High Energy Conversion Efficiency Research Articles

Synergistic effects of low temperature and alkali on the anaerobic digestion of corn stover

Combined with the climatic conditions in cold areas, the effect of the NaOH-pretreatment at low temperature on the methane yield of corn stover was studied by anaerobic digestion at batch mode. For the alkali/freezing pretreatment, the sample reached a maximum specific methane yield of 280.48 ± 21.75 mL/g VS at the conditions of freezing time of 15 days and 2.0 % NaOH. Lower temperature-alkali pretreatment had an obvious effect on the structure of samples, with significant changes in the contents of elemental C, N, cellulose, and lignin, as well as an increase in crystallinity. In addition, a higher energy conversion efficiency (77.9 %) was obtained for the sample pretreated by alkaline/freezing. The results showed that the methane yield after pretreatment followed by alkali/freezing treatment > water/freezing treatment > freezing treatment. Therefore, alkali/freezing pretreatment is an effective method to improve the performance of the anaerobic digestion of corn stover. This study could provide a pathway for developing a low-temperature pretreatment by combining with the climate characteristics of cold areas.

Research Progress on the Composite Methods of Composite Electrolytes for Solid-State Lithium Batteries.

In the current challenging energy storage and conversion landscape, solid-state lithium metal batteries with high energy conversion efficiency, high energy density, and high safety stand out. Due to the limitations of material properties, it is difficult to achieve the ideal requirements of solid electrolytes with a single-phase electrolyte. A composite solid electrolyte is composed of two or more different materials. Composite electrolytes can simultaneously offer the advantages of multiple materials. Through different composite methods, the merits of various materials can be incorporated into the most essential part of the battery in a specific form. Currently, more and more researchers are focusing on composite methods for combining components in composite electrolytes. The ion transport capacity, interface stability, machinability, and safety of electrolytes can be significantly improved by selecting appropriate composite methods. This review summarizes the composite methods used for the components of composite electrolytes, such as filler blending, embedded framework, and multilayer bonding. It also discusses the future development trends of all-solid-state lithium batteries (ASSLBs).

Interfacial engineering of high-performance Fe2P2O7-based electrocatalysts for alkaline exchange membrane fuel cells

Fuel cells promise high energy density and energy conversion efficiency but are plagued by the scarcity of platinum for facilitating the oxygen reduction reaction (ORR). Herein, a facile synthesis of a heterojunction electrocatalyst of ZIF-8 derived carbon (Z8C) supported Fe2P2O7 (Fe2P2O7@Z8C) is reported. The electrocatalyst exhibited higher half-wave potential than the state-of-the-art Pt/C catalyst by more than 33 mV and achieved a peak power density of 152.47 mW cm−2, outperforming the Pt/C-driven cell by ca. 14.5 mW cm−2 in alkaline membrane electrode assemblies under similar operating conditions. X-ray photoelectron and X-ray absorption spectroscopic studies suggested a spontaneous electron redistribution across the heterojunction interface in Fe2P2O7@Z8C. Density functional theory calculations indicated that the electron redistribution may remarkably promote the intrinsic activity of Fe2P2O7@Z8C toward the four-electron ORR pathway. These findings offer an indispensable strategy for rational design of highly efficient and durable non-noble electrocatalysts.

Hierarchically aligned channels in the distillation membrane enable efficient solar powered desalination

Solar-powered interfacial evaporation attracts enormous attention to solve the water crisis as a low-energy consumption, high energy conversion efficiency, and environmental-friendliness technology. Balancing water transport, water content and interfacial temperature is critical to promote evaporation performance. However, fabrication methods and investigation of dedicatedly-designed structures and channel sizes for solar-powered interfacial evaporation have been rarely reported. Herein, we propose to employ vertically aligned channels with hierarchy sizes to modulate water evaporation and energy efficiency. This unique structure is fabricated by a three-step procedure including freeze-drying, ion cross-linking, and hydrogen bond reconstruction in sequence, which achieves a membrane with vertically aligned channels ranging from 1 nm to tons of micrometers. Our solar-powered distillation membrane with finely-modulated hierarchical structure exhibits a high pure water generation rate of 2.37 kg m−2 h−1 under one sun illumination. Even when treated with seawater, it can achieve a capacity of 2.34 kg m−2 h−1 (10 wt% seawater) and stabilize a high evaporation rate for at least 50 h, which is superior to most reported solar empowered distillation membranes. Our distillation membrane features a high mechanical strength and low cost, making it an appealing candidate for the actual application in desalination.

Experimental and numerical study on the integration of a built-in wave energy converter(BIWEC) and floating platform

Nowadays generating electricity continuously in real waves over extended periods is a big challenge due to harsh ocean environment for wave energy converters (WECs). In this study, in order to enhance the reliability of WEC, a novel BIWEC which can form an integrated system by combing with existing floating platforms is proposed. This design method provides a robust mechanism for using wave energy efficiently and has been validated through the numerical simulations and physical model experiments of integrated systems. In addition, a comprehensive study and analysis on the coupling dynamic characteristics of the integrated system, as well as the influence of different power take-off (PTO) parameters on the power generation performance of BIWEC are conducted. Furthermore, using the typical wave conditions in the South China Sea (2–10 s wave period and 2 m wave height) as an example, the capture power and capture width ratio of BIWEC under various effective motion strokes and mass ratios are investigated. The research results indicate that the BIWEC has the characteristics of dual resonance frequencies, a wide range of wave frequency capture, and high energy conversion efficiency, and the results of the physical experiments are consistent with those of numerical simulations, validating the reliability of the physical experiments. In the physical experimental tests, the average mechanical efficiency of the BIWEC model is 49.17%. The research results presented in this paper have significant implications for the further promoting of commercialization of WEC.

Atom-Pd catalysts supported by hollow N-doped carbon nanospheres for ultra-efficient nitrogen reduction reaction

Electrochemical N2 reduction reaction (eNRR) presents a promising alternative to the Haber-Bosch process, owing to its mild preparation conditions, absence of costly reagents, and high energy conversion efficiency. However, the process poses significant challenges due to its poor selectivity and low yield. Here, single atom Pd is successfully anchored on N-doped hollow carbon nanospheres via a simple wet impregnation method under relatively mild loading temperature, anhydrous and anaerobic environments. Our experiment demonstrates that SA-Pd/N@C exhibits outstanding catalytic performance in comparison to Pd nanoparticles which is consistent with the results of the DFT calculations, achieving an NH3 yield rate of 132.8 μg·h − 1·mgcat−1 and a corresponding FE of 6 % at -0.2 V versus RHE in HCl electrolyte (pH=1), as well as superior stability with only 5 % decrease after 10 consecutive cycles of electrochemical testing at room temperature, positioning it as one of the most effective catalyst materials reported for eNRR. The exceptional eNRR activity and stability can be attributed to the abundant active sites resulting from the relatively mild loading temperature, as well as electronic effects and structural engineering, which further diminish *H adsorption and efficiently suppress hydrogen evolution reaction. This work will provide a novel approach to enhance the eNRR performance through the effective design of Pd single-atom catalyst

Designing Atomic Interface in Sb2S3/CdS Heterojunction for Efficient Solar Water Splitting.

In the emerging Sb2S3-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 Sb2S3/CdS interface induces detrimental defects but is often overlooked. Designing a stable interface in the Sb2S3/CdS heterojunction is essential to achieve high solar energy conversion efficiency. As a proof of concept, this study reports that the modification of the Sb2S3/CdS heterojunction with an ultrathin Al2O3 interlayer effectively suppresses the interfacial defects by preventing the diffusion of Cd2+ cations into the Sb2S3 layer. As a result, a water-splitting photocathode based on Ag:Sb2S3/Al2O3/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:Sb2S3/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.

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.