High Energy Conversion Efficiency Research Articles

Designing Atomic Interface in Sb2 S3 /CdS Heterojunction for Efficient Solar Water Splitting.

In the emerging Sb2 S3 -based solar energy conversion devices, a CdS buffer layer prepared by chemical bath deposition is commonly used to improve the separation of photogenerated electron-hole pairs. However, the cation diffusion at the Sb2 S3 /CdS interface induces detrimental defects but is often overlooked. Designing a stable interface in the Sb2 S3 /CdS heterojunction is essential to achieve high solar energy conversion efficiency. As a proof of concept, this study reports that the modification of the Sb2 S3 /CdS heterojunction with an ultrathin Al2 O3 interlayer effectively suppresses the interfacial defects by preventing the diffusion of Cd2+ cations into the Sb2 S3 layer. As a result, a water-splitting photocathode based on Ag:Sb2 S3 /Al2 O3 /CdS heterojunction achieves a significantly improved half-cell solar-to-hydrogen efficiency of 2.78% in a neutral electrolyte, as compared to 1.66% for the control Ag:Sb2 S3 /CdS device. This work demonstrates the importance of designing atomic interfaces and may provide a guideline for the fabrication of high-performance stibnite-type semiconductor-based solar energy conversion devices.

A Nickel-Based Semiconductor Hybrid Material with Significant Dielectric Constant for Electronic Capacitors.

A novel semiconducting Ni(II)-based hybrid material with the formula (C7H12N2) NiCl4, which exhibits interesting optical and electrical properties, is reported. The crystal structure was investigated using SCXRD, whereas physical properties were studied by means of thermal analysis, Ft-Infrared, optical, and electrical measurements. Its crystal packing is formed through organic rings surrounded by inorganic [NiCl4]2- tetrahedral and stacked along the a-crystallographic axis. This arrangement is stabilized by a dense network of intermolecular hydrogen bonds. The investigated compound displayed a wide absorption range across the visible spectrum, characterized by an optical gap energy of 2.64 eV, indicating its semiconducting nature and efficient sunlight absorption capabilities across various wavelengths. Such features are of utmost importance in achieving a high energy conversion efficiency in solar cell applications. Further analyses of the thermal behavior using differential scanning calorimetry revealed a single-phase transition occurring at around 413 K, which was further confirmed through electrical measurements. A deep investigation of the electric and dielectric performances demonstrated a significant dielectric constant (ε' ∼ 104) at low frequencies and low dielectric loss at high frequencies. Thus, it highlights its exceptional dielectric potential, particularly in applications related to electronic capacitors.

Enhancing interpretability in the exploration of high-energy conversion efficiency in CsSnBr3−xIx configurations using crystal graph convolutional neural networks and adversarial example methods

Enhancing interpretability in the exploration of high-energy conversion efficiency in CsSnBr3−xIx configurations using crystal graph convolutional neural networks and adversarial example methods

The emerging Sr2FeMoO6-based electrocatalysts for solid oxide electrochemical cell: synthesis, modulation and applications

Solid oxide cells (SOCs) are regarded as a promising energy technology due to their large current density, diverse range of fuels, and high energy conversion efficiency. The double perovskite Sr2FeMoO6 (SFM) has attracted considerable attention for SOCs due to its tunable structure with superior performance of high conductivity, excellent thermal stability, and remarkable carbon deposition resistance in a reducing atmosphere. However, the electrocatalytic activity of SFM is considerably lower than that of commercial Ni-based SOC electrodes. A timely summary of the synthesis, modulation, and application of SFM perovskites is of great significance for its further development for SOCs. In this review, the methods employed in the preparation of SFM electrocatalysts are introduced first. Then, the advancements in the application of different SFM-based electrocatalysts in the field of SOCs are reviewed, and the research progress in the in situ exsolution of SFM-based electrocatalysts through ion regulation is assessed. Finally, the future issues associated with SFM-based electrocatalysts are addressed in the realm of electrocatalysis, to advance their application.

Growth of CuS nanowire on copper mesh for efficient solar-driven water evaporation and wastewater purification

This study proposed a multifunctional material, CuS nanowire, grown on a copper mesh (CM), for application in wastewater purification. CuS/CM could rapidly evaporate and collect water under solar irradiation. CuS nanowires were successfully synthesized on CM through a liquid–solid reaction at room temperature, followed by sulfidation. Water evaporation experiments conducted using meshes suspended in water to determine the most efficient configuration revealed that CuS/CM was the most efficient material. Owing to the localized surface plasmon resonance induced by oxygen vacancies, CuS/CM exhibited a high water evaporation rate (4.0523 kg·m-2h−1 @ 3 sun) and energy conversion efficiency (96.1 %) in Structure A with a vertical length of 4 cm under 3 sun irradiation. To evaluate its effectiveness in wastewater treatment, CuS/CM was used to evaporate and collect methylene blue (MB)-contaminated water at rates of 1.5747 and 0.8624 kg·m-2h−1. Furthermore, CuS/CM demonstrated photocatalytic activity during MB degradation. Under xenon lamp illumination for 6 h, CuS/CM exhibited a 73 % degradation efficiency for MB, indicating its photocatalytic properties. CuS/CM effectively purify dyeing wastewater due to their fast water evaporation rate and the photocatalytic capability of CuS, making them promising for wastewater treatment and desalination applications.

Maximum power point tracking improvement using type-2 fuzzy controller for wind system based on the double fed induction generator

Introduction. In this paper, to maximize energy transmission in wind power system, various Maximum Power Point Tracking (MPPT) approaches are available. Among these techniques, we have proposed the one based on typical fuzzy logic. Despite the somewhat reduced performance of fuzzy MPPT. For a number of reasons, fuzzy MPPT can replace conventional optimization techniques. In practice, the effectiveness of conventional MPPT methods depends mainly on the accuracy of the information given and the wind speed or knowledge of the aerodynamic properties of the wind system. Novelty. Our new MPPT for monitoring the maximum power point has been proposed. We developed an algorithm to improve control performance and govern the stator’s developed active and reactive power using the typical fuzzy logic 2 and enable robust control of a grid-connected, doubly fed induction generator. Purpose. MPPT which implies the wind turbine’s rotating speed should be modified in real time to capture the most wind energy, is necessary to achieve high efficiency for wind energy conversion, according to the aerodynamic characteristics of the wind turbine. Methods. Developing a mathematical model for a wind energy production system is complex, can be strongly affected by wind variation and is a non-linear problem. Thanks to these characteristics, thus, the Lyapunov technique is combined with a sliding mode control to ensure overall asymptotic stability and robustness with regard to parametric fluctuations in order to accomplish this goal. We contrasted our fuzzy type-2 algorithm’s performance with that of the fuzzy type-1 and Perturbation & Observation (P&O) suggested in the literature. Practical value. The simulation results demonstrate that the control performance is satisfactory when using the fuzzy logic technique. From these results, it can be said for the optimization of energy conversion in wind systems, the fuzzy type-2 technique may offer a workable option. Since it presents a great possibility to avoid problems either technical or economics linked to conventional strategies.

Largely Enhanced Service Life and Energy Harvesting Stability of Dielectric Elastomer Generator by Designing and Optimizing Compliance of Electrodes.

Dielectric elastomer generator (DEG), which consists of a dielectric elastomer (DE) film sandwiched between two flexible electrodes (FEs), has the advantages of lightweight, high energy density, and high energy conversion efficiency, providing a simple and feasible solution for harvesting energy from human motion or nature. As crucial constituents of DEG, FEs are expected to possess excellent conductivity and compliance. Nevertheless, there is currently no quantitative characterization method for FE compliance. In addition, the impact mechanism of FE compliance on the energy harvesting performance and fatigue life of the DEG remains unclear. In this study, the dynamic mechanical property (DMP) was used to assess the compliance of FEs, and the quantitative characterization method of FE compliance was proposed. A series of silicone rubber electrodes (SREs) with different DMPs and compliance were designed and prepared, and the impact mechanism of FE compliance on the energy harvesting stability and fatigue life of the DEG was investigated. The results indicate that the key to achieving excellent FE compliance lies in reducing the difference in the magnitude of the complex modulus and phase angle between the FEs and DE, which can significantly reduce interfacial friction and extend the fatigue life of DEG. Benefiting from the enhanced FE compliance, the fatigue life and full-life energy density of the DEG device increase by 20.3 times and 26.4 times, respectively, compared with those of the commonly used carbon-based electrodes.

Synthesis of a Mesoporous SnO2 Catalyst Support and the Effect of Its Pore Size on the Performance of Polymer Electrolyte Fuel Cells.

The aim of this study was to clarify the effectiveness and challenges of applying mesoporous tin oxide (SnO2)-based supports for Pt catalysts in the cathodes of polymer electrolyte fuel cells (PEFCs) to simultaneously achieve high performance and high durability. Recently, the focus of PEFC application in automobiles has shifted to heavy-duty vehicles (HDVs), which require high durability, high energy-conversion efficiency, and high power density. It has been reported that employing mesoporous carbon supports improves the initial performance by mitigating catalyst poisoning caused by sulfonic acid groups of the ionomer as well as by reducing the oxygen transport resistance through the Pt/ionomer interface. However, carbon materials in the cathode can degrade oxidatively during long-term operation, and more stable materials are desired. In this study, we synthesized connected mesoporous Sb-doped tin oxides (CMSbTOs) with controlled mesopore sizes in the range of 4-11 nm and tested their performance and durability as cathode catalyst supports. The CMSbTO supports exhibited higher fuel cell performance at a pore size of 7.3 nm than the solid-core SnO2-based, solid-core carbon, and mesoporous carbon supports under dry conditions, which can be attributed to the mitigation of the formation of the Pt/ionomer interface and the better proton conductivity within the mesopores even at the low-humidity conditions. In addition, the CMSbTO supports exhibited high durability under oxidative conditions. These results demonstrate the promising applicability of mesoporous tin oxide supports in PEFCs for HDVs. The remaining challenges, including the requirements for improving performance under wet conditions and stability under reductive conditions, are also discussed.

Reduced graphene oxide incorporated triple network hydrogels for enhancing solar desalination performance

Solar-driven hydrogel evaporator has attracted great attention in desalination recently. However, it remains a challenge to develop high performance hydrogel evaporators with outstanding mechanical property, high evaporation efficiency and excellent durability. In this study, 2-hydroxyethyl methacrylate (HEMA), sodium alginate (SA) and graphene oxide (GO) were employed for fabricating triple network hydrogels, which were used for solar desalination. The hydrogels were composed of poly(2-hydroxyethyl methacrylate) (PHEMA), SA and reduced graphene oxide (rGO) networks. The rGO network could well wrap on PHEMA and SA networks, forming an interpenetrated structure with good mechanical property. After being reduced of GO, the PHEMA/SA/rGO hydrogels showed excellent solar absorption and evaporation performance due to better photothermal effect of rGO than that of GO. Due to outstanding light absorption characteristic, the as-prepared hydrogels showed maximal energy efficiency of 95.59 % under one sun illumination. The hydrogel evaporator also exhibited excellent reusability for effective desalination. This stable performance may be attributed to its enough water molecules embedded in the crosslinked network, which prevented salt supersaturation. The outdoor solar desalination experiment suggested that concentration of four typical ions (Na+, Mg2+, K+, Ca2+) in purified water fully met drinking water standards. This work may provide a new idea for design and creation of hydrogel evaporator with high mechanical strength and solar energy conversion efficiency for solar steam generation.

Nuanced dilute doping strategy enables high-performance GeTe thermoelectrics

In thermoelectrics, doping is essential to augment the figure of merit. Traditional strategy, predominantly heavy doping, aims to optimize carrier concentration and restrain lattice thermal conductivity. However, this tactic can severely hamper carrier transport due to pronounced point defect scattering, particularly in materials with inherently low carrier mean-free-path. Conversely, dilute doping, although minimally affecting carrier mobility, frequently fails to optimize other vital thermoelectric parameters. Herein, we present a more nuanced dilute doping strategy in GeTe, leveraging the multifaceted roles of small-size metal atoms. A mere 4% CuPbSbTe3 introduction into GeTe swiftly suppresses rhombohedral distortion and optimizes carrier concentration through the aid of Cu interstitials. Additionally, the formation of multiscale microstructures, including zero-dimensional Cu interstitials, one-dimensional dislocations, two-dimensional planar defects, and three-dimensional nanoscale amorphous GeO2 and Cu2GeTe3 precipitates, along with the ensuing lattice softening, contributes to an ultralow lattice thermal conductivity. Intriguingly, dilute CuPbSbTe3 doping incurs only a marginal decrease in carrier mobility. Subsequent trace Cd doping, employed to alleviate the bipolar effect and align the valence bands, yields an impressive figure-of-merit of 2.03 at 623 K in (Ge0.97Cd0.03Te)0.96(CuPbSbTe3)0.04. This leads to a high energy-conversion efficiency of 7.9% and a significant power density of 3.44 W cm−2 at a temperature difference of 500 K. These results underscore the invaluable insights gained into the constructive role of nuanced dilute doping in the concurrent tuning of carrier and phonon transport in GeTe and other thermoelectric materials.

Piezoelectric polarization field tuning Schottky barrier of Ni/Mn0.2Cd0.8S composite for hot electrons transfer to enhance photocatalytic hydrogen evolution

Coupling piezoelectric effect with local surface plasmon resonance (LSPR) for visible-light-driven photocatalytic hydrogen evolution is of great significance to realize the high-efficiency solar energy conversion. In this work, Ni/Mn0.2Cd0.8S plasmon piezo-photocatalysts were constructed by combining plasma metal Ni with structural distortion-enhanced Mn0.2Cd0.8S for piezo-photocatalytic hydrogen evolution. The influence of integrating plasma Ni with piezoelectric Mn0.2Cd0.8S on the photocatalytic performance was investigated together with the wavelength dependent experiments. Under simultaneous illumination and ultrasound, the optimized 1.5 wt%-Ni/Mn0.2Cd0.8S displayed ultrahigh piezo-photocatalytic hydrogen evolution rate of 72.38 mmol g−1 h−1, which was approximately 11.8 and 25.0-fold that of Mn0.2Cd0.8S and CdS, respectively. The significantly enhanced performance was assigned to the coupling of piezoelectric and LSPR effect, through which the internal piezoelectric polarization field generated by Mn0.2Cd0.8S could change the local contact characteristics of Mn0.2Cd0.8S and Ni interface, decreasing the degree of upward bending of the band and reducing the Schottky barrier height, thus promoting the interfacial transfer of plasmon hot electrons for photocatalytic hydrogen evolution. This work provides a reliable reference for developing high-performance plasmonic piezo-photocatalysts materials based on piezoelectric and LSPR effect.

Ferro/Nonferroelectric Vertical Heterostructure Superlattice as a Visible-Light-Responsive Photocatalyst: A DFT Prediction.

Developing narrow-band-gap ferroelectric semiconducting photocatalysts is a promising strategy for efficient photocatalytic water splitting with high energy conversion efficiency. Within this context, six ferro/nonferroelectric vertical heterostructure superlattices (VHSs) are constructed in this work by stacking ferroelectric SiS or GeS with nonferroelectric layered organic photocatalysts (C2N, g-C3N4, and melon), layer by layer. The geometry and electronic structures of these six VHSs are systematically investigated by density functional theory calculations. Consequently, four VHSs (SiS/g-C3N4, GeS/C2N, GeS/g-C3N4, and GeS/melon) are predicted to simultaneously possess several important and highly desirable features for photocatalytic water splitting, namely excellent visible-light adsorption, remarkable spontaneous polarization (0.49-0.70 C/m2), spatial charge separation, as well as suitable band-edge positions, thus serving as potential candidates for photocatalytic water splitting to produce hydrogen. This work not only provides a new strategy to use narrow-band-gap ferroelectric semiconductors for photocatalytic water splitting but also offers inspiration for developing photocatalysts with high energy conversion efficiency.

Stable Efficient Dye‐Sensitized Solar Cell Using Waste Polyvinyl Chloride (PVC) Derived Porous Carbon as Counter Electrode

AbstractAt the time, the world critically requires renewable energy. The challenge is figuring out how to meet expanding global energy consumption. Dye‐sensitized solar cells (DSCs) have attracted a lot of interest due to their high energy conversion efficiency, low cost, environmental friendliness, and easy production procedure. First, the study prepares standard cell platinum, which is the most expensive and in low supply. By replacing PVC‐derived porous carbon for expensive platinum in the DSScs counter electrode. The standard efficiency of platinum counter electrode comes out to be 1.94 and efficiency of PVC derived porous carbon electrode comes out to be 0.46.

Electromechanical coupling of a 3.88 W harvester with circumferential step-size field: modeling, validation and self-powered wearable applications

The fast advances in wearable electronic devices require clean and wearable power sources. This study presents a wearable electromagnetic energy harvester (EMEH) with high output performance mounted on the knee to obtain human vibration energy. The design forms a circumferential step-change magnetic field with high electromechanical coupling for high-efficiency energy conversion. We first formulate a theoretical model and simulate the analytical voltage via MATLAB. To predict the output performance of the EMEH, we conduct simulations via ANSYS. Subsequently, experiments are conducted to explore the output performance of the harvester in terms of the voltage, the output power, and the charging rate. The prototype generates a peak power of 3.88 W with a 449 Ω resistor under the excitation of 2.0 Hz. Additionally, the prototype charges a battery to 33.9% within 300 s at a running speed of 8 km h−1. This study provides a new perspective for advancing the development of watt-level self-powered wearables.

Recent Advances in Bridge-Less Power Factor Correction Converter

Power Factor Corrector (PFC) is a device used in electrical systems to improve power efficiency by reducing reactive power and harmonics, resulting in a higher power factor and reduced energy consumption. It enhances the utilization of electrical networks and minimizes wastage of power resources.This paper reviews the current research on the new bridge-less PFC converter, firstly comparing and analyzing seven configurations and control strategies of traditional Boost, bridge-less Boost, bi-directional switched bridge-less Boost, Pseudo totem bridge-less Boost, dual diode bridge-less Boost, and five-level flying across capacitor bridge-less, and then discussing the characteristics of the bridge-less PFC based on the practical application of the GaN power device. Through the study of bridge-less PFC converter, this paper discusses its advantages and applications in depth, and provides technical support for the realization of high-efficiency, stable and sustainable energy conversion, so as to better promote the development of the energy field.

Robust control of wind turbines to reduce wind power fluctuation

AbstractThe wind power generation system of a 5 MW horizontal axis wind turbine has a high wind energy conversion efficiency. The proportion of installed capacity in practical production applications is increasing year on year, so that the stability of its operation becomes a central factor in determining the productivity of the wind farm in question. This paper takes a 5 MW wind turbine as the research object and proposes a parameter‐adaptive robust model predictive control method to achieve self‐optimization of controller parameters through a Bayesian optimization approach. A robust model predictive control strategy, aiming to reduce the power fluctuation while maximizing the power output, is developed in this paper to enhance the dynamic economic performance under uncertain wind speed variation. A Bayesian algorithm is used in this paper to optimize the parameters of the controller. Moreover, wind speeds are simulated using TurbSim for different turbulence intensities of 5%, 10%, and 15% turbulence. Finally, the robust model predictive control toolbox in MATLAB is designed and simulated. The results show that the operational instability of the wind energy system is overcome. Meanwhile, the robustness of the wind energy system operation is improved compared to the traditional model predictive control approach.

Pseudocapacitance behavior enables efficient and stable electrochemical energy conversion and storage in glucose/air enzymatic biofuel cells

Constructing an integrated system with high-efficiency and stable energy conversion and storage (ECS) is of great significance but remains challenges. Herein, we report a biodevice consisting of a bioanode of tetrathiafulvalene/glucose oxidase (TTF/GOx) immobilized on asphalt-derived porous carbon (APC) for catalyzing glucose oxidation and a biocathode of 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonate)/bilirubin oxidase (ABTS/BOD) immobilized on APC for catalyzing oxygen reduction, to achieve ECS with high-efficiency and excellent stability. The redox mediators, TTF and ABTS, used at the bioanode and biocathode, respectively, simultaneously mediate electron transfer to release electric current on discharging and serve as pseudocapacitors to achieve charge storage at open-circuit conditions, enabling high power density and self-charge capability. The biodevice of the above configuration delivers a peak power output of 5.01 mW cm−2 in the pulse discharge mode with cell voltage remaining 93.7 % of its initial value after 100 pulse discharge/self-charge cycles. This work provides a highly efficient solution to address the low power density and poor stability of the conventional enzymatic biofuel cells, showing great implications for small, implantable and wearable electronics.

Low‐voltage ride‐through control strategy for flywheel energy storage system

AbstractDue to its high energy storage density, high instantaneous power, quick charging and discharging speeds, and high energy conversion efficiency, flywheel energy storage technology has emerged as a new player in the field of novel energy storage. With the wide application of flywheel energy storage system (FESS) in power systems, especially under changing grid conditions, the low‐voltage ride‐through (LVRT) problem has become an important challenge limiting their performance. In this paper, we propose a machine‐grid side coordinated control strategy based on model predictive current control (MPCC) for the insufficient LVRT capability of traditional FESS during grid faults. Excellent dynamic properties are demonstrated by the technique, which allows the grid‐side converter output current to swiftly follow the reference current instruction. The FESS's LVRT capability is increased when the grid‐side converter uses the MPCC current inner loop rather than the proportional–integral current inner loop during grid voltage dips. This greatly increases the reactive power response speed and efficiently supports the quick recovery of grid voltage. According to simulation verification carried out by Matlab/Simulink, the suggested control approach can assure the long‐term dependable operation of the FESS during voltage dips. This study can also be used as a reference for improving the FESS's LVRT capabilities in the future.

Controlling surface co-exsolution nanoparticle in double perovskite for boosted CO2 electrocatalytic kinetics based symmetric solid oxide electrolysis cells

Symmetric solid oxide cells (SSOCs) have attracted much attention due to their high energy conversion efficiency and simple manufacturing. The present study involves the synthesis of a class of double perovskite oxides, which serve as electrodes for SSOCs. These oxides exhibit exceptional stability in an oxidizing atmosphere, maintaining their single-phase double perovskite structure. Moreover, they facilitate the co-exsolution of metal nanoparticles from both A and B-sites under reducing conditions. By optimizing the doping amount of Bi in Sr2-xBixFeTiO6−δ (SBxFT), co-exsolved Bi and Fe nanoparticles decorated double perovskite oxides were obtained in reducing atmosphere and employed as high-performance electrodes for SSOCs. With Sr1.2Bi0.8FeTiO6-δ as the electrode, the maximum power density achieves 537 mW cm−2 at 850 °C. In electrolysis mode, the current density for pure CO2 electrolysis reaches 1.43 A cm−2 at an applied voltage of 1.5 V and 850 °C. All of these results indicate that co-exsolution of components on perovskite is an effective design technique for creating materials with desirable features.

Design and performance of a novel magnetically induced penta-stable piezoelectric energy harvester

The magnetically induced multi-stable piezoelectric vibration energy harvesters have garnered significant attention due to their strong nonlinear characteristics, wide operating bandwidths, and high electromechanical energy conversion efficiency. However, a traditional penta-stable design typically requires four rectangular external magnets. The excessive number of structural parameters amplify complexities in system optimization, dynamic analysis, and prototype installation, impeding harvester manufacturing and application. This study presents a novel penta-stable harvester design that utilizes interaction forces among a rectangular magnet and two annular magnets, resulting in a simplified system requiring only two external magnets. This design approach streamlines system design, dynamic analysis, and prototype installation, providing a fresh perspective on magnetic penta-stable vibration energy harvester design. The magnetizing current method is employed to accurately determine the system’s magnetic field and magnetic force. Stability analysis indicates that the multi-stability of the harvester is influenced by both the vertical magnetic force and equivalent linear elastic force, which can be effectively controlled by adjusting the system’s components. Dynamic simulations conducted under Gaussian white noise excitation confirm the penta-stable behavior of the system, and the dynamic responses verify that a shallower potential well depth contributes to the system’s ability to attain a higher output voltage. Experimental validations closely align with simulation results, providing strong evidence for the accuracy of the study’s findings. Furthermore, a practical application experiment demonstrates the harvester’s capability to power a hygrothermograph, highlighting its potential for real-world energy harvesting applications.