Search Results (326)

Rapid progress on the fabrication of lead halide perovskite has led to the development of high performance optoelectronic devices, particularly in the field of solar cell technologies. This initial success has subsequently inspired investigations into layered 2D-halide perovskite structures, motivated in part by their good environmental stability, but more significantly by their intriguing fundamental photo-physics. They have recently been used to improve the photoresponsivity of monolayer transition metal dichalcogenides in hybrid heterostructures. In this paper, we report on the synthesis of the (PEA)₂(MA)_n−1Pb_nI_3n+1 series (with n = 1, 2, 3) of 2D-halide perovskites, in order to develop a platform that provides ultra-thin layers for the fabrication of hybrid heterostructures. The crystal synthesis method and its basic structural and optical characterization are shown, highlighting the differences in the crystal synthesis processes. Furthermore, we explore the preparation of 2D halide perovskite ultra-thin flakes using the mechanical exfoliation method, and few-layer-areas of n = 1 member of the series are identified using atomic force microscopy. Finally, we study the deposition of thin and ultra-thin films using the spin coating technique to provide an alternative process to the exfoliation. Full article

Gold (Au) is one of the noble metals most used as a catalyst in the growth of one-dimensional nanostructures. Usually, an ultra-thin Au film is coated followed by thermal annealing to obtain Au nanoclusters. Although annealing temperature, duration and film thickness parameters have been heavily studied, there are no studies on the sputter working gas pressure, which also greatly affects the film microstructure. In this study, low (5 mTorr) and high (15 mTorr) working gas pressures were examined in addition to Au film thicknesses of 2 nm, 5 nm and 8 nm. Additionally, copper indium gallium selenide (CIGS) films were deposited on Au films with different thicknesses and argon (Ar) gas pressures. It was confirmed from SEM and AFM images that the Au films undergo drastic morphology change from smooth to extremely porous film surfaces with increasing thickness regardless of gas pressure. However, the porosity of films is increased at higher growth pressure for each thickness. Specifically, the most porous film was obtained at a 5 nm thickness with 15 mTorr, and it was filled with nanomounds. Not surprisingly, the only apparent columnar-type formation was observed for CIGS deposition, which was carried out on the most porous film. It can be interpreted that Au nanomounds behave like catalysts on which the CIGS nanocolumns grow. Full article

Stainless steel forms a native film of mixed metal oxides, and organic impurities are likely to adsorb on the surface upon exposure to ambient conditions. For many applications, oxides and impurities should be removed, and several techniques have been used for decades. An innovative method is presented in this paper. The organic impurities were oxidized using a water solution of 1 M peroxynitric acid (PNA). Stainless steel samples were immersed in the solution, and the oxidation of organic impurities was evaluated by the ultra-thin depth profiling using secondary ion mass spectrometry (SIMS). A minute of treatment with PNA caused oxidation of organic impurities and a decrease in the SIMS CN^– signal over an order of magnitude. Prolonged treatment caused the selective removal of the native iron oxide film, leaving a protective film of chromium oxide. Removal of the iron oxide film was also observed when stainless steel was treated with 1 M HNO₃. The PNA method is useful for routine cleaning of stainless steel to remove the organic contaminants from the surface and keep the passive chromium oxide film intact. It is ecologically friendly and enables rapid decomposition of the traces of organic impurities likely to be adsorbed on the metallic surfaces. Full article

Graphene, owing to its exceptional mechanical properties and interfacial modulation capability, is considered an ideal material for enhancing the interfacial strength and damage resistance during the fabrication of ultra-thin lithium foils. Although previous studies have demonstrated the reinforcing effects of graphene on lithium metal interfaces, most analyses have been restricted to single-temperature or idealized substrate conditions, lacking systematic investigations under practical, multi-temperature environments. Consequently, the influence of graphene coatings on lithium-ion conductivity and mechanical stability under real thermal conditions remains unclear. To address this gap, we employ LAMMPS-based molecular dynamics simulations to construct atomic-scale models of pristine lithium and graphene-coated lithium (C/Li) interfaces at three representative temperatures. Through comprehensive analyses of dislocation evolution, root-mean-square displacement, frictional response, and lithium-ion diffusion, we find that graphene coatings synergistically alleviate interfacial stress, suppress crack initiation, reduce friction, and enhance ionic conductivity, with these effects being particularly pronounced at elevated temperatures. These findings reveal the coupled mechanical and electrochemical regulation imparted by graphene, providing a theoretical basis for optimizing the structure of next-generation high-performance lithium metal anodes and laying the foundation for advanced interfacial engineering in battery technologies. Full article

Hybrid bonding technology has emerged as a critical 3D integration solution for advanced semiconductor packaging, enabling simultaneous bonding of metal interconnects and dielectric materials. However, conventional hybrid bonding processes face significant contamination challenges during O₂ plasma treatment required for OH group formation on SiCN or the other dielectric material surfaces. The aggressive plasma conditions cause Cu sputtering and metal migration, leading to chamber and substrate contamination that accumulates over time and degrades process reliability. In this work, we present a novel approach to address these contamination issues by implementing a molybdenum disulfide (MoS₂) barrier layer formed through plasma-enhanced chemical vapor deposition (PECVD) sulfurization of Mo films. The ultrathin MoS₂ layer acts as an effective barrier preventing Cu sputtering during O₂ plasma processing, thereby eliminating chamber contamination, and it also enables post-bonding electrical connectivity through controlled Cu filament formation via memristive switching mechanisms. When voltage is applied to the Cu-MoS₂-Cu structure after hybrid bonding, Cu ions migrate through the MoS₂ layer to form conductive filaments, establishing reliable electrical connections without compromising the bonding interface integrity. This innovative approach successfully resolves the fundamental contamination problem in hybrid bonding while maintaining excellent electrical performance, offering a pathway toward contamination-free and high-yield hybrid bonding processes for next-generation 3D-integrated devices. Full article

Water electrolysis represents a viable and scalable green hydrogen production technology, which mitigates carbon emissions and contributes to environmental sustainability. Transition metal-based layered double hydroxides (LDHs) exhibit excellent oxygen evolution reaction (OER) efficiency, attributed to their adjustable interlayer spacing combined with abundant active sites. Here, we report a uniform multimetallic catalyst, demonstrating robust and efficient OER performance for high-performance water splitting. SEM and TEM confirmed its ultrathin hierarchical nanosheet structure. The characteristic peaks of LDH in XRD and Raman spectra further verified the successful synthesis of the LDH material. Fe-CoZn LDH delivers exceptional OER performance in 1 M KOH, requiring overpotentials of just 209, 238, and 267 mV to reach 10, 100, and 400 mA cm⁻², respectively. The catalyst also demonstrates exceptional hydrogen evolution reaction (HER) performance, achieving 10 mA cm⁻² at 119 mV. It also has excellent stability, with stable operation for up to 100 h under 100 mA cm⁻² in 1 M KOH electrolyte solution. Full article

Lithium-oxygen batteries (LOBs) are limited by sluggish oxygen redox kinetics and cathode instability. Herein, we report a cobalt particle catalyst encapsulated in nitrogen-doped carbon (Co@NC) with a three-dimensional hierarchical architecture, synthesized via a chitosan-derived hierarchical porous carbon framework. This innovative design integrates uniformly dispersed ultra-thin carbon shells (11.7 nm), pyridinic nitrogen doping, and Co particles (1.41 μm) stabilized through carbon-support electronic coupling. The hierarchical porosity facilitates rapid O₂/Li⁺ mass transport, while pyridinic N sites act as dual-function electrocatalytic centers for Li₂O₂ nucleation and charge transfer kinetics. Co@NC achieves 11,213 mAh g⁻¹ at 200 mA g⁻¹ (126.5% higher than nitrogen-doped carbon) and maintains 1.54 V overpotential (500 mAh g⁻¹). These metrics outperform benchmark catalysts, addressing kinetic and stability challenges in LOBs. The study advances electrocatalyst design by integrating structural optimization, heteroatom doping, and electronic coupling strategies for high-performance metal–air batteries. Full article

Hexagonal boron nitride (h-BN) possesses a unique combination of a wide bandgap, high thermal conductivity, and chemical inertness, making it a key insulating and thermal management material for advanced electronics and nanocomposites. However, its intrinsic hydrophobicity and strong interlayer van der Waals forces severely limit exfoliation efficiency and dispersion stability, particularly in scalable liquid-phase processes. Here, we report a synergistic exfoliation strategy that integrates acid-induced hydroxylation with gallium (Ga) intercalation to achieve high-yield (>80%) production of ultrathin (<4 nm) hydrophilic h-BN nanosheets. Hydroxylation introduces abundant -OH groups, expanding interlayer spacing and significantly increasing surface polarity, while Ga intercalation leverages its native Ga₂O₃ shell to form strong interfacial interactions with hydroxylated basal planes. This oxide-mediated adhesion facilitates efficient layer separation under mild sonication, yielding nanosheets with well-preserved lateral dimensions and exceptional dispersion stability in polar solvents. Comprehensive characterization confirms the sequential chemical and structural modifications, revealing the crucial roles of hydroxylation-induced activation and Ga₂O₃ assisted wettability enhancement. This combined chemical activation–soft metallic intercalation approach provides a scalable, solution-processable route to high-quality h-BN nanosheets, opening new opportunities for their integration into dielectric, thermal interface, and multifunctional composite systems. Full article

An overview of research on superconducting materials has been provided, including brief annotations of published papers and scientific cooperation among the Commonwealth of Independent States (CIS) countries: Armenia, Azerbaijan, Belarus, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan. It is shown that fundamental research on superconducting materials is being funded for development and study more at the government level in each republic than from private funds or organizations. One of the most promising materials, as indicated by recent studies, are those synthesized from metal hydrides, particularly lanthanum hydride, which exhibits superconducting properties at 203–253 K, close to room temperature. Unfortunately, this type of material’s practical application is currently limited because of the extremely high pressure necessary during exploitation. The most promising direction, as inferred from research conducted in CIS countries, is the development of cuprate superconductors doped with rare-earth elements such as yttrium, lanthanum, and other metals. There are also iron–nitrogen junctions, metallic and organic superconductors, and research into improving technologies for producing ultrathin substrates using laser or plasma deposition methods. CIS countries have established a strong scientific foundation in superconductivity, with Russia leading fundamental and experimental advances in high- and low-temperature superconducting materials. Future research will likely focus on improving synthesis techniques for ultrathin superconducting films and exploring novel doped hydride systems to achieve stable superconductivity near ambient temperatures. Full article

Surface-enhanced Raman Scattering (SERS) enables ultrasensitive detection but is often hindered by biocompatibility and sustainability concerns due to its reliance on noble metal substrates. To overcome these limitations, we develop a semiconductor-based SERS platform utilizing ultrathin tungsten trioxide (WO₃) nanofilms synthesized via a facile annealing process on fluorine-doped tin oxide (FTO). This system achieves an impressive Raman enhancement factor of 1.36 × 10⁶, enabling ultrasensitive detection of rhodamine 6G (R6G) and methylene blue (MB) at ultralow concentrations, surpassing conventional metal-based SERS platforms. It is further suggested that this is a substrate that can be easily coupled to other metals. An application for the detection of adenine molecules is realized through layered WO₃-Au NPs composites, where embedded gold nanoparticles act as plasma “hot spots” to amplify the sensitivity. Density functional theory (DFT) calculations and band structure analysis confirm that synergistic interface charge transfer and naturally formed oxygen vacancies enhance performance. By combining semiconductor compatibility with other metal amplification, this WO₃-based SERS platform offers a sustainable and high-performance alternative to conventional substrates, paving the way for environmentally friendly and scalable Raman sensing technologies. Full article

Electrochemical CO₂ reduction reaction (CO₂RR) represents a promising pathway for carbon neutralization. Here, we report hierarchical CuO nanorod arrays synthesized via cyclic voltammetry (CV) treatment as freestanding electrodes for selective CO₂RR. The CV activation process generates ultrathin nanosheets on CuO nanorods, creating abundant interfaces that facilitate formate production. Optimized CV-2000-CuO achieves 42% Faradaic efficiency (FE) for formate at −1.4 V vs. RHE while suppressing hydrogen evolution reaction (HER). Comprehensive characterization reveals that CV treatment promotes partial surface reduction to metallic Cu and generates high-density grain boundaries during CO₂RR operation. These structural features enhance CO₂RR activity and stability compared to pristine CuO (P-CuO). This work demonstrates a novel electrode engineering strategy combining freestanding architecture with electrochemical activation for efficient CO₂-to-formate conversion. Full article

The development of ternary metal oxide electrocatalysts with optimized electronic structures and surface morphologies has emerged as one of the effective strategies to improve the performance of electrochemical water splitting. In this work, ternary CoMoCe (CMC)-oxide electrocatalysts were successfully synthesized on nickel foam substrates via a hydrothermal technique and employed for their catalytic activity in an alkaline electrolyte. For comparison, binary counterparts (CoMo, CoCe, and MoCe) were also fabricated under similar conditions. The synthesized catalysts’ electrodes exhibited diverse surface architectures, including microporous-flake hybrids, ultrathin flakes, nanoneedle-assembled microspheres, and randomly oriented hexagonal structures. Among them, the ternary CoMoCe-oxide electrode exhibited outstanding bifunctional electrocatalytic activity, delivering low overpotentials of 124 mV for the hydrogen evolution reaction (HER) at −10 mA cm⁻², and 340 mV for the oxygen evolution reaction (OER) at 100 mA cm⁻², along with excellent durability. Furthermore, in full water-splitting configuration, the CMC||CMC and RuO₂||CMC electrolyzers required cell voltages of 1.69 V and 1.57 V, respectively, to reach a current density of 10 mA cm⁻². Remarkably, the CMC-based electrolyzer reached an industrially relevant current density of 1000 mA cm⁻² at a cell voltage of 2.18 V, maintaining excellent stability over 100 h of continuous operation. These findings underscore the impact of an optimized electronic structure and surface architecture on design strategies for high-performance ternary metal oxide electrocatalysts. Herein, a robust and straightforward approach is comprehensively presented for fabricating highly efficient ternary metal-oxide catalyst electrodes, offering significant potential for scalable water splitting. Full article

In this study, the influence of HfO₂ interlayer thickness on the performance of heteroepitaxial α-Ga₂O₃ layer-based metal–insulator–semiconductor–insulator–metal (MISIM) ultraviolet photodetectors is examined. A thin HfO₂ interlayer enhances the interface quality and reduces the density of interface traps, thereby improving the performance of UVC photodetectors. The fabricated device with a 1 nm HfO₂ interlayer exhibited a significantly reduced dark current and higher photocurrent than a conventional metal–semiconductor–metal (MSM). Specifically, the 1 nm HfO₂ MISIM device demonstrated a photocurrent of 2.3 μA and a dark current of 6.61 pA at 20 V, whereas the MSM device exhibited a photocurrent of 1.1 μA and a dark current of 73.3 pA. Furthermore, the photodetector performance was comprehensively evaluated in terms of responsivity, response speed, and high-temperature operation. These results suggest that the proposed ultra-thin HfO₂ interlayer is an effective strategy for enhancing the performance of α-Ga₂O₃-based UVC photodetectors by simultaneously suppressing dark currents and increasing photocurrents and ultimately demonstrate its potential for stable operation under extreme environmental conditions. Full article

The electrocatalytic CO₂ reduction reaction (CO₂RR) offers an energy-saving and environmentally friendly approach to producing hydrocarbon fuels. The use of a gas diffusion electrode (GDE) flow cell has generally improved the rate of CO₂RR, while the gas diffusion layer (GDL) remains a significant challenge. In this study, we successfully engineered a novel metal–organic framework (MOF) heterojunction through the controlled coating of zeolitic imidazolate framework (ZIF-L) on ultrathin nickel—metal–organic framework (Ni-MOF) nanosheets. This innovative architecture simultaneously integrates GDL functionality and exposes abundant solid–liquid–gas triple-phase boundaries. The resulting Ni-MOF@ZIF-L heterostructure demonstrates exceptional performance, achieving a formate Faradaic efficiency of 92.4% while suppressing the hydrogen evolution reaction (HER) to 6.7%. Through computational modeling of the optimized heterojunction configuration, we further elucidated its competitive adsorption behavior and electronic modulation effects. The experimental and theoretical results demonstrate an improvement in electrochemical CO₂ reduction activity with suppressed hydrogen evolution for the heterojunction because of its hydrophobic interface, good electron transfer capability, and high CO₂ adsorption at the catalyst interface. This work provides a new insight into the rational design of porous crystalline materials in electrocatalytic CO₂RR. Full article

Titanium alloy/carbon fiber-reinforced polymer (TA1/CFRP) laminates, representing the latest fourth generation of fiber metal laminates (FMLs), is a kind of high-performance composite material. However, the fragility of the fiber/resin and metal/resin interface layers in these composites directly impacts their mechanical properties. To enhance these properties, this paper investigates the preparation process of multi-walled carbon nanotube (MWCNT)-reinforced ultra-thin TA1/CFRP laminates and explores the impact of MWCNT content on the interlayer properties of these ultra-thin TA1/CFRP laminates. Initially, the challenge of dispersing carbon nanotubes using ultrasonic dispersion devices and dispersants was addressed. Vacuum-curing pressure studies revealed minimal overflow at 0.8 bar vacuum. Subsequently, the impact of MWCNT content on interlayer properties was investigated. The results indicated a significant increase in interlayer shear strength and interlayer fracture toughness with MWCNT additions at 0.5 wt% and 0.75 wt%, whereas the interlayer properties decreased at 1.0 wt% MWCNT. Fracture morphology analysis revealed that MWCNT content exceeding 0.75 wt% led to agglomeration, resulting in resin cavity formation and stress concentration. Full article