Search Results (58)

Borophene, a two-dimensional (2D) allotrope of boron, has emerged as a highly promising material owing to its exceptional mechanical strength, electronic conductivity, and diverse structural phases. Unlike graphene and other 2D materials, borophene exhibits inherent anisotropy, flexibility, and metallicity, offering unique opportunities for advanced nanotechnological applications. This review presents a comprehensive summary of recent progress in borophene synthesis methods, highlighting both bottom–up strategies such as chemical vapor deposition (CVD) and molecular beam epitaxy (MBE), and top–down approaches, including liquid-phase exfoliation and sonochemical techniques. A key challenge discussed is the stabilization of borophene’s polymorphs, as bulk boron’s non-layered structure complicates exfoliation. The influence of substrates and doping strategies on structural stability and phase control is also explored. Moreover, the intrinsic physicochemical properties of borophene, including its high flexibility, oxidation resistance, and anisotropic charge transport, were examined in relation to their implications for electronic, catalytic, and sensing devices. Particular attention was given to borophene’s performance in hydrogen storage and hydrogen evolution reactions (HERs), where functionalization with alkali and transition metals significantly enhances H₂ adsorption energy and storage capacity. Studies demonstrate that certain borophene–metal composites, such as Ti- or Li-decorated borophene, can achieve hydrogen storage capacities exceeding 10 wt.%, surpassing the U.S. Department of Energy targets for hydrogen storage materials. Despite these promising characteristics, large-scale synthesis, long-term stability, and integration into practical systems remain open challenges. This review identifies current research gaps and proposes future directions to facilitate the development of borophene-based energy solutions. The findings support borophene’s strong potential as a next-generation material for clean energy applications, particularly in hydrogen production and storage systems. Full article

Brine purification is an important process unit in chlor-alkali industrial plants for the production of sodium hydroxide, chlorine, and hydrogen. The membrane cell process requires ultrapure brine, which is obtained through mechanical filtration, chemical precipitation and fine polishing, and ion exchange using polymer resins. Temperature variations can lead to the degradation of the exchange properties of these resins, primarily causing a decrease in their exchange capacity, which negatively impacts the efficiency of the brine purification. After multiple ion exchange regeneration cycles, significant quantities of spent resins may be generated. These must be managed in accordance with resource efficiency and hazardous waste management to ensure the sustainability of the industrial process. In this paper, a comparative study is conducted to characterize the long-term stability of a new commercial chelating resin used in the industrial electrolysis process. The spectroscopic methods of physicochemical characterization included: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR). The thermal behavior of the polymer resins was evaluated using the following thermogravimetric methods: thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA), while the moisture behavior was studied using dynamic vapor sorption (DVS) analysis. To assess the energy potential, the polymer resins were analyzed to determine their calorific value and overall energy content. Full article

Hydrogen and some of its derivatives (such as e-methanol, e-methane, and e-ammonia) are promising energy carriers that have the potential to replace conventional fuels, thereby eliminating their harmful environmental impacts. An innovative use of hydrogen as a zero-emission fuel is forming weakly ionized plasma by seeding the combustion products of hydrogen with a small amount of an alkali metal vapor (cesium or potassium). This formed plasma can be used as a working fluid in supersonic open-cycle magnetohydrodynamic (OCMHD) power generators. In these OCMHD generators, direct-current (DC) electricity is generated straightforwardly without rotary turbogenerators. In the current study, we quantitatively and qualitatively explore the levels of electric conductivity and the resultant volumetric electric output power density in a typical OCMHD supersonic channel, where thermal equilibrium plasma is accelerated at a Mach number of two (Mach 2) while being subject to a strong applied magnetic field (applied magnetic-field flux density) of five teslas (5 T), and a temperature of 2300 K (2026.85 °C). We varied the total pressure of the pre-ionization seeded gas mixture between 1/16 atm and 16 atm. We also varied the seed level between 0.0625% and 16% (pre-ionization mole fraction). We also varied the seed type between cesium and potassium. We also varied the oxidizer type between air (oxygen–nitrogen mixture, 21–79% by mole) and pure oxygen. Our results suggest that the ideal power density can reach exceptional levels beyond 1000 MW/m³ (or 1 kW/cm³) provided that the total absolute pressure can be reduced to about 0.1 atm only and cesium is used for seeding rather than potassium. Under atmospheric air–hydrogen combustion (1 atm total absolute pressure) and 1% mole fraction of seed alkali metal vapor, the theoretical volumetric power density is 410.828 MW/m³ in the case of cesium and 104.486 MW/m³ in the case of potassium. The power density can be enhanced using any of the following techniques: (1) reducing the total pressure, (2) using cesium instead of potassium for seeding, and (3) using air instead of oxygen as an oxidizer (if the temperature is unchanged). A seed level between 1% and 4% (pre-ionization mole fraction) is recommended. Much lower or much higher seed levels may harm the OCMHD performance. The seed level that maximizes the electric power is not necessarily the same seed level that maximizes the electric conductivity, and this is due to additional thermochemical changes caused by the additive seed. For example, in the case of potassium seeding and air combustion, the electric conductivity is maximized with about 6% seed mole fraction, while the output power is maximized at a lower potassium level of about 5%. We also present a comprehensive set of computed thermochemical properties of the seeded combustion gases, such as the molecular weight and the speed of sound. Full article

The moisture content in a building material has a negative impact on its technical parameters. This problem applies in particular to highly porous materials, including those based on aerogel. This paper presents moisture tests on a new generation of alkali-activated materials (AAMs) with different aerogel contents. Silica aerogel particles were used as a partial replacement for the lightweight sintered fly ash-based aggregate at levels of 10, 20, and 30 vol%. The experiment included four formulations: R0 (without the addition of aerogel) and the recipes R1, R2, and R3, with an increasing content of this additive. The level at which moisture stabilizes in a material in contact with the environment of a given humidity and temperature depends on whether the equilibrium state is reached in the process of moisture absorption by a dry material or in the process of the drying out of a wet material. The equilibrium states achieved in these processes are described by sorption and desorption isotherms, determined at a given temperature, but at different levels of relative humidity. The SSS (saturation salt solution) method has been used for years to determine them. Unfortunately, measurements carried out using this method are difficult and highly time-consuming. For this reason, a more accurate and faster DVS (dynamic vapor sorption) method was used in this study of R0–R3 composites. The research program assumed 10 step changes in humidity in the sorption processes and 10 step changes in humidity in the desorption processes. As a result, the course of the sorption and desorption isotherms of each of the four composites was accurately reproduced, and the hysteresis scale was assessed, which was most evident in the cases of the R0 composite (made without the addition of aerogel) and R1 composite (made with the lowest aerogel content). Studies have shown that the increased addition of aerogel resulted in an increase in the amount of water absorbed. This was true for all ten relative humidity levels tested. As a result, the highest values in the entire hygroscopic range were observed in the course of the sorption isotherm determined for the R3 composite with the highest aerogel content, and the lowest values were for the sorption isotherm of the R0 composite without the addition of aerogel. Full article

The ubiquitous, evolutionarily oldest RNAs and proteins exclusively use rather rare zinc as transition metal cofactor and potassium as alkali metal cofactor, which implies their abundance in the habitats of the first organisms. Intriguingly, lunar rocks contain a hundred times less zinc and ten times less potassium than the Earth’s crust; the Moon is also depleted in other moderately volatile elements (MVEs). Current theories of impact formation of the Moon attribute this depletion to the MVEs still being in a gaseous state when the hot post-impact disk contracted and separated from the nascent Moon. The MVEs then fell out onto juvenile Earth’s protocrust; zinc, as the most volatile metal, precipitated last, just after potassium. According to our calculations, the top layer of the protocrust must have contained up to 10¹⁹ kg of metallic zinc, a powerful reductant. The venting of hot geothermal fluids through this MVE-fallout layer, rich in metallic zinc and radioactive potassium, both capable of reducing carbon dioxide and dinitrogen, must have yielded a plethora of organic molecules released with the geothermal vapor. In the pools of vapor condensate, the RNA-like molecules may have emerged through a pre-Darwinian selection for low-volatile, associative, mineral-affine, radiation-resistant, nitrogen-rich, and polymerizable molecules. Full article

Wireless power transmission has become a research hotspot in the field of energy transmission, in which laser power transmission is one of the best methods for long-distance wireless transmission. Since laser has the advantages of high directivity, high energy density and no electromagnetic interference, laser power transmission technology can be applied to the energy supply of unmanned aerial vehicles (UAVs), micro-vehicles, airships and other flight systems. Long-distance laser power transmission can enable high-altitude flight systems to operate continuously without the need to return to the base station for charging, im-proving their operational efficiency. Therefore, high-altitude flight systems have a demand for laser power transmission. However, the commonly used lasers in laser power transmission are semiconductor lasers and fiber lasers, which are only suitable for short-distance transmission of about 1 km. In this paper, taking high-flying UAVs as an example, the transmission efficiency of different lasers used for laser power transmission is analyzed theoretically, and the results show that the diode pumped alkali vapor laser (DPAL) has a high transmission efficiency in high-power long-distance laser power transmission. The transmission efficiency of rubidium lasers which is 1.5 to 4 times that of other lasers can reach 21.94%, which illustrates that DPAL is expected to become a new type of laser source in laser power transmission technology. Full article

We propose a non-magnetic transparent heating film based on silver nanowires (Ag-NWs) for application in spin-exchange relaxation-free (SERF) magnetic field measurement devices. To achieve ultra-high sensitivity in atomic magnetometers, the atoms within the alkali metal vapor cell must be maintained in a stable and uniform high-temperature environment. Ag-NWs, as a transparent conductive material with exceptional electrical conductivity, are well suited for this application. By employing high-frequency AC heating, we effectively minimize associated magnetic noise. The experimental results demonstrate that the proposed heating film, utilizing a surface heating method, can achieve temperatures exceeding 140 °C, which is sufficient to vaporize alkali metal atoms. The average magnetic flux coefficient of the heating film is 0.1143 nT/mA. Typically, as the current increases, a larger magnetic field is generated. When integrated with the heating system discussed in this paper, this characteristic can effectively mitigate low-frequency magnetic interference. In comparison with traditional flexible printed circuits (FPC), the Ag-NWs heating film exhibits a more uniform temperature distribution. This magnetically transparent heating film, leveraging Ag-NWs, enhances atomic magnetometry and presents opportunities for use in chip-level gyroscopes, atomic clocks, and various other atomic devices. Full article

The present paper proposes an advanced process to effectively recover and fully use iodine from steel dust-derived zinc suboxide, with considerations of effectiveness in the process and industrial viability. It includes, for example, alkali wash for the dissolution of iodine into an alkaline solution from steel dust and uses mechanical vapor recompression (MVR) to concentrate the dissolved iodine by preparing the solution for the air-blowing-out process. The hydrogen iodide is also oxidized under acidic conditions with the addition of hydrogen peroxide to form crude iodine, estimated at about 20 tons annually. As a matter of fact, using this process, up to 1.2 million tons of steel waste dust can be treated in a year, turning what was previously considered waste into something of value. The thermodynamic relationship between iodine recovery and pH value is further discussed in this study, pointing out that under alkaline conditions, iodine is predominantly in the form of iodide (I⁻) and iodate (IO₃⁻), while at less than pH 2.8, it is in its molecular form I₂. These insights would provide a theoretical backbone for maximum extraction efficiency, guiding process parameters toward optimum recovery and judicious use of the resource. Full article

Due to their inability to biodegrade, petroleum-based plastics pose significant environmental challenges by disrupting aquatic, marine, and terrestrial ecosystems. Additionally, the widespread presence of microplastics and nanoplastics induces serious health risks for humans and animals. These pressing issues create an urgent need for designing and developing eco-friendly, biodegradable, renewable, and non-toxic plastic alternatives. To this end, agro-industrial byproducts such as soyhulls, which contain 29–50% lignocellulosic residue, are handy. This study extracted lignocellulosic residue from soyhulls using alkali treatment, dissolved it in ZnCl₂ solution, and crosslinked it with calcium ions and glycerol to create biodegradable films. The film formulation was optimized using the Box–Behnken design, with response to tensile strength (TS), elongation at break (EB), and water vapor permeability (WVP). The optimized films were further characterized for color, light transmittance, UV-blocking capacity, water absorption, contact angle, and biodegradability. The resulting optimized film demonstrated a tensile strength of 10.4 ± 1.0 MPa, an elongation at break of 9.4 ± 1.8%, and a WVP of 3.5 ± 0.4 × 10⁻¹¹ g·m⁻¹·s⁻¹·Pa⁻¹. Importantly, 90% of the film degrades within 37 days at 24% soil moisture. This outcome underscores the potential of soyhull-derived films as a sustainable, innovative alternative to plastic packaging, contributing to the circular economy and generating additional income for farmers and allied industries. Full article

The article investigates the potential for producing hydrogen by combining the methods of water splitting under cavitation and the chemical activation of aluminum in a high-speed cavitation–jet flow generated by a specialized hydrodynamic reactor. The process of cavitation and water spraying causes the liquid heating itself until it reaches saturated vapor pressure, resulting in the creation of vapor–gaseous products from the splitting of water molecules. The producing of vapor–gaseous products can be explained through the theory of non-equilibrium low-temperature plasma formation within a high-speed cavitation–jet flow of fluid. Special focus is also given to the interactions occurring at the interface boundary phase of aluminum and liquid under cavitation condition. The primary solid products formed on aluminum surfaces are bayerite, copper oxides (I and II), iron carbide, and a compound of magnesium oxides and aluminum hydroxide. A high hydrogen yield of 60% was achieved when using a 0.1% sodium hydroxide solution as a working liquid compared to demineralized water. Moreover, hydrogen methane was also detected in the volume of the vapor–gas mixture, which could be utilized to address the challenges of decarbonization and the recycling of aluminum-containing solid industrial and domestic waste. This work provides a contribution to the study of the mechanism of hydrogen generation by cavitation–jet processing of water and aqueous alkali solutions, in which conditions are created for double cavitation in the cavitation–jet chamber of the hydrodynamic reactor. Full article

We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. This method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signals of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows us to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs; it does not require strong magnetic fields or careful shielding of cells containing cesium atoms. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach units or tens of kilohertz in a one hertz bandwidth. Full article

Chip-scale devices harnessing the interaction between hot atomic ensembles and light are pushing the boundaries of precision measurement techniques into unprecedented territory. These advancements enable the realization of super-sensitive, miniaturized sensing instruments for measuring various physical parameters. The evolution of this field is propelled by a suite of sophisticated components, including miniaturized single-mode lasers, microfabricated alkali atom vapor cells, compact coil systems, scaled-down heating systems, and the application of cutting-edge micro-electro-mechanical system (MEMS) technologies. This review delves into the essential technologies needed to develop chip-scale hot atomic devices for quantum metrology, providing a comparative analysis of each technology’s features. Concluding with a forward-looking perspective, this review discusses the future potential of chip-scale hot atomic devices and the critical technologies that will drive their advancement. Full article

Organometallic complexes containing reactive alkali metals, such as lithium (Li), represent a promising material approach for electron injection layers and electron transport layers (EILs and ETLs) to enhance the performance of Organic Light-Emitting Diodes (OLEDs). 8-Quinolinolato Lithium (Liq) has shown remarkable potential as an EIL and ETL when conveyed in very thin films. Nevertheless, the deposition of nano-layers requires precise control over both thickness and morphology. In this work, we investigate the optical properties and morphological characteristics of Liq thin films deposited via Organic Vapor Phase Deposition (OVPD). Specifically, we present our methodology for analyzing the measured pseudodielectric function <ε(ω)> using Spectroscopic Ellipsometry (SE), alongside the nano-topography of evaporated Liq nano-layers using Atomic Force Microscopy (AFM). This information can contribute to the understanding of the functionality of this material, since ultra-thin Liq interlayers can significantly increase the operational stability of OLED architectures. Full article

A novel double-cycle alternating-flow diode-pumped potassium vapor laser is proposed, theoretically modeled and simulated. The results show that the optical-to-optical efficiency of the laser increases with increasing gas flow rates, although at high flow rates the rate of increase in efficiency decreases. The optical-to-optical efficiency reaches 74.8% at a pump power density of 30 kW/cm² and a gas flow rate of 50 m/s. The optical-to-optical efficiency of the laser is greater with a narrow linewidth pump and high buffer gas pressure. The optical-to-optical efficiency of a flow gas cell is higher than that of a static gas cell. There is an optimal gas cell length that provides the highest optical-to-optical efficiency. At higher pump power densities, higher flow rates are required to obtain higher optical-to-optical efficiencies. Full article

Heat exchangers, as essential devices for facilitating heat transfer, have found a variety applications in various industries. However, the occurrence of corrosion-related failures in real-world scenarios remains a prevalent problem that can lead to catastrophic incidents. This paper investigates the problem of corrosion perforation on the outlet flange of a heat exchanger in a sour steam stripper from a petrochemical company. Failure analysis was performed using physical testing and chemical analysis, metallographic examination, microscopic observation, and energy spectrum analysis. Intergranular corrosion experiments and flow calculations were performed to verify the analysis. The results indicate that the main cause of the flange corrosion perforation was the formation of a highly concentrated NH₄HS aqueous solution during the cooling process of the NH₃, H₂S, and water vapor in the fluid passing through the heat exchanger, and the velocity was too high, which triggered alkali-sour water washout corrosion. To prevent the recurrence of similar corrosion perforations, recommendations for material and process optimization are proposed to effectively reduce the safety production risks in refinery units and provide valuable information for the safe long-term operation of a sour steam stripper. Full article