Search Results (328)

As the presence of renewable energy production grows, so does the need to find alternative solutions for long–term energy storage. One solution may be hydrogen, and more generally, power-to-gas systems, which could allow energy storage for longer periods than batteries. However, the problem of hydrogen storage remains a limitation to the deployment of this technology. A possible solution for the hydrogen storage could be metal hydrides. In this work, a power-to-gas system based on a $2.5\mathrm{kW}$ commercial electrolyzer coupled to a pair of AB2-type metal hydride cylinders with a total volume of $4\mathrm{L}$ is studied. A special focus is placed on the electrolyzer power converter. In particular, the current ripple generated on the side connected to the stack and the efficiency of the converter are studied. A series of tests are carried out to verify the behavior of the system with varying types of thermal conditioning of the hydrides. The results show that the converter used is not optimized for the chosen application, and the thermal conditioning influences the hydrogen adsorption rate and thus the electrolyzer’s behavior. Finally, a technique to operate the system at maximum efficiency is proposed. Full article

Platinum- and/or palladium-containing silica-based supports were applied for the selective catalytic reduction of NO_x with hydrogen (H₂-SCR-DeNO_x). To obtain enhanced activity and N₂ selectivity below 150 °C, we varied the type and loading of noble metals (Pt and Pd both individually and paired, 0.1–1.0 wt.-%), silica-containing supports (ZrO₂/SiO₂, ZrO₂/SiO₂/Al₂O₃, Al₂O₃/SiO₂/TiO₂), as well as the H₂ concentration in the feed (2000–4000 ppm). All of these contributed to enhancing N₂ selectivity during H₂-SCR-DeNO_x over the (0.5 wt.-%)Pt/Pd/ZrO₂/SiO₂ catalyst in the presence of 10 vol.-% of O₂. H₂ was completely consumed at 150 °C. A comparison of the catalytic results obtained during H₂-SCR-DeNO_x,(H₂-)NH₃-SCR-DeNO_x, as well as stop-flow H₂-SCR-DeNO_x and temperature-programmed studies, revealed that in the temperature range between 150 and 250 °C, the continuously coupled or overlaying mechanism of NO reduction by hydrogen and ammonia based on NH₃ formation at lower temperatures, which is temporarily stored at the acid sites of the support and desorbed in this temperature range, could be postulated. Full article

Hydrogen (H₂) has become a more important alternative source in the current energy transition process. Beyond its role in clean energy production, it also serves as a key reactant in a wide range of industrial chemical transformations, such as hydrogenation and hydroprocessing. A fundamental step in many of these processes is the dissociation of hydrogen on catalyst surfaces. This short review provides an overview of the fundamental mechanisms involved in hydrogen dissociation over catalysts, with a specific emphasis on heterolytic pathways. Meanwhile, the influence of surface coordination environments on hydrogen activation is discussed, focusing on key factors—Lewis acid–base pairs, lattice oxygen and oxygen vacancies, and metal–support interfaces. With recognizing the significance of understanding the reaction mechanisms, we provide a critical review of experimental techniques, including spectroscopy, temperature-programmed methods, and kinetic analysis, that have been successfully applied or appear promising for probing active sites, reaction dynamics, chemisorbed intermediates, and elementary steps. Our goal is to highlight how these techniques contribute to a mechanistic understanding and to outline future directions, making this review a valuable resource for both new and experienced researchers. Full article

Terahertz (THz) metamaterials based on phase-change materials (PCMs) offer promising approaches to the dynamic modulation of electromagnetic responses. In this study, we design and experimentally demonstrate a tunable THz metamaterial composed of a symmetric split-ring resonator (SRR) pair, with the left halves covered by a 35 nm thick epitaxial vanadium dioxide (VO₂) film, enabling the simultaneous exploitation of both permittivity- and conductivity-induced modulation mechanisms. During the metal–insulator transition (MIT) of VO₂, cooperative changes in permittivity and conductivity lead to the excitation, redshift, and eventual disappearance of a quasi-bound state in the continuum (QBIC) resonance. Finite element simulations, using optical parameters of VO₂ film defined by the Drude–Smith model, predict the evolution of the transmission spectra well. These results indicate that the permittivity change originating from mesoscopic carrier confinement is a non-negligible factor in THz metamaterials hybridized with VO₂ film and also reveal the potential for developing reconfigurable THz metamaterials based on the dielectric modulation effects of VO₂ film. Full article

Interfacial modification strategies for lithium metal anodes have emerged as a promising method to improve cycling stability, suppress lithium dendrite growth, and increase Coulombic efficiency. However, the reported chemical synthesis methods lead to side reactions and side products, which hinder their electrochemical performance. In this study, we propose a novel and facile red phosphorus-assisted solid-state friction method to in situ fabricate a uniform Li₃P interphase directly on the surface of lithium metal. Interestingly, the as-formed artificial Li₃P interphase with high ionic conductivity and lithium affinity features significantly enhanced interfacial stability and electrochemical kinetics. The symmetric cells based on Li@P with the Li₃P interphase achieved a prolonged lifespan, over 1000 h, at 1 mA/cm² with low polarization. When paired with a high-loading LiFePO₄ cathode (10.5 mg/cm²), the Li@P||LiFePO₄ full cell retained 88.9% of its capacity after stable cycling for 550 cycles at 2 C and further demonstrated the excellent performance and stability of the Li@P‖LiCoO₂ full pouch cell. This study provides an efficient and scalable strategy for stabilizing lithium metal anodes, expanding new ideas for the development of next-generation high-energy-density batteries. Full article

Porcine epidemic diarrhea virus (PEDV), a primary pathogen causing diarrhea in pigs, particularly in piglets, has a mortality rate of up to 100%. Field PEDV strains circulating in pig production can be phylogenetically divided into two genotypes, GI and GII. Differential diagnosis of clinical strains with different genotypes is helpful for understanding disease epidemiology, vaccine selection, and prevention and control measures. The loop-mediated isothermal amplification method (LAMP), a novel nucleic acid amplification technique, has been utilized to detect a variety of pathogens in practice. In this study, we developed a distinguished RT-LAMP method to identify genotypes GI and GII strains of PEDV. Two pairs of primers, PEDV-LM and PEDV-LS, were designed based on the membrane and spike genes of PEDV, respectively. PEDV-LM primers exhibited specificity for all PEDV strains, while PEDV-LS primers specifically targeted the PEDV genotype GI. The diagnostic sensitivity of both primers was 1 × 10² copies/reaction, which is 100 times more sensitive than RT-PCR. The RT-LAMP reaction process was completed at 65 °C for 40 min just in a water bath or metal bath. A cross-reactivity assay confirmed that this method is specific for PEDV GI and GII, with no cross-amplification observed with other swine-origin viruses such as PDCoV, PoRV, PRV, and PRRSV. Therefore, this refined LAMP technique offers a rapid, sensitive, and reliable method with which to detect and differentiate between PEDV GI and GII, making it a superior tool for the large-scale clinical surveillance of PEDV infections. Full article

This review analyzes TiO₂-based coatings formed by the plasma electrolytic oxidation (PEO) process of titanium for the photocatalytic degradation of methyl orange (MO) under simulated solar irradiation conditions. PEO is recognized as a useful technique for creating oxide coatings on various metals, particularly titanium, to assist in the degradation of organic pollutants. TiO₂-based photocatalysts in the form of coatings are more practical than TiO₂-based photocatalysts in the form of powder because the photocatalyst does not need to be recycled and reused after wastewater degradation treatment, which is an expensive and time-consuming process. In addition, the main advantage of PEO in the synthesis of TiO₂-based photocatalysts is its short processing time (a few minutes), as it excludes the annealing step needed to convert the amorphous TiO₂ into a crystalline phase, a prerequisite for a possible photocatalytic application. Pure TiO₂ coatings formed by PEO have a low photocatalytic efficiency in the degradation of MO, which is due to the rapid recombination of the photo-generated electron/hole pairs. In this review, recent advances in the sensitization of TiO₂ with narrow band gap semiconductors (WO₃, SnO₂, CdS, Sb₂O₃, Bi₂O₃, and Al₂TiO₅), doping with rare earth ions (example Eu³⁺) and transition metals (Mn, Ni, Co, Fe) are summarized as an effective strategy to reduce the recombination of photo-generated electron/hole pairs and to improve the photocatalytic efficiency of TiO₂ coatings. Full article

With the growing demand for electric vehicles and consumer electronics, lithium-ion batteries with a high energy density are urgently needed. Lithium-rich manganese-based materials (LRMs) are known for their high theoretical specific capacity, rapid electron/ion transfer, and high output voltage. Constructing electrodes with a substantial amount of active materials is a viable method for enhancing the energy density of batteries. In this study, we prepare thick LRM electrodes through a dry process method of binder fibrillation. A point-to-line-to-surface three-dimensional conductive network is designed by carbon agents with various morphologies. This structural design improves conductivity and facilitates efficient ion and electron transport due to close particle contact and tight packing. A high-loading cathode (35 mg cm⁻²) is fabricated, achieving an impressive areal capacity of up to 7.9 mAh cm⁻². Moreover, the pouch cell paired with a lithium metal anode exhibits a remarkable energy density of 949 Wh kg⁻¹. Compared with the cathodes prepared by the wet process, the dry process optimizes the pathways for e⁻/Li⁺ transport, leading to reduced resistance, superior coulombic efficiency, retention over cycling, and minimized side reaction. Therefore, the novel structural adoption of the dry process represents a promising avenue for driving innovation and pushing the boundaries for enhanced energy density for batteries. Full article

Intensified complementary metal-oxide semiconductor (ICMOS) sensors involve multiple steps, including photoelectric conversion and photoelectric multiplication, each of which introduces noise that significantly impacts image quality. To address the issues of insufficient denoising performance and poor model generalization in ICMOS image denoising, this paper proposes a systematic solution. First, we established an experimental platform to collect real ICMOS images and introduced a novel noise generation network (LD-NGN) that accurately simulates the strong sparsity and spatial clustering of ICMOS noise, generating a multi-scene paired dataset. Additionally, we proposed a new noise evaluation metric, KL-Noise, which allows a more precise quantification of noise distribution. Based on this, we designed a denoising network specifically for ICMOS images, MAST-Net, and trained it using the multi-scene paired dataset generated by LD-NGN. By capturing multi-scale features of image pixels, MAST-Net effectively removes complex noise. The experimental results show that, compared to traditional methods and denoisers trained with other noise generators, our method outperforms both qualitatively and quantitatively. The denoised images achieve a peak signal-to-noise ratio (PSNR) of 35.38 dB and a structural similarity index (SSIM) of 0.93. This optimization provides support for tasks such as image preprocessing, target recognition, and feature extraction. Full article

In this paper, we design a frequency reconfigurable antenna for terahertz communication. The antenna is based on a Yagi design, with the main radiating elements being a pair of dipole antennas printed on the top and bottom of a dielectric substrate, respectively. The director and reflector elements give the antenna end-fire characteristics. The ends of the two arms of the dipole are constructed by staggered metal and graphene parasitic patches. By utilizing the effect of gate voltage on the conductivity of graphene, the equivalent length of the dipole antenna arms are altered and thereby adjust the antenna’s operating frequency. The proposed reconfigurable hybrid Yagi–Uda antenna can operate in five frequency bands separately at a peak gain of 4.53 dB. This reconfigurable antenna can meet the diverse requirements of the system without changing its structure and can reduce the size and cost while improving the performance. Full article

The S-Scheme heterojunction design offers a promising pathway to enhance the photocatalytic activity of semiconductors for antibiotic degradation in aquatic environments. Graphitic carbon nitride (g-C₃N₄) stands out due to its robust visible light absorption, exceptional charge separation efficiency, and abundant active sites, rendering it an ideal candidate for sustainable and energy-efficient photocatalysis. This review delves into the potential of g-C₃N₄-based S-Scheme heterojunctions in antibiotic degradation, with a particular emphasis on the photocatalytic principles, inherent advantages, and application prospects. We discuss various semiconductor materials, including metal oxides, multicomponent metal oxides, magnetic oxides, multicomponent magnetic oxides, metal sulfides, and multicomponent metal sulfides, which can be paired with g-C₃N₄ to fabricate S-Scheme heterojunctions. Furthermore, we explore common preparation techniques for synthesizing g-C₃N₄-based S-Scheme heterojunction composites, such as the hydrothermal method, solvothermal method, calcination method, self-assembly method, in situ growth, etc. Additionally, we summarize the applications of these g-C₃N₄-based S-Scheme heterojunctions in the degradation of antibiotics, focusing specifically on quinolones and tetracyclines. By providing insights into the development of these heterojunctions, we actively contribute to the ongoing exploration of innovative technologies in the field of photocatalytic antibiotic degradation. Our findings underscore the vast potential of g-C₃N₄-based S-Scheme heterojunctions in addressing the challenge of antibiotic contamination in water sources. Full article

RFID technology has been widely researched and used for structural health applications because of its compact, wireless, and scalable nature. This technology is divided into chipped and chipless sensors. Chipped sensors are costly due to their chipped tags, have narrowband operations, and contribute to shortcomings in detection capability. Chipless tags provide real-time monitoring of cracks in harsh environments like high-temperature areas and high electromagnetic interference areas. This paper presents a design of a novel chipless hybrid circular-hexagon sensor that uses the frequency signature-based method for metal crack detection and characterization using wideband frequency. This sensor is small in size (16 mm × 16 mm × 1.4 mm) and easily mountable in hard-to-reach areas. It is a low-cost, passive chipless sensor that can wirelessly monitor the cracks in metallic structures. The radar cross-section of the chipless tag shows a shift in the resonant frequency of the tag under crack and no crack conditions. Key contributions of this work are that through simulations and experimental investigation, the tag is shown to be able to detect mm-scale cracks, validating the concept and correlating the presence and size of the cracks based on the shift in resonant frequencies in which a pair of Vivaldi antennas are used as a transmitter and receiver to connect to the VNA. The designed small sensor tag is tested in a benchtop setup with no prior calibration, imitating the real-time environment conditions for crack detection. Full article

Solid-state electrolytes are currently receiving increasing interest due to their high mechanical strength and chemical stability for safe battery construction. However, their poor ion conduction and unclear conduction mechanism need further improvement and exploration. This study focuses on a hybrid solid-state electrolyte containing MOF-based scaffolds, using metal salts as the conductor. In this paper, we employ an ion substitution strategy to manipulate the scaffold structure at the lattice level by replacing hydrogen with larger alkali cations. The research systematically presents how changes in the lattice affect the physical and chemical properties of MOFs and emphasizes the role of scaffold–salt interactions in the evolution of ion conduction. The results reveal that long range-ordered structural distortion can enhance permittivity at 1 Hz, from 58 ohms to more than 10 M ohms, which can boost ion pairs dissociation and improve the transference number from 4.7% to 22.6%. Defects in the lattice can help stabilize the intermediate state in the charge transfer process and lower the corresponding impedance from 2.6 MΩ to 559 Ω. Full article

Metal vanadates are a developing group of semiconducting metal oxide materials that are gaining increasing attention due to their great redox potential, effective separation of photogenerated electron–hole pairs, and tunability of structural and physicochemical properties. Their rational design as effective photocatalysts can find use in various applications, including energy conversion/storage and environmental remediation. In particular, one of the viable ways to address energy-related issues can be through the sustainable production of hydrogen (H₂), a clean fuel produced by photocatalysis using metal vanadates. However, the rapid recombination of photogenerated electron–hole pairs limits their practical use as effective photocatalysts, and thus, many efforts have been devoted to optimizing metal vanadates to enhance their efficiency. Herein, we provide a comprehensive review that deals with the recent development strategies of metal (Ni, Fe, Zn, Ag, In, Bi, rare earth, etc.) vanadates with the working mechanisms. Their synthesis, doping, cocatalyst loading, heterojunction creation, and carbon loading are also reviewed for photocatalytic H₂ production. The challenges that metal vanadate-based photocatalysts have been facing are also discussed along with their significant potential for environmentally friendly and sustainable clean fuel production. Full article

The present study is concerned with the power transfer efficiency enhancement using a combination of the multi-hop node (MHN) and the Intelligent Reflecting Surface (IRS)-based passive beamforming technologies. The primary objective is to ensure a high RF-DC converter power conversion efficiency (PCE) used at the receiving end, which is difficult to achieve due to path loss and multi-path propagation. An electronically tunable reconfigurable reflectarray (RRA) designed to operate at the sub-GHz ISM band (865.5 MHz) is utilized to implement the IRS concept. Both the MHN and RRA were developed and studied in our earlier research. The RRA redirects the reflected power-carrying wave amplified by the MHN toward the intended receiver. It comprises two layers: the RF layer containing tunable phase shifters and the ground plane. Each phase shifter comprises two identical eight-shaped metal patches coupled by a pair of varactor diodes used to achieve the reflection phase tuning. The phase gradient method is used to synthesize the RRA phase profiles, ensuring different desired reflection angles. The RRA prototype, composed of 36 phase shifters, is employed in conjunction with the MHN equipped with two antennas and an amplifier. The RRA parameter optimization is accomplished by randomly varying the varactor diode voltages and measuring the corresponding received power levels until the power reflected in the desired direction is maximized. Two measurement scenarios are examined: power transmission without and with the MHN. In the first scenario, the received power is calculated and measured at several distinct beam steering angles for different distances between the Tx antenna and RRA. The same procedure is applied to different distances between the RRA and MHN in the second scenario. The effect of slight deviations in the operating frequency from the designed one (865.5 MHz) on the RRA performance is also examined. Additionally, the received power levels for both scenarios are estimated via full-wave analysis performed using the full-wave simulation software Ansys HFSS 2023 R1. A Huygens’ surface equivalence principle-based model decomposition method was developed and employed to reduce the CPU time. The calculated results are consistent with the measured ones. However, some discrepancies attributed to the adverse effect of RRA diode biasing lines, manufacturing tolerances, and imperfection of the indoor environment model are observed. Full article