High Energy Conversion Efficiency Research Articles

Direct methanol oxygen-ion conducting solid oxide fuel cell with an integrated in-situ cracking reactor

Methanol, as an indirect hydrogen storage medium rich in hydrogen, is considered an ideal fuel for fuel cells. Oxygen-ion conducting solid oxide fuel cells (O-SOFCs) powered by methanol are renowned for their high energy conversion efficiency and minimal environmental impact, offering broad application prospects. However, challenges to their stable power generation arise from the rate of hydrogen production through methanol decomposition at the anode and carbon deposition on nickel-based anodes. To address these issues, this study explores the optimal operating temperature and concentration of methanol as an O-SOFCs fuel, while also developing a novel cell design. In this design, an in-situ cracking reactor for internal conversion of methanol is constructed by loading Ru-GDC high-efficiency nanofiber catalysts on dendritic anode microchannels, significantly enhancing the cell's power generation performance. Experimental results demonstrate that at 800°C and a 30% methanol concentration, the system increases the maximum power density (MPD) from 0.622 W cm−2 to 0.893 W cm−2, exhibiting a 43.57% increase in power density and a 13.03% improvement in methanol utilization. Additionally, the system effectively mitigates carbon deposition and nickel anode deactivation, thereby enhancing the cell's operational stability.

Advances in the development of few-cycle gigawatt-peak-power mid-IR optical parametric amplifiers pumped by Cr:Forsterite laser using non-oxide nonlinear crystals

We demonstrate an experimental and theoretical comparison of non-oxide LiGaS2, HgGa2S4, and AgGaS2 crystals performance for wavelength conversion into the near and mid-IR range 1.5–8 μm in optical parametric amplifier pumped by Cr:Forsterite laser, delivering 100 fs pulses at 1.24 μm. It is shown that exceptionally high total energy conversion efficiency into the idler (4–5 μm) and signal (1.65–1.8 μm) waves up to 18% can be achieved using the HGS crystal, providing high nonlinearity, while the LGS crystal is more preferable for generating few-cycle mid-IR pulses due its unique dispersive properties. Our source features high peak power in gigawatt regime (0.4–2.4 GW) with pulse duration below 80 fs and optical synchronization with high harmonic generation (HHG) and THz beamlines, which is ideal for pump-probe experiments of nonlinear and strong-field physics.

Interface Engineering to Operate Reversible Protonic Ceramic Electrochemical Cells Below 500 °C

AbstractThe low‐temperature (<500 °C) operation of reversible protonic ceramic electrochemical cells (PCECs) is desirable in achieving efficient and sustainable electricity generation, as well as green hydrogen production. However, significant interfacial resistance, which contributes to both ohmic and polarization resistance, remains a hurdle in lowering the operating temperature. In this study, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) and BaZr0.4Ce0.4Y0.1Yb0.1O3‐δ (BZCYYb) mono‐grain composite interlayers are introduced, which significantly extend the electrode/electrolyte interface and increase the concentration of vertically aligned oxygen vacancies along the heterointerface. This unique design achieves the lowest ohmic and polarization resistances among previously reported values in solid electrolyte‐based electrochemical cells. As a result, the PCEC can operate at extremely low temperature of 350 °C with an exceptional peak power density of 0.50 W cm−2 in fuel cell mode and current density of 0.25 A cm−2 at 1.3 V in electrolysis cell mode. Furthermore, it demonstrates high energy conversion efficiency and excellent stability under static and dynamic operating conditions.

Efficient water recovery and power generation system based on air-cooled fuel cell with semi-closed cathode circulation mode

Air-cooled proton exchange membrane hydrogen fuel cell with on-line hydrogen production by hydrolysis has potential for portable applications due to its high volumetric power density and self-humidification. However, plenty of reserve water significantly reduces the power density of fuel cell system. Moreover, water recovery from fuel cell tail gas is difficult, because the tail gas humidity is very low due to excess cathode air as coolant. In this work, the dead-ended anode and semi-closed cathode proton exchange membrane fuel cell is proposed to achieve efficient water recovery and energy conversion via semi-closed cathode circulation mode. In this mode, cathode O2-poor tail gas is recycled as coolant instead of fresh air, which helps to enlarge the tail gas humidity by reducing the stoichiometric ratio of cathode to anode gas. The system lumped model with detailed component description is developed for optimization. >96% water production can be recycled under atmosphere temperature. The demand of fresh air is greatly reduced from 56 to 2 times of the consumption. Besides, the multi-objective optimization between water recovery and electrochemical performance shows high-efficiency water recovery of 94.70% and high energy conversion efficiency of 54.82%.

Active self-powered human motion assist system

Harvesting human energy currently occurs to power wearable devices or monitor human signs, these applications make the energy harvester less applicable to and seldom used for assisting human motion. However, there is a high demand for using such collected energy with the assistance of human motion. This paper presents a novel energy harvester that is designed to collect negative work, assist human motion, and realize self-powering. An active self-powered human motion assist system (HMAS) is developed. The system consists of a human motion assist device, a flexible rack, an electronic circuit module, and a supercapacitor. The HMAS can collect negative work from the human body, provide the user with additional motion assistance, and reduce stamina consumption. A series of experiments verify that HMAS has a high negative work collection power and a high energy conversion efficiency. The average output power is 0.93 W measured by the negative work collection test bed at a simulated knee bend angle of 40° and a frequency of 2 Hz. The energy conversion efficiency is up to 48.2%. Human motion assistance experiments verify that HMAS can provide volunteers with up to 2.57% assisting moment and minimize the metabolic cost of volunteers by 6.07% compared to without wearing HMAS. This research work is proposed to contribute to the development of active self-powered exoskeleton technology. This technology can be practically applied in the fields of rehabilitation therapy, logistics transportation, and military combat.

3D-honeycomb architectures evaporator toward mutual reinforcement of evaporation and catalysis for efficient freshwater harvesting

Solar-driven freshwater harvesting has emerged as an effective and sustainable technology to mitigate global water scarcity due to its high energy conversion efficiency. Nevertheless, achieving mutual reinforcement of photothermal and photocatalysis processes is in high demand because the contamination of harmful and highly concentrated volatile organic compounds (VOCs) will inevitably evaporate and condense alongside water. Herein, an integrated 3D-honeycomb fabric (NPPF) evaporator decorated with polydopamine (PDA), polypyrrole (PPy), and hydrotalcite (LDH) nanoflowers was designed innovatively by synergistically cooperating photothermal evaporation and advanced catalytic oxidation techniques. With periodically concave arrays, it can create the maximum level of light-trapping through multiple scattering and omnidirectional light absorption, thereby increasing its photothermal catalytic degradation ability. Meanwhile, introducing the LDH nanoflowers boosted the photothermal evaporation capacity of the NPPF evaporator. Therefore, it demonstrated high solar absorption efficiency of ~98.02% and an evaporation rate of ~2.02 kg m−2 h−1 under one sun. Furthermore, it can achieve superb degradation activity, especially for high-concentration VOCs, with efficiency of ~93.99%, surpassing most of the other evaporators reported previously. Besides, the outdoor experiment demonstrated its practicability. More importantly, it can remove tetracycline and phenol with efficiency of ~98.85% and ~ 92.06%. The advantages make this evaporator a promising representative for cooperative freshwater production.

Influence of graphene dispersion on the photovoltaic performance of tandem solar cells with four-terminal perovskite–polycrystalline silicon configuration

Silicon’s prominence in photovoltaic technology stems from its abundance and safety. While Si-based solar cells demonstrate high energy conversion efficiency and long-term stability, they encounter challenges such as high costs, intricate fabrication processes, and suboptimal efficiency. To address these issues, researchers have developed tandem solar cells that combine silicon with perovskite cells. This research specifically investigates the use of the spin coating technique with graphene dispersion solutions to deposit graphene layers in perovskite solar cells (PSCs), providing a flexible and cost-effective alternative to conventional methods. By employing graphene as a protective sealant for the perovskite interlayer to prevent degradation, the study aims to enhance the overall performance and stability of tandem solar cells. Graphene was applied onto the hole transport layer at varying concentrations (1, 5, and 10 mg ml−1) in isopropanol. Notably, the introduction of graphene resulted in decreased power conversion efficiencies (PCEs) in PSC top cells over 60 h, with efficiency reductions of 43%, 24%, and 17% for different concentrations. Importantly, these efficiency declines were significantly lower compared to cells lacking a graphene layer, which experienced a sharp 93% decrease. This investigation underscores the critical role of graphene layers in improving the stability of PSC top cells while maintaining compatibility with the stability of poly-Si bottom cells.

A Self‐Powered Photodetector Based on Graphene Enhanced WSe2/PtSe2 Heterodiode with Fast Speed and Broadband Response

AbstractNarrow bandgap 2D layered material platinum selenide (PtSe2) with good environmental stability, high carrier mobility, and high light absorption, has been widely investigated for uncooled midwave‐infrared (MWIR) photodetection. However, the phototransistor based on the PtSe2 operation at room temperature suffered from the high dark current and background noise. Here, a graphene (G)‐enhanced G‐WSe2/PtSe2 hetero‐diode placed on a metal electrode is reported. To enhance the photogain, a graphene layer placed on the WSe2/PtSe2 heterodiode as a local gating layer is designed. The device exhibits an ultra‐high light on/off ratio of up to 108 and ultra‐fast photoresponse speed with raising time τr = 0.9 µs and decay time of τd = 1.5 µs in the visible spectra range. Notably, ultrabroad band photoresponse from 405 to 3366 nm is demonstrated under the self‐power model. Notably, the device presented a competitive photovoltaic effect with a high energy conversion efficiency (PCE) of 3.45%. The results pave the way toward a new approach to tuning the performance of the atomic thin layered materials photodetector.

Nanostructured Materials for Enhanced Performance of Solid Oxide Fuel Cells: A Comprehensive Review

Solid oxide fuel cells (SOFCs) have emerged as promising candidates for efficient and environmentally friendly energy conversion technologies. Their high energy conversion efficiency and fuel flexibility make them particularly attractive for various applications, ranging from stationary power generation to portable electronic devices. Recently, research has focused on utilizing nanostructured materials to enhance the performance of SOFCs. This comprehensive review summarizes the latest advancements in the design, fabrication, and characterization of nanostructured materials integrated in SOFC. The review begins by elucidating the fundamental principles underlying SOFC operation, emphasizing the critical role of electrode materials, electrolytes, and interfacial interactions in overall cell performance, and the importance of nanostructured materials in addressing key challenges. It provides an in-depth analysis of various types of nanostructures, highlighting their roles in improving the electrochemical performance, stability, and durability of SOFCs. Furthermore, this review delves into the fabrication techniques that enable precise control over nanostructure morphology, composition, and architecture. The influence of nanoscale effects on ionic and electronic transport within the electrolyte and electrodes is thoroughly explored, shedding light on the mechanisms behind enhanced performance. By providing a comprehensive overview of the current state of research on nanostructured materials for SOFCs, this review aims to guide researchers, engineers, and policymakers toward the development of high-performance, cost-effective, and sustainable energy conversion systems.

En-route charge scheduling for an electric bus network: Stochasticity and real-world practice

Bus electrification, with its high energy conversion efficiency and zero tailpipe emissions, has a significant impact on addressing the petroleum crisis and lowering carbon emissions in urban transportation. However, long charging times and uncertain operational risks hinder their wider adoption. This paper explores the robust en-route charge scheduling problem for electric buses to overcome uncertain energy consumption while ensuring charging accessibility. The problem is first described as a deterministic mixed-integer linear programming model that employs a time-of-use electricity price to balance the charging demand. Additionally, a robust counterpart model is formulated to account for stochastic energy. Numerical studies are designed to evaluate the proposed model in a real network, followed by a sensitivity analysis to investigate the impact of battery type, fleet composition, and depth of discharge on the charging schedule. The results show that the robust optimization model provides system feasibility against uncertainty with a comparable price and emissions.

A High-Performance Flexible Hydroacoustic Transducer Based on 1-3 PZT-5A/Silicone Rubber Composite.

In recent years, hydroacoustic transducers made of PZT/epoxy composites have been extensively employed in underwater detection, communication, and recognition for their high energy conversion efficiency. Despite the ease with which these transducers can be formed into complex shapes, their lack of mechanical flexibility limits their versatility across various sizes of underwater vehicles. This study introduces a novel flexible piezoelectric composite hydroacoustic transducer (FPCHT) based on a 1-3 PZT-5A/silicone rubber composite and an island-bridge flexible electrode, which can break the limitations of existing hydroacoustic transducers that do not have flexibility. The finite element method is used to optimize the structural parameters of high-performance 1-3 FPC. A large-sized (187 mm × 47 mm × 5.12 mm) FPC is fabricated using an improved cutting-filling method and packaged into the FPCHT. Compared with the planar rigid PZT/epoxy composite hydroacoustic transducer (RPCHT) of the same size, the TVR (186.5 db) of the FPCHT has increased by about 7 dB, indicating that it has better acoustic radiation performance and electroacoustic conversion efficiency. Furthermore, its electroacoustic performance exhibits excellent stability under different bending states. Therefore, the FPCHT with high electroacoustic performance is an ideal substitute for the existing RPCHT and promotes the development of hydroacoustic transducers towards flexibility and portability.

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.

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.