Search Results (160)

The development of high-performance adsorbent materials is crucial for any sorption-based energy conversion process. In such a context, composite sorbent materials, although promising in terms of performance and stability, are often challenging to shape into complex geometries. Additive manufacturing, also known as 3D printing, has emerged as a powerful technique for fabricating intricate structures with tailored properties. In this paper, an innovative three-dimensional structure, constituted by zeolite as filler and sulfonated polyether ether ketone as matrix, was obtained using additive manufacturing technology, which is mainly suitable for sorption-based energy conversion processes. The lattice structure was tailored in order to optimize the synthesis procedure and material stability. The complex three-dimensional lattice structure was obtained without a metal or plastic reinforcement support. The composite structure was evaluated to assess its structural integrity using morphological analysis. Furthermore, the adsorption/desorption capacity was evaluated using water-vapor adsorption isobars at 11 mbar at equilibrium in the temperature range 30–120 °C, confirming good adsorption/desorption capacity. Full article

Direct chemical vapor deposition (CVD) growth of hexagonal boron nitride (h-BN) on insulating substrates offers a promising pathway to circumvent transfer-induced defects and enhance device integration. This comprehensive review systematically evaluates recent advances in CVD techniques for h-BN synthesis on insulating substrates, including metal–organic CVD (MOCVD), low-pressure CVD (LPCVD), atmospheric-pressure CVD (APCVD), and plasma-enhanced CVD (PECVD). Key challenges, including precursor selection, high-temperature processing, achieving single-crystalline films, and maintaining phase purity, are critically analyzed. Special emphasis is placed on comparative performance metrics across different growth methodologies. Furthermore, crucial research directions for future development in this field are outlined. This review aims to serve as a reference for advancing h-BN synthesis toward practical applications in next-generation electronic and optoelectronic devices. Full article

The incorporation of MAX phase interface layers into silicon carbide (SiC) composites has been shown to significantly enhance mechanical properties, particularly under irradiation conditions. However, conventional Ti-based MAX phases suffer from thermal instability and tend to decompose at high temperatures. In this work, an Sc₂SnC coating was successfully synthesized onto the surface of SiC fibers (SiC_f) via an in situ reaction between metals and pyrolytic carbon (PyC) in a molten salt environment. The PyC layer, pre-deposited by chemical vapor deposition (CVD), served as both a carbon source and a structural template. Characterization by SEM, XRD, and Raman spectroscopy confirmed the formation of Sc₂SnC coatings with a distinctive hexagonal flake-like morphology, accompanied by an internal ScC_x intermediate layer. By turning the Sc-to-Sn ratio in the molten salt, coatings with varied morphologies were achieved. ScC_x was identified as a critical intermediate phase in the synthesis process. The formation of numerous defects during the reaction enhanced element diffusion, resulting in preferential growth orientations and diverse grain structures in the Sc₂SnC coating. Full article

The aim of this study is to investigate a green and efficient hydrothermal synthesis method for obtaining a high-purity MIL-100(Fe) metal–organic framework (MOF) without using hazardous HF acid or other toxic reagents. The influence of various synthesis conditions (reactant ratios and reaction times) and washing protocols on the MOF’s properties and crystallinity was investigated. Additionally, the adsorption capacities of the synthesized MIL-100(Fe) for hydrogen (H₂), carbon dioxide (CO₂), and water vapor were evaluated at different temperatures and pressures. By analyzing the adsorption behavior, this research study aims to assess the potential of this material for thermal or specific gas storage applications. MF-S1 synthesis, using less iron and water, produces the purest MIL-100(Fe), as confirmed by XRD and FTIR. MF-S1-W2, with additional washing, is ideal for gas adsorption due to its crystallinity, purity, and high surface area. It effectively stores hydrogen (0.25 wt.% at 5 °C), CO₂ (32.6 wt.% at 5 °C), and water vapor (47.5 wt.% at 30 °C). Full article

Two-dimensional transition metal dichalcogenides have attracted considerable attention in electrocatalytic hydrogen evolution due to their unique layered structures and tunable electronic properties. However, prior research has predominantly focused on the intrinsic catalytic activity of planar few-layer structures, which offer limited exposure of edge-active sites due to their restricted two-dimensional geometry. Moreover, van der Waals interactions between layers impose substantial barriers to electron transport, significantly hindering charge transfer efficiency. To overcome these limitations, this study presents the innovative synthesis of high-quality single-screw WS₂ with a 5° dislocation angle via physical vapor deposition. Second harmonic generation measurements revealed a pronounced asymmetric polarization response, while the selected area electron diffractionand atomic force microscopy elucidated the material’s distinctive screwed dislocation configuration. In contrast to planar monolayer WS₂, the conical/screw-structured WS₂—formed through screw-dislocation-mediated growth—exhibits a higher density of exposed edge-active catalytic sites and enhanced electron transport capabilities. Electrochemical performance tests revealed that in an alkaline medium, the screwed WS₂ nanosheets exhibited an overpotential of 310 mV at a current density of −10 mA/cm², with a Tafel slope of 204 mV/dec. Additionally, under a current density of 18 mA/cm², the screwed WS₂ can sustain this current density for at least 30 h. These findings offer valuable insights into the design of low-cost, high-efficiency, non-precious metal catalysts for hydrogen evolution reactions. Full article

We prepared antimony metal films via electrodeposition, followed by the synthesis of Sb₂S₃ films through a chemical vapor phase reaction. Finally, an Sb₂O₃ film was deposited onto the Sb₂S₃ film using a chemical bath method, successfully constructing a heterojunction photocathode of Sb₂S₃/Sb₂O₃; the synthesized Sb₂S₃/Sb₂O₃ heterojunction is classified as a Type I heterostructure. The resulting Sb₂S₃/Sb₂O₃ heterojunction exhibited a photocurrent density of −0.056 mA cm⁻² at −0.15 V (vs. RHE), which is 1.40 times higher than that of Sb₂S₃ alone under simulated solar illumination. Additionally, the Sb₂S₃/Sb₂O₃ heterojunction demonstrated a lower carrier recombination rate and a faster charge transfer rate compared to Sb₂S₃, as evidenced by photoluminescence and electrochemical impedance spectroscopy tests. For these reasons, the Sb₂S₃/Sb₂O₃ heterojunction obtained a hydrogen precipitation rate of 0.163mL cm⁻² h⁻¹, which is twice the hydrogen precipitation rate of Sb₂S₃, under the condition of 60 min of light exposure. The significant enhancement in photoelectrochemical performance is attributed to the formation of the Sb₂S₃/Sb₂O₃ heterojunction, which improves both carrier separation and charge transfer efficiency. This heterojunction strategy holds promising potential for visible light-driven photoelectrochemical water splitting. Full article

Metal halide perovskites have emerged as a groundbreaking material class for photovoltaic applications, owing to their exceptional optoelectronic properties, tunable bandgap, and cost-effective fabrication processes. This review offers a comprehensive analysis of recent advancements in synthesis, structural engineering, and characterization of metal halide perovskites for efficient solar energy conversion. We explore a range of fabrication techniques, including solution processing, vapor deposition, and nanostructuring, emphasizing their impact on material stability, efficiency, and scalability. Additionally, we discuss key characterization methods, such as X-ray diffraction, electron microscopy, impedance spectroscopy, and optical analysis, that provide insights into the structural, electrical, and optical properties of these materials. Despite significant progress, challenges related to long-term stability, degradation mechanisms, and environmental sustainability persist. This review delves into current strategies for enhancing the durability and performance of perovskite-based photovoltaics and highlights emerging trends in device integration and commercialization. Finally, we provide future perspectives on optimizing material design and overcoming existing limitations to guide continued research in this rapidly advancing field. Full article

Transition metal sulfide (TMS)-based electrocatalysts have received considerable attention in the field of sustainable energy, especially for their high activity in the hydrogen evolution reaction (HER). This review summarizes how researchers have improved the performance of TMSs by adjusting their composition. This review introduces the research background of transition metal sulfides and clarifies the reaction mechanism of the HER and its performance evaluation indicators. Then, it elaborates on the general synthesis techniques for preparing TMS materials, including hydrothermal methods, electrochemical deposition, liquid-phase exfoliation, chemical vapor deposition, and other methods. Moreover, it discusses the realization of excellent electrocatalytic performance in the HER through doping, hole treatment, heterostructures, and multi-sulfides. Finally, this review summarizes the current challenges and future development opportunities of TMS materials in the field of water electrolysis for hydrogen production. Full article

We report the synthesis and characterization of new, user-friendly gold(I) [Au₄(μ-(NH)₂CC₂F₅)₄]_n coordination polymer and [Au₂Cl₂(NH₂(NH=)CC₂F₅)₂]_n complex. These compounds were investigated for potential application as precursors in chemical vapor deposition (CVD) and focused electron/ion beam-induced deposition (FEBID/FIBID), which are additive methods to produce nanomaterials. Single-crystal X-ray diffraction, elemental analysis, and infrared spectroscopy were used to determine the complexes’ composition and structure. We studied their thermal stability and volatility using thermal analysis and variable-temperature infrared spectroscopy (VT IR) and by conducting sublimation experiments. The gold(I) amidinate [Au₂(μ-(NH)₂CC₂F₅)₂]_n sublimates at 413 K under 10⁻² mbar pressure. The electron-induced decomposition of the complexes’ molecules in the gas phase and of their thin layers on silicon substrates was analyzed using electron impact mass spectrometry (EI MS) and microscopy studies (SEM/EDX), respectively, to provide insights for FEBID and FIBID precursor design. The [Au₂Cl₂(NH₂(NH=)CC₂F₅)₂]_n hydrogen chloride molecules evolved during heating, with the formation of gold(I) amidinate. The obtained results revealed that the new gold(I) amidinate may be a promising source of metal for nanomaterial fabrication by gas-assisted methods. Full article

This review summarized the developments in the field of volatile silver complexes, which can serve as precursors in gas-transport reactions for the production of thin films and metal nanoparticles via chemical vapor deposition (CVD) and atomic layer deposition (ALD). Silver-based films and nanoparticles are widely used in various high-tech fields, including medicine. For effective use in CVD and ALD processes, the properties of silver precursors must be balanced in terms of volatility, thermal stability, and reactivity. In this review, we focus on the synthesis and comprehensive analysis of structural and thermal characteristics for the most promising classes of volatile silver complexes, as well as organometallic compounds. Following the specifics of silver chemistry, some features of the use of precursors and their selection, as well as several key directions to improving the efficiency of silver material deposition processes, are also discussed. Full article

Boron nitride nanostructures (BNNs), including nanotubes, nanosheets, and nanoribbons, are renowned for their exceptional thermal stability, chemical inertness, mechanical strength, and high surface area, making them suitable for advanced material applications. Metal–organic frameworks (MOFs), characterized by their porous crystalline structures, high surface area, and tunable porosity, have emerged as excellent candidates for gas adsorption and storage applications, particularly in the context of hydrogen. This paper explores the synthesis and properties of BNNs and MOFs, alongside the innovative approach of integrating BNNs within MOFs to create composite materials with synergistic properties. The integration of BNNs into MOFs enhances the overall thermal and chemical stability of the composite while improving hydrogen sensing and storage performance. Various synthesis methods for both BNNs and MOFs are discussed, including chemical vapor deposition, solvothermal synthesis, and in situ growth, with a focus on their scalability and reproducibility. Furthermore, the mechanisms underlying hydrogen sensing and storage are examined, including physisorption, chemisorption, charge transfer, and work function modulation. Electrochemical characterization techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge, are used to analyze the performance of BNN-MOF systems in hydrogen storage and sensing applications. These methods offer insights into the material’s electrochemical behavior and its potential to store hydrogen efficiently. Potential industrial applications of BNN-MOF composites are highlighted, particularly in fuel cells, hydrogen-powered vehicles, safety monitoring in hydrogen production and distribution networks, and energy storage devices. The integration of these materials can contribute significantly to the development of more efficient hydrogen energy systems. Finally, this study outlines key recommendations for future research, which include optimizing synthesis techniques, improving the hydrogen interaction mechanisms, enhancing the stability and durability of BNN-MOF composites, and performing comprehensive economic and environmental assessments. BNN-MOF composites represent a promising direction in the advancement of hydrogen sensing and storage technologies, offering significant potential to support the transition toward sustainable energy systems and hydrogen-based economies. Full article

Pore engineering is commonly used to alter the properties of metal–organic frameworks. This is achieved by incorporating different linker molecules (L) into the structure, generating isoreticular frameworks. CPO-27, also named MOF-74, is a prototypical material for this approach, offering the potential to modify the size of its one-dimensional pore channels and the hydrophobicity of pore walls using various linker ligands during synthesis. Thermal activation of these materials yields accessible open metal sites (i.e., under-coordinated metal centers) at the pore walls, thus acting as strong primary binding sites for guest molecules, including water. We study the effect of the pore size and linker hydrophobicity within a series of Ni²⁺-based isoreticular frameworks (i.e., Ni₂L, L = dhtp, dhip, dondc, bpp, bpm, tpp), analyzing their water sorption behavior and the water interactions in the confined pore space. For this purpose, we apply water vapor sorption analysis and Fourier transform infrared spectroscopy. In addition, defect degrees of all compounds are determined by thermogravimetric analysis and solution ¹H nuclear magnetic resonance spectroscopy. We find that larger defect degrees affect the preferential sorption sites in Ni₂dhtp, while no such indication is found for the other materials in our study. Instead, strong evidence is found for the formation of water bridges/chains between coordinating water molecules, as previously observed for hydrophobic porous carbons and mesoporous silica. This suggests similar sorption energies for additional water molecules in materials with larger pore sizes after saturation of the primary binding sites, resulting in more bulk-like water arrangements. Consequently, the sorption mechanism is driven by classical pore condensation through H-bonding anchor sites instead of sorption at discrete sites. Full article

Aqueous phase reforming (APR) is a promising method for producing hydrogen from biomass-derived feedstocks. In this study, carbon-supported Pt catalysts containing particles of different sizes (below 3 nm) were deposited on different commercially available carbons (i.e., Vulcan XC72 and Ketjenblack EC-600JD) using the metal vapor synthesis approach, and their catalytic efficiency and stability were evaluated in the aqueous phase reforming of ethylene glycol, the simplest polyol containing both C–C and C–O bonds. High-surface-area carbon supports were found to stabilize Pt nanoparticles with a mean diameter of 1.5 nm, preventing metal sintering. In contrast, Pt single atoms and clusters (below 0.5 nm) were not stable under the reaction conditions, contributing minimally to catalytic activity and promoting particle growth. The most effective catalyst Pt_A/C^K, containing a mean Pt NP size of 1.5 nm and highly dispersed on Ketjenblack carbon, demonstrated high hydrogen site time yield (8.92 min⁻¹ at 220 °C) and high stability under both high-temperature treatment conditions and over several recycling runs. The catalyst was also successfully applied to the APR of polyethylene terephthalate (PET), showing potential for hydrogen production from plastic waste. Full article

Acetone detection is of significant importance in various industries, from cosmetics to pharmaceuticals, bioengineering, and paints. Sensor manufacturing involves the use of different semiconductor materials as well as different metals for doping and functionalization, allowing them to achieve advanced or unique properties in different sensor applications. In the healthcare field, these sensors play a crucial role in the non-invasive diagnosis of various diseases, offering a potential way to monitor metabolic conditions by analyzing respiration. This article presents the synthesis method, using chemical solutions and rapid thermal annealing technology, to obtain Al-functionalized and Ni-doped copper oxide (Al/CuO:Ni) nanostructured thin films for biosensors. The nanocrystalline thin films are subjected to a thorough characterization, with examination of the morphological properties by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis. The results reveal notable changes in the surface morphology and structure following different treatments, providing insight into the mechanism of function and selectivity of these nanostructures for gases and volatile compounds. The study highlights the high selectivity of developed Al/CuO:Ni nanostructures towards acetone vapors at different concentrations from 1 ppm to 1000 ppm. Gas sensitivity is evaluated over a range of operating temperatures, indicating optimum performance at 300 °C and 350 °C with the maximum sensor signal (S) response obtained being 45% and 50%, respectively, to 50 ppm gas concentration. This work shows the high potential of developed technology for obtaining Al/CuO:Ni nanostructured thin films as next-generation materials for improving the sensitivity and selectivity of acetone sensors for practical applications as breath detectors in biomedical diagnostics, in particular for diabetes monitoring. It also emphasizes the importance of these sensors in ensuring industrial safety by preventing adverse health and environmental effects of exposure to acetone. Full article

To qualify as competent sorbents for airborne contaminants such as iodine vapor, permanent porosity and chemical stability are key criteria for the selection of candidate metal-organic frameworks (MOFs). To ensure these characteristics, in the present study, an unsymmetrical bifunctional ligand incorporating both carboxylic acid and hydroxamic acid groups was employed for MOF [Zn(CBHA)](DMF) [SUM-13; CPHA = 4-carboxyphenylhydroxamate, DMF = N,N-dimethylformamide] design and synthesis. Though coupled with Zn²⁺, which does not typically yield kinetically robust MOFs with hard acids, the SUM-13 featuring differentiated coordination modes of chelating, bridging and monodentate bonding exhibited exceptional chemical stability and permanent porosity, with a Brunauer–Emmett–Teller (BET) surface area of 296.9 m²/g and a total pore volume of 0.1196 cm³/g. Additionally, with porosity and open metal sites at the five-coordinate Zn²⁺ centers, SUM-13 was demonstrated to be an eligible iodine adsorbent, reaching a maximum uptake of 796 mg/g. These findings underscore the validity and potential of the design strategy in constructing stable metal–organic frameworks. Full article