Electrodes For Devices Research Articles

(Invited) 3D Printing of 2D Materials for Optimized Electrochemical Performance

Electrochemical energy storage (EES) and conversion devices (e.g. batteries, supercapacitors, and reactors) are emerging as primary methods for global efforts to shift energy dependence from limited fossil fuels towards sustainable and renewable resources. These devices, while showing great potential for meeting some key metrics set by conventional technologies, still face significant limitations. For example, an EES device tends to exhibit large energy density (e.g. lithium-ion battery) or power density (e.g. supercapacitor), but not both. This inability of a single device to simultaneously achieve both metrics represents a major obstacle to widespread adoption of EES devices. Similarly, many catalytic processes depend on expensive platinum group metals (PGM) because non-PGM materials have poor performance or durability. Though the integration of 2D materials (e.g. graphene, dichalcogenides, MXene, etc.) into electrochemical devices has yielded some exciting results towards tackling these issues, significant improvements are still needed. One approach to optimizing the performance of these devices is to focus on one of the fundamental processes that occur in these systems: mass (or charge) transport. The efficient transport of ions within EES and conversion devices is critical to realizing better performance and durability. The pore structure of the electrode is a key factor in determining this transport phenomena, but in many cases, engineering the pore structure in a highly deterministic fashion can be challenging. In this work, we explore a number of additive manufacturing methods (e.g. direct ink write, projection microstereolithography, etc.) to engineer the pore structure of device electrodes. We also determine effective electrode geometries using both simple theory and topology optimization techniques. The topology optimization couples the solution of the forward electrochemical problem over the full electrode domain with gradient-based optimization. The output of our code is a three-dimensional CAD representation which optimizes over specific performance metrics and which can be used to print functional electrodes. This work provides a systematic path toward automated design and fabrication of engineered electrodes with precise control over the fluid and species distribution.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Treating Scars After Burns With Pulsed Electric Fields in the Rat Model.

Reducing scar size after severe burn injuries is an important and challenging medical, technological, and social problem. We have developed a battery-powered pulsed electric field (PEF) device and surface needle electrode applicator to deliver PEFs to the healing dorsal burn wound in rats. The pulsed electric field was used to treat residual burn wounds caused by metal contact in rats starting 10 days after the injury for 4 months every 11 or 22 days for 4 months using varying time applied voltages at 250-350 V range, 400 mA current, 40 pulses, 70 μs duration each, delivered at pulse repetition frequency 10 Hz at 5 locations inside the wound. We found 40%-45% reduction in the scar size in comparison with untreated controls in both upper and lower dorsal locations on rats' backs 2 months after the last PEF application. We have not detected significant histopathological differences in the center of the scars besides the thickness of the newly generated epidermis, which was thicker in the PEF-treated group. We showed that minimally invasively applied PEFs through needle electrodes are effective method and device for treating residual burn wounds in the rat model, reducing the size of the resulting scars, without any adverse reaction.

Tagetes erecta-Mediated Biosynthesis of Mn3O4 Nanoparticles: Structural, Electrochemical, and Biological Investigations.

Mn3O4 nanoparticles (NPs) find diverse applications in the fields of medicine, biomedicine, biosensors, water treatment and purification, electronics, electrochemistry, and photoelectronics. The production of Mn3O4 NPs was reported earlier through various physical, chemical, and green routes, but no studies have still been performed on their biosynthesis from Tagetes erecta. We synthesized manganese oxide NPs, i.e., (Mn3O4)L and (Mn3O4)P NPs, by utilizing leaves and petals, respectively, of T. erecta as reducing and stabilizing agents. The investigated green path is eco-friendly and does not involve any hazardous raw materials. The structural properties of NPs were determined by X-ray diffraction (XRD) analysis, spectroscopies (Fourier transform infrared (FTIR), Raman, and UV-visible), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The NPs were also evaluated for their electrochemical properties by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). XRD analysis was performed to verify their tetragonal geometry, and the crystallite size (19.24 nm) of (Mn3O4)P was smaller than that (20.84 nm) of (Mn3O4)L NPs. SEM images displayed a porous and spherical morphology with a diameter of 14-35 nm. FTIR spectra of (Mn3O4)L and (Mn3O4)P displayed Mn-O vibrations at 605.69 and 616.87 cm-1, respectively, and the hydrous nature of the material. Raman spectroscopy revealed the existence of tetrahedral and octahedral units along with A1g, T2g, and Eg active modes of Mn3O4 and 2TO mode. UV-visible analyses of (Mn3O4)L and (Mn3O4)P NPs showed absorption peaks at 272.3 and 268.8 nm, along with band gaps of 4.83 and 5.49 eV, respectively. TGA curves displayed good thermal stabilities up to 600 °C and a loss of moisture content. DSC curves exhibited exothermic/endothermic peaks with glass transition temperatures of 258.9 and 308.7 °C for (Mn3O4)P and (Mn3O4)L, respectively. The CV curves showed redox peaks and confirmed that the electrochemical reaction takes place in the Mn3O4 material. GCD scans revealed the capacitive behavior of NPs and their suitability as electrodes in energy storage devices. However, (Mn3O4)L will act as a good material for energy storage applications as compared to (Mn3O4)P NPs. The synthesized NPs were also tested for their antibacterial efficacy by biofilm inhibition and agar well diffusion methods. The NPs showed higher activities against Staphylococcus aureus (Gram-positive) than against Escherichia coli (Gram-negative), and (Mn3O4)P was more bioactive than (Mn3O4)L.

Experimental and theoretical investigations of the threshold actuation voltages of aqueous solutions, glycerol–water solutions, and ethanol–water solutions on a coplanar electrode device

In digital microfluidics, actuation voltage is critical in droplet manipulation using electrowetting-on-dielectric. Compared to parallel electrode devices, the droplet manipulation on coplanar electrodes requires a higher actuation voltage due to its structure. This study derives an equation related to the threshold actuation voltage and many critical parameters (applied frequency, surface tension, fluid conductivity, droplet volume, dielectric thickness, etc.). Our developed model has three innovations: (1) liquid and device parameters related to the threshold actuation voltage are integrated into the model, (2) the absolute value of the complex permittivity of the fluid is added into our model to clarify the conductivity-dependent and frequency-dependent threshold actuation voltage, and (3) the extrand model is used to derive the effects of the surface tension, contact angles, and droplet radius on the threshold actuation voltage. Additionally, we used many solutions for biochemical and biomedical assays—DI (Deionized) water, DMEM (Dulbecco's Modified Eagle Medium), PBS (phosphate buffered saline), glycerol–water solutions, ethanol–water solutions, potassium chloride solutions, and sodium chloride solutions—to verify the developed Vth in our model. By using the model and conducting an experiment, we investigated the Vth of different liquids on coplanar electrodes. Our model can successfully explain the difference of Vth between these solutions on coplanar electrode devices. The model and experimental data can be utilized to predict the actuation voltage for a broad range of buffers and organic solvents on coplanar electrodes.

(Sm3+/Eu3+/Tm3+)-TiO2 heterostructures for electrochemical and photovoltaic applications

This study reports on the synthesis of lanthanide oxides triply doped titania, forming a novel hetero-system known as (Sm3+/Eu3+/Tm3+)-TiO2. An environmentally friendly sol gel method was used to synthesize the energy-efficient (Sm3+/Eu3+/Tm3+)-TiO2, and thin films were deposited by spin coating. Electrode and solar cell devices were fabricated under ambient conditions, and rare earth doping enhanced the opto-electronic aspects of the host by narrowing the band gap up to 3.92, 3.85, and 3.56 eV. Particle sizes for the pure and doped materials were 85.15 and 82.72 nm, respectively. With a specific capacitance of 667.34 F g−1, the lanthanide-doped ornamented nickel foam electrode outperformed the pristine electrode, which had a specific capacitance of 169.59 F g−1. Moreover, this electrode exhibited tiny equivalent series resistance (Rs) of 0.13 Ω, indicating quicker response kinetics at the interface, in addition to its electrical double layer capacitance behavior. Electrochemical studies revealed that (Sm3+/Eu3+/Tm3+)-TiO2 semiconductor has a high specific power density of 8157.03 W kg−1, compared to 4079.73 W kg−1 for undoped titania. This improved specific power density demonstrates its suitability for practical scale applications. The produced materials were an excellent HER electro-catalyst with remarkably lower overpotential and Tafel slopes i.e., of 137 mV and 87.6 mV dec−1, in a respective manner, in comparison to the reference TiO2 with 147 mV and 104.5 mV dec−1, respectively. The electro-catalyst's response to the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was enhanced upon lanthanide doping. Additionally, this substance successfully retrieved electrons from a perovskite solar cell device, achieving efficiency levels of 16.49 and 16.75 % in both forward and reverse bias with fill factor increase.

The plausibility and ideal design of electrochemical disinfection for drinking water in hospital susceptible to Legionella and E. coli contamination, compared to traditional methods

Legionella and Escherichia coli (E. coli), bacteria lethal to humans, are widespread in drinking water. Traditional disinfection methods using chlorine gas, temperature control, and ultraviolet are widely applied today but have several drawbacks. In contrast, the electrochemical disinfection methods could address the problems. This study reviews the literature on electrochemical disinfection and compares traditional disinfection methods with electrochemical ones under evaluation of cost, E. coli contamination efficiency, and effect. Results show that titanium meshed electrodes are the most cost-efficient compared to more effective electrodes with significantly higher production costs. The application of the proposed electrochemical disinfection device gains a financial advantage over traditional methods, suggesting a promising future for the disinfection method. Meanwhile, investigations on the electrocoagulation method aim to disinfect the water to the drinking water level. Results show that the combination of electrocoagulation and the titanium meshed electrode device proves to have a better disinfection effect than individual methods and a lower cost than traditional methods. This research provides insight into the properties of biofilms, traditional disinfection methods, and different electrochemical disinfection methods. After reviewing the literature and evaluating various factors, we offer an ideal design for Legionella and E. coli-contaminated water disinfection devices with a promising future once applied.

Improvement of the technique of positioning the endocardial electrodes of the cardiac contractility modulation device in patients with CHF with reduced ejection fraction and atrial fibrillation

To evaluate the efficacy and safety of the advanced technique for positioning the endocardial electrodes of a cardiac contractility modulation (CCM) device. The CCM system was implanted in 100 patients, of which 60 CCM electrodes were positioned in the most optimal zones of myocardial perfusion, in particular, in the zone of the minor focal-scar/fibrotic lesion (the Summed Rest Score of 0 to 1-2, the intensity of the radiopharmaceutical at least 30%), and in 40 patients according to the standard procedure. Before the implantation of the CCM system, 60 patients underwent tomography (S-SPECT) of the myocardium with 99mTc-methoxy-isobutyl-isonitrile at rest to determine the most optimal electrode positioning zones and 100 patients underwent transthoracic echocardiography at baseline and after 12 months to assess the effectiveness of surgical treatment. Improved ventricular electrode positioning technique is associated with the best reverse remodeling of the left ventricular myocardium, especially in patients with ischemic chronic heart failure, with less radiation exposure to the surgeon and the patient, and without electrode-related complications. At the preoperative stage, it is recommended to perform a synchronized single-photon emission computed tomography of the myocardium with 99mTc-methoxy-isobutyl-isonitrile at rest before implantation of the CCM device to assess the presence of scar zones/myocardial fibrosis in the anterior and inferior septal regions of the interventricular septum of the left ventricle, followed by implantation of ventricular electrodes in the zone of the minor scar/fibrous lesion, which will allow to achieve optimal stimulation parameters, increase the effectiveness of CCM therapy, reduce the radiation exposure on medical personnel and the patient during surgery.

Ultra-Wide Interlayered WxMo2xSy Alloy Electrode Patterning through High-Precision Controllable Photonic-Synthesis.

Ultra-thin 2D materials have great potential as electrodes for micro-supercapacitors (MSCs) because of their facile ion transport channels. Here, a high-precision controllable photonic-synthesis strategy that provided 1inch wafer-scale ultra-thin film arrays of alloyed WxMo2xSy with sulfur vacancies and expanded interlayer (13.2Å, twice of 2H MoS2) is reported. This strategy regulates the nucleation and growth of transition metal dichalcogenides (TMDs) on the picosecond or even femtosecond scale, which induces Mo-W alloying, interlayer expansion, and sulfur loss. Therefore, the diffusion barrier of WxMo2xSy is reduced, with charge transfer and ion diffusion enhancing. The as-prepared symmetric MSCs with the size of 100×100µm2 achieve ultrahigh specific capacitance (242.57mFcm-2 and 242567.83Fcm-3), and energy density (21.56Whcm-3 with power density of 485.13Wcm3). The established synthesis strategy fits numerous materials, which provides a universal method for the flexible synthesis of electrodes in microenergy devices.

High Specific Surface Area TiO2 Aerogels Incorporated in situ with Co/Mn Oxides as Stable Electrochemical Capacitor Electrodes

Nanocomposite aerogels comprised of TiO2 and metal (Co and Mn) oxides are synthesized via an in situ sol–gel method in this study, and their structural, compositional and electrochemical properties are evaluated for possible applications as electrodes in energy storage devices. The inclusion of metallic oxides into TiO2 aerogels hinder the formation of titania crystalline phases, preserved particle sizes close to their original dimensions and yielded higher specific surface areas compared to pure TiO2 aerogels after heat treatment. High specific surface areas in aerogels positively affect the electrochemical properties, allowing a high electrochemical activity of the electrodes, in addition to intensifying the transport of ions and solvents through the mesoporous network of this material. Evaluation of the electrochemical properties of the aerogel‐based nanocomposites involves galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. The nanocomposites exhibit enhanced electrochemical properties and stable performance within the range suitable for supercapacitor applications, as indicated by the Ragone chart. Notably, aerogels with higher incorporation of cobalt and manganese oxides in TiO2 aerogels exhibit significantly elevated specific surface areas, reaching 562 and 555 m2 g−1, respectively. These values are notably high for nanocomposites, underscoring the potential of these electroactive materials for electrochemical capacitors.

Self-assembly of Sr2P2O7@2D rGO nano/micro-architecture for highly durable and bendable solid-state supercapattery

Metal pyrophosphate-based materials for supercapattery have recently attracted significant research interest due to their high energy density, structural stability, and cyclability. Despite this, the low electric conductivity of such compounds severely limits the rate efficiency of supercapattery. To address this challenge, self-assembly of strontium pyrophosphate (Sr2P2O7) on 2D reduced graphene oxide (rGO) was produced (Sr2P2O7@2D rGO) with varying urea and rGO proportions employing a two-stage procedure: (i) layer-by-layer (LBL) deposition of rGO nanosheets, followed by (ii) a hydrothermal method to produce strontium pyrophosphate (SP) microflakes. The effective integration of conductive rGO with Sr2P2O7 flakes has been verified by structural and morphological investigation, which indicates that rGO nanosheets offer a large number of active sites, high electrical conductivity, and a wide surface area. However, when compared to the other electrodes, the optimized SP/rGO-3 hybrid electrode possesses battery-like properties, with an outstanding specific capacity of 205 mAh/g (738C/g) in 1 M KOH at a current density of 2 A/g and maintains 99 % durability after 10000 cycles. These outcomes imply a synergistically enhanced surface redox charge storage mechanism through the inclusion of rGO (optimal) and the influence of SP nano/microarchitecture, resulting in an extended cycle lifespan and remarkable electrochemical characteristics. Furthermore, a hybrid solid-state (HSS) supercapattery developed by employing SP/rGO-3 as the cathode and rGO as the anode (SP/rGO-3//rGO) achieved a maximum specific (areal) capacity of 189C/g (52 mAh/g, 133 mF cm−2), (areal) energy density of 42.04 Wh/kg (47.3 mWh cm−2), and a power density of 2755.6 W/kg (3.1 mW cm−2). In addition, the HSS device demonstrates remarkable long-term cyclability, retaining 96 % capacity after 10000 cycles. The present research suggests that Sr2P2O7@2D rGO composites have extraordinary electrochemical properties, highlighting their potential as nano/micro-structured electrodes for future energy storage devices.

Superior Electrochemical Performance and Cyclic Stability of WS2@CoMgS//AC Composite on the Nickel-Foam for Asymmetric Supercapacitor Devices

Two-dimensional (2D) sulfide-based transition metal dichalcogenides (TMDs) have shown their crucial importance in energy storage devices. In this study, the tungsten disulfide (WS2) nanosheets were combined with hydrothermally synthesized cobalt magnesium sulfide (CoMgS) nanocomposite for use as efficient electrodes in supercapattery energy storage devices. The characteristics of the WS2@CoMgS nanocomposite were better than those of the WS2 and CoMgS electrodes. XRD, SEM, and BET analyses were performed on the nanocomposite to examine its structure, morphology, and surface area in depth. In three-electrode assemblies, the composite (WS2@CoMgS) electrode showed a high specific capacity of 874.39 C g−1 or 1457.31 F g−1 at 1.5 A g−1. The supercapattery device (WS2@CoMgS//AC) electrode demonstrated a specific capacity of 325 C g−1 with an exceptional rate capability retention of 91% and columbic efficiency of 92% over 7000 cycles, according to electrochemical studies. Additionally, the high energy storage capacity of the WS2@CoMgS composite electrode was proved by structural and morphological investigations.

The Preparation of N, P-Doped NiSe Nanorod Electrode Materials on Nickel Foam Using the Microwave Method for High-Performance Supercapacitors.

Transition metal selenides have the leading position in the field of energy storage and conversion due to their high theoretical capacity, good electrical conductivity, and cycling stability. Nickel is widely used for the construction of positive electrodes in devices due to its good conductivity, variable valence state, and ideal redox activity. NiSe materials have high internal resistance and are prone to volume change during charging and discharging, thus affecting the practical application of this electrode material, and the reported NiSe materials have not achieved a more desirable capacity value. Therefore, in this study, N, P-NiSe nanoelectrode materials were prepared using nickel foam as the nickel source and hexachlorocyclotriphonitrile as the nitrogen and phosphorus dopant using an efficient, energy-saving, and simple microwave method. It was also characterised by XRD and XPS to confirm the successful preparation of N, P-NiSe materials. In addition, the material yielded a high capacitance value (3184 F g-1) and good cycling stability (72% of the initial capacitance value was retained after 4000 cycles) in electrochemical tests. To demonstrate its excellent suitability for practical applications, an asymmetric supercapacitor was assembled using N, P-NiSe as the anode and activated carbon as the cathode. At an operating voltage of 1.6 V, the device achieved an energy density of 289.06 Wh kg-1 and a power density of 799.26 W kg-1 and retained 80% of its initial capacity after 20,000 cycles.

3D oxidation-resistant MXene electrode supported by softened wood toward high-performance flexible supercapacitors

With the rapid evolution of emerging electronics, MXene materials hold great potential in developing high-performance electrodes for energy storage devices. However, MXenes usually suffer from severe self-stacking, mechanical fragility and susceptibility to oxidation, greatly limiting their further applications. Herein, a simple yet potent strategy is proposed to solve the above challenges by constructing a 3D porous and oxidation-resistant MXene-ascorbic acid/flexible wood electrode (MVFW). FW is employed as a soft and porous framework to solve the self-stacking and mechanical fragility problems of MXenes, ensuring the continuously conductive pathways and rapid ion transport. Ascorbic acid (VC) is introduced to further inhibit the restacking of MXenes and protect them against oxidation, improving the accessibility of active sites/ions and oxidation-resistant stability (capacitance retention of 70 % even after 2 months) of the electrode. Such electrode possesses an intrinsic flexibility with remarkable tensile strength (0.66 MPa) and toughness (0.96 MJ m−3), excellent electrical conductivity (5.4 S cm−1), large areal capacitance (1301 mF cm−2 at 5 mA cm−2) and high rate performance (75 %). The symmetric flexible supercapacitor demonstrates a notable energy density (13.9 μWh cm−2 at 139.7 μW cm−2) and favorable stability after 10,000 cycles or under bending at various angles (30°, 90° and 120°). This study opens up a promising path for the development of flexible, porous and oxidation-resistant MXene electrodes for next-generation wearable energy devices.

Synthesis of 3D FeS embedded into N, S co–doped carbon nanotube/graphene framework for electrochemical application

Constantly striving to develop a facile and scalable way to construct advanced electrodes is essential for the advancement of batteries and electrocatalysis. In this work, an artful K2FeO4 oxidation cooperated with subsequent annealing process is proposed to produce 3D FeS embedded into N, S co–doped carbon nanotube/graphene (FeS/NSCNT/NSG) framework, which simultaneously achieves successful exfoliation of graphite, effective N, S co–doping and desirable integration of 3D framework by FeS and carbon matrix. The adopted procedure is simple, rapid and recyclable. Furthermore, the obtained FeS/NSCNT/NSG exhibits a unique 3D architecture, high doping level and favorable FeS dispersion status, thus displaying excellent performance towards lithium–ion batteries and oxygen evolution reaction. Undoubtedly, our research opens a new pathway for the development of advanced electrodes for energy storage and conversion devices.

Iron-carbon based materials as negative electrode for energy storage devices

The effect of various carbon nanofibers (CNF) on the electrochemical properties of iron/carbon (Fe/C) composite electrodes has been investigated to find a suitable carbon additive for iron-based battery anode. The structure and characteristics of carbon such as particle size, surface area strongly affected the cycling performance of Fe/C composite electrode. Different types of CNF structures (herringbone and tubular) have been investigated and tubular type exhibited higher discharge capacity. The x-ray energy dispersive spectroscopy (EDS) revealed that iron species are dispersed on carbon surface during cycling, which may improve the electrochemical properties of the Fe/C composite electrodes. The aggregation of iron species into large particles on the carbon surface via dissolution-deposition process during cycling increased the resistance of the Fe/C electrode. This phenomenon caused the reduced redox current and discharge capacity of electrode during cycling. The electrochemical active material type and their particle size also influenced the cycling performance of electrode. When Fe was replaced by Fe2O3, the Fe2O3/C composite electrode provided larger capacity than Fe/C composite electrode. The discharge capacity of nano-Fe2O3/tubular CNF composite electrode was larger than that of micro-Fe2O3/tubular CNF composite electrode.

MXene and polyaniline coated 3D-printed carbon electrode for asymmetric supercapacitor

ABSTRACT 3D printing has emerged as an attractive manufacturing technique in supercapacitor electrodes owing to the precise and customisable fabrication of complex electrode designs, enhancing the performance and efficiency of the device. Despite the advantages, 3D-printed electrodes are limited by their low conductivity and electrochemical properties, predominantly due to the lack of availability of suitable conductive materials. To address this limitation, we modified the 3D-printed nanocarbon (3D-PnC) electrode by activation and surface deposition of Ti3C2Tx MXene. A solid-state asymmetric supercapacitor was fabricated by using 3D-PnC/Ti3C2Tx as the negative electrode and polyaniline (PANI) electrodeposited 3D-printed nanocarbon electrode (3D-PnC@PANI) as the positive electrode. The fabricated symmetric supercapacitor exhibits enhancement in overall voltage window, areal capacitance and energy density. The successful operation of the supercapacitor was demonstrated by the illumination of the red light-emitting diodes. Furthermore, this research opens the possibility of utilising MXene-modified 3D-printed electrodes for various electrochemical applications and devices.

Tuning the Topo-Morphological properties of ITO Films using Al-Ag interlayer for Low-Resistance Optoelectronics Devices

Indium tin oxide (ITO) is recently attracting intense attention for application as transparent conducting electrode in different optoelectronic devices including solar cells, liquid crystal displays and organic light emitting diodes. This is attributed to their high optical transmittance in the visible region and good electrical conductivity. In this work, surface topological-morphological (topo-morphological) and electrical properties of ITO based multilayer films with aluminum-silver (Al-Ag) metal interlayer (ITO/Al-Ag/ITO) are investigated after post annealing treatment at 300-500oC by atomic force microscopic (AFM), field emission scanning electron microscopy (FESEM), four-point probe and hall-effect techniques respectively. The ITO/Al-Ag/ITO films are deposited by direct current and radio frequency magnetron sputtering techniques on p-type Si at room temperature. The results showed a smooth surface topology by as-deposited film with films smoothness improving after post annealing treatment as analyzed by AFM method. Sharp crystallites peaks were obtained by all the films with smaller peaks diffusing and recombining to form larger films with increasing post-annealing temperature. The films root means square roughness increased as the temperature increases with film annealed at 500oC showing a superior and enhanced microstructure. Compared to as-deposited film, careful observation shows that surface morphology smoothness increased with increase in temperature with films annealed at 400oC and 500oC showing highest increasing surface smoothness pattern as determined by FESEM technique. Similarly, higher grain sizes are observed especially by films annealed at 400oC and 500oC due to the heat absorption which causes the particles to expand thereby narrowing the grain boundaries and subsequently improve the surface smoothness. These FESEM findings are consistent with AFM measurements confirming the high surface property and enhanced grain size with increasing post annealing temperature. The films exhibit decreased electrical resistivity and sheet resistance while carrier concentration and Hall mobility increased with increasing post annealing treatment indicating highest corresponding values of...

Angle Dependence of Electrode Lead-Related Artifacts in Single- and Dual-Energy Cardiac ECG-Gated CT Scanning-A Phantom Study.

Background: The electrodes of implantable cardiac devices (ICDs) may cause significant problems in cardiac computed tomography (CT) because they are a source of artifacts that obscure surrounding structures and possible pathology. There are a few million patients currently with ICDs, and some of these patients will require cardiac imaging due to coronary artery disease or problems with ICDs. Modern CT scanners can reduce some of the metal artifacts because of MAR software, but in some vendors, it does not work with ECG gating. Introduced in 2008, dual-energy CT scanners can generate virtual monoenergetic images (VMIs), which are much less susceptible to metal artifacts than standard CT images. Objective: This study aimed to evaluate if dual-energy CT can reduce metal artifacts caused by ICD leads by using VMIs. The second objective was to determine how the angle between the electrode and the plane of imaging affects the severity of the artifacts in three planes of imaging. Methods: A 3D-printed model was constructed to obtain a 0-90-degree field at 5-degree intervals between the electrode and each of the planes: axial, coronal, and sagittal. This electrode was scanned in dual-energy and single-energy protocols. VMIs with an energy of 40-140 keV with 10 keV intervals were reconstructed. The length of the two most extended artifacts originating from the tip of the electrode and 2 cm above it-at the point where the thick metallic defibrillating portion of the electrode begins-was measured. Results: For the sagittal plane, these observations were similar for both points of the ICDs that were used as the reference location. VMIs with an energy over 80 keV produce images with fewer artifacts than similar images obtained in the single-energy scanning mode. Conclusions: Virtual monoenergetic imaging techniques may reduce streak artifacts arising from ICD electrodes and improve the quality of the image. Increasing the angle of the electrode as well as the imaging plane can reduce artifacts. The angle between the electrode and the beam of X-rays can be increased by tilting the gantry of the scanner or lifting the upper body of the patient.

Synergy of Charge Storage Properties of CuO and Polypyrrole in Composite CuO-Polypyrrole Electrodes for Asymmetric Supercapacitor Devices

Synergy of Charge Storage Properties of CuO and Polypyrrole in Composite CuO-Polypyrrole Electrodes for Asymmetric Supercapacitor Devices

Carbon nanotube-grid infrared transparent electrodes for flexible electrochromic devices with visible to mid-infrared dual-band modulation

Flexible mid-infrared electrochromic devices (MIR-ECDs) have attracted wide attention due to the growing demands for thermal camouflage and body comfort. However, the normal conductive films (e.g., indium tin oxide/polyethylene terephthalate (ITO/PET) films) are unsuitable for MIR-ECDs due to low infrared transmittance. Herein, the infrared transparent carbon nanotube (CNT) grid films were prepared by designing the grid structure. The infrared transmittance of CNT grid film could reach 72 %; meanwhile, the visible transmittance could reach 75 %. The CNTs exhibited infrared modulation under different voltages due to the doping/de-doping of ions in electrolytes into the CNT network. The flexible electrochromic devices with visible to mid-infrared dual-band modulation were prepared by using CNT grid film as the electrode and poly (3,4 ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as the electrochromic layer, which could realize the infrared synergistic modulation of PEDOT:PSS and CNT grid in the mid-infrared range and reversible color changes between light blue and dark blue in the visible range, showing promising applications in adaptive camouflage and thermal management.