Output Current Research Articles

Underwater blade-free triboelectric nanogenerator for harvesting current energy in low-speed current

Ocean current energy bears the characteristics of wide distribution and high energy density. Harvesting current energy as the in-situ power for distributed ocean sensors will greatly enhance the sustainability of ocean sensing. In many parts of the ocean, the current speed is not desirable (low or unstable) for conventional current energy harvesting devices. Here, an underwater blade-free triboelectric nanogenerator (UBF-TENG) is developed to effectively utilize the low-speed currents through the flow-induced vibration (FIV). The power generation unit is fully enclosed inside the shell, effectively reducing the direct impact and underwater corrosion. The study demonstrates that within the established experimental parameters space, the optimized UBF-TENG can facilitate a start-up speed as low as 0.14 m/s. The UBF-TENG has achieved a maximum open-circuit voltage output of 250 V and a maximum short-circuit current output of 2.2μA at 0.76 m/s. The charging capacity of the UBF-TENG is tested with various capacitors, demonstrating the application potential of the UBF-TENG as an in-situ power supply underwater.

Extending the design space of minimized VA rating inductive wireless power transfer links operating in restricted sub-resonant frequency region with constant current output

Wireless power transfer systems are typically required to operate under varying geometrical positioning (vertical distance, misalignment) between the transmitter and receiver coils while supporting a load with non-constant characteristics. This creates the need for robust systems that can operate over a range of coupling coefficients under time-varying load. Widespread control methods utilized to support such an operation typically suffer from volt-ampere (VA) over-rating of the inductive wireless power transfer link (IWPTL) transmitter. Sub-resonant frequency control has proven to be an effective solution to this problem, attaining robust operation and minimized transmitter VA rating by utilizing operational frequency as the control variable for system output regulation under above-mentioned constraints. However, allowed operating frequency range is usually restricted in practical applications (e.g. to 79 kHz–90 kHz by SAE J2954 EV charging standard), limiting the misalignment tolerance of sub-resonant control method. Recently, extension of the classical sub-resonant control methodology was proposed in order to overcome this limitation. However, no clear guidelines were given for designing practical IWPTLs operating under extended sub-resonant control. To this end, this work bridges the gap between academical findings and practical applications by establishing generalized guidelines for designing sub-resonant controlled series-series (SS) compensated IWPTL with minimized transmitter VA rating, allowing to maximize misalignment tolerance under given operating frequency and output voltage ranges. The proposed methodology is accurately validated by simulations and experiments, demonstrate close correlation with analytical predictions. Experimental framework reveals that IWPTL operating under extended sub-resonant control methodology attains 50 % increase of tolerable coupling coefficients range compared to a classical system designed to operate under sub-resonant control under identical operating conditions while achieving nearly similar DC-to-DC efficiency.

High-Current Water-Enabled Electricity Generation in Mushrooms via Synergistic Ion Sieving and Adsorption.

Water-enabled electricity generation (WEG), which harvests energy from the natural water cycle, is a novel strategy for producing green electricity. Taking advantage of the ion sieving effect based on evaporation-induced water flows in charged nanopores, various WEG devices have been developed. Here, we report that a carbonized mushroom produces a record-high current output of up to 96.7 μA, which is attributed to a unique ion adsorption effect combined with an ion sieving effect. Specifically, the natural gradient potential from root to cap in a mushroom caused by tissue differentiation adsorbs different ions, enhancing the traditional ion sieving current. In synergy with the two effects, the mushroom can operate under a broad range of concentrations (0 to 0.6 mol L-1) and represents significant improvements in current, duration, and total charge transfer. These findings reveal the hidden talent of mushrooms as natural materials for WEG, providing inspiration for the development of high-performance WEG devices.

Synergistically enhanced PVDF-based nanofiber membranes randomly embedded with ZnWO4@PDA nanorods for self-powered sensors with multi-mode free switching

In spite of the high level of attention paid to multifunctional sensors, the flexible and multifunctionality are still intractable challenges to be tackled. Herein, we design a flexible, hydrophobic and stable multifunctional sensing material by electrostatic spinning of PVDF/ZnWO4@PDA (PZP). The incorporation of ZnWO4@PDA into PVDF nanofibers can act as an effective nucleating agent and photosensitizer, which increases the polar crystalline phase and photovoltaic properties of PVDF. With the synergy of PVDF and ZnWO4@PDA, PZP based piezoelectric sensors offer significantly superior electrical output (28.4 V, 600 nA) and high sensitivity (1.04 V/kPa). Moreover, it is particularly surprising that photoelectric sensor based on PZP textiles has excellent optical properties, as confirmed by the response/recovery time (0.6 s/0.66 s) of simulated sunlight detection. Piezoelectric photoelectric effect exists in PZP textiles, as evidenced by the significant increase in the strain output current of photoelectric sensor when irradiated with sunlight. Furthermore, based on the coupling of piezoelectric effect and triboelectric effect of PZP composite, the contact out nano-triboelectric generator has enhanced the electrical output and electromechanical conversion efficiency. Therefore, this work has successfully prepared multifunctional sensing materials that integrate pressure sensing, audio recognition, underwater communication, optoelectronic detection and triboelectric energy collection, paving a new way for the flexible multifunctional sensors.

Study on the Improvement of the Degradation Efficiency of Methylene Blue Using Pulsed Direct-Current Self-Power Supply.

Effective treatment of dye wastewater is currently a great concern and a research hotspot. Electrocatalysis has unique advantages in treating toxic and harmful refractory dye wastewater; however, it requires an external power supply, which increases energy consumption and cost. As a new energy collection technology, triboelectric nanogenerators (TENGs) have gained considerable attention. In this study, an origami multilayer spherical friction nanogenerator (Q-TENG) was developed for the removal of methylene blue (MB) from dye wastewater. The current and voltage output performances of Q-TENG were explored, and the removal and degradation mechanisms of MB were discussed. Results indicated that when the water wave acceleration a = 3 m/s2, the open-circuit voltage and short-circuit current reached the maximum values of 179 V and 9.4 μA, respectively. The self-powered catalytic degradation of MB using Q-TENG can produce more •OH and SO4-•, and the free radicals increase with increasing action time of Q-TENG, thus increasing the degradation efficiency of MB. This study provides a new strategy for solving the problem of high energy consumption during electrochemical reactions in wastewater treatment.

Polypyrrole@TiO2 Composite Nanotube System with Enhanced Capillary Fluid and Charge Transfer for High‐Current Hydrovoltaic Energy Generation and Seawater Purification

AbstractHarnessing the energy generated from the evaporation of water has received considerable research attention in materials science; however, challenges such as poor conversion efficiency and low current output persist. Herein, an innovative synergistic material system based on titanium dioxide nanotubes coated with polypyrrole (PPy@TiO2NTs) is introduced for the simultaneous production of electricity and clean water from solar energy and seawater. The tubular structure of PPy@TiO2NT and the molecular interactions between TiO2 and PPy produce enhanced charge transfer, thereby providing the advantages of the hydrovoltaic effect, solar‐driven water evaporation (SWE), and photocatalysis. Consequently, PPy@TiO2NT‐loaded melamine foam can produce tens or more than a hundred microamperes of current in water of various salinities, which is an order of magnitude improvement over previously reported hydrovoltaic evaporation systems. In addition, under 1 sun irradiation, the system achieved an SWE rate of 2.13 kg m−2 h−1 and a methylene blue removal rate of more than 90% within 2 h. The proposed material system, featuring high electrical output and outstanding dual‐mechanism water treatment capabilities, shows high potential for synergistically harnessing solar energy and seawater, as well as for environmental management.

Piezoelectricity in NbOI2 for piezotronics and nanogenerators

2-dimensional (2D) piezoelectric materials have gained significant attention due to their potential applications in flexible energy harvesting and storage devices. Recently, niobium oxide dihalides NbOI2 stands out as a multifunctional anisotropic semiconductor family with an exceptionally high lateral piezoelectric constant (~21.8 pm/V), making it a promising candidate for energy conversion applications. Here we report the experimental observation of anisotropic in-plane piezoelectricity in multilayer NbOI2. Current-voltage relationships reveal a significant piezotronic effect in two typical crystalline orientations. Additionally, cyclic tensile and release experiments demonstrate an intrinsic current output of up to 140 pA when subjected to a tensile strain of 0.51%. A flexible piezoelectric nanogenerator prototype is demonstrated on the human finger and wrist, which opens up new avenues for the development of wearable electronic devices and provides valuable insights for further exploration in this field.

A RANDOMIZED CARRIER-BASED DISCONTINUOUS PULSE WIDTH MODULATION STRATEGY FOR NEUTRAL POINT CLAMPED THREE-LEVEL INVERTER

This article introduces a novel approach called randomized carrier-based discontinuous pulse width modulation (RCDPWM) to address the challenge of mitigating both low-order and high-order harmonics concentrated at the switching frequency and its integer multiples in the output voltage and current of a three-level inverter. The proposed strategy reduces switching losses and a wide dispersion of voltage and current harmonics with significantly smaller amplitudes by integrating features from discontinuous and randomized PWM methods. This characteristic proves beneficial for enhancing efficiency and electromagnetic compatibility. The RCDPWM strategy involves three schemes: two simple schemes (one random parameter), randomized pulse position modulation (RPP-DPWM) and randomized carrier frequency modulation (RCF-DPWM), and a dual scheme combining the two previous ones (RPPRCF-DPWM). Power spectral density (PSD) is used to assess the effectiveness of the proposed strategy in quantitatively analyzing the harmonic dispersion degree. The results demonstrate that the proposed RCDPWM strategy significantly expands harmonic clusters around the switching frequency, reducing its intensity. The spectrum analysis revealed that the RPPRCF-DPWM scheme is the most effective in spreading the output voltage and current spectrum compared to simple schemes (RPP-DPWM and RCF-DPWM).

Electrothermal Averaged Model of a Half-Bridge DC–DC Converter Containing a Power Module

This article proposes an electrothermal averaged model of a half-bridge DC–DC converter containing a power module. This kind of model enables the computation of characteristics of DC–DC converters using DC analysis. The form of the elaborated model is presented. Both the electrical and thermal properties of the analyzed DC–DC converter are included in this model. This is the first averaged electrothermal model of a DC–DC converter which makes it possible to compute the junction temperature of all the semiconductor devices and magnetic components. The accuracy of the model was experimentally verified in a wide range of switching frequencies and output currents. Particularly, the influence of mutual thermal couplings between the transistors contained in the considered module on the characteristics of the converter and the junction temperature of the transistors is analyzed.

Modeling and simulation of a photovoltaic generator for analyzing the impact of faults on the I-V curve

The rapid expansion of the solar industry has underscored the importance of photovoltaic installations in the ongoing transition to sustainable energy. With this growth comes the crucial task of effectively monitoring and controlling the power generated. Photovoltaic systems are particularly vulnerable to defects due to their exposure to challenging environmental conditions, which can lead to reduced power output and an increased risk of fire. Therefore, a thorough analysis of any faults is essential in order to mitigate potential damage to the system. The present study proposes a comprehensive analysis of the behavior of a photovoltaic generator comprising four modules. MATLAB/Simulink software is used to model the generator in healthy operation. Subsequently, a simulation of the generator in faulty conditions is conducted, considering four fault cases: partial shading (PS), open circuit fault (OCF), bypass diode disconnected (PSBD), and twinned fault bypass diode disconnected plus open circuit (PSBDOC). A detailed examination of the simulation results for the faults above reveals that the twinned fault results in a substantial reduction in the output current, as well as an elimination of the open circuit voltage of the photovoltaic generator. This contrasts the behavior observed in a system comprising two modules, wherein the open circuit voltage remains unaltered. This particular fault offers a compelling rationale for the monitoring of photovoltaic installations, to enhance overall productivity while avoiding any potential damage to the system.

ZIF-67 Assists ultra-high piezoelectric output based on PVDF flexible nanogenerator

As smart electronics and self-powered devices continue to evolve, the emergence of piezoelectric polymers has sparked significant research interest. In this pioneering project, we have successfully synthesized ZIF-67 particles/tetrabutylammonium hexafluorophosphate (TBAHP)/polyvinylidene fluoride (PVDF) tree-like nanofiber structures for the first time, which was characterized by a large number of branching nanofibers (down to 5 nm) and a uniform diameter trunk fiber (about 400 nm). And the synergistic interaction between these two distinct additives yields exceptional multifunctional properties. By optimizing the quantities of ZIF-67 and TBAHP, we enhanced the β-phase content and piezoelectric performance of PVDF through diameter refinement, interface coupling enhancement, and the introduction of a micro-capacitance mechanism. Notably, the improvements surpassed those achieved with a single additive. Specifically, the piezoelectric energy harvester fabricated using TBAHP/PVDF-TLNMs doped with 0.5 wt% ZIF-67 exhibited an output current of 4.25 μA and a peak voltage of 17.32 V, marking an increase of approximately 1187 % and 831 %, respectively, over pure PVDF nanofiber membranes. Furthermore, the device demonstrated sensitivity to motor movements and effectively harvested energy from diverse bodily motions.

Recent Advances in Linear Polarization‐Sensitive Photodetectors Based on Perovskites with Different Molecular Dimensions

AbstractThe function of photodetectors is to convert optical signals into current or voltage output. Polarization‐sensitive perovskite photodetectors have attracted significant interest because of their potential applications in imaging and remote sensing technologies. This study provides an overview of the advancements in research on halide perovskite photodetectors, particularly focusing on their capability for linear polarization‐sensitive detection. First, there is a brief description of the background and strengths of linear polarization‐sensitive photodetectors. Then, the core parameters of linear polarization‐sensitive photodetectors are introduced briefly. Third, according to the classification of active layer materials, linear polarization‐sensitive photodetectors are divided into 3D perovskites and low‐dimensional perovskites. The research on linear polarization‐sensitive perovskite detectors are reviewed. Finally, the developments and challenges faced by linear polarization‐sensitive perovskite photodetectors are analyzed.

Intrinsically safe DAB converter for reliable power supply in harsh environment via extended phase shift pulse train control

AbstractIn this article, an extended‐phase‐shift‐based pulse train control (EPS‐PT) for an intrinsically safe dual active bridge (DAB) converter is proposed to satisfy the safe and reliable power supply in harsh environments such as gas stations, chemical plants, and mining tunnels in complex power systems. A discrete pulse switching control method is introduced, and the input voltage and output current are sampled to calculate the primary target phase shift angle of the DAB converter, followed by the inner phase shift angle, while the secondary phase shift angle is rapidly adjusted by the voltage feedback. In order to meet the requirements of effective control and safe power supply in harsh environments, the system parameters are designed by comprehensively considering the control performance and intrinsically safe requirements. The simulation and experimental results demonstrate that the proposed DAB converter exhibits rapid dynamic response and intrinsic operation safety.

Golden eagle optimized fractional-order PI controller design for a PFC SEPIC converter in EV charging

The power factor correction converter is the function of the front-end converter, followed by the DC–DC converter of the electric vehicle charger. It improves the power factor and regulates the output voltage and current. This research article proposes the Golden Eagle optimization for fractional order PI (FOPI) controller for Single Ended Primary Inductor Converter (SEPIC) power factor correction. The Golden eagle optimization is based on its knowledge of hunting tactics at various degrees of spiral trajectories to catch the prey. The FOPI controller has a broad range of controller parameters that provide better control and performance of the converter. The tuning of the parameters of the FOPI controller is optimized in Golden Eagle Optimization, and the Integral Absolute error with Integral Square error is used for the objective function. The optimized parameters of FOPI compare with the conventional PI controller performance. The SEPIC converter is designed and derived from the state space model by state space averaging, and the reduced model is obtained through the moment matching method. This system is tested under MATLAB/SIMULINK, and simulation results show improved settling time, fast dynamic response, reduction of inrush current, less harmonic distortion, and stability.

PTFE-based hydrophobic layers influence bioelectrical performance of sediment microbial fuel cells with floating air-cathode

Sediment microbial fuel cells (SMFC) provide scalable power generation, but their low performance is primarily due to poor oxygen reduction reaction (ORR) at cathode. The study aims to improve ORR efficiency by constructing triple-phase interphase (TPI) with multiple hydrophobic polytetrafluoroethylene (PTFE) layers on floating air-cathode. Multiple PTFE layers of 0 (HL0), 1 (HL1), 2 (HL2), 3 (HL3), 4 (HL4), 5 (HL5) and 6 (HL6) are coated on single-sided cathode by brushing method. HL3 generates the highest output current of 204 mA, which is three times higher than control case (HL0). The polarization test shows that HL3 achieves the highest maximum power of 48.88 mW/m2, which corresponds to a 6.8-fold increase compared to HL0 (7.06 mW/m2). HL4 performance improves over time but requires long start-up time before increase in bioelectricity production was achieved. Hydrophobic PTFE layer increases the maximum power density of floating air-cathode, mitigates cathodic limitations and improves SMFC performance.

Comprehensive compensation method for co‐phase power supply in electrified railways based on V/v transformer and electromagnetic single‐phase var compensator

AbstractTo solve the problem of negative‐sequence and reactive power in electrified railway, this paper proposes a comprehensive compensation method based on V/v transformer and electromagnetic single‐phase var compensator (ESVC) for co‐phase power supply. First, based on the principles of static var generator and single‐phase rotary phase shifting transformer, the topology and model of ESVC have been established, and the compensation mechanism has been analysed. Second, the topological structure and mathematical model of co‐phase power comprehensive compensation device (CPCD) are put forward based on the principles of V/v transformer and ESVC, and the operation mode of CPCD in multiple scenarios is designed. Then the strategy of CPCD with double closed loop control is analysed: corresponding compensation mode is selected according to negative‐sequence unbalance degree and expected power factor value. In this strategy, the compensated current output by ESVC is taken as the quantity of external loop control, and the rotation angle of ESVC is taken as the quantity of internal loop control to realize double‐closed loop control of CPCD. Finally, the comprehensive CPCD compensation model is built on the simulation platform and validated the accuracy of the mathematical model and the effectiveness of the control strategy.

ADDITIONAL PURIFICATION BY ULTRAVIOLET RADIATION OF RED SPD DYE AFTER ELECTROCHEMICAL DESTRUCTION

Surface water pollution by industrial wastewater is one of the serious environmental problems of the Republic of Uzbekistan. A significant source of pollution is the textile industry, whose wastewater contains organic dyes and various related substances. This article presents the results of a study of the photooxidation of the active dye Red SPD after electrochemical degradation in an electrolytic cell with insoluble anodes. Studies have been carried out to determine the efficiency of active chlorine synthesis in the process of electrolysis of chloride solutions, the effect of active chlorine concentration, electrolyte composition, power consumption when using the combined electrochemical/ultraviolet irradiation process, and changes in the spectral characteristics of the dye solution for carrying out the photooxidation process have been studied. The technological parameters of the method of photooxidative post-treatment in treated water after electrochemistry are established, considering the concentration of oxidizing agents. The maximum current output of active chlorine occurs at a treatment time of 10 minutes. The use of NaCl as an electrolyte in comparison with Na2SO4 showed the best result in the purification process. When using NaCl with a concentration of 1.625 g L-1 in the composition of a sulfate-containing electrolyte, it can reduce the concentration of Red SPD to 1.0 mg L-1. Photooxidative degradation can become an alternative for post-treatment of wastewater from textile enterprises. The developed technology confirms the efficiency of using the combined cleaning method.

Effect of Three Different Types of Biochar on Bioelectricity Generated from Plant Microbial Fuel Cells under Unsaturated Soil Condition.

Plant microbial fuel cell (PMFC) is an emerging technology, showing promise for environmental biosensors and sustainable energy production. Despite its potential, PMFCs struggle with issues like low power output and limited drought resistance. Recent studies proposed that integrating biochar may enhance PMFC performance due to its physicochemical properties. The influence of different biochar types on PMFC efficiency has been minimally explored. This study aims to fill this gap by evaluating the performance of PMFCs integrated with various biochar types under unsaturated soil conditions. The study found that the addition of biochar types─specifically reed straw biochar (RSB), apple wood biochar (AWB), and corn straw biochar (CSB)─significantly influenced the performance of PMFCs. RSB, with its large surface area and porous structure, notably increased the current output by reducing soil resistance and enhancing electron transfer efficiency in microbial reduction reactions, achieving a peak power density of approximately 1608 mW/m2. AWB, despite its less porous structure, leveraged its high cation exchange capacity and hydrophilic functional groups to foster microbial community growth and diversity, thereby also increasing bioelectricity output. Conversely, CSB, with its large surface area, showed the least improvement in PMFC performance due to its layered structure and lower water retention capacity. Additionally, under drought conditions, PMFCs with added RSB and AWB exhibited better drought resistance due to their ability to improve soil moisture characteristics and enhance soil conductivity. The addition of biochar reduced soil resistance, increasing the bioelectric output of PMFCs and maintaining good performance even under low moisture conditions. This study highlights the critical role of biochar's surface area and functional groups in optimizing PMFC performance. It enhances our understanding of PMFC optimization and might offer a novel power generation method for the future, while also presenting a fresh strategy for soil monitoring.

Enhancing output performance of triboelectric nanogenerators with ZnFe2O4 nanoparticles in biodegradable polylactic acid for sustainable energy harvesting

ABSTRACT The development of triboelectric nanogenerators (TENGs) using sustainable materials addresses the global electronic waste issue. This research focuses on fabricating a TENG device with biodegradable polylactic acid (PLA) as the tribopositive material and polytetrafluoroethylene (PTFE) as the tribonegative material. ZnFe2O4 nanoparticles are incorporated into the PLA matrix to enhance surface charge density and synthesised via a simple combustion method. PLA-ZnFe2O4 composite films were prepared by solvent casting with varying nanofiller content (0.25, 0.45, 0.65, and 0.85 g). Prepared composites were characterised by Powder X-ray Diffraction (PXRD) for crystalline nature and phase purity, Fourier Transform Infrared Spectroscopy (FTIR) for vibrational analysis, and Scanning Electron Microscopy (SEM) for surface morphology. The inclusion of ZnFe2O4 nanoparticles improves TENG output performance, with a maximum output voltage of 18.4 V and a current of 1.57 µA observed for a PLA (poly(lactic acid)) composite with 39.39% nanoparticle content. Electrical studies on the optimised device show successful charging of various capacitors and powering 20 LEDs and a calculator. Body movements like walking and jumping were also tested to measure voltage and current outputs. These findings highlight new possibilities for developing smart, self-powered electronic devices.

A linear compensation method for inference accuracy improvement of memristive in-memory computing

Memristive computing system (MCS), with the feature of in-memory computing capability, for artificial neural networks (ANNs) deployment showing low power and massive parallelism, is a promising alternative for traditional Von-Neumann architecture computing system. However, because of the various non-idealities of both peripheral circuits and memristor array, the performance of the practical MCS tends to be significantly reduced. In this work, a linear compensation method (LCM) is proposed for the performance improvement of MCS under the effect of non-idealities. By considering the effects of various non-ideal states in the MCS as a whole, the output error of the MCS under different conditions is investigated. Then, a mathematic model for the output error is established based on the experimental data. Furthermore, the MCS is researched at the physical circuit level as well, in order to analyze the specific way in which the non-idealities affect the output current. Finally, based on the established mathematical model, the LCM output current is compensated in real time to improve the system performance. The effectiveness of LCM is verified and showing outstanding performance in the residual neural network-34 network architecture, which is easily affected by the non-idealities in hardware. The proposed LCM can be naturally integrated into the operation processes of MCS, paving the way for optimizing the deployment on generic ANN hardware based on the memristor.