limiting step for *OOH formation during OER. Relative to CoOOH-SeOx2− with limited SeOx2− residues, CoOOH-CO32−/SeOx2− with elevated SeOx2− retention by CO32− regulation exhibited a 5.6-fold increase in current density and a remarkable lower Tafel slope towards OER. This strategy paves a rational avenue to design efficient catalysts for electrooxidation reactions through finely regulating self-released oxyanions at reconstructed structures.

Thermal management and switching performance of β-Ga2O3 vertical FinFET with diamond-gate structure

In this paper, a beta-phase gallium oxide (β-Ga2O3) vertical FinFET with diamond-gate has been studied by Silvaco-ATLAS simulation. The diamond-gate structure achieves adjustable pin (p-insulator-n) junction owing to the diamond-SiO2-Ga2O3 heterostructure. This design also enhances heat dissipation by virtue of the high thermal conductivity of the diamond. Compared to conventional FinFETs, the diamond-gate FinFET (DG-FinFET) reduces the static operating temperature rise by around 17.30%. Additionally, due to its greater heat dissipation capacity, DG-FinFETs provide a 5.84% increase in current density at 1 kA cm−2 current density level. The structural changes in the diamond-gate also result in a significant reduction in the gate-source capacitance (C GS). At 1 MHz operating frequency and the same gate voltage, DG-FinFETs have 69.29% less gate-source charge (Q GS), 70.80% less charge/discharge delay time, 73.70% less switching loss, and 57.15% less conduction loss. Overall, the simulation and analysis presented in this work indicate a promising advancement of the DG-FinFET structure in high-power and rapid switching applications.

Effects of transcranial direct current stimulation on brain activity and cortical functional connectivity in children with autism spectrum disorders.

Transcranial direct current stimulation (tDCS) has emerged as a therapeutic option to mitigate symptoms in individuals with autism spectrum disorder (ASD). Our study investigated the effects of a two-week regimen of tDCS targeting the left dorsolateral prefrontal cortex (DLPFC) in children with ASD, examining changes in rhythmic brain activity and alterations in functional connectivity within key neural networks: the default mode network (DMN), sensorimotor network (SMN), and dorsal attention network (DAN). We enrolled twenty-six children with ASD and assigned them randomly to either an active stimulation group (n=13) or a sham stimulation group (n=13). The active group received tDCS at an intensity of 1mA to the left DLPFC for a combined duration of 10 days. Differences in electrical brain activity were pinpointed using standardized low-resolution brain electromagnetic tomography (sLORETA), while functional connectivity was assessed via lagged phase synchronization. Compared to the typically developing children, children with ASD exhibited lower current source density across all frequency bands. Post-treatment, the active stimulation group demonstrated a significant increase in both current source density and resting state network connectivity. Such changes were not observed in the sham stimulation group. tDCS targeting the DLPFC may bolster brain functional connectivity in patients with ASD, offering a substantive groundwork for potential clinical applications.

One-shot design elevates functional expression levels of a voltage-gated potassium channel.

Membrane proteins play critical physiological roles as receptors, channels, pumps, and transporters. Despite their importance, however, low expression levels often hamper the experimental characterization of membrane proteins. We present an automated and web-accessible design algorithm called mPROSS (https://mPROSS.weizmann.ac.il), which uses phylogenetic analysis and an atomistic potential, including an empirical lipophilicity scale, to improve native-state energy. As a stringent test, we apply mPROSS to the Kv1.2-Kv2.1 paddle chimera voltage-gated potassium channel. Four designs, encoding 9-26 mutations relative to the parental channel, were functional and maintained potassium-selective permeation and voltage dependence in Xenopus oocytes with up to 14-fold increase in whole-cell current densities. Additionally, single-channel recordings reveal no significant change in the channel-opening probability nor in unitary conductance, indicating that functional expression levels increase without impacting the activity profile of individual channels. Our results suggest that the expression levels of other dynamic channels and receptors may be enhanced through one-shot design calculations.

Polyvinyl Chloride-Based Luminescent Downshifting Film with High Flame Retardancy and Excellent UV Resistance for Silicon Solar Cells.

Solar power generation, as a clean energy source, has significant potential for development. This work reports the recent efforts to address the challenge of low power conversion efficiency in photovoltaic devices by proposing the fabrication of a luminescence downshifting layer using polyvinyl chloride (PVC) with added fluorescent dots to enhance light utilization. A photoluminescent microsphere (HCPAM) is synthesized by cross-linking hexachlorocyclotriphosphazene, 2-iminobenzimidazoline, and polyethyleneimine. Low addition of HCPAM can improve the fire safety of PVC films, raising the limiting oxygen index of PVC to 32.4% and reducing the total heat release and smoke production rate values by 14.5% and 42.9%, respectively. Additionally, modified PVC film remains a transparency of 88% and shows down-conversion light properties. When the PVC+1%HCPAM film is applied to the solar cell, the short-circuit current density increases from 42.3 to 43.8mAcm-2, resulting in a 7.0% enhancement in power conversion efficiency. HCPAM also effectively delays the photooxidative aging of PVC, particularly at a 3% content, maintaining the surface morphology and optical properties of PVC samples during ultraviolet aging. This study offers an innovative strategy to enhance the fire and UV-resistant performance of PVC films and expand their applications in protecting and efficiently utilizing photovoltaic devices.

Ion‐Impregnated Intermediate Layer for Enhancing Triboelectric Nanogenerator Performance

AbstractThe triboelectric nanogenerator (TENG) is gaining recognition as a highly promising, eco‐friendly self‐powered device for the growth of the Internet of Things (IoT). To improve the performance of TENGs, diverse materials are employed as interlayers. However, challenges related to cost and stability persist. Herein, a strategy that incorporates ion‐containing electrolyte polymers as interlayers is presented. This approach effectively mitigates charge decay and maximizes TENG efficiency by leveraging the high charge capacitance of the ionic electric double layer (iEDL). The incorporation of iEDL into TENG results in an approximate tenfold increase in current density (10–92 mA m−2) and a 13‐fold increase in power density (2–26 W m−2). The robust energy generation capabilities of iEDL‐TENG enable the operation of 100 LED lights and the charging of a 470 µF capacitor. Furthermore, the demonstrated device exhibits significant stability across 10,000 operational cycles and effectively maintains its performance when subjected to external physical forces such as blade‐induced cuts, penetrating wounds, and severe crumpling.

Localized oxygen evolution and transport analysis in PEM water electrolysis on local static pressure, temperature and current density

With the escalating severity of the global climate crisis and the strengthening global demand for carbon neutrality, hydrogen produced from renewable energy offers a pathway towards achieving carbon neutrality. To reduce the cost of eco-friendly hydrogen production, we need to increase the current density in proton exchange membrane water electrolysis for green hydrogen production, a promising technology. One problem arising from an increase in current density is that it leads to a significant generation of oxygen, resulting in mass transfer losses. However, there have been few studies on oxygen transport near the anode catalyst layer, with most studies only measuring current density. In this study, local static pressure and temperature were measured in real-time to elucidate the relationship between voltage and current. At 2.1 V (corrected voltage = 2.03 V), the static pressure amplitude is approximately −5 to 5 kPa. At 2.55 V (correction voltage = 2.41 V), it decreased by about 50 % to about −2.5 to 2.5 kPa, and the frequency became faster. With increasing voltage, the decrease in static pressure amplitude and the increase in frequency occur because oxygen rapidly increases in the catalyst layer, resulting in a reduction in residence time. At 1.65 V (corrected voltage = 1.63 V), there is little change in local static pressure, indicating the dominance of the liquid single phase. At 3.6 V (corrected voltage = 3.05 V), there is little change in local static pressure. This is due to the rapid detachment of oxygen bubbles, leading to the dominance of the gas single phase. This elucidates how oxygen bubbles are influenced by fluctuations in local static pressure, leading to the conclusion that efficient design patterns for future anode flow fields can be achieved.

Investigation on the Passive Behavior of Ti-9Mn Alloy in 3.5 wt% NaCl Solution

Ti-9Mn alloy, widely used in aerospace and hydrogen storage, was recently introduced for marine and offshore structures because of its competitive mechanical characteristics. In this study, passive behavior of Ti-9Mn alloy was compared to the commercially pure titanium (cp-Ti). Ti-9Mn exhibited lower charge-transfer resistance than cp-Ti. Under steady-state condition, resistivity at metal/oxide film interface for Ti-9Mn alloy, which increased as fa unction of applied passive potential in range of 0.5 to 1.5 VSCE, was found to be lower than that of cp-Ti. Complex-capacitance (C ∞) value for Ti-9Mn alloy was higher than that of cp-Ti. Presence of Mn in the alloy induced significant increase in current density when potential exceeds 1.5 VSCE. Corrosion current density of Ti-9Mn (16.2 ± 4.0 nA cm−2) was three times higher than that of cp-Ti (4.57 ± 0.7 nA cm−2) after 21 days immersion in 3.5 wt% NaCl. The study may allow us to realize the full potential passivation behavior of Ti-9Mn for future marine and offshore applications.

Optimization of cobalt-based MOFs for super-capacitor electrode materials of new energy vehicle

Super-capacitors (SCs), as new energy conversion storage elements, have attracted much attention, but there is still a research gap in the design of electrode materials. In this study, the optimization scheme of Metal-Organic Frameworks (MOFs) and cobalt-based MOF composites as electrode materials for SCs in new energy vehicles is explored, and a series of experiments are conducted to evaluate their performance. Scanning Electron Microscope (SEM) images reveal that the cobalt-based MOF composites have a surface morphology of particles with uniform distribution. The electrochemical performance test results show that the specific capacitance of the cobalt-based MOF composites is much higher than the sum of the two individual electrode materials and presents a remarkable increase with the scanning rate. Additionally, in the constant current charge-discharge test, cobalt-based MOF composites exhibit the longest charge-discharge time and good symmetry. Electrolyte particle contact tests for samples at different preparation temperatures display that high-temperature samples have better structural stability and electrolyte ion contact. In Cyclic Voltammetry (CV) and Galvanostatic Charge Discharge (GCD) tests, the 250 °C sample demonstrates the best electrochemical properties and the highest specific capacitance (269 F/g). Moreover, as the current density increases, the specific capacitance of the 600 °C sample decreases at a lower rate, showing stronger stability. However, the use of cobalt-based MOF materials may pose environmental and safety risks, such as the environmental impact of cobalt resource mining, instability under high-temperature conditions, and the possible production of hazardous substances. Therefore, these factors need to be fully considered when designing and using SCs to ensure the environmental friendliness and safety of cobalt-based MOFs. These results provide an important reference for selecting and optimizing electrode materials for SCs in new energy vehicles. Furthermore, this study offers research suggestions for improving new energy materials, filling the research gaps in related fields, and supporting the further development of SC technology.