Epitaxial Growth Research Articles

Preparation of unique corn-stalk-like MnO₂/CoNi nanowires via in situ epitaxial attachment growth for monitoring environmental pollutant hydrazine

This paper presents the synthesis of a novel corn-stalk-like MnO₂/CoNi oxide composite using an in situ epitaxial attachment growth strategy, in which CoNi oxide nanosheets are anchored onto MnO₂ nanowires. The one-dimensional MnO₂ nanowires, with their large specific surface area, serve as a support to enhance the electronic conductivity of the CoNi oxides. Hexamethylenetetramine (HMTA) is employed as an alkaline linking agent, playing a key role in shaping the CoNi oxide nanosheets and ensuring their successful growth on the MnO₂ nanowires. The MnO₂/CoNi oxide composite-based electrochemical sensor exhibits excellent synergistic and interfacial effects, promoting electron transfer and charge migration. This composite material shows outstanding electrocatalytic performance for hydrazine detection, with a broad linear range (0.48−6106.58 μM), low detection limit (0.286 μM, S/N = 3), and high sensitivity (0.037 μA μM⁻1). Moreover, when tested for hydrazine detection in water samples, the sensor achieved a recovery rate of 95.7–105 %, highlighting its high sensitivity and rapid response in practical applications.

Core-shell MIL-53(Al)–NH2@UiO-66 coated solid-phase microextraction Arrow for the selective enrichment of nine alkylphenols in milk

Metal-organic frameworks (MOFs) hold significant potential for sample preparation, but single-MOF materials often face limitations in selectivity and extraction efficiency. To overcome these, a mesoporous MIL-53(Al)–NH2@UiO-66 composites with a core–shell structure was synthesized using an epitaxial growth strategy. This composite leverages the complementary properties of both MOFs, offering enhanced active sites and interaction forces for analytes. The structure and integration of the composite were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction, confirming their successful integration. To address the challenge of detecting alkylphenols (APs) in food matrices, known for their endocrine-disrupting properties and low concentrations, a new solid-phase microextraction (SPME) Arrow was fabricated using the MIL-53(Al)–NH2@UiO-66 composite combined with polyacrylonitrile as a binder. APs were detected using ultra-performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-ToF/MS). The developed SPME Arrow-UPLC-ESI-Q-ToF/MS method exhibits good linearity (R2 ≥ 0.9958), wide linear range (0.01–1000 μg L–1), and high sensitivity (limits of detection ranging from 0.005 to 0.01 μg L–1) for APs determination. This method was validated for determining nine APs in milk samples from various packing materials, with spiked recoveries ranging from 85.2 % to 115 % and relative standard deviations from 3.4 % to 13.6 %. This study demonstrates the potential of MOF-on-MOF composites in enhancing the performance of adsorbents for SPME pretreatment, offering a promising approach for improving analytical methodologies in food safety.

The role of SiO2 buffer layer in the molecular beam epitaxy growth of CsPbBr3 perovskite on Si(111)

Here we present the growth of molecular beam epitaxy (MBE) CsPbBr3 perovskite films in the orthorhombic crystal structure, with unique structural and morphological properties. CsPbBr3 MBE perovskite films, with thickness ranging from a few nm to 300 nm, were grown in ultra-high vacuum on a Si(111)7 × 7 reconstructed surface, and after the formation of about 2 nm of SiO2, obtained exposing the clean reconstructed Si surface to molecular oxygen that serves to decouple the film from substrate. X-ray diffraction, and electron microscopies, such as scanning electron microscopy and high-angle annular dark-field scanning transmission electron microscopy measurements showed remarkable structural, as well as morphological features, indicating extremely high crystallinity over a large area and across the bulk of the perovskite film. Through the X-ray diffraction patterns we found very narrow (002) and (110) reflections of CsPbBr3 in pure orthorhombic phase, exhibiting a full width at half maximum of only 0.035°, value similar to a bulk Si single crystals, and a surface morphology composed of flat areas up to micrometres in lateral size. Our results shed new light both on preparation of high crystal quality perovskite films, and on the intrinsic properties of this striking fully-inorganic materials, which are exploitable for potential applications in electronic/optoelectronic devices and next generation photovoltaic solar cells.

Host-guest charge transfer for scalable single crystal epitaxy of a metal-organic framework

Methods to grow large crystals provide the foundation for material science and technology. Here we demonstrate single crystal homoepitaxy of a metal-organic framework (MOF) built of zinc, acetate and terephthalate ions, that encapsulate arrays of octahedral zinc dimethyl sulfoxide (DMSO) complex cations within its one-dimensional (1D) channels. The three-dimensional framework is built of two-dimensional Zn-terephthalate square lattices interconnected by anionic acetate pillars through diatomic zinc nodes. The charge of the anionic framework is neutralized by the 1D arrays of Zn(DMSO)62+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\rm{Zn}}}{({{\\rm{DMSO}}})}_{6}^{2+}$$\\end{document} cations that fill every second 1D channel of the framework. It is demonstrated that the repeatable and scalable epitaxy allows square cuboids of this charge-transfer MOF to grow stepwise to sizes in the centimeter range. The continuous growth with no size limits can be attributed to the ionic nature of the anionic framework with cationic 1D molecular fillers. These findings pave the way for epitaxial growth of bulk crystals of MOFs.

Molecular beam epitaxial growth and physical properties of AlN/GaN superlattices with an average 50% Al composition

Abstract We report molecular beam epitaxial growth and electrical and ultraviolet light emitting properties of (AlN)m/(GaN)n superlattices (SLs), where m and n represent the numbers of monolayers. Clear satellite peaks observed in XRD 2θ-ω scans and TEM images evidence the formation of clear periodicity and atomically sharp interfaces. For (AlN)m/(GaN)n SLs with an average Al composition of 50%, we have obtained an electron density up to 4.48×1019 cm-3 and a resistivity of 0.002 Ω·cm, and a hole density of 1.83×1018 cm-3 with a resistivity of 3.722 Ω·cm, both at room temperature. Furthermore, the (AlN)m/(GaN)n SLs exhibit a blue shift for their photoluminescence peaks, from 403 nm to 318 nm as GaN reduced from n=11 to n=4 MLs, reaching the challenging UVB wavelength range. The results demonstrate that the (AlN)m/(GaN)n SLs have the potential to enhance the conductivity and avoid the usual random alloy scattering of the high-Al-composition ternary AlGaN, making them promising functional components in both UVB emitter and AlGaN channel high electron mobility transistor applications.

High Temperature, Isothermal Growth Promotes Close Packing and Thermal Stability in DNA-Engineered Colloidal Crystals.

We report a strategy to accelerate the synthesis and increase the crystallinity of colloidal crystals (CCs) engineered with DNA. Specifically, by holding the DNA-modified Au particle building blocks above the Tm of the DNA bonding elements (i.e., free from the particles), but slightly below the Tm of the anticipated CC during the assembly process, crystallinity is increased, and enthalpically favored phases with high degrees of facet registration are observed. We studied the utility of this approach with systems for which the commonly adopted slow-cooling approach yielded primarily amorphous aggregates. In particular, we used it to synthesize high-volume fraction CCs from large (80 nm) anisotropic nanoparticles (cubes and rhombic dodecahedra) with short (<14 nm) DNA designed to restrict the degrees of freedom for the DNA bonds and maintain the anisotropy of the particle building block. Small-angle X-ray scattering and electron microscopy studies show that the crystalline phases synthesized via this method are more thermally stable than their corresponding aggregate phases, likely due to an increased number of DNA-DNA bonds between particles. Crystal size tunability (between 0.5 and 15 μm edge lengths) and epitaxial growth were demonstrated using this strategy by modulating the NaCl concentration in tandem with previously synthesized CC nuclei. Taken together, this isothermal strategy demonstrates how to deliberately crystallize a wide variety of anisotropic colloidal materials and expands the phase space accessible to nanoparticles modified with DNA.

Unraveling the multistage phase transformations in monolayer MoTe2−x

Monolayer MoTe2 exhibits a variety of derivative structural phases and associated intriguing electronic properties that enable a wealth of potential applications in future electronic and optoelectronic devices. However, a comprehensive study focusing on the complexities of the controllable phase evolution in this atomically thin film has yet to be performed. This work aims to address this issue by systematically investigating molecular beam epitaxial growth of monolayer Mo–Te compounds on bilayer graphene substrates. By utilizing scanning tunneling microscopy, we explored a series of thermally driven structural phase evolutions, including distinct T′-MoTe2, H-MoTe2, Mo6Te6 nanowires, and multistoichiometric MoTe2−x. Furthermore, we carefully investigated the critical effects of the growth parameters—annealing temperature and time and tellurium concentration—on the controllable and reversible phase transformation within monolayer MoTe2−x. The findings have significant implications for understanding the thin film synthesis and phase transformation engineering inherent to two-dimensional crystals, which can foster further development of high-performance devices.

Selective area epitaxy of gallium phosphide-based nanostructures on microsphere lithography-patterned Si wafers for visible light optoelectronics

In this study, we present the selective area plasma-assisted molecular beam epitaxial growth of GaP-based nanoheterostructures (nanostubs), incorporating direct bandgap GaAsP or GaPN segments, on patterned SiO2/Si(001) wafers. A microsphere optical lithography and anisotropic Si wet-etching techniques were employed for wafer-scale surface patterning through SiO2 growth mask, allowing to obtain either planar or pyramidal pit nucleation site morphologies. X-ray diffraction reciprocal space mapping and Raman microspectroscopy studies confirm compositional homogeneity of the nanostub arrays. The dilute nitride nanostubs display the narrowest and most intense visible red photoluminescence response at room temperature, which is an order of magnitude higher compared to the GaAsP ones. The formation of the nitrogen sub-band in GaPN alloy was confirmed in the framework of density functional theory, providing insights for interpreting the experimental results. These findings demonstrate the feasibility of the proposed approach for fabricating the ordered arrays of nanoscale visible light emitters on silicon.

Pioneering the future with silicon carbide integrated photonics

Silicon carbide (SiC) integrated photonics is advancing rapidly, promising to overcome the limitations of other integrated photonics platforms and enable new quantum devices. This progress is driven by SiC’s exceptional optical properties and significant advancements in epitaxial growth technologies, enabling wafer-scale production and manufacturability. The development of photonic components in SiC and SiC on Insulators at the wafer scale marks a paradigm shift in the role of SiC in photonics, a field dating back over 20 years. These advancements are seamlessly incorporating SiC into both integrated photonics and the emerging quantum photonics sector. SiC’s wide bandgap, high thermal conductivity, and robust nonlinear optical response make it ideal for a range of applications, from resilient photonic circuits in harsh environments to quantum devices that could revolutionize computing and communication. As research progresses, SiC-integrated photonics is poised to deliver cutting-edge, energy-efficient, and high-performance solutions that align with the goals of a sustainable and technologically advanced future.

Wafer-Scale Freestanding Monocrystalline Chalcogenide Membranes by Strain-Assisted Epitaxy and Spalling.

Monocrystalline chalcogenide thin films in freestanding forms are very much needed in advanced electronics such as flexible phase change memories (PCMs). However, they are difficult to manufacture in a scalable manner due to their growth and delamination challenges. Herein, we report a viable strategy for a wafer-scale epitaxial growth of monocrystalline germanium telluride (GeTe) membranes and their deterministic integrations onto flexible substrates. GeTe films are epitaxially grown on Ge wafers via a tellurization reaction accompanying a formation of confined dislocations along GeTe/Ge interfaces. The as-grown films are subsequently delaminated off the wafers, preserving their wafer-scale structural integrity, enabled by a strain-engineered spalling method that leverages the stress-concentrated dislocations. The versatility of this wafer epitaxy and delamination approach is further expanded to manufacture other chalcogenide membranes, such as germanium selenide (GeSe). These materials exhibit phase change-driven electrical switching characteristics even in freestanding forms, opening up unprecedented opportunities for flexible PCM technologies.

Epitaxial growth of bottom-crosslinked ZnGa2O4 nanowire arrays on c-plane GaN/Al2O3 substrate

The epitaxial growth of highly ordered ZnGa2O4 nanowire arrays and the construction of connectivity states between the individually segregated nanowires would significantly improve the performance of ZnGa2O4-based devices and expand their application fields. Herein, a strategy to construct high crystalline quality and well-aligned bottom-crosslinked ZnGa2O4 nanowire arrays along seven equivalent crystallographic directions of [111], [111̅], [11̅1], [1̅11], [11̅1̅], [1̅11̅] and [1̅1̅1] on Au-coated (0001) GaN/Al2O3 substrates using chemical vapor deposition (CVD) is proposed. The vapor-liquid-solid (VLS) mechanism dominates the entire growth process. The horizontal nanowires induced to nucleate and grow by catalyst droplets encountered and then turned towards inclined nanowires. Meanwhile, catalyst droplets that failed to move horizontally were enclosed by horizontal nanowires, resulting in the induction of perpendicular nanowire growth. The film-like horizontal nanowires connected all the inclined and perpendicular nanowires to form the bottom-crosslinked nanowire arrays. Additionally, the morphology, structure and optical properties of the ZnGa2O4 nanowire arrays, as well as the influence of Au layer thickness and growth time on the growth of ZnGa2O4 nanowires, were further characterized and thoroughly investigated. The proposed strategy achieved the growth of epitaxial well-aligned ZnGa2O4 nanowire arrays with bottom cross-linking, which is conducive to the application of ZnGa2O4 nanowires in optoelectronics.

Tailored porosity in additive manufacturing of 7075 aluminum alloy for crack suppression and high strength

Laser-directed energy deposition (LDED) additive manufacturing of 7075 aluminum (Al) alloy is highly challenging due to the inherent poor printability and high cracking tendency. Here, we disclose a new approach to suppress cracking in LDED-processed 7075 Al alloy by engineered porosity (about 1.14 %). The crack-free 7075 Al alloy was achieved by slightly sacrificing the densification. Further increasing the density of the material by increasing laser energy input leads to cracking. The mechanisms of minor pores in alleviating cracks are mainly reflected in three aspects: (i) pores disrupt the epitaxial growth of columnar grains; (ii) free-form surfaces surrounding pores could release the accumulated residual stress, and (iii) more dislocations near pore drive nucleation of near equiaxed grains. The LDED-processed crack-free 7075 Al alloy after heat treatment shows an ultimate tensile strength of 464 ± 12 MPa and break elongation of 9.7 ± 1.2 %, attaining a good strength-ductility synergy among many additively manufactured 7075 Al alloys in the current literature. Unlike the mainstream additive manufacturing of metallic materials, which pursues high densification to attain high-performance components, this work demonstrates the positive roles of pores in the additive manufacturing of cracking-sensitive materials. The findings of this work highlight new insights regarding the balance between pores and cracks for better manufacturability and higher mechanical performance of materials.

Optimization of sodium-ion battery cathode performance by nickel-based Prussian blue epitaxial growth with iron-based Prussian blue core-shell structure

To address the structural defects and poor electrical conductivity of conventional Prussian blue analogues (PBAs) samples, in this study, nickel hexacyanoferrate (NiHCF) and nickel hexacyanoferrate epitaxially grown with iron hexacyanoferrate (Ni@FeHCF-X) series of samples were successfully synthesized by co-precipitation combined with epitaxial growth technique, and their structural and electrochemical properties were systematically characterized. X-ray powder diffractometer (XRD) results show that all the samples maintain a cubic crystal system structure, and the diffraction peaks of the (220) and (400) crystal planes are shifted to a lower angle with the epitaxial growth of ferric hexacyanoferrate (FeHCF). The successful embedding of Fe was confirmed by inductively coupled plasma (ICP) measurement data. Scanning electron microscope (SEM) images show that the samples are in a cubic morphology, and the surfaces gradually become rounded from sharp to rounded with the increase of the Fe content. High-resolution transmission electron microscope (HRTEM) and energy-dispersive spectrometer (EDS) analyses confirm the successful construction of the core-shell structure and the homogeneous distribution of the elements. Electrochemical testing showed that the Ni@FeHCF-X samples exhibited higher specific capacities and superior rate performance compared to NiHCF, particularly the Ni@FeHCF-4 sample, which delivered a high specific capacity of 73.4 mAh·g⁻¹ at a current density of 100 mA·g⁻¹, significantly outperforming the 38.2 mAh·g⁻¹ achieved by NiHCF. Additionally, the capacity retention rate of Ni@FeHCF-4 reached 42.16 %. Electrochemical impedance spectroscopy (EIS) further confirmed the reduced charge transfer resistance and enhanced reversibility of the electrochemical reactions in the Ni@FeHCF-X samples. These results demonstrate that Ni@FeHCF-4 significantly enhances the electrochemical performance of the samples in aqueous sodium-ion battery, providing new insights into the design of cathode materials for sodium-ion batteries.

Intensity noise and modulation dynamics of an epitaxial mid-infrared interband cascade laser on silicon

Interband cascade lasers typically have significantly lower threshold current and power consumption than quantum cascade lasers. They can also have advantages regarding costs and compactness with the photonic integration onto silicon substrates by epitaxial growth. This research introduces a novel examination of the relative intensity noise and the modulation dynamics of a silicon-based Fabry–Perot interband cascade laser emitting at 3.5 μm. The investigation delves into crucial parameters, such as relaxation oscillation frequency, differential gain, gain compression, and K-factor. The resonance patterns identified in relative intensity noise curves can provide essential insights for the thorough characterization of high-defect mid-infrared semiconductor structures intended for high-speed applications. Moreover, this study demonstrates the feasibility of reaching 10 Gbit/s free-space transmission using a silicon-based interband cascade laser in conjunction with an interband cascade infrared photodetector.

Microstructural and mechanical properties of TiN/CrN and TiSiN/CrN multilayer coatings deposited in an industrial-scale HiPIMS system: Effect of the Si incorporation

Surface engineering through the deposition of advanced coatings, particularly multilayer coatings has gained significant interest for enhancing the performance of coated parts. The incorporation of Si into TiN coatings has shown promise for improving hardness, oxidation resistance, and thermal stability, while high-power impulse magnetron sputtering (HiPIMS) has emerged as a technique to deposit coatings with exceptional properties. However, TiN/CrN and TiSiN/CrN coatings deposited by HiPIMS remain relatively unexplored. In this study, different TiN/CrN and TiSiN/CrN multilayer coatings with different bilayer periods from 5 to 85 nm were deposited using an industrial-scale HiPIMS reactor, and their microstructure and mechanical properties were investigated using advanced characterization techniques. Results revealed successful deposition of smooth and compact coatings with controlled bilayer periods. X-ray diffraction analysis showed separate crystalline phases for coatings with high bilayer periods, while those with smaller bilayer periods exhibited peak-overlapping and superlattice overtones, especially for the TiN/CrN coatings. Epitaxial grain growth was confirmed by high-resolution transmission electron microscopy (HRTEM). HRTEM and electron energy-loss spectroscopy measurements confirmed Si incorporation into the TiN crystal lattice of TiSiN/CrN coatings reducing the crystallinity, especially for coatings with smaller bilayer periods. Nanoindentation tests revealed that coatings with a bilayer period of 15–20 nm displayed the highest hardness values regardless of the composition. The mechanical properties of the TiSiN/CrN coatings showed no improvement over those of the TiN/CrN coatings, attributed to the Si induced amorphization of the Ti(Si)N phase and the absence of SiNx phase segregation within the TiN nanocrystals in these coatings. These findings provide valuable insights into the microstructure and mechanical properties of TiN/CrN and TiSiN/CrN multilayer coatings deposited by HiPIMS in an industrial scale reactor, paving the way for their application in various industrial sectors.

Confined synthesis of ultrafine NiCu nanoalloy anchored nanoflower derived from natural attapulgite for efficient catalytic hydrogenation of p-nitrophenol

Improving the performance of catalysts through precise microstructural design is important for their applications. Herein, a series of nanoflower-shaped NiCu nanoalloy/nickel-copper silicate (NiCuSi)/attapulgite (ATP) nanocomposite catalysts was successfully constructed. Initially, the NiCuSi/ATP substrates were prepared using Ni2+ and Cu2+ ions to induce the epitaxial growth of acid-leached ATP. Afterwards, the domain-limited Ni2+ and Cu2+ ions in the silicon framework of NiCuSi were transformed to ultra-small NiCu nanoalloy particles (∼5.71 nm) through an in-situ reduction process. Due to the unique morphology and structure, the catalyst exhibited a specific surface area of up to 227.05 m2/g, which exposed abundant active sites to contact with the reactant molecules. The uniformly dispersed ultra-small NiCu nanoalloys effectively promoted the rapid transfer of interface electrons, resulting in excellent catalytic efficiency of the catalyst. Its catalytic reduction rate for PNP is as high as 0.374 s−1, equivalent to those of the precious metal catalysts, and the excellent catalytic efficiency remains at 98.53 % even after 10 cycles. This study provides a universal and efficient method to develop highly active and stably nanocomposite catalysts from natural and green carries.

TiO2 Films with Macroscopic Chiral Nematic-Like Structure Stabilized by Copper Promoting Light-Harvesting Capability for Hydrogen Generation.

Cellulose nanocrystals (CNCs) have inspired the synthesis of various advanced nanomaterials, opening opportunities for different applications. However, a simple and robust approach for transferring the long-range chiral nematic nanostructures into TiO2 photocatalyst is still fancy. Herein, a successful fabrication of freestanding TiO2 films maintaining their macroscopic chiral nematic structures after removing the CNCs biotemplate is reported. It is demonstrated that including copper acetate in the sol avoids the epitaxial growth of the lamellar-like structure of TiO2 and stabilizes the chiral nematic structure instead. The experimental results and optical simulation demonstrate an enhancement at the blue and red edges of the Fabry-Pérot reflectance peak located in the visible range. This enhancement arises from the light scattering effect induced by the formation of the chiral nematic structure. The nanostructured films showed 5.3 times higher performance in the photocatalytic hydrogen generation, compared to lamellar TiO2, and benefited from the presence of copper species for charge carriers' separation. This work is therefore anticipated to provide a simple approach for the design of chiral nematic photocatalysts and also offers insights into the electron transfer mechanisms on TiO2/CuxO with variable oxidation states for photocatalytic hydrogen generation.

Probing microstructural evolution behaviors in laser welding of dissimilar GH4169/GH3039 subjected to varied preheating temperatures

The present study examined the evolution of interfacial microstructure and on the element distribution of GH4169/GH3039 dissimilar joints by laser welding under different preheating temperatures. The results indicated that the microstructure observed in the interface layer on the GH4169 side exhibited distinct layers, namely diffusion layer and transition layer, which varied depending on the varied preheating temperature. Within the weld seam (WS), two types of dendrites were predominantly present: lath-like columnar dendrite and cellular dendrite. In the GH3039 side, the grain structure was mainly dominated by columnar dendrites, exhibits perpendicular growth to the fusion line and demonstrates a certain epitaxial growth morphology. Moreover, excessive preheating temperature intensified the migration of elements and phase transition behavior. As the preheating temperature increased, the low-angle grain boundaries (LAGBs) percentage decreased from 13% to 9.4%. The average grain size of the WS at room temperature, 200°C and 400°C is 44.1 μm, 53.3 μm and 58.2 μm, respectively. This paper provides a basis for tuning microstructure and element behavior via preheating temperature optimization in laser welding of dissimilar GH4169/GH3039 for further engineering application.

High-quality heteroepitaxial growth of β-Ga2O3 with NiO buffer layer based on Mist-CVD

The heteroepitaxial growth of β-Ga2O3 on the commonly used sapphire substrate presents great challenges due to their large lattice mismatch. To address this, a NiO buffer layer is proposed to improve the quality of the heteroepitaxial β-Ga2O3, as it has a lower lattice mismatch(0.46%) with β-Ga2O3 compared to sapphire(6.6%). Traditional epitaxial growth methods for Ga2O3 are not compatible with NiO growth, so an inexpensive, non-vacuum, and convenient Mist-CVD technology is used for heterogeneous β-Ga2O3 growth in this study. XRD and TEM results demonstrate the high quality of β-Ga2O3 sample with the clear interface between materials. Introducing a NiO buffer layer enables the Full Width at Half Maximum (FWHM) and root-mean-square (RMS) roughness of β-Ga2O3 to reduce from 0.726° to 0.514° and from 7.47 nm to 3.34 nm respectively. Additionally, through the UDM analysis model, micro-strain within the film is found to significantly decrease. This work proposes a novel approach to improve the quality of β-Ga2O3 heteroepitaxial growth on sapphire substrate, contributing to the advancement of Ga2O3 materials and devices.

Bimetallic Fe–Cu metal-organic frameworks for capturing of radioactive iodine in solution and vapor phases

Effectively removing radioactive iodine from the environment is critical for mitigating the risks associated with nuclear accidents. This research presents a brand-new Fe-Cu-BTC metal-organic framework (MOF) composite that works very well to absorb iodine. We employed a facile one-pot solvothermal method to achieve epitaxial growth of Fe-BTC on a Cu-BTC substrate. A full analysis using SEM, EDS, FTIR, XRD, BET, TEM, XPS, Raman, and TGA/DTA showed that the composite was successfully made while the crystalline structure of the CuBTC was kept. It was amazing how well the Fe-Cu-BTC composite could absorb iodine, reaching maximum capacities of 217.92 mg/g in solution and 623.21 mg/g in vapor phases, respectively, within the time limits given. The material demonstrated remarkable stability and recyclability, retaining its structural integrity and efficiency over five consecutive adsorption-desorption cycles. The high BET surface area of 820.35 m/g, pore volume of 0.328 cm/g, and pore diameter of 2.950 nm of the composite contributes to its superior adsorption performance. The composite exhibits exceptional stability under acidic conditions with a pH of 2>8.Studies of the adsorption isotherm and kinetics showed that the Langmuir and pseudo-second-order models correctly describe how iodine binds, with R² values of 0.995 and 0.994, respectively. XPS and Raman spectroscopy with peak values (72.21, 104.4, and 167.04) cm-1 confirmed the formation of polyiodides (I₃⁻ and I₅⁻) on the MOF surface, suggesting a physical adsorption mechanism.The Fe-Cu-BTC composite has a controlled synthesis, millimeter-scale dimensions, a porous structure, is very stable, and can be recycled easily. It looks like it could be a good way to capture and store iodine from a variety of environmental sources, such as reprocessing plant off-gas streams and liquid effluents.