Asymmetric Electrode Research Articles

Pyrolysis-assisted synthesis of two-dimensional graphitic carbon nitride nanosheets embedded with transition metal oxide (Ni or Fe) for high-performance asymmetric supercapacitors

This study employed a one-step pyrolysis-assisted technique to successfully synthesized with two different transition metal oxides (M = Ni, Fe) embedded on graphitic carbon nitride nanosheets (g-C3N4-NS). The resulting nanocomposites exhibit exceptional electrochemical performance in supercapacitor applications due to various parameters such as morphology, specific surface area and crystallinity. Notably, the NiO/g-C3N4-NS and Fe2O3/g-C3N4-NS electrodes simplify the Faradaic reactions and achieve the maximum capacitance of 816 F g−1 and 703 F g−1 at 0.5 A g−1, respectively. Additionally, these electrodes demonstrate superior cycling stability, retaining approximately 96 % of their capacity retention after 5000 cycles. Furthermore, the NiO/g-C3N4-NS//AC and Fe2O3/g-C3N4-NS//AC devices exhibit promising supercapacitor device performance, yielding respectable specific capacity of 53 F g−1 (NiO/g-C3N4-NS//AC) and 43.5 F g−1 (Fe2O3/g-C3N4-NS//AC) at 0.5 A g−1, underscoring the commendable rate capability of the asymmetric electrodes and the energy densities of 19 Wh kg−1 and 16 Wh kg−1 at a power density of 400 W kg−1, respectively. These findings underscore the potential of metal oxide/g-C3N4-NS composites as an electrode material for power storing applications, as demonstrated by these asymmetric supercapacitor devices.

An asymmetric membrane electrode assembly for high-performance proton exchange membrane fuel cells

The membrane electrode assembly (MEA) is a critical part of proton exchange membrane fuel cells (PEMFCs) and has a significant impact on their performance. A novel preparation method of MEA is proposed in this work to inhibit the swelling and deformation of the proton exchange membrane (PEM) during MEA preparation and improve the interface between the PEM and cathode catalyst layer (CL). Using this novel fabrication method, an asymmetric MEA is prepared, where the anode and cathode parts are fabricated separately and then integrated by a hot-pressing process. The cathode part is prepared by covering the gas diffusion electrode (GDE) onto a layer of a perfluorosulfonic acid dispersion to form a membrane-coated electrode according to a wet-contact interface design, thereby ensuring a tight and concave-convex PEM/CL interface on the cathode. The anode part is prepared by spraying the CL onto a commercial PEM with a substrate to form a CL-coated PEM. An MEA was also prepared according to the traditional catalyst-coated membrane (CCM) method for comparison. The asymmetric MEA based on the new manufacturing process performs better than the traditional CCM-type MEA under the same PEM thickness prerequisite. The peak power densities of the asymmetric MEA are verified to be 18% (H2/air) and 31% (H2/O2) higher than conventional CCM-type MEA. In addition, the asymmetric MEA shows less cell performance degradation after 3000 dry/wet test cycles than the CCM-type MEA.

Asymmetric Electrode Design for High-Area Capacity and High-Energy Efficiency Hybrid Zn Batteries.

Compared to Zn-air batteries, by integrating Zn-transition metal compound reactions and oxygen redox reactions at the cell level, hybrid Zn batteries are proposed to achieve higher energy density and energy efficiency. However, attaining relatively higher energy efficiency relies on controlling the discharge capacity. At high area capacities, the proportion of the high voltage section can be neglected, resulting in a lower energy efficiency similar to that of Zn-air batteries. Here, a high-loading integrated electrode with an asymmetric structure and asymmetric wettability is fabricated, which consists of a thick nickel hydroxide (Ni(OH)2) electrode layer with vertical array channels achieving high capacity and high utilization, and a thin NiCo2O4 nanopartical-decorated N-doped graphene nanosheets (NiCo2O4/N-G)catalyst layer with superior oxygen catalytic activity. The asymmetric wettability satisfies the wettability requirements for both Zn-Ni and Zn-air reactions. The hybrid Zn battery with the integrated electrode exhibits a remarkable peak power density of 141.9mWcm-2, superior rate performance with an energy efficiency of 71.4% even at 20mAcm-2, and exceptional cycling stability maintaining a stable energy efficiency of ≈84% at 2mAcm-2 over 100 cycles (400 h).

Facile synthesis of N-doped NiCo-LDH nanowire with rich oxygen vacancies by nonthermal plasma for high-performance asymmetric capacitor electrode

Layered double hydroxides (LDHs) have been served as potential pseudo-capacitive materials, especially for high-performance supercapacitors. However, the characteristics like limited capacitance, poor conductivity, and stability of LDHs severely confine their extensive applications for future energy-storage devices. It is urgent to seek a new and simple method to modify LDH materials, to improve its electrochemical performance and apply it to supercapacitors. Herein, a facile in-situ non-thermal plasma (NTP) treatment is conducted to modify NiCo-LDH nanowires for better electrochemical performance, resulting from the introduction of N-doping and oxygen vacancies by N2 NTP. All these instructive synergies provide the optimum electrode (P-NiCoNW/CC-150) after the NTP treatment under the power of 150 W with outstanding capacitance performance of 4320 mF/cm2 at 2 mA/cm2, and superior cycling stability along with capacitance retention of 117.3 %. Most importantly, an asymmetric supercapacitor device is assembled, employing P-NiCoNW/CC-150 and oxidized carbon cloth as cathode and anode electrodes respectively, exhibiting a particularly high energy density of 364 μWh/cm2 when the power density is 4505 μW/cm2. This work confirms a feasible and green NTP method to synthesize high-performance electrodes for practical applications in future energy-storage devices but not limited to supercapacitors.

Fast chromium determination in pharmaceutical tablets by using electrochemical sensors: Preparation and comparison

In the present paper, three electrodes were prepared with the aim of detecting chromium (III) in pharmaceutical tablets and comparing their capabilities and efficiency. At first, N-(pyridine-2-ylcarbamothioyl) benzamide (NP2YCTB) was synthesized and characterized by 1H NMR, FTIR, and 13C NMR spectroscopy methods. Then, it is used as a sensing material to prepare three types of chromium potentiometry sensors including solid-state electrodes (SSE), coated wire electrodes (CWE) as asymmetric electrodes, and liquid membrane electrodes (LME) as symmetric electrodes. The responses of all electrodes were Nernstian. Field-emission scanning electron microscopy was utilized to investigate the liquid membrane morphology. The presence of chromium (III) in the membrane was proved using Energy-dispersive X-ray spectroscopy and the coordination of NP2YCTB heteroatoms with chromium (III) was confirmed by Fourier transform infrared spectroscopy. The limit of detection for SSE (3 × 10−9 mol/L) was enhanced compared with LME (7 × 10−6 mol/L) and CWE (3 × 10−7 mol/L). The response time of electrodes was very short so it was about 5–6 s for LME and CWE and 5–8 s for SSE. The sensors were used for the potentiometric determination of chromium (III) in pharmaceutical tablets and in the potentiometric titration of it with EDTA.

Self-Powered Photodetector Based on Ag/CH3NH3PbI3/C Asymmetric Dual-Terminal Device.

CH3NH3PbI3 is capable of exhibiting a superior photoresponse to visible light, but its self-powered devices are typically formed through p-n junctions. In this study, we fabricated a Ag/CH3NH3PbI3/C dual-terminal asymmetric electrode device using a single CH3NH3PbI3 perovskite micro/nanowire, enabling both the photoresponse and self-powered characteristics of CH3NH3PbI3 to visible light. Compared with traditional p-n junction devices, this simple device demonstrates enhanced interface photovoltaic effects by optimizing the combination of the Ag electrode with CH3NH3PbI3, resulting in superior self-powered characteristics. Under low bias voltage, the device achieves a significant on/off ratio of 103, with superior sensitivity and responsivity as well as a maximum rectification ratio of about 12. The photogenerated voltage and current reach approximately 0.8 V and 2 nA, respectively. This simple, compact, and self-powered asymmetric device exhibits great potential for applications in self-powered optoelectronics and wearable devices. This research provides a promising approach for recognizing and utilizing surface state effects in single nanoscale structures.

Coupling Dynamics and Three-Dimensional Trajectory Optimization of an Unmanned Aerial Vehicle Propelled by Electroaerodynamic Thrusters

Electroaerodynamic unmanned aerial vehicles (EAD-UAVs) are innovative UAVs that use high-voltage asymmetric electrodes to ionize air molecules and Coulomb force to push these ions to produce thrust. Unlike fixed-wing and rotor UAVs, EAD-UAVs contain no moving surfaces and have the advantages of very low noise, low mechanical fatigue, and no carbon emissions. This paper proposes an EAD-UAV configuration with an orthogonal arrangement of multiple EAD thrusters to adjust the EAD-UAV attitude and flight trajectory through voltage distribution control alone. Based on a one-dimensional dynamic model of an EAD thruster, the attitude–path coupling dynamics of the EAD-UAV were derived. To achieve EAD-UAV flight control for a specified target, the Bezier shaping approach (BSA) was implemented to realize rapid trajectory optimization considering the coupling dynamic constraints. The numerical simulation results indicate that the BSA can quickly procure an optimized flight trajectory that satisfies the dynamic and boundary constraints. Compared with the Gaussian pseudospectral method (GPM), the BSA changes the optimization index of the objective function by nearly 1.14% but demands only nearly 1.95% of the computational time on average. Hence, the improved integrative Bezier shaping approach (IBSA) can overcome the poor convergence issue of the BSA under the continuous acceleration constraint of multi-target flight trajectories.

The thermoelectric power investigation of the ϒ2-graphyne molecule device

Graphyne, is an interesting carbon nanostructure, with unique properties such as high carrier mobility, thermal stability, and electronic band characteristics shaped by sp and sp2 hybridizations. Due to its intrinsic porous nature, graphyne exhibits higher phonon scattering, and lower thermal conductance compared to graphene, making it an excellent nominee to be investigated as an organic nanoscale thermoelectric material. In this study, we delve into the thermoelectric power properties of the ϒ2-Graphyne structures using the modeling and simulated approaches. Our modeling studies focus on unit cell base vector variation at temperatures higher and lower than the Fermi temperature, additionally, the hopping energy variation is calculated in the same temperatures. We have employed the semi-classical Boltzmann transport equation to analyze these effects, considering the relaxation time factor, as a way of exploring the phonon scatterings, and the changing system behavior. It is concluded structural variation leads to a change in the scattering mechanisms. ATK Quantum Wise simulations on three groups of ϒ2-Graphyne structures are carried out. In the first two groups, the influence of the electrode length and the asymmetry are investigated, but for the last group, only the main region variation is considered. Generally, the number of the unit cells in the main region is changed from one group to the other. The density of states, the transmission spectrum, and electrical conductance values are calculated moreover, the effect of the temperature on thermoelectric power for all groups of devices is simulated. The figure of merit (Z) values at room temperature for all the structures is determined and the highest value of ZT is for the device with one unit cell and asymmetric electrodes are reported.

A comparative study of photoelectric performance of Ga2O3 solar-blind photodetectors with symmetric and asymmetric electrodes

Gallium oxide (Ga2O3) thin films were deposited on quartz substrates under different oxygen flow ratios (O2/[O2+Ar], 0%−5%) by radio-frequency (RF) magnetron sputtering technique followed by thermal annealing at 900 °C for 2 h under N2 atmosphere. The influence of the oxygen concentration on the structural and optical characteristics of Ga2O3 thin films was investigated. The Ga2O3 thin films prepared under an oxygen flow ratio of 1% exhibited optimum crystal quality and the lowest oxygen vacancy (VO) concentration according to X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) investigations. All as-prepared polycrystalline Ga2O3 thin film samples exhibited high average transmittance above 87.8% in the visible spectral region and the 0% and 1% thin films had optical bandgap energies of about 4.9 eV. We also fabricated metal−semiconductor−metal (MSM) photodetectors based on 1% Ga2O3 thin films by employing pairs of Ni−Ni symmetrical or Ni−Al asymmetrical interdigitated electrodes. The Ni−Ni photodetector had a high on/off current ratio (Ion/Ioff > 105), a responsivity of 88.7 mA/W, and specific detectivity of 4.81×1010 J at 10 V bias under ultraviolet light-C (UVC) illumination, and the Ni−Al photodetector exhibited self-driven behavior along with short rise and fall times (0.45 s and 0.69 s, respectively).

CO2 Dissociation in Barrier Corona Discharges: Effect of Elevated Pressures in CO2/Ar Mixtures

The formation of carbon monoxide, oxygen and ozone in a barrier corona discharge (BCD) operating in pure carbon dioxide (CO2) and binary mixtures of CO2 and argon is studied. The asymmetric electrode configuration of the BCDs allows plasma operation at pressures exceeding 1 atm, up to 6 bar, at moderate high-voltage amplitudes below 15 kV. Charge–voltage plots and an equivalent circuit model are employed to characterize the electrical parameters at different pressures and gas compositions. Depending on these conditions and the voltage amplitude, full or partial coverage of the electrodes with plasma is obtained. The existence of an optimum pressure for power dissipation for each given operation voltage amplitude and gas composition can be confirmed and explained by the equivalent circuit model. Increasing the CO2 concentration in the working gas increases the mean reduced electric field strength E/N while pressure reduces it in the BCD. The CO2 conversion shows a maximum efficiency of about 4% at 1.5 bar for the gas mixture Ar/CO2 = 1:1 and a voltage amplitude of about 10 kV. The calculation of thermodynamic equilibrium parameters reveals that a relatively small increase in pressure can affect both, the equilibrium parameters and the reaction rates. As a result, the specific required energy for the reaction (ΔH/SEI\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta \\mathrm{H}/\\mathrm{SEI}$$\\end{document}) shows an optimum, but only 8% of the electrical input energy is spent for CO2 dissociation at these optimum conditions.

Mechanism of rectification and negative differential resistance in single-molecule junctions with asymmetric anchoring groups: a DFT study.

This study aims to investigate the electronic transport properties of tetracene molecule connected to gold (Au) electrodes with asymmetric anchoring groups. More specifically, we investigate the effect of asymmetric electrode coupling on the rectification ratio of tetracene-based molecular device. To introduce coupling asymmetry in these junctions, one end of the tetracene molecule is terminated with thiol (-SH) or isocyanide (-NC) while the other end with amine (-NH2) or nitro (-NO2) anchoring group. The results indicate that the electronic transport behavior is affected by the nature of molecule-electrode coupling, and the rectification ratio can be modulated by a proper choice of the anchoring groups. We reveal that the tetracene molecule when connected with isocyanide and amine combination exhibits remarkable rectifying performance (with a rectification ratio of 74) in contrast with other configurations. Furthermore, a prominent negative differential resistance (NDR) feature is observed when the molecule is connected with thiol as one of the anchors. Our present findings with excellent rectifying performance and negative differential resistance pave a new roadmap for designing multifunctional molecular devices. By applying non-equilibrium Green's function (NEGF) formalism combined with density functional theory (DFT) Atomistic Tool Kit software package, the electronic transport properties of tetracene molecule connected to gold electrodes with asymmetric anchoring groups have been investigated. The calculations were performed using the Perdew-Burke-Ernzerhof (PBE) parameterization of DFT within generalized gradient approximation (GGA) exchange-correlation functional. To improve calculation precision and save computational efforts, the molecule and anchor groups were double-ζ (DZ) polarized, while single-ζ (SZ) polarized basis set was used for gold electrodes.

Tunable Contacts of Bi2 O2 Se Nanosheets MSM Photodetectors by Metal-Assisted Transfer Approach for Self-Powered Near-Infrared Photodetection.

Owing to the Fermi pinning effect arose in the metal electrodes deposition process, metal-semiconductor contact is always independent on the work function, which challenges the next-generation optoelectronic devices. In this work, a metal-assisted transfer approach is developed to transfer Bi2 O2 Se nanosheets onto the pre-deposited metal electrodes, benefiting to the tunable metal-semiconductor contact. The success in Bi2 O2 Se nanosheets transfer is contributed to the stronger van der Waals adhesion of metal electrodes than that of growth substrates. With the pre-deposited asymmetric electrodes, the self-powered near-infrared photodetectors are realized, demonstrating low dark current of 0.04 pA, high Ilight /Idark ratio of 380, fast rise and decay times of 4 and 6ms, respectively, under the illumination of 1310nm laser. By pre-depositing the metal electrodes on polyimide and glass, high-performance flexible and omnidirectional self-powered near-infrared photodetectors are achieved successfully. This study opens up new opportunities for low-dimensional semiconductors in next-generation high-performance optoelectronic devices.

A moist-electric generator based on oxidized and aminated regenerated cellulose

Moist-electric generation has been more focused in recent years, which is an emerging sustainable energy harvesting technology. Moist-electric generator (MEG) is a prospective energy harvesting device that collects energy only from humidity. While the existed researches focused on the ionic wood, cellulose nanofibril and cellulose acetate, this work pays attention to the oxidized regenerated cellulose (ORC) and aminated regenerated cellulose (ARC) prepared by urea/NaOH/water system from pulp, which has excellent hydrophilicity and abundant active sites attributing to the abundant functional groups and three-dimension porous structure. Its asymmetric active electrode and asymmetric ORC and ARC structure cause a humidity gradient between the two electrodes as exposed in a humidity environment, which produce potential difference under the ion concentration gradient for the directional transport of protons derived from the ionization effect, thus generating an electric current in external circuit. Of which, 12-ORC-MEG can generate an open-circuit voltage of 1.07 V at 85%RH humidity. 5-ARC-MEG can produce the output voltage as high as 4.20 V for the brought more isoelectric points by grafting amino, which is about 4 times than that of 12-ORC-MEG. The MEG as a sensor and generator can generate a certain output voltage in contact with sweaty fingers or intermittent fog. Just one 5-ARC-MEG can power micro-electronic devices, such as LED lamp and watch. This work develops a simple, inexpensive, and green MEG with renewable cellulose material that can generate sustainable moist-electric conversion from ambient humidity. It has great potential in green energy and opens up new possibilities for portable electronic products.

Enhanced capacitive deionization of Cr(VI) using functionalized metal carbide 2D framework and badam tree leaf-derived carbon as the asymmetric electrode materials

The development of high-value-added biomass-derived carbonaceous as electrode material from agricultural wastes has received considerable attention. In this study, the activated biochar (AB) derived from the badam tree leaves (BTL) and functionalized 2D metal-carbide materials, V2AlC-OHx, have been successfully synthesized by alkaline treatment and microwave-assisted hydrothermal method, respectively, and then used as the asymmetric electrode materials for capacitive deionization application to remove Cr(VI) ions from aqueous solutions. The large specific surface area and the interconnected meso- and macro-porous channels of AB provide active sites and short ion diffusion paths to accelerate ion transport and electrosorption. In addition, the highly crystalline 2D architecture of V2AlC-OHx offers suitable lattice fringes for electron transfer. The conversion of Cr(VI) into Cr(III) on the surface of V2AlC-OHx, followed by the capture of Cr(III) onto the AB cathode has triggered the enhanced removal of Cr(VI). The AB//V2AlC-OHx asymmetric CDI device exhibits superior deionization performance for Cr(VI) removal with a specific electrosorption capacity of 47.2 mg g−1 and removal efficiency of 99 %. Excellent cyclic performance for at least 20 adsorption–desorption cycles is also observed, indicating the excellent durability of the fabricated materials. These results demonstrate that AB and V2AlC-OHx are promising CDI electrodes for the removal of metal ions and other hazardous pollutants from industrial effluents.

Triboelectric nanogenerator with asymmetric multilayer arc electrodes to improve performance

The role of wind energy in the emerging energy market is crucial and it holds the potential to emerge as a promising clean energy source. The triboelectric nanogenerator represents a revolutionary paradigm in wind energy harvesting devices, having engendered considerable scholarly interest due to its innovative approach and potential implications. Among its various working modes, freestanding mode is considered the most effective for harvesting rotating energy. In this paper, a freestanding mode multilayer triboelectric nanogenerator is proposed, which is characterized by asymmetric arc electrode structure, and the usual freestanding mode electrodes are positioned at a certain angle to improve the output of the generator. Operating at a frequency of 1 Hz, it is exclusively the single-layer arc electrode that can yield an instantaneous power output of 1.625 mW, while concurrently facilitating the transfer of a charge quantified at 197 nC. Compared to an untreated electrode, exhibiting an enhancement of 11-fold in terms of power output and 3.5-fold with respect to charge transfer. Additionally, the generator’s electrodes are cleverly designed with an asymmetric multilayer structure, resulting in higher space utilization within the generator. The asymmetric arc triboelectric nanogenerator (AA-TENG) presents a viable solution for effectively harvesting wind energy in nature.

Self‐Assembled Asymmetric Electrodes for High‐Efficiency Thermogalvanic Cells

AbstractThe thermogalvanic cell (TGC) is considered a promising thermoelectric device for directly converting low‐grade waste heat into electricity due to its low‐cost and scalable properties. However, the low output and conversion efficiency limit its practical application. Herein, record‐high thermoelectric conversion performances are achieved in the aqueous ferri/ferrocyanide ([Fe(CN)6]3−/[Fe(CN)6]4−) based TGC by using the electrode of cobaltous oxide nanowires array on carbon cloth fiber. Because of the temperature‐dependence reaction activity between CoO with [Fe(CN)6]4−, the asymmetric electrodes of Co2Fe(CN)6 and CoO nanowires array on carbon cloth fiber are constructed at the hot anode and cold cathode, respectively. These self‐assembled asymmetric electrodes exhibit specific catalysis toward electrode reactions at both ends of TGC, leading to a significant reduction in electronic activation energy. It is demonstrated that the electrodes have high catalytic activity and high specific surface area, enabling the construction of a high‐efficiency TGC with a Carnot‐relative efficiency (ηr) of 14.8% and a maximum output power density (Pmax) of 24.5 W m−2. This work offers an asymmetric electrode engineering pathway for the continuous evolution of TGCs.

Pseudocapacitive deionization of high concentrations of hexavalent chromium using NiFe-layered double hydroxide/polypyrrole asymmetric electrode

The wastewater polluted by high concentrations of aqueous hexavalent chromium (Cr(VI)) has serious adverse effects on ecological environment and human health. As a burgeoning, environmental-friendly, and promising wastewater treatment technology, capacitive deionization (CDI) process for efficient removal of aqueous Cr(VI) needs to be investigated. In this work, pseudocapacitive NiFe-layered double hydroxide/ polypyrrole (NiFe-LDH/PPy, denoted as NiFe/PPy) electrode was synthesized by the in-situ polymerization of PPy on the NiFe-LDH surface. Results of characterizations manifested that NiFe/PPy had the chain spherical structure of PPy. In particular, excellent PPy provides effective reversible capacitance and ion diffusion and improves the conductivity and pseudocapacitance performance of NiFe-LDH. Then, the NiFe/PPy anode and activated carbon (AC) cathode were assembled into the CDI cell for capacitive removal of high concentrations of aqueous Cr(VI). In 20 mL/min of flow velocity, 1.2 V, and 100 mL 100 mg/L of Cr(VI) solution, the Cr(VI) electrosorption capacity and removal ratio attained to 47.95 mg/g and 95.89%, respectively. The electrosorption of Cr(VI) slightly decreased under the common competing anions of Cl−, NO3−, SO42−, HCO3−, and CO32−. Based on Langmuir isotherm model, the maximum theoretical removal capacity of NiFe/PPy for Cr(VI) was 111 mg/g. The electrostatic attraction, reduction, and surface complexation played primary roles in the CDI system of NiFe/PPy//AC asymmetric electrodes. The outstanding electrosorption performance makes this CDI system have a favorable application prospect in the actual wastewater treatment containing high concentrations of Cr(VI).

Novel 2D CeO2 nanoflakes as a high-performance asymmetric supercapacitor electrode material

Enhancing the performance and durability of benchmarked metal catalysts using nanostructured non-metallic materials is an active area of research that is exciting from both a fundamental and an application perspective. The 2D CeO2 nanoflakes are characterized using structural and electrochemical techniques. Galvanostatic charge-discharge (GCD) revealed that the material delivers a specific capacitance of 1801 F/g at 1 A/g, among the best-reported values for transition and rare earth metal oxide electrode material. Due to its nanoflake-like structure, the sample has a modest surface area (12.6 m2/g). Asymmetric supercapacitor device (CeO2//AC) fabricated delivered an energy density of 57.6 Wh/kg and a power density of 771 W/kg with 83 % capacitance retention after 1000 cycles in 3 M KOH. This study reveals that CeO2 is a promising electrode material for energy storage applications.

A Comparative Study between Silicon Carbide and Silicon Nitride based Single Cell CMUT

This research explores the design and conducts a comparative analysis of a non-insulated Capacitive Micromachined Ultrasonic Transducer (CMUT) featuring an innovative asymmetric electrode configuration to improve the performance of the device. Specifically, this configuration involves the utilization of a top electrode with a smaller radius in comparison to the bottom electrode. The study encompasses an investigation into the effects of varying biasing voltage within the range of 40 V to 100 V. The materials employed in this study are carefully selected to optimize the CMUT's performance. The substrate material is silicon, and the bottom and top electrodes are made from aluminium. Additionally, silicon dioxide is utilized as the foundation material within the device's structure.

Removal and Recovery of Copper from Industrial Waste Streams: Design of an Electrochemical Cell

Copper (Cu) exists in a variety of wastewater and process streams in a host of chemical, manufacturing, and commercial industries. These instances include complex streams from chemical-mechanical planarization (CMP) processes in the semiconductor industry, rinse streams from plating baths at electroplaters, and commercial discharge to surface waters requiring Cu concentrations to be well below 1 ppm. Conventionally, the removal of Cu from wastewater has followed two routes: (1) precipitation with an iron-based coagulant and (2) ion exchange (IX) to selectively removal lower concentrations of Cu.1 Coagulation approaches, while effective, produce a notable amount of sludge waste that must be disposed of properly. Recovery of specific metals from this sludge is also quite difficult, meaning that the value in the metals that are removed with the sludge would be lost. IX, while also a long-validated technology, needs to be used under highly specific conditions and often leads to unreliable separations, particularly during production upsets in upstream equipment.Electrochemical separations can alleviate many of the problems in existing wastewater treatment techniques. In particular, capacitive deionization (CDI) as an electrochemical separation route has seen significant development over the last decade, highlighting the ability for electrochemical cells to be used in new and useful ways.2 However, CDI often suffers from diminished separation lifetime and lack of high selectivity during the separation process, although gains in selectivity have been recently explored.3 In this talk, the use of a new electrochemical process will be reviewed for the selective removal and recovery of Cu.4 Use of asymmetric carbon electrodes in an electrochemical cell is found to provide localized conditions capable of effectively removing >95% of Cu from an influent stream while symmetric configurations offer much lower levels of Cu removal. Design of the carbon electrodes for fast Cu removal kinetics along with approaches to design of the electrochemical cell for high throughput will be reviewed. Electrode density, surface area, and spacing are found to impact the effectiveness of the resulting separation. Lifetime of this new separation process will also be reviewed with demonstrations of >20 hours of operation. Degradation mechanisms and the ability to mitigate loss of performance will be presented.