Lattice Parameters Research Articles

Customizing Bonding Affinity with Multi-Intermediates via Interfacial Electron Capture to Boost Hydrogen Evolution in Alkaline Water Electrolysis.

Developing efficient and earth-abundant alkaline HER electrocatalysts is pivotal for sustainable energy, but co-regulating its intricate multi-step process, encompassing water dissociation, OH- desorption, and hydrogen generation, is still a great challenge. Herein, we tackle these obstacles by fabricating a vertically integrated electrode featuring a nanosheet array with prominent dual-nitride metallic heterostructures characterized by impeccable lattice matching and excellent conductivity, functioning as a multi-purpose catalyst to fine-tune the bonding affinity with alkaline HER intermediates. Detailed structural characterization and theoretical calculation elucidate that charge redistribution at the heterointerface creates electron-accumulating W-W sites, which reduces the O p-W d and H s-W d interactions vs. single nitride, thereby enhancing OH- transfer and H2 release. As anticipated, the resulting WN-NiN/CFP catalyst demonstrates a gratifying low overpotential of 36.8 mV at 10 mA/cm² for alkaline HER, while concurrently maintainingoperational stability for 1300 h at 100 mA/cm² for overall water splitting. This work presents an effective approach to meticulously optimize multiple site-intermediate interactions in alkaline HER, laying the foundation for efficient energy conversion.

Phase stability of solid solution La1-xRxRh3B (R = Gd, Lu and Sc) compounds with cubic anti-perovskite type structure

We have investigated the solid solution range of single phase La1-xRxRh3B (R = Gd, Lu and Sc) compounds with a cubic anti-perovskite type structure. The behaviors of lattice parameters, hardness, and thermogravimetry–differential thermal analysis (TG-DTA) were also investigated. The cubic anti-perovskite phase exists over the entire composition range x from 0.0 to 1.0 for all La-Gd, La-Lu and La-Sc systems. Both the lattice parameters and the hardness in all La-Gd, La-Lu and La-Sc systems show a linear dependence on the degree of the substitution x of La atom. The results of TG-DTA measurements indicate that oxidation of the compounds in air begins at about 500–600 K. The mixed phases of RBO3, R2O3 and Rh are identified as oxidized products around x = 0.4 to 0.6 composition. The oxidation onset temperature, and weight gains due to the oxidation depend on the degree of substitution x. The behavior of crystallographic and physical/chemical properties in the present compounds La1-xRxRh3B strongly depend on the atomic size of the rare-earth atoms that form the cubic framework.

Structural evolution and magnetic, optical, and optoelectronic properties changes in annealed Co0.5Sr0.5Fe2O4 nanoparticles: A comprehensive study

A sample of Co0.5Sr0.5Fe2O4 nanoparticles was synthesized by the coprecipitation technique to explore the effect of annealing on the structure and some physical properties of the produced material. The coprecipitated sample consists of an orthorhombic strontium carbonate phase and the required cubic Co0.5Sr0.5Fe2O4. Annealing at elevated temperatures (900 °C) leads to the formation of cubic and hexagonal phases. This crystal structure was confirmed by X-ray diffraction analysis (XRD). The accuracy of the cation distribution of the cubic phase determined from the Rietveld analysis of XRD patterns is demonstrated by matching the experimental and theoretical lattice constants. There are several noticeable changes in aspects as the annealing temperature goes up. The transmission electron microscopy (TEM) images indicated that heating substantially affects the growth and densification of the smaller nanoparticles. There is a drop in the longitudinal and transverse wave velocities, bulk, rigidity, Young's moduli, Poisson ratio (σ), and Debye temperature (θD) with annealing and grain growth. The saturation magnetization and coercive field are enhanced with annealing. The particle size distribution calculated from TEM is confirmed and supported by the switching field distribution. The indirect optical bandgap energy (Eg) decreased with annealing. The present study concentrated on the thermal treatment impacts on various optical parameters, such as the refractive index and extinction coefficient. The optoelectrical parameters, such as the dielectric constant, dielectric loss, and optical and electrical conductivity, were extensively investigated, giving valuable insights, and their results were interpreted. These findings suggest potential applications in magnetic storage, sensors, and optoelectronics fields.

“Investigating impact of Ni-Cd substitution on structural magnetic and optical properties of nanosize Al ferrites”

Ferrites are among the most extensively studied materials, specifically due to their amazing and diverse characteristics. Therefore, we synthesized NixCd1-xAlyFe2-yO4 (NCAF) ferrites using a microwave auto-combustion process, with x varying from 0.0 to 1.0 and y set at 0.1. We conducted a meticulous characterization of their structural, surface morphological, magnetic, molecular vibrational and optical properties. X-ray diffraction confirms the lattice parameter and a single-phase spinel structure. Rietveld refined XRD patterns identified the Fd-3m space group cubic spinel phase. HR-TEM examination shows pseudo-spherical particles with an average size of 40–45 nm. Surface topography exhibits tiny, spherical microstructures. The lognormal histogram showed an average particle size of 56.6 nm–124.8 nm, decreasing with nickel concentration. At a nickel concentration (x) of 0.6, saturation magnetization (Ms) increases and then decreases at 1.0. FTIR confirms no organic phase and spinel development. Absorption measurements determined the band gap energy, which Tauc plot revealed to be 2.5870–2.1657 eV. We used the Kubelka-Munk function to find the band gap energy in the UV–Vis diffuse reflectance spectra (DRS), which was between 2.0027 and 1.6817 eV.

Investigation of Structural, Elastic and Magnetic Properties of CoCr2-xZrxO4 Nanoparticles.

This study investigates the impact of zirconium substitution on the structural, elastic and magnetic properties of CoCr2O4 nanoparticles. A series of CoCr2-xZrxO4 nanoparticles, x = 0.00, 0.05, 0.10, 0.15 and 0.20, are synthesized via the co-precipitation method. X-ray diffraction (XRD) patterns affirm the formation of single-phase cubic structure with the space group Fd3m. Special attention is given to accurately calculating the average crystallite size (D) and lattice parameter (a) using Williamson-Hall (W-H) analysis and the Nelson-Riley (N-R) extrapolation function, respectively. The increase in Zr4+ content leads to a reduction in crystallite size and an increase in the lattice parameter. Elastic properties are estimated from force constants and the lattice constant, determined from FTIR and XRD, respectively. The observed changes in the elastic constants are attributed to the strength of interatomic bonding. The stiffness constants decrease, while Poisson's ratio increases with increasing Zr4+ content, reflecting the increase in the ductility of the prepared samples. As the Zr4+ content increases, the stiffness constants decrease, and Poisson's ratio increases, reflecting enhanced ductility of the samples. Furthermore, as Zr4+ content rises, Young's modulus, the rigidity modulus and Debye temperature decrease. The magnetic hysteresis loop measurements are carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of 25 kg. Unsubstituted CoCr2O4 exhibits ferrimagnetic behavior. As Zr4+ content increases, saturation magnetization (Ms) and magnetic moment decrease, while remanent magnetization (Mr) and coercivity (Hc) initially decrease up to x = 0.10, then increase with further increases in x. The novel key of this study is how Zr4+ substitution in CoCr2O4 nanoparticles can effectively modify their elastic moduli and magnetic properties, making them suitable for various applications such as flexible electronics, protective coatings, energy storage components and biomedical implants.

Determination of rare earth elements in synthetic calcium phosphates by high-resolution continuum source electrothermal atomic absorption spectrometry

Ceramic, cement and composite biomaterials have been developed based on hydroxyapatites (HA) and tricalcium phosphates (TCP), which are analogous in phase and chemical composition to the mineral component of bone tissue. The crystal structures of HA and TCP are arranged in isomorphic substitutions. Recently, research has focused on the modification of HA and TCP structures with ions of various metals, including rare earth ions (REEs), with the aim of creating materials with a range of beneficial properties for medical applications. REEs are known to have a number of useful properties, including antibacterial, antitumour, catalytic, magnetic and luminescent properties. The replacement of some of the Ca ions in the structures of HA and TCP with REE ions therefore makes it possible to obtain a material with biocompatibility and biological activity, giving it the required properties depending on the REE used and its concentration. In order to achieve the specified properties, it is necessary to control not only the structure (phase composition, lattice parameters of the powders) and the presence of characteristic functional groups, but also the chemical elemental composition. Modifications of hydroxyapatites and tricalcium phosphates containing from one to several different alloying elements are currently being developed. Various analytical methods are used for this purpose, including X-ray, atomic emission and a number of others. This article is devoted to the study of the analytical capabilities of the method of atomic absorption spectrometry with electrothermal atomization and a continuous spectrum source in relation to the determination of Eu and Yb in hydroxyapatites and tricalcium phosphates. The article considers the optimal conditions and modes of analysis, including temperature-time programs, the use of modifiers, the construction of calibration curves, and other factors that can be adjusted for more precise results. The results demonstrated the possibility of simultaneous determination of both Eu and Yb in the concentration range of 0.09 to 2 wt.%, with a relative standard deviation of less than 6 rel.%.

Quantum Physical Unclonable Function Based on Multidimensional Fingerprint Features of Single Photon Emitters in Random AlN Nanocrystals

AbstractPhysical unclonable function (PUF) has emerged as a unique physical'fingerprint' that is inherently difficult to replicate. It shows tremendous application value in various hardware security areas such as identity authentication, chip anticounterfeiting, communication encryption, blockchain, etc. However, with the rapid development of 3D nanoprinting, classical PUFs constructed with disordered micro‐nanostructures face tremendous threats from physical cloning attacks. Herein, this study proposes and demonstrates the utilization of room‐temperature single‐photon emitters derived from atomic defects in randomly distributed pyramidal aluminum nitride (AlN) nanocrystals as a novel quantum PUF to resist physical cloning attacks. The fabrication of this quantum PUF on silicon (Si) wafers enables seamless integration with silicon photonic integrated circuits. The multidimensional fingerprint features of the single‐photon emitters are highly sensitive to the lattice parameters of the uneven AlN nanocrystals. Furthermore, each single photon emitter can work as a quantum random number generator to ensure the fundamental unpredictability of PUFs. The subatomic precision requirement coupled with unpredictable quantum emission behavior makes it practically impossible to attack the proposed quantum PUF, providing a promising solution for information security in the post‐quantum era.

Phase and microstructural characterization of swat soapstone (Mg3Si4O10(OH)2)

Abstract This study focuses on the comprehensive exploration of Swat soapstone, employing a range of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and X-ray fluorescence (XRF) spectroscopy. XRD was used to identify the phase and lattice parameters of the soapstone. SEM further scrutinizes the dispersed soapstone particles, revealing different structural characteristics such as a slightly elongated, cubic-like structure, a straight rod-like formation, and a rough, textured surface. EDX spectroscopy was utilized for studying the elemental composition of the soapstone. The analysis identifies talc as the primary mineral in Swat soapstone, with iron, an element, also contributing notably to its composition. This underscores the complexity of Swat soapstone’s internal structure. XRF analysis further contributes to the elemental characterization, revealing a dominant composition of silicon (Si) at 48.567 wt% and a notable contribution from iron (Fe) at 16.108 wt%. FTIR analysis confirmed the absorption of infrared radiation at the non-bridging oxygen (Si–O–) within the silicate network and the Si–O–Si bending vibration. This work investigates the chemical and morphological details of the Swat soapstone.

Electronic structure evolution during martensitic phase transition in all-d-metal Heusler compounds: the case of Pd2MnTi

Abstract In this study, taking Pd2MnTi as a representative example, the electronic structure evolution during martensitic phase transition in all-d-metal Heusler compounds was systematically studied and revealed theoretically. The calculation and theoretical analysis suggest that Pd2MnTi is not stable in cubic structure and prones to transform to low-symmetric tetragonal structure. By tetragonal deformation, the shrinkage of lattice parameters and the decrease of symmetry promote the electron accumulation between Pd and its first nearest neighboring Ti atom, resulting in the increased covalent hybridization. The occurrence of pesudogap in density of states (DOSs) of tetragonal Pd2MnTi near the Fermi level also verifies the enhancement of covalent bond. Comparatively, the stronger interatomic bond in tetragonal Pd2MnTi, i.e., covalent bond here, would strengthen interatomic coupling and consequently lower the energy of the material. By the martensitic phase transition, more stable state in energy was achieved. Thus, based on the analysis of electronic structure evolution, the nature of martensitic phase transition is a process wherein symmetry breaking weakens the original weak chemical bonds in high-symmetric parent phase and induces the strong chemical bond to lower the energy of the materials and achieve a more stable state. This study could help to deepen the understanding of martensitic phase transition and the exploration of novel materials for potential technical applications.

Implementing Lattice and Energy Level Matching to Optimize Buried Interfaces for High-Performance Perovskite Solar Cells.

In n-i-p type perovskite solar cells (PSCs), mismatches in energy level and lattice at the buried interface is highly detrimental to device performance. Here, thin PbS interconnect layer in situ coating on the SnO2 surface is grown. The function of PbS at the interface is different from the commonly used function of crystalline seeds in perovskite bulk. The theoretical calculation show that it helps construct an interconnect structure of SnO2/PbS/Perovskite with matched energy level and lattice. This not only increases conductivity of SnO2, but also upshifts Fermi energy levels (EF) of both SnO2 and buried perovskite due to charge transfer and perovskite's internal defect changes. Such a suitable energy level arrangement ensures a better energy level match at the interface, favoring efficient charge transfer and less open circuit voltage (Voc) loss. Additionally, in situ PL reveals that the template effect of PbS enable perovskite grain to grow bottom-up because of their highly matched lattice parameters. This growth mode optimizes buried interface contact and crystallinity of perovskite. Ultimately, after PbS modification, a remarkable power conversion efficiency (PCE) exceeding 24% and better device stability are obtained. This work demonstrates an effective interconnect layers strategy to realize ideal interface contact toward high-performance PSCs.

Reduced lattice spacing of birnessite type manganese dioxide/ expanded graphite cathode for stable aqueous zinc-ion batteries

Manganese oxides (MnOx) have attracted much attention due to abundant resource, low cost and eco-friendliness. In this study, birnessite type manganese dioxide/expanded graphite composites (KMO/EG) with a reduced lattice spacing of nanoflower and nanowire heterostructure KMO have been synthesized by a one-step hydrothermal method. The morphology of KMO has transformed from nanoflower to nanowire with a reduced lattice spacing due to nucleation sites on the surface of EG. The KMO/EG achieves a specific capacity of 444.5mAh g−1 and remains at 387.9mAh g−1 after 100 cycles at 0.1 A g −1 for Zn-ion battery. The enhanced specific capacity of KMO/EG is mainly attributed to the capacity contribution of EG and the good stability is related to the more stable structure of KMO caused by reduced lattice spacing.

Bandgap Characteristics of Boron-Containing Nitrides—Ab Initio Study for Optoelectronic Applications

Hexagonal boron nitride (h-BN) is recognized as a 2D wide bandgap material with unique properties, such as effective photoluminescence and diverse lattice parameters. Nitride alloys containing h-BN have the potential to revolutionize the electronics and optoelectronics industries. The energy band structures of three boron-containing nitride alloys—BxAl1−xN, BxGa1−xN, and BxIn1−xN—were calculated using standard density functional theory (DFT) with the hybrid Heyd–Scuseria–Ernzerhof (HSE) function to correct lattice parameters and energy gaps. The results for both wurtzite and hexagonal structures reveal several notable characteristics, including a wide range of bandgap values, the presence of both direct and indirect bandgaps, and phase mixing between wurtzite and hexagonal structures. The hexagonal phase in these alloys is observed at very low and very high boron concentrations (x), as well as in specific atomic configurations across the entire composition range. However, cohesive energy calculations show that the hexagonal phase is more stable than the wurtzite phase only when x > 0.5, regardless of atomic arrangement. These findings provide practical guidance for optimizing the epitaxial growth of boron-containing nitride thin films, which could drive future advancements in electronics and optoelectronics applications.

Influence of Y Substitutions on the Structural and Magnetic Properties of Mn-Zn Ferrites

The ordinary solid-state reaction method has been used to produce polycrystalline Mn0.5Zn0.5Fe2–xYxO4. X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to study the structural and surface morphology of the samples, respectively. The formation of cubic spinel crystal structure is observed in XRD patterns. The Nelson-Riley function is used to determine the lattice parameters. Vegard's rule is followed by the lattice parameter change with Y content in different Mn0.5Zn0.5Fe2–xYxO4. The x-ray density, and the bulk density both increase with Y content due to the higher atomic weight of Y compared to atomic weight of Fe, as well as porosity decreases. SEM micrographs demonstrate that the average grain size decreases with the increase of Y contents. When x = 0.05, the initial permeability shows maximum then starts to decrease for further increase of Y content. For the composition Mn0.5Zn0.5Fe1.95Y0.05O4, the relative quality factor (RQF) is found maximum (3477). With the increase of Y content, the peak value of the relative quality factor shifts to higher frequencies region which is the consequence of Snoek relation. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 53−63

Reactive scattering of H2 on Cu(111) at 925K: Effective Hartree potential vs sudden approximation.

We present new quantum dynamical results for the reactive scattering of hydrogen molecules from a Cu(111) surface at a surface temperature of 925K. Reaction, scattering, and diffraction probabilities are compared for results obtained using both an effective Hartree potential (EfHP) and a sudden approximation approach, implemented through the static corrugation model (SCM), to include surface temperature effects. Toward this goal, we show how the SRP48 DFT-functional and an embedded atom potential perform when used to calculate copper lattice constants and thermal expansion coefficients based on lattice dynamics calculations within the quasi-harmonic approximation. The so-calculated phonons are then used in the EfHP approach to replace the normal modes of a fictitious copper cluster used in earlier work. We find that both the EfHP and SCM approaches correctly predict the reaction probability curve broadening effect when the surface temperature is increased. Similarly, results for rovibrationally elastic scattering appear to be improved, predominantly for the SCM model. The behavior of the EfHP results appears to remain much closer to that of a Born-Oppenheimer static surface approach, which excludes any surface temperature effects. Finally, for the diffraction, we show very clear attenuation effects for the SCM approach, significantly decreasing specular diffraction probabilities at 925K surface temperature. These results demonstrate that state-of-the-art theoretical models are able to reproduce strictly quantum mechanical scattering effects with a sudden approximation model and open up interesting opportunities for further comparisons to experimental diffraction results.

Crystal and Local Structures of Pr2Co7Dx during Its Deuterium Absorption Process Determined by Neutron Diffraction.

We investigated crystal and local structures of Pr2Co7, Pr2Co7D2.7 and Pr2Co7D7.2 by neutron diffraction. The determined structural model of Pr2Co7D2.7 was the Ce2Ni7-type structure by Rietveld refinement, where the deuterium atoms occupied both the CaCu5-type (I) and the MgZn2-type cells. The deuterium contents in these cells were 0.10 and 0.80 D/M, respectively. The expansions of the lattice parameters of Pr2Co7D2.7 from the original intermetallics were Δa = 0.3% and Δc = 7.3%. The crystal structure transformed in the order Ce2Ni7-type Pr2Co7 → Ce2Ni7-type Pr2Co7D2.7 → orthorhombic Pr2Co7D7.2. The expansions of the lattice parameters of Pr2Co7D7.2 from the original intermetallics were Δa = 5.9%, Δb = 6.2%, and Δc = 6.4%; nearly isotropic expansion was observed. The deuterium contents in the MgZn2-type, CaCu5-type (I), and CaCu5-type (II) cells were 1.11, 0.44, and 0.83 D/M, respectively. The refined structural parameters by a pair distribution function (PDF) analysis on Pr2Co7 (0.18 < r < 5.0 nm) and Pr2Co7D2.7 (0.13 < r < 5.0 nm) obtained were consistent with those obtained by Rietveld refinement. The Rietveld refinement results of the refined lattice parameters of Pr2Co7D7.2 corresponded with the PDF analysis results in the region of 0.13 < r < 5.0 nm, whereas the refined atomic coordinates of the atoms D1, D2, D4, D6, and D9 obtained by the two methods differed. The refined structural parameters of the short-range structure (0.13 < r < 1.0 nm) in Pr2Co7D7.2 did not correspond to those of the long-range structure (0.13 < r < 5.0 nm). The local distortion within the domain of approximately 1.0 nm in size exists in Pr2Co7D7.2.

Elevating NIR photonic integration with tantalum-niobium pentoxide

In this study, we present a novel material platform based on tantalum-niobium pentoxide (TaNbO5) for integrated photonics applications. TaNbO5 demonstrates exceptional attributes suitable for both linear and nonlinear optics across a wide range of near-infrared wavelengths. Our analysis of the TaNbO5 unit cell revealed crucial lattice parameters and a direct band gap value of 2.268 eV. At a wavelength of 1550 nm, TaNbO5 exhibits a refractive index of 2.22, an extinction coefficient of 5.24 × 10−4, and other optical properties. We determine a 0.8 μm cut-off core width for single-mode TaNbO5 waveguides, which achieve efficiencies exceeding 99% for single-mode configurations and 98% for multimode structures. When coupled with conventional waveguides, TaNbO5 waveguides demonstrate excellent transmission characteristics. Notably, at a wavelength of 1.55 μm, the single-mode waveguide exhibits minimal excess loss. These findings highlight the significant potential of TaNbO5 waveguides for various near-infrared applications, emphasizing their versatility and promising performance.

Synthesis, Optical, Electrical, Fluorescence, Dielectric, Thermal, and Mechanical Characterization of 3-Aminopyridine (Scaffold in Drugs) Single Crystal

Objectives: To screen the optical, electrical, fluorescence, dielectric, thermal, and mechanical behavior of the 3-aminopyridine single crystal for its suitability in optoelectronic applications. Methods: A good single crystal of 3-aminopyridine (3-AP) was grown by the slow evaporation method. Findings: The lattice parameters of the grown crystal were determined using a single crystal X-ray diffractometer as, a = 6.184 (4) Å, b = 15.350 (6) Å, c = 5.361 (7) Å and the required functional groups C-N, NH2 bonds of 3-AP were recognized by the FTIR studies. The grown crystal was screened using the UV-Vis-NIR spectrum to understand the transmission and absorption character of the crystal. The various optical constants such as absorption coefficient, optical conductivity, and electrical conductivity of the crystal have been determined from the UV-Vis transmission plot. The lower cut-off wavelength of the 3-AP crystal was observed at 250 nm. The band gap of the grown crystal is found to be 4.5 eV. The emission property of the crystal was studied using fluorescence spectra. Violet, blue, and red emissions are observed from the fluorescence spectra. Thermal screening of the 3-AP crystal was performed using TGA and DTA. The 3-AP crystal remains stable up to 220 ºC and then the crystal begins to decompose up to 260 ºC due to the loss of the -NH2 group of the 3-aminopyridine. The Vickers hardness test revealed the nature of the material as soft type with Meyer’s index (n) of 2. The electronic polarization behavior of the crystal was examined using the dielectric study. Novelty: The lower cut-off wavelength of 250 nm, wide band gap of 4.5 eV, excellent transparency in the entire visible and near-infrared region, violet, blue, and red emission by the material are the distinguishing and mandatory features for optoelectronic applications. These features are good as compared to the 3-AP derivatives reported earlier. Keywords: Unit cell, Absorption, Emission, Conductivity, Strength, Loss

Energy Transfer by Mechanical Alloying and Electrocatalytic Performance of the As‐Sintered Self‐Supported High‐Entropy Alloy FeNiCoCuMo

Efficient, stable, and cost‐effective electrocatalysts for the oxygen evolution reaction (OER) are essential for clean energy generation through water splitting. This study presents a FeNiCoCuMo high‐entropy alloy (HEA) synthesized via mechanical alloying (MA) and sintering using hot‐pressing. The energy transfer from the milling process influences phase transformations, with the High‐Entropy Alloys Prediction Software (HEAPS) predicting the formation of an FCC phase. X‐ray diffraction (XRD) and scanning electron microscopy reveal an FCC phase after 150 h of milling, with no elemental segregation observed. The Burgio kinetic model estimates 448 kJ mol−1 is needed to achieve a 99% FCC phase. The crystallite size is 4 nm, with a lattice parameter of 0.371 nm. The as‐milled phases were preserved during hot‐pressing sintering. Electrodes (M1, M2, M3) fabricated from the HEA demonstrated high electrocatalytic efficiency, with an average overpotential of 380 mV and Tafel slope of 77 mV dec−1. At a current density of 10 mA cm−2, the electrodes maintained operation for up to 100 h. The synergy between constituent elements is key to the superior electrocatalytic performance of FeNiCoCuMo HEAs, demonstrating their potential as promising materials for OER electrocatalysis.

Epitaxial (AlxGa1−x−yIny)2O3 alloys lattice matched to monoclinic Ga2O3 substrates

We have epitaxially stabilized a series of monoclinic (AlxGa1−x−yIny)2O3 alloys by careful choice of molecular beam epitaxy growth conditions, which balance alloy growth with suboxide desorption. The films are pseudomorphic to (010) β-Ga2O3 substrates at thicknesses up to 150 nm with compositions ranging from (Al0.01Ga0.83In0.16)2O3 to (Al0.24Ga0.75In0.03)2O3. The absorption edge shifts from approximately 4.62–5.14 eV with coincidently increasing Al and decreasing In mole fractions. J–V measurements reveal an increase in resistivity over four orders of magnitude with a maximum value of 4.2 × 105 Ω-cm for (Al0.17Ga0.76In0.07)2O3, which has nearly identical lattice parameters (both in-plane and out-of-plane) to the underlying β-Ga2O3. Scanning transmission electron microscopy of this sample reveals a mostly uniform and single crystalline film, though we identify areas of non-uniform In incorporation and some γ-phase inclusions. This work demonstrates the feasibility of thick layers lattice-matched to β-Ga2O3 with increased bandgap compared to phase-separation limited (Al,Ga)2O3. These alloys can enable higher bandgap epitaxial dielectrics and high sheet charge density transistors by increasing the conduction band offset with respect to β-Ga2O3.

Homo-Nuclear Hetero-Atomic Conjugated Reticular Oligomers for Heterojunction: A Novel "Electron Medium" for Panel Photoelectrocatalysis.

A substantial challenge in employing covalent organic frameworks (COFs) for photoelectrochemical (PEC) water splitting lies in improving their solution-processability while concurrently facilitating the transfer of charges and mass to the catalytic sites. Herein, we synthesize a solution-processable conjugated reticular oligomers (CROs), and further embed ruthenium (Ru) into the CRO, forming a CRO-Ru with homo-nuclear hetero-atomic. Thereafter, CRO and CRO-Ru construct an organic-organic heterojunction membrane at the nanoscale. Thisdesign achieves perfect lattice matching, significantly reducing the energy barrier of mass transfer, and effectively lowering the recombination rate of charge carriers. The optimized photocathode, CuI/CRO-Bpy:CRO-Bpy-Ru-1:1+P3HT/SnO2/Pt, exhibits an efficiency of 111.0µAcm-2 at 0.4V versus a reversible hydrogen electrode (RHE). Compared with the original bulk COFs and CROs, the efficiency is significantly improved. The apparent improvements in charge carrier separation and transfer are responsible for the high PEC activity. In the heterojunction, the incorporation of CRO-Bpy-Ru with a longer excited-state lifetime and a substantial built-in electric field has effectively accelerated the photo-induced electron transfer from the conduction band (CB) of CRO-Bpy to the valence band (VB) of CRO-Bpy-Ru, effectively suppressing the recombination of charges. These findings offer significant guidance for the design and optimization of high-performance photoelectrochemical catalysts.