Range Of Applied Voltages Research Articles

Fabrication and formation mechanism of gradient TiO2 nanotubes via bipolar anodization

Bipolar electrochemistry is a promising technology especially in the fields of micro- and nanoscience, but it does not receive enough attention at present. In this paper, bipolar electrochemistry was successfully employed to fabricate TiO2 nanotubes with the diameter, length and composition gradients on titanium foils (as bipolar electrodes, BPE) within an applied voltage range of 50–120 V. The formation mechanism of the nanotube gradients and the role of the interface potential difference between BPE and the electrolyte on the forming driving force were thoroughly discussed. The results showed that the TiO2 nanotubes geometries could readily be controlled by adjusting the location on BPE and the applied voltages. The largest diameter and tube length occurred near the edge of BPE anode and then decreased with the distance away, but increased with the applied voltages. However, at certain locations, 35 mm away from the edge of BPE anode at 120 V, 30 mm at 100 V, 25 mm at 75 V and 15 mm at 50 V, massive little cylindrical oxides, rather than hollow nanotubes began to appear. The formation mechanism of the gradient nanotubes was generalized into the filed-assisted oxidation, chemical and field-assisted dissolution, and the synergy of two processes, which corresponded to three stages of the current density-time curves, the initial exponential drop, then rapid rise, and subsequent increase at different rates at 50–120 V, respectively. The average current density was also increased with an increase of the applied voltage. The interface potential difference E between the electrolyte and BPE titanium, instead of the applied voltages Etotal, essentially determined the driving force of anodic actions, leading to the formation of TiO2 nanotube gradients. Since E was less than Etotal, the largest diameter and length of nanotubes were less than those in conventional anodization at the same applied voltages. However, at 30 V, the insufficient interface potential difference E cannot bring about hollow tubular structure on the whole BPE titanium. This study on the fabrication and formation mechanism of the gradient TiO2 nanotubes will provide important scientific values and engineering application prospects, such as in screening the performance of catalytic, sensing and biomedical materials, or steering the molecular or macroscopic motion.

Efficient removal of sixteen priority polycyclic aromatic hydrocarbons from textile dyeing sludge using electrochemical Fe2+-activated peroxymonosulfate oxidation-A green pretreatment strategy for textile dyeing sludge toxicity reduction

It is urgent to remove polycyclic aromatic hydrocarbons (PAHs) from textile dyeing sludge (TDS) before its final deposal due to their recalcitrant nature and generation of toxic byproducts during TDS treatment. In this study, an electrochemical Fe2+-activated peroxymonosulfate (PMS) oxidation process for removing 16 priority PAHs from real TDS was firstly investigated. The results showed that the removal efficiency of the ∑16PAHs in TDS was positively correlated to the concentration of Fe2+ released from sacrificial iron anode and the concentration of electroregenerated Fe2+ in the cathode by the reduction of Fe3+ within the applied voltage range of 3–7 V, but a higher voltage of 10 V did not lead to further improvement in ∑16PAHs removal due to the radical scavenging reaction resulted from the excessive accumulation of Fe2+. 64.7% and 16.1% of the ∑16PAHs were removed in the anodic and cathodic chamber under the optimum reaction conditions of 400 mg/g PMS/VSS, pH 3 and applied voltage 7 V, respectively. low-ring PAHs were preferentially degraded compared to high-ring PAHs. The O⋅Hplayed a major role while SO4⋅—had a minor role in PAHs degradation in TDS. The intracellular PAHs released from cracked sludge cells were found to undergo further degradation under free radical attack.

Analog-to-digital and self-rectifying resistive switching behavior based on flower-like δ-MnO2

Memristors can be divided into two types, analog and digital, according to the characteristics of current gradients and sudden changes. It is particularly important to realize analog and digital switching behaviors in the same device to facilitate the development of analog–digital circuits. In this work, the flower-like δ-MnO2 was prepared on fluorine doped tin oxide (FTO) substrate by chemical bath deposition method, and it can be used as dielectric layer of memristor. Analog and digital types of resistive switching behaviors were achieved in the same device with Ag/δ-MnO2/FTO structure by adjusting the applied voltage range on top electrode of memristor. Moreover, the digital type of resistive switching behavior with multi-level and self-rectifying properties was realized in this device. The charge transport and resistive switching mechanism of the device with analog to multi-level self-rectifying digital types was explained by analyze its current–voltage (I-V) curve. Therefore, this new type of memristive device with both analog and digital properties can simplify the circuit complexity, and the multilevel and self-rectification behavior can greatly improve the storage density and solve the misreading problem of memristive devices.

Scalable high-efficiency multilayered anti-icing/de-icing coating: Superhydrophobic upper layer boosts the performance of the electrothermal system

The formation and accumulation of ice can easily cause serious safety issues and damage. The superhydrophobic surface can delay ice formation due to its liquid repellence feature, but does not work very well under super cold temperatures. The electrothermal coating can effectively prevent ice formation, while it is very energy-consuming. In this work, a multilayered system that combined electrothermal layer (ET) with energy-saving superhydrophobic layer (SH) (SH@ET system) was fabricated to improve the energy efficiency of anti-icing/de-icing coatings. A programmable automatic spraying machine was used to prepare the graphene nanoplates (GNP)-based electrothermal coating with controllable electrical resistance and excellent electrothermal performance. After spraying the SH layer, the SH@ET coating showed excellent water repellency, superior anti-icing performance, and extremely low ice adhesion strength (15 kPa). During the anti-icing test, there was no ice accumulation on the surface of assembled SH@ET system even under low power (0.5 W) at −19 °C for 20 min, confirming its practical application prospects. The SH@ET system also exhibited superior deicing performance than the ET coating. An obvious difference appeared at the low applied voltage range, under which ice continuously formed on the surface of ET coating, while no ice formed on the SH layer. The results can be ascribed to the better water repellency and low ice adhesion strength of the SH layer. This work provides a feasible approach for designing multilayer anti-/de-icing systems for practical large-area applications.

A Novel Sensitive Photonic Crystal Fiber Based Voltage Sensor Filled With Nematic Liquid Crystal

A novel photonic crystal fiber (PCF) based on highly sensitive voltage sensor is proposed and numerically analyzed where Silicate glass (SF57) is used as the base material. All the air holes of the PCF’s cladding are proposed to be filled with Nematic Liquid Crystal (NLC) (E7) which is sensitive with the applied external voltage. The maximum sensitivity response of 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$nm/V$</tex-math></inline-formula> can be reached for the applied voltage range from 300 V to 400 V. Besides that, the values of the birefringence, coupling length, effective mode area and the resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.34\times 10^{-4}$</tex-math></inline-formula> , 43.12 nm, 337.7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\mu } m^2$</tex-math></inline-formula> , and 12 nm are gained for the applied voltage of 360 V. All the investigations are performed under the temperature of 20°C. Moreover, the sensor contains simple structure which is feasible to fabricate. Generally, experiments are performed to verify the outcomes of the simulated model. The liquid filling process is one end of the proposed fiber is put into the NLC and then the other end is kept in the air; through this fusion process, the NLC will flow into the air holes by capillary force. However, the proposed voltage sensor with high sensitivity response and good linearity could be the effectively used in voltage measurement applications within this range.

Mechanisms of negative differential resistance in glutamine-functionalized WS2 quantum dots

Understanding the mechanism of the negative differential resistance (NDR) in transition metal dichalcogenides is essential for fundamental science and the development of electronic devices. Here, the NDR of the current–voltage characteristics was observed based on the glutamine-functionalized WS2 quantum dots (QDs). The NDR effect can be adjusted by varying the applied voltage range, air pressure, surrounding gases, and relative humidity. A peak-to-valley current ratio as high as 6.3 has been achieved at room temperature. Carrier trapping induced by water molecules was suggested to be responsible for the mechanism of the NDR in the glutamine-functionalized WS2 QDs. Investigating the NDR of WS2 QDs may promote the development of memory applications and emerging devices.

A low voltage-powered soft electromechanical stimulation patch for haptics feedback in human-machine interfaces

One grand challenge in haptic human-machine interface devices is to electromechanically stimulate sensations on the human skin wirelessly by thin and soft patches under a low driving voltage. Here, we propose a soft haptics-feedback system using highly charged, polymeric electret films with an annulus-shape bump structure to induce mechanical sensations on the fingertip of volunteers under an applied voltage range of 5–20 V. As an application demonstration, a 3 × 3 actuators array is used for transmitting patterned haptic information, such as letters of ‘T’, ‘H’, ‘U’ letters and numbers of ‘0’, ‘1’, ‘2’. Moreover, together with flexible lithium batteries and a flexible circuit board, an untethered stimulation patch is constructed for operations of 1 h. The analytical model, design principle, and performance characterizations can be applicable for the integration of other wearable electronics toward practical applications in the fields of AR (augmented reality), VR (virtual reality) and robotics.

Catalyst-induced enhancement of direct methane synthesis in solid oxide electrolyser

CO2 valorisation to fuels and chemicals in solid oxide electrolytic cells (SOECs) has been a topic of great interest for the past few years. Methane is one such highly valuable fuel, but its in-situ generation in SOECs is an emerging technology. For the first time, we explain how the introduction of a methanation catalyst metal into the cathode affects the electrokinetics of in-situ methane generation in an electrolyte-supported symmetric tube cell while electrolysing a mixture of H2/CO2 . Fe–Ag and Fe–GDC–Ag electrodes were studied in the applied voltage range of 1.3–1.8 V and temperature range of 500–700°C. While Fe guaranteed good catalytic activity towards methanation reactions, Ag ensured good electrical conductivity of the electrode. Addition of GDC to the cathode remarkably improved CO2 electrolysis and modified Fe work function under loaded conditions, thus increasing methane generation to a maximum of 2.5% at 600°C and 1.6 V. For the Fe–Ag electrode, gaseous mass transport at the cathode was the rate-limiting step up to ~1.4 V, whereas at higher potentials, CO2 electrolysis at the triple-phase boundary became the rate-determining step. Short-term cell testing at 1.7 V and 500°C revealed the presence of a Fe3C phase on the cathode, which affected the electrochemical performance of the cell.

Electrically heated wearable textiles produced by conventional pigmented inks containing carbon black

PurposeThe purpose of this study is to investigate the utility of carbon black containing coating formulations that are conventionally used for pigment printing of textiles in fabricating electrically heated fabrics.Design/methodology/approachSpecifically, electrical and thermal characterisation of the coating system was carried out to establish the feasibility of the system for use in the manufacturing of flexible heating elements on textile substrates. The coating formulations were applied via a simple padding technique followed by stitching the electrodes using a conductive yarn.FindingsThe heating elements of different sizes thus produced showed Ohmic behaviour as a resistor and attained a targeted temperature difference of up to 40°C within the applied voltage range. A prototype heater was also produced, and thermography results showed uniform heating and cooling of the heater that was incorporated into a jacket.Originality/valueThe proposed method is envisaged to be very practical for the realisation of completely textile-based heating elements of different shapes and sizes. Furthermore, the proposed manufacturing method can be used to convert conventional ready-made articles of clothing into heated textiles for various applications.

Tailoring of graphene–organic frameworks membrane to enable reversed electrical-switchable permselectivity in CO2 separation

Membrane separation has been an efficient and energy saving technique in dealing with greenhouse gases, but the traditional membrane designs might not be able to handle the concomitant environmental pollution due to their fixed properties. Correspondingly, the use of an active-responsive smart membrane appears to be a new trend for membrane development in the coming future, which shows great potential to deal with the obstacles. In this research, we demonstrate a smart graphene-organic framework membrane to enable reversed electrical-switchable permselectivity in CO2 separation. The addition of polydopamine (PDA) to the polyvinylidene fluoride/Graphene (PVDF/G) membranes was done to (i) induce the β-phase of PVDF, since –NH2-functionalized graphene has specific interactions (dipole induced dipole interaction) between graphene-PDA and PVDF; (ii) modify the organic PVDF-inorganic graphene interface; and (iii) facilitate CO2 selective separation. Permeability and permselectivity was increased after applying voltage that resulted in the increase of gas permselectivity in response to the lowest applied voltage range (0–3 V) to the membrane. Digital image correlation method depicted the response of the membrane to voltage and proved that the membrane has high piezoelectric properties that is switchable. Furthermore, PALS studies confirmed the free volume and interlayers in the membrane. This membrane has unique properties because the pore changes from bimodal to single pore distribution.

Effect of Operational Conditions on Arsenic Removal from Aqueous Solution Using Electrodialysis

ABSTRACT The potential application of electrodialysis (ED) for arsenic (As) removal from water was investigated by evaluating the influence of operational parameters on removal efficiency of As. The applied voltage and the initial concentration of As in the feed solution have significant effects on the removal efficiency of As in the transfer As from feed to concentrate compartments. The mass-transfer coefficient is increased with increase in applied voltage, and those of As(V) are always higher than those of As(III). The pH of feed solution has little effect on the mass-transfer coefficients of As(III) and As(V) within the applied voltage range.

Droplet three-dimension manipulation in parallel liquid-infused membrane plates configuration

Abstract In this paper, we demonstrated the droplets three-dimension (3D) manipulation between a pair of parallel liquid-infused membrane plates with patterned electrodes by programmably controlling electrical direct current signals. The asymmetric electrowetting behaviors of droplet between the parallel slippery liquid-infused porous surface (SLIPS) plates configuration were investigated firstly. The droplet tends to move from the higher potential plate to the lower potential plate. The transport of the deionized water droplet in the vertical direction with electrostatic force was investigated in detail subsequently. A model was developed to study the dynamic transport behavior of the droplet movement in the vertical direction. It is found the droplet velocity increases with time, while tends to a maximum value due to the increase of drag force. We also experimentally demonstrated the droplet was driven accelerated from the higher potential plate to the lower one, and the transport time exponentially decreases with the increase of applied voltage. However, note that the excessive applied voltage would cause irregularly jumping of droplets between two plates. The applied voltage range for driving a 0.5 μl droplet was determined experimentally with various parallel-plate spacings. Finally, we demonstrated the 3D manipulation of one droplet and two droplets in two parallel plates configuration with patterned electrodes by the hybrid forces, namely, by asymmetric electrowetting force in the horizontal direction and by electrostatic force in the vertical direction. The 3D droplet manipulation on SLIPS provides a promising solution for high-throughput analysis and integrated device with high density on the digital microfluidic chip.

Unitary matrix approach for a precise voltage dependent characterization of reflective liquid crystal devices by average Stokes polarimetry

Precise characterization of parallel-aligned liquid crystal on silicon microdisplays has an important impact in many advanced photonics applications. We show liquid crystal on silicon (LCoS) modeled as a non-absorbent reciprocal device. Combined with time-average Stokes polarimetry, LCoS enables us to demonstrate robust measurements across the whole applied voltage range for the retardance and its flicker, and also as a novelty for the director orientation. We obtain that the director orientation changes across the voltage range, especially at larger applied voltages. This is a small effect, but it may provide a deeper insight into the internal dynamics in the liquid crystal layer, and in sensitive phase-only applications will produce a coupling between amplitude and phase.

Electrowetting on Langmuir-Blodgett films from epicuticular wax

Langmuir and Langmuir-Blodgett (LB) films were fabricated from epicuticular wax, that had been extracted from Vitis vinifera. For Langmuir films, the influence of subphase temperature on their structure was examined, whereas for LB films, the surface morphology at various temperatures and the effect of the layer number on electrowetting were investigated. Isotherms of surface pressure revealed no well-defined phase transition or collapse on Langmuir films at 22 °C, whereas Brewster angle microscopy showed that even before starting the compression procedure, there are platelets of epicuticular wax floating on the subphase. Those platelets give rise to the Langmuir films of epicuticular wax during compression. In contrast, for higher temperatures (40 °C and 50 °C), a well-defined phase transition was found – without epicuticular wax platelets, with a behavior close to those found in typical fatty acids. For LB films, atomic force microscopy images indicated a decreasing of roughness as a function of the subphase temperature as a result of greater organization of the epicuticular wax film. A significant modulation of about 20 ° (under applied voltage range of 0 to 100 V) was demonstrated of the electrowetting on LB films, which did not depend on the LB layer number. Our results suggest that epicuticular wax LB films have the potential for being applied in electrowetting-based devices. Furthermore, the Langmuir-Blodgett technique is feasible to fabricate films with various compositions focusing on the electrowetting.

Comprehensive characterization of Gunn oscillations in In0.53Ga0.47As planar diodes

In this work, In0.53Ga0.47As planar Gunn diodes specifically designed for providing oscillations at frequencies below 30 GHz have been fabricated and characterized. Different types of measurements were used to define a set of consistent methods for the characterization of the oscillations that can be extended to the sub-THz frequency range. First, negative differential resistance and a current drop are found in the I–V curve, indicating the potential presence of Gunn oscillations (GOs), which is then confirmed by means of a vector network analyzer, used to measure both the S 11 parameter and the noise power density. The onset of unstable GOs at applied voltages where the negative differential resistance is hardly visible in the I–V curve is evidenced by the observation of a noise bump at very low frequency for the same applied voltage range. Subsequently, the formation of stable oscillations with an almost constant frequency of 8.8 GHz is observed for voltages beyond the current drop. These results have been corroborated by measurements performed with a spectrum analyzer, which are fully consistent with the findings achieved by the other techniques, all of them applicable to Gunn diodes oscillating at much higher frequencies, even above 300 GHz.

Effect of the physical parameters of longitudinally polarized PZT tubes on PZT sensors

Lead zirconium titanate (PZT) sensors have been investigated in various fields. Related research focuses mainly on experiments, analyses are hardly conducted in PZT parameters and PZT sensor performance. In order to improve the PZT sensors’ performance from PZT structural parameter design, simulations on PZT tube’s deformations and resonance frequencies are conducted and analyzed, PZT-fiber Bragg grating (FBG) voltage sensors with different PZT tubes are established for validation tests. It is found in simulation results that the applied voltage range can be decided by polarized direction parameter, and the lowest resonance frequency of PZT tubes, which is decisive to sensor flat frequency response range, are closely related to tubes’ radial parameters. It is also indicated in PZT-FBG sensor tests that PZT’s coupled efficiency with other sensing elements is also an important concern to sensor performance. PZT tube parameter design suggestions for different sensing purposes and for PZT-FBG voltage sensor enhancement are proposed at last. Results in this paper can also be a reference for PZT sensors’ performance enhancement with PZT tubes.

Strongly coupled metal-organic frameworks on layered bimetallic hydroxide derived N, S Co-doped porous carbon frameworks embedding with CoS2 for energy storage

In this work, we propose the fabrication of N, S co-doped carbon framework with confined CoS2 nanoparticles and rooted carbon nanotubes (NSPCF@CoS2). As LIBs anode, the NSPCF@CoS2 electrode gives an inceptive discharge capacity of 921.5 mA h g−1, with Coulombic efficiency of above 97% during the 200 cycles (except for the previous 5 cycles). As SIBs anode (the applied voltage range is 0.4–3 V), the NSPCF@CoS2 electrode performs a steady and relatively high capacity (over 448.0 mA h g−1) during the 1650 cycles, and an extremely low capacity decay rate of 0.018% per cycle is obtained. Also, the NSPCF@CoS2 electrode shows a high capacity of 545.3 mA h g−1 even at 8 A g−1 (the applied voltage range is 0.1–3 V). This NSPCF@CoS2 electrode shows a comparable or even higher rate performance than many reported transition metal chalcogenides materials, confirming its promising usage. The presence of pseudocapacitive contribution is verified, after the deep investigation on Li+/Na+ storage behavior and reaction kinetics. In addition, this rationally designed structure gives potential application in supercapacitor.

Nanostructured Cerium-Oxide-Based Screen Printed Electrode for Electrochemical Detection of Melamine via Ascorbic Acid

Nanostructured cerium oxide (CNP) was synthesized via co-precipitation and used as a base matrix to construct an enzyme-less electrochemical sensing platform for a non-electroactive analyte (i.e., melamine in the presence of ascorbic acid (AA)). CeO2 was screen printed (SP) on prefabricated gold electrodes for the indirect detection of melamine. The melamine concentrations varied in the range of 0.01 ppb to 10 ppm with a fixed amount of ascorbic acid (i.e., 50 ppm). Absorption spectra were obtained from 220 to 400 nm for all melamine concentrations. The cyclic voltammogram (CV) for different melamine concentrations was obtained in the applied voltage range of –1 to +1 V. The peak oxidation current reduced as a function of increased melamine concentration in the presence of ascorbic acid, which was supported by absorption studies. The obtained melamine sensitivities were 64.9 and 80.8 μA/ppb/mm2, respectively, without and with ascorbic acid. The limits of detection estimated from three times the signal-to-noise ratio were 1.5 × 10–3 and 2.4 × 10–3 ppb, which are the lowest values so far reported to the best of our knowledge. The electrochemical impedance study predicted the increase of the charge transfer characteristics in the presence of AA, which comprehensively correlated with the CV data. The developed sensor can be used for the detection of melamine in milk, dairy products, and other food items.

Effects of Low Frequency-Low Voltage Alternating Electric Current on Apoptosis Progression in Bioelectrical Reactor Biofilm.

Bioelectrochemical systems have undergone several modifications to promote the enzymes or pathways used to reduce the energy required for microbial metabolism. Changes in dominant bacteria, population, and growth rates occur when an electric current is applied intermittently. Applying electricity to bioelectrical reactor (BER) biofilms can either stimulate cells or lead to cell death; therefore, determining the applied voltage range that leads to viable and stimulated bacteria is crucial. We investigated the progression of apoptosis induced by a low frequency-low voltage alternating electric current (AC) in a BER biofilm and found that biofilms on carbon cloth (CC) and stainless steel (SS) 304 electrodes had pHzpc values of 8.67. The pHzpc of the biofilms increased by two compared to that of the inoculant bacteria mass. Furthermore, the Henderson–Hasselbalch equation reveals that the compositions of cell walls of the biofilms that formed on the CC and SS304 electrodes are very similar. In contrast, the CC and SS304 biofilms differ from the inoculant biomass without the influence of an AC field; this indicates that there are differences in the compositions of the cell walls in the present bacteria. Fourier transform infrared spectroscopy was used to compare spectra of the biofilms with that of the inoculation mass, and there were differences in shape and absorbance intensity, indicating variability in the composition, and quantity of each individual biofilm component. In addition, the dehydrogenase activity (DHA) content varied under different applied voltages; the highest DHA was obtained at 8 Vpp. A flow cytometry analysis showed a relatively low number of apoptotic cells (10.93 ± 5.19%) for the AC amplitudes studied. Thus, a low voltage-low frequency AC likely induces significant changes in bacterial metabolic activity but causes no significant change in their viability.

SrTiO3/Epoxy Nanodielectrics as Bulk Energy Storage and Harvesting Systems: The Role of Conductivity

Composite nanodielectric materials with strontium titanate nanoparticles embedded within an epoxy resin matrix were prepared and studied, varying the filler content. Broadband dielectric spectroscopy was employed for determining the dielectric response of the prepared specimens. Dielectric results reveal the presence of three relaxations processes, which are attributed to (a) glass to rubber transition of the polymer matrix (α-mode), (b) rearrangement of polar side groups (β-mode), and (c) interfacial polarization between systems’ constituents. The stored and harvested energy of the examined nanodielectrics was also evaluated under DC conditions in the applied voltage range of 10–240 V. The coefficient of energy efficiency (neff) was determined for all filler’s content, varying the applied temperature and field. The effect of temperature appears to be pronounced, causing a sigmoidal dependence of neff. Furthermore, filler content enhances neff, reaching the highest value of 69.41% for the 10 phr SrTiO3 nanocomposite at 50 V. Finally, both AC and DC conductivities were evaluated as a function of filler and temperature, and the corresponding activation energies were calculated. Hopping conductivity appears to be the predominant conduction mechanism in all nanocomposite systems, since experimental data are in accordance with variable range hopping model.