Search Results (171)

There is a lack of an effective approach to measure vacuum conditions inside sealed vacuum electronic devices (VEDs) and other small-space vacuum instruments. In this study, the application performance of an innovative low-pressure gas sensor based on the emission enhancements of multi-walled carbon nanotube (MWCNT) field emitters was investigated, and the in situ vacuum performance of X-ray tubes was studied for the advantages of miniature dimension and having low power consumption, extremely low outgassing, and low thermal disturbance compared to conventional ionization gauges. The MWCNT emitters with high crystallinity presented good pressure sensing performance for nitrogen, hydrogen, and an air mixture in the range of 10⁻⁷ to 10⁻³ Pa. The miniature MWCNT sensor is able to work and remain stable with high-temperature baking, important for VED applications. The sensor monitored the in situ pressures of the sealed X-ray tubes successfully with high-power operations and a long-term storage of over two years. The investigation showed that the vacuum of the sealed X-ray tube is typical at a low 10⁻⁴ Pa level, and pre-sealing degassing treatments are able to make the X-ray tube work under high vacuum levels with less outgassing and keep a stable high vacuum for a long period of time. Full article

Integrated energy systems (IESs) serve as pivotal platforms for realizing the reform of energy structures. The rational planning of their equipment can significantly enhance operational economic efficiency, environmental friendliness, and system stability. Moreover, the inherent randomness and intermittency of renewable energy generation, coupled with the peak and valley characteristics of load demand, lead to fluctuations in the output of multi-energy coupling devices within the IES, posing a serious threat to its operational stability. To address these challenges, this paper focuses on the economic and stable operation of the IES, aiming to minimize the configuration costs of hybrid energy storage systems, system voltage deviations, and net load fluctuations. A multi-objective optimization planning model for an electric–hydrogen hybrid energy storage system is established. This model, applied to the IEEE-33 standard test system, utilizes the Multi-Objective Artificial Hummingbird Algorithm (MOAHA) to optimize the capacity and location of the electric–hydrogen hybrid energy storage system. The Multi-Objective Artificial Hummingbird Algorithm (MOAHA) is adopted due to its faster convergence and superior ability to maintain solution diversity compared to classical algorithms such as NSGA-II and MOEA/D, making it well-suited for solving complex non-convex planning problems. The simulation results demonstrate that the proposed optimization planning method effectively improves the voltage distribution and net load level of the IES distribution network, while the complementary characteristics of the electric–hydrogen hybrid energy storage system enhance the operational flexibility of the IES. Full article

Hydrogen gas sensing is critical for energy storage, industrial safety, and environmental monitoring. However, traditional sensors still face challenges in selectivity, sensitivity, and stability. This work introduces an innovative N-polar GaN/AlGaN high-electron-mobility transistor (HEMT) with a 10 nm Pd catalytic layer as a hydrogen sensor. The device achieves ppm-level H₂ detection with rapid recovery and reusability, which is comparable to or even exceeds the performance of conventional Ga-polar HEMTs. The N-polar structure enhances sensitivity through its unique polarization-induced 2DEG and intrinsic back barrier, while the Pd layer catalyzes H₂ dissociation, forming a dipole layer that can modulate the Schottky barrier height. Experimental results demonstrate superior performance at both room temperature and elevated temperatures. Specifically, at 200 °C, the sensor exhibits a response of 102% toward 200 ppm H₂, with response/recovery times of 150 s/17 s. This represents a 96% enhancement in sensitivity and a reduction of 180 s/14 s in response/recovery times compared to room-temperature conditions (23 °C). These findings highlight the potential of N-polar HEMTs for high-performance hydrogen sensing applications. Full article

Hydrogen (H₂) monitoring demonstrates significant practical importance for safety assurance in industrial production and daily life, driving the demand for gas-sensing devices with enhanced performance and reduced power consumption. This study developed a room-temperature (RT) hydrogen-sensing platform utilizing two-dimensional (2D) Ag-doped SnS₂ nanomaterials activated by light illumination. The Ag-SnS₂ nanosheets, synthesized through hydrothermal methods, exhibited exceptional H₂ detection capabilities under blue LED light activation. The synergistic interaction between silver dopants and photo-activation enabled remarkable gas sensitivity across a broad concentration range (5.0–2500 ppm), achieving rapid response/recovery times (4 s/18 s) at 2500 ppm under RT. Material characterization revealed that Ag doping induced S vacancies, enhancing oxygen adsorption, while simultaneously facilitating photo-induced hole transfer for surface hydrogen activation. The optimized sensor maintained good response stability after five-week ambient storage, demonstrating excellent operational durability. Experimental results further demonstrated that Ag dopants enhanced hydrogen adsorption–activation, while S vacancies improved the surface oxygen affinity. This work provides fundamental insights into defect engineering strategies for the development of optically modulated gas sensors, proposing a viable pathway for the construction of energy-efficient environmental monitoring systems. Full article

Graphyne, a hypothetical carbon allotrope comprising sp and sp² hybridized carbon atoms, has garnered significant attention for its potential applications in next-generation technologies. Unlike graphene, graphyne’s distinctive acetylenic linkages endow it with a tunable electronic structure, directional charge transport, and superior mechanical flexibility. This review delves into the structural variety, theoretical underpinnings, and burgeoning experimental endeavors associated with various graphyne allotropes, including α-, β-, γ-, and 6,6,12-graphyne. It examines synthesis methods, structural and electronic characteristics, and the material’s prospective roles in diverse fields, such as nanoelectronics, transistors, hydrogen storage, and desalination. Additionally, it highlights the use of computational modeling techniques—density functional theory (DFT), GW approximation, and nonequilibrium Green’s function (NEGF)—to anticipate and validate properties without fully scalable experimental data. Despite substantial theoretical progress, the practical implementation of graphyne-based devices faces several challenges. By critically assessing current research and identifying strategic directions, this review underscores graphyne’s potential to revolutionize advanced materials science. Full article

In recent years, dielectric films with a high energy-storage capacity have attracted significant attention due to their wide applications in the fields of renewable energy, electronic devices, and power systems. Their fundamental principle relies on the polarization and depolarization processes of dielectric materials under external electric fields to store and release electrical energy, featuring a high power density and high charge–discharge efficiency. In this study, sodium bismuth titanate (NBT) micro-flakes synthesized via a molten salt method were treated with hydrogen peroxide and subsequently blended with a polyvinylidene fluoride (PVDF) matrix. An oriented tape-casting process was utilized to fabricate a dielectric thin film with enhanced energy storage capacity under a weakened electric field. Experimental results demonstrated that the introduction of modified NBT micro-flakes facilitated the interfacial interactions between the ceramic fillers and polymer matrix. Additionally, chemical interactions between surface hydroxyl groups and fluorine atoms within PVDF promoted the phase transition from the α to the β phase. Consequently, the energy storage density of PVDF-NBT composite increased from 2.8 J cm⁻³ to 6.1 J cm⁻³, representing a 110% enhancement. This design strategy provides novel insights for material innovation and interfacial engineering, showcasing promising potential for next-generation power systems. Full article

The growing demand for energy, coupled with the unsustainable nature of fossil fuels due to global warming and the greenhouse effect, have led to the advancement of renewable energy production concepts. Innovations such as photovoltaics, wind energy, and infrared energy harvesters are emerging as viable solutions. The challenge lies in the stochastic nature of renewable energy sources, which necessitates the implementation of electrical energy storage solutions, whether through batteries, supercapacitors, or hydrogen production. In this regard, innovative materials are essential to address the questions associated with these technologies. Metal-organic frameworks (MOFs) are crucial for achieving clean and efficient energy conversion in fuel cells and storage in batteries and supercapacitors. Metal-organic frameworks (MOFs) can be used as electrocatalytic materials, membranes for electrolytes, and energy storage materials. They exhibit exceptional design versatility, large surface, and can be functionalized with ligands with several charges and metallic centers. This article offers an in-depth examination of materials and devices utilizing metal-organic frameworks (MOFs) for electrochemical processes concerning the generation, transformation, and storage of electrical energy. This review specifically focuses on rechargeable batteries and fuel cells that incorporate MOFs. Finally, an outlook on the potential applications of MOFs in electrochemical industries is presented. Full article

International projects study the safety aspects of the storage and long-distance transportation of liquid hydrogen at large scales. Catalytic recombiners, which are today key elements of hydrogen risk mitigation in nuclear power plants, could become an efficient safety device to prevent flammable gas mixtures after liquid hydrogen leakages in closed rooms. This study tackles fundamental questions about the operational behavior of typical recombiner catalysts related to the conditions of the start-up and the termination of the catalytic reaction. For this purpose, small-scale catalyst sheets with coatings containing either platinum or palladium as active materials were exposed to gas mixtures of air and hydrogen of up to 4 vol.% at temperatures between −50 °C and 20 °C. Both platinum and palladium showed variation to performance and had stochastic results. Overall, the initialized platinum catalyst was better than the palladium. The experimental results show that the transfer of the recombiner technology from its current application is not easily possible. Full article

Lithium (Li) metal’s exceptional low electrode potential and high specific capacity for next-gen energy storage devices make it a top contender. However, the unregulated and unpredictable proliferation of Li dendrites and the instability of interfaces during repeated Li plating and stripping cycles pose significant challenges to the widespread commercialization of Li metal anodes. We introduce the creation of a hydrogen bond network solid electrolyte interphase (SEI) film that integrates zwitterionic groups, designed to facilitate the stability and longevity of lithium metal batteries (LMBs). Here, we design a PVA/P(SBMA-MBA) hydrogen bond network film (PSM) as an artificial SEI, integrating zwitterions and polyvinyl alcohol (PVA) to synergistically regulate Li⁺ flux. The distinctive zwitterionic effect in the network amplifies the SEI film’s ionic conductivity to 1.14 × 10⁻⁴ S cm⁻¹ and attains an impressive Li⁺ ion transfer number of 0.84. In situ Raman spectroscopy reveals dynamic hydrogen bond reconfiguration under strain, endowing the SEI with self-adaptive mechanical robustness. These properties facilitate a homogeneous Li flux and exceptionally suppress dendritic growth. The advanced Li metal anode may endure over 1200 h at 1 mA cm⁻² current density and 1 mAh cm⁻² area capacity in a Li|Li symmetric battery. And in full cells paired with LiFePO₄ cathodes, 93.8% capacity retention is reached after 300 cycles at 1C. Consequently, this work provides a universal strategy for designing dynamic interphases through molecular dipole engineering, paving the way for safe and durable lithium metal batteries. Full article

In this work, the structural and optical properties of calcium monochalcogenide nanoparticles were numerically examined by using Density Functional Theory and Time Dependent Density Functional Theory. The composition of the examined nanoparticles was obtained from an initial cubic-like building block of the form Ca₄Y₄, where Y could be one of the chalcogen elements sulfur, selenium, and tellurium, after its proper numerical examination to check their structural stability. The examined nanoparticles were then created from these initial cubic-like building blocks after their elongation along one, two, and three perpendicular directions. Τhe Absorption Spectrum, the Binding Energy, together with the highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) gap, were included in the calculations of the studied calcium monochalcogenides. The calculations provided numerical evidence regarding the existence of stable structures for a wide range of morphologies. In addition, the examination of the properties of such nanostructures after placing different kinds of defects was also included in the calculations, thus leading to new groups of nanoparticles with several potential uses in technological applications, such as hydrogen storage, CO₂ capture, and ultraviolet-responsive devices. Full article

Hydrogen energy, as a medium for long-term energy storage, needs to ensure the continuous and stable operation of the electrolyzer during the production of green hydrogen using wind energy. In this paper, based on the overall model of a wind power hydrogen production system, an integrated control strategy aimed at improving the quality of wind power generation, smoothing the hydrogen production process, and enhancing the stability of the system is proposed. The strategy combines key measures, such as the maximum power point tracking control of the wind turbine and the adaptive coordinated control of the electrochemical energy storage system, which can not only efficiently utilize the wind resources but also effectively ensure the stability of the bus voltage and the smoothness of the hydrogen production process. The simulation results show that the electrolyzer can operate at full power to produce hydrogen while the energy storage device is charging when wind energy is sufficient; the electrolyzer continuously produces hydrogen according to the wind energy when the wind speed is normal; and the energy storage device will take on the task of maintaining the operation of the electrolyzer when the wind speed is insufficient to ensure the stability and reliability of the system. Full article

Supercapacitors have a better power density than batteries; however, there is room for improvement in energy density. Co₃V₂O₈ nanoparticles were synthesized using the hydrothermal approach, with the reaction duration tuned to enhance energy density. At a 10 h hydrothermal reaction time, bundles of nanowires with void spaces were obtained, demonstrating excellent areal capacitance of 4.67 F/cm², energy density of 94 μWh/cm², and power density of 573 μW/cm² at a current density of 3 mA/cm². With activated carbon (AC) and Co₃V₂O₈ nanoparticles prepared over a 10-h hydrothermal reaction period, an asymmetric supercapacitor (ASC) was assembled. The device performed admirably in terms of energy storage capacity, with an areal capacitance of 781 mF/cm² and a volumetric capacitance of 1.43 F/cm³. The ASC’s cyclic stability demonstrated capacity retention of 83.40% after 5000 cycles. The powering of red LEDs was used to show practical applications. In a 2M KOH electrolyte, the optimized Co₃V₂O₈ electrode demonstrated good electrocatalytic performance for the hydrogen evolution process, with an overpotential of 259 mV at a current density of 10 mA/cm². Overall, water splitting studies revealed a potential of 1.78 V with little potential enhancement after 8 h of Chrono potentiometric stability. As a result, Co₃V₂O₈ nanoparticles prepared at a 10 h hydrothermal reaction time offer excellent electrode materials for energy storage in supercapacitors and electrocatalytic applications for total water splitting. Full article

Borophene, a revolutionary two-dimensional (2D) material with exceptional electrical, physical, and chemical properties, holds great promise for high-performance, highly integrated information storage systems. However, its metallic nature and structural instability have significantly limited its practical applications. To address these challenges, hydrogenated borophene has emerged as an ideal alternative, offering enhanced stability and semiconducting properties. In this study, we report a novel and scalable method for synthesizing hydrogenated borophene via the in situ thermal decomposition of potassium borohydride in a substrate-free environment. This approach enables the production of borophene with outstanding crystallinity, uniformity, and continuity, representing a significant advancement in borophene fabrication techniques. Furthermore, the hydrogenated borophene-based non-volatile memory device we developed exhibits a high ON/OFF-current ratio exceeding 10⁵, a low operating voltage of 2 V, and excellent long-term cycling stability. These groundbreaking results demonstrate the immense potential of 2D borophene-based materials in next-generation high-performance information storage devices. Full article

To enhance the accommodation capacity of renewable energy and promote the coordinated development of multiple energy, this paper proposes a novel economic dispatch method for an integrated electricity–heat–hydrogen energy system on the basis of coupling three energy flows. Firstly, we develop a mathematical model for the hydrogen energy system, including hydrogen production, storage, and hydrogen fuel cells. Additionally, a multi-device combined heat and power system is constructed, incorporating gas boilers, waste heat boilers, gas turbines, methanation reactors, thermal storage tanks, batteries, and gas storage tanks. Secondly, to further strengthen the carbon reduction advantages, the economic dispatch model incorporates the power-to-gas process and carbon trading mechanisms, giving rise to minimizing energy purchase costs, energy curtailment penalties, carbon trading costs, equipment operation, and maintenance costs. The model is linearized to ensure a global optimal solution. Finally, the experimental results validate the effectiveness and superiority of the proposed model. The integration of electricity–hydrogen coupling devices improves the utilization rate of renewable energy generation and reduces the total system operating costs and carbon trading costs. The use of a tiered carbon trading mechanism decreases natural gas consumption and carbon emissions, contributing to energy conservation and emission reduction. Full article

The polar energy router is a key device in the polar clean energy system which converges the output of wind power, photovoltaic units, energy storage units and hydrogen fuel cells through the power electronic power converter to the DC bus, which requires the use of a variety of specifications of DC/DC converters; as a result, the efficiency of the DC/DC converter is directly connected to the efficiency of the polar energy router. This paper presents an enhanced isolated DC/DC converter with a phase-shifted full-bridge topology designed to meet the high-efficiency conversion requirements of polar energy routers. Although soft switching can be realized naturally in phase-shifted full-bridge topology, it also faces challenges, such as the difficulty of realizing soft switching under light load conditions, large circulation losses, a loss of duty cycle and oscillation in the secondary-side voltage. To solve these problems, an improved scheme of the phase-shifted full-bridge converter with an active clamp circuit is proposed in this paper. The scheme realized zero-voltage switch (ZVS) under light load by utilizing clamp capacitor energy. The on-state loss was reduced by zeroing the primary-side current during the circulating phase. This paper provides a detailed description of the topology, working principle and performance characteristics of the improved scheme, and its feasibility has been verified through experiments. Full article