Distinct Crystalline Structures Research Articles

Green synthesis and antimicrobial evaluation of Ag/TiO2 and Ag/SeO2 Core-Shell nanocomposites using r. Officinalis extract: A combined experimental and docking study

The escalating threat of antibiotic resistance necessitates the development of novel, sustainable antibacterial agents. This study investigates the potential of utilizing Rosmarinus officinalis leaf extracts to synthesize Ag/TiO2 and Ag/SeO2 nanocomposites. R. officinalis extract, a rich source of phenolic and flavonoid compounds, effectively and safely acts as a reducing and capping agent for the green synthesis of Ag/TiO2 and Ag/SeO2 nanocomposites. Characterization of nanocomposites revealed the nanoparticles’ nanoscale size, ranging from 43.34 to 96.58 nm for Ag/TiO2 and 8.04 to 21.72 nm for Ag/SeO2. Both types of nanoparticles exhibited a spherical morphology and distinct crystalline structure. The nanoparticles demonstrated significant antibacterial properties against multiple bacterial strains. The effective concentration for antibacterial activity was determined to be 30.99 mg/mL for Ag-TiO2 and 32.41 mg/mL for Ag-SeO2 nanoparticles. The surface charge of the nanoparticles was measured to be −14.0 mV for Ag-TiO2 and −15.4 mV for Ag/SeO2. Molecular docking simulations investigated the interactions between rosmarinic acid, its derivatives, and the antibiotic cefotaxime with a bacterial protein (e.g., DNA gyrase). These simulations provided insights into the distinct antibacterial mechanisms of these compounds. Briefly, this research highlights the potential of R. officinalis-derived nanocomposites as promising antibacterial agents. The eco-friendly synthesis and promising results pave the way for their development and application in medicine, biochemistry, and environmental fields.

Comparative Study of Zirconium Nitride Multilayer Coatings: Crystallinity, In Vitro Oxidation Behaviour and Tribological Properties Deposited via Sputtering and Arc Deposition.

This study aims to evaluate and compare the properties of a biomedical clinically established zirconium nitride (ZrN) multilayer coating prepared using two different techniques: pulsed magnetron sputtering and cathodic arc deposition. The investigation focuses on the crystalline structure, grain size, in-vitro oxidation behaviour and tribological performance of these two coating techniques. Experimental findings demonstrate that the sputter deposition process resulted in a distinct crystalline structure and smaller grain size compared to the arc deposition process. Furthermore, in vitro oxidation caused oxygen to penetrate the surface of the sputtered ZrN top layer to a depth of 700 nm compared to 280 nm in the case of the arc-deposited coating. Finally, tribological testing revealed the improved wear rate of the ZrN multilayer coating applied by sputter deposition.

Effect of Crystalline Phase and Facet Nature on the Adsorption of Phosphate Species onto TiO2 Nanoparticles.

The current use of TiO2 nanoparticles raises questions about their impact on our health. Cells interact with these nanoparticles via the phospholipid membrane and, in particular, the phosphate head. This highlights the significance of understanding the interaction between phosphates and nanoparticles possessing distinct crystalline structures, specifically anatase and rutile. It is crucial to determine whether this adsorption varies based on the exposed facet(s). Consequently, various nanoparticles of anatase and rutile TiO2, characterized by well-defined morphologies, were synthesized. In the case of the anatase samples, bipyramids, needles, and cubes were obtained. For the rutile samples, all exhibited a needle-like shape, featuring {110} facets along the long direction of the needles and facets {111} on the upper and lower parts. Phosphate adsorption experiments carried out at pH 2 revealed that the maximum adsorption was relatively consistent across all samples, averaging around 1.5 phosphate·nm-2 in all cases. Experiments using infrared spectroscopy on dried TiO2 powders showed that phosphates were chemisorbed on the surfaces and that the mode of adsorption depended on the crystalline phase and the nature of the facet: the anatase phase favors bidentate adsorption more than the rutile crystalline phase.

Improved Reversibility of Thin-Film Solid Oxide Cells at 500 °C by Tailoring Sputtering Processes for Depositing Yttria-Stabilized Zirconia Electrolyte.

The present study investigates the impact of sputtering configurations on the microstructure and crystallinity of thin-film yttria-stabilized zirconia electrolytes for anodized aluminum oxide-supported all-sputtered thin-film reversible solid oxide cells. Employing various sputtering parameters, such as target-substrate distance and substrate rotation speed, the present study reveals distinct surface characteristics and crystalline structures of thin-film yttria-stabilized zirconia. The microstructure analysis includes scanning electron microscopy and atomic force microscopy examinations, uncovering the influence of the process parameters on the surface morphology, roughness, and grain size. X-ray diffraction data illustrate the texture preferences and crystallite characteristics. The electrochemical characterization of the reversible solid oxide cells demonstrates that the optimized sputtering configuration significantly outperforms the others in both SOFC and SOEC modes, showing exceptional current densities of 964 mA/cm2 at 1.3 V in electrolysis mode at 500 °C. Electrochemical impedance spectroscopy further reveals improved charge transfer reactions at the interface of the electrolyte. The enhanced electrochemical performance is attributed to the unique microstructure and crystallinity of the thin film of yttria-stabilized zirconia. The record-breaking electrolysis performance of this work at 500 °C underscores the potential of tailored sputtering parameters in optimizing the reversible solid oxide cell performance.

Structural transformation investigations of δ to α manganese dioxides: Phosphate sorption and its mechanism

The elevation of environmental phosphate levels can negatively impact both the natural environment and human health. To address this issue, a series of MnO2 sorbents were investigated in this study. A facile one-pot synthesis method was employed to fabricate distinct morphologies and crystalline structures by controlling the hydrothermal duration. As the hydrothermal duration was prolonged, the samples demonstrated a pronounced enhancement of stability and crystalline phases, along with a corresponding increase in structural oxygen vacancies. A series of sorption performance tests were conducted, including pH effect, sorption isotherm, sorption kinetics, co-existing ions and sorption–desorption cycles experiments. It was revealed that manganese dissolution, the surface charge of the sorbents, and the phosphate species at different pH values collectively influenced the sorption process. The sorbent α-MnO2-120 h, with the highest oxygen vacancy ratio, exhibited the best sorption performance towards phosphate ions, with the maximum sorption capacity at pH 7. The highest removal rate and kd value were 82.63 % and 2.29 × 103 mL g−1, respectively, at the initial concentration of 30.7 mg PO4 g−1. The α-MnO2-120 h sorbent exhibited excellent selectivity in the presence of NO3−, SO42−, CO32−, and SiO32−. Furthermore, the regenerated material exhibited only a 6 % decrease in phosphate removal efficiency after five cycles, with no structural changes observed. A novel mechanism was proposed, highlighting the dominance of covalent chemical reactions in the sorption process. In particular, the participation of oxygen vacancies in sorbents contributed to enhancing the effective removal of phosphate ions. Overall, this study successfully demonstrated that synthesized α-MnO2 is a promising sorbent for phosphate removal.

In‐situ Synthesis of Highly Potent Antibacterial Copper‐Based MOFs/Sodium Alginate Composite Beads

AbstractThe present study reports an environmentally friendly in‐situ synthesis of novel antibacterial copper‐based MOFs within the hydrogel network of sodium alginate. Two different copper‐based MOF/sodium alginate composite beads were prepared via the post‐treatment of copper‐ion‐crosslinked alginate hydrogels with two different ligand solutions, namely, tartaric acid and oxalic acid, at 100 °C for 24 h. The structural, thermal, and morphological properties of the prepared samples were investigated using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), and their antibacterial activities against gram‐positive (Staphylococcus aureus and Bacillus) and gram‐negative (Escherichia coli and Pseudomonas aeruginosa) strains were examined using the conventional disc diffusion method. The results demonstrated the success of the in‐situ synthesis of two distinct copper‐based MOFs with FTIR spectra, confirming the existence of characteristic bands of the ligands complexed to the sodium alginate matrix. Moreover, the XRD diffractograms revealed the formation of two distinct crystalline structures with well‐defined morphologies observed in the SEM images. In addition, thermal analysis showed that the prepared composite beads had enhanced thermal stability compared to the copper‐ion‐crosslinked alginate beads. Antibacterial testing revealed the strong capacity of the copper‐based MOFs/sodium alginate composite beads to deactivate the growth of all the bacterial strains used, with a minimum inhibition zone of 23 mm, which highlights the potential of the synthesized materials as highly potent antibacterial agents.

Meticulous Molecular Engineering of Crystal Orientation and Morphology in Conjugated Polymer Thin Films for Field-Effect Transistors.

The ability to precisely tailor molecular packing and film morphology in conjugated polymers offers a robust means to control their optoelectronic properties. This, however, remains a grand challenge. Herein, we report the dependency of molecular packing of an important conjugated polymer, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), on a set of intrinsic parameters and unveil the correlation between their crystalline structures and charge transport characteristics. Specifically, a family of PBTTT with varying side chains (i.e., hexyl, octyl, decyl, dodecyl, tetradecyl, and hexadecyl referred to as C6, C8, C10, C12, C14, and C16, respectively) and molecular weights (MWs) with a focus on C14 are judiciously designed and synthesized. Various crystalline structures are yielded by tuning the alkyl chain and MW of PBTTT together with thermal annealing. It reveals that extending the alkyl chain length of PBTTT to C14, along with a larger MW and heating at 180 °C, promotes the formation of edge-on crystallites with significantly improved orientation and ordering. Furthermore, these distinct crystalline structures greatly impact their charge mobilities. This study sheds light on the tailored design of crystalline structures in PBTTT through a synergetic approach, which paves the way for potential applications of PBTTT and other conjugated polymers in optoelectronic devices with enhanced performance.

Uncovering the Crystalline Packing Advantages of Asymmetric Y‐Series Acceptors for Efficient Additive‐Insensitive and Intrinsically Stable Organic Solar Cells

AbstractOrganic solar cells (OSCs) hold immense potential as renewable energy sources, but the performance‐stability conundrum remains a major obstacle on the road to OSC commercialization. To address this, in this study, molecular packing behaviors of representative state‐of‐the‐art Y‐series non‐fullerene acceptors (NFAs) are studied, focusing on their terminal group symmetries. Utilizing grazing‐incidence wide‐angle X‐ray scattering, the distinct crystalline packing structure of these NFAs is revealed. Remarkably, NFAs with asymmetric terminals exhibited excellent additive insensitivity and thermal stability for their crystalline structure, unlike their symmetric counterparts. Molecular dynamics simulations confirmed the stable and robust crystalline feature of asymmetric NFAs and attributed to their large molecular dipole moments. These findings showed the great potential of asymmetric NFAs in fabricating efficient and intrinsically stable additive‐free OSC devices for real applications.

Poly(vinylidene fluoride) Aerogels with α, β, and γ Crystalline Forms: Correlating Physicochemical Properties with Polymorphic Structures.

Strategic customization of crystalline forms of poly(vinylidene fluoride) (PVDF) aerogels is of great importance for a variety of applications, from energy harvesters to thermal and acoustic insulation. Here, we report sustainable strategies to prepare crystalline pure α, β, and γ forms of PVDF aerogels from their respective gels using a solvent exchange strategy with green solvents, followed by a freeze-drying technique. The crucial aspect of this process was the meticulous choice of appropriate solvents to enable the formation of thermoreversible gels of PVDF by crystallization-induced gelation. Depending on the polymer-solvent interactions, the chain conformation of PVDF can be modulated to obtain gels and aerogels with specific crystalline structures. The crystalline pure α-form and piezoelectric β-form aerogels were readily obtained by using cyclohexanone and γ-butyrolactone as gelation solvents. On the other hand, the γ-form aerogel was obtained using a binary solvent system consisting of dimethylacetamide and water. These aerogels with distinct crystalline structures exhibit different morphologies, mechanical properties, hydrophobicities, acoustic properties, and electrical properties. Measurement of thermal conductivity for these aerogels showed exceptionally low thermal conductivity values of ∼0.040 ± 0.003 W m-1 K-1 irrespective of their crystal structures. Our results showcase the fabrication approaches that enable PVDF aerogels with varied physicochemical properties for multifunctional applications.

Topotactic transformation of perovskite-based manganite film triggered via simple oxygen getter layer

Stoichiometric composition, in particular, oxygen concentration, is of critical importance for distinct crystalline structures and emergent electronic properties of strongly correlated perovskite oxides. Using manganite La0.7Sr0.3MnO3 as a model system, we study oxygen vacancy (VO) driven regulations of coordination chemistry, crystalline structure and associated physical property of La0.7Sr0.3MnO3 film by means of capping oxygen-deficient binary oxide (Al2O3-δ or TiO2-δ) ultrathin layer. High-efficient migrations of VO at the interface of capped La0.7Sr0.3MnO3 heterostructure give rise to tunable Mn–O coordination units, topotactic transformations and concomitant electronic modulations. A distinct perovskite-brownmillerite (PV-BM) topotactic transformation is observed for the capped La0.7Sr0.3MnO3 film, accompanying by a crossover from ferromagnetic-metallic phase to antiferromagnetic-insulating one. This facile control of oxygen concentration of perovskite-based oxides has significant implications for rational design of functional oxides with unique coordination frameworks, electronic states and emergent performances.

Influence of Coconut Fiber Waste and Rice Husk Ash on Green Concrete

Purpose: To develop cementitious materials, concrete, incorporating coconut fiber waste (CFW) and rice husk ash (RHA), with the aim of producing innovative, cost-effective, and readily available products for use in economically and environmentally friendly construction applications. Environmental impacts can be minimized by making these practices efficient and sustainable through the utilization of these waste materials. Theoretical framework: The use of agro-industrial waste in concrete matrices has been extensively studied due to their effectiveness in influencing material properties. The incorporation of coconut fiber waste and rice husk ash into concrete can lead to improvements in compressive strength, increased durability, and a reduction in the amount of CO2 generated during production. The concrete developed with the incorporation of waste products has the potential to minimize environmental impacts, reduce costs, and extend its lifespan. The pursuit of sustainability drives the exploration of innovative materials to preserve natural resources and mitigate ecological impact in the construction industry. Method: The coconut fiber waste was subjected to 24-hour drying process in an oven at 100°C to remove moisture and was subsequently crushed in a ball mill until its particle size exhibited characteristics similar to the binder. The CFW and RHA were characterized through Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Specific Surface Area analysis. Different percentages of CFW (0.25% - 0.75%) and RHA (2% - 10%) were separately incorporated into the concrete mix. The mixing ratio used was 1:1.9:3.1 (cement, sand, aggregate), with a water-to-cement (w/c) ratio of 0.60. Workability tests, electrical resistivity tests, capillary water absorption by capillary rise, and axial compressive strength tests were conducted. Additionally, a sulfate ion penetration test was performed by immersing specimens in a 2.5% sulfuric acid (H2SO4) solution for 7 days. Results: SEM images of CFW reveal an angular and fibrous microstructure, maintaining the original properties of the waste even after its transformation into ash. RHA particles exhibit irregular shapes and sizes with microporous cellular structures on the surface, consistent with literature. X-Ray Diffraction patterns of CFW indicate a material without a distinct crystalline structure. However, Electron Dispersive Spectroscopy analysis suggests the predominance of carbon (C), potassium oxide (K2O), and silica (SiO2). RHA shows broad amorphous diffraction at 22° and some sharp diffraction peaks, suggesting the formation of crystallites, consistent with cristobalite. There was a slight improvement in the workability of fresh concrete compared to the reference mix as the percentage of waste incorporation increased. The electrical resistivity of the produced specimens showed a significant increase in all cases, except for the 0.25% RHA sample. The 5.0% CFW content exhibited the best performance, with a 29.47% increase, indicating a microstructure with few voids and suggesting greater material durability. Samples with higher fiber percentages showed higher water absorption values. Concrete incorporated with RHA exhibited higher porosity and suboptimal performance. However, the incorporation of 0.25% CFW showed a slight improvement compared to the reference concrete. The best performances observed in the compressive strength test were with 5.0% RHA and 0.5% CFW, with the latter showing the best result compared to the reference specimens. In the sulfate attack test, only the concrete with 5.0% RHA showed better performance in an aggressive environment. Increasing the percentage of CFW also reduced mass loss, suggesting potential improvement of the compound at higher proportions. The study demonstrated that agro-industrial residues can be satisfactorily utilized in construction, and the implementation of this new process can reduce global warming and mineral resource depletion. Research implications: This work contributes to a sustainable circular economy with a novel process for utilizing agro-industrial waste in concrete. Originality/Value: The findings will be promising for the utilization of coconut fiber waste and rice husk ash in the production of environmentally sustainable concrete.

Radiation shielding performance of recycled waste CRT glasses doped with Li2O and Y2O3: Potential applications in medical facilitates

In this study, waste cathode ray tube screen glass (WCSG) doped with Li2O and Y2O3 was prepared and investigated for physical properties, structural definition, and their charged radiation and neutron shielding competence through a series of experimental and theoretical approaches. Using the cold isostatic press method, WCSG-infused Li2O + Y2O3 composite glass ceramic samples were prepared. The Li2O + Y2O3 composite concentrations were varied from 0 (STV), 10 (STV-YLI1), and 20 (STV-YLI2) wt%. The prepared glasses were sintered, and their crystal structure and surface microstructure were probed using the XRD technique and SEM images. The prepared samples were analysed for their radiation shielding abilities, starting from the computation of parameters related to their interaction with charged radiation and neutrons. The ESTAR, PSTAR, ASTAR, and STRIM software. In addition, the fast neutron (FN) removal cross section (FNRCS) and thermal neutron (TN) total cross-section (σtot) for the prepared glasses were evaluated theoretically using established models. The XRD spectra of the samples showed distinct crystalline structure and the formation of glass-ceramic material. The addition of the Li2O + Y2O3 composite reduced surface pores, increased hardness, and increased the sample density. The Vickers hardness values were calculated as 495, 527, and 552 HV for the STV, STV-YLi1, and STV-YLi2 samples, respectively, while the corresponding densities were 2.506, 2.592, and 2.634 g/cm3. The addition of Li2O + Y2O3 to the WCSG slightly improved the glass-ceramic system's charged particle shielding ability. The FNRCS of STV, STV-YLi1, and STV-YLi2 are 0.0775, 0.0827, and 0.0867 cm-1 respectively. The ability of the prepared glass ceramics to absorb fast and thermal neutrons improved with the addition of Li2O + Y2O3. The materials are recommended for use as environmental friendly radiation shields.

Unraveling the Complex Polymorphic Crystallization Behavior of the Alternating Copolymer DMDS-alt-DVE.

A complex crystallization behavior was observed for the alternating copolymer DMDS-alt-DVE synthesized via thiol-ene step-growth polymerization. Understanding the underlying complex crystallization processes of such innovative polythioethers is critical for their application, for example, in polymer coating technologies. These alternating copolymers have polymorphic traits, resulting in different phases that may display distinct crystalline structures. The copolymer DMDS-alt-DVE was studied in an earlier work, where only two crystalline phases were reported: a low melting, L - Tm, and high melting, H - Tm phase. Remarkably, the H - Tm form was only achieved by the previous formation and melting of the L - Tm form. We applied calorimetric techniques encompassing seven orders of magnitude in scanning rates to further explore this complex polymorphic behavior. Most importantly, by rapidly quenching the sample to temperatures well below room temperature, we detected an additional polymorphic form (characterized by a very low melting phase, denoted VL - Tm). Moreover, through tailored thermal protocols, we successfully produced samples containing only one, two, or all three polymorphs, providing insights into their interrelationships. Understanding polymorphism, crystallization, and the resulting morphological differences can have significant implications and potential impact on mechanical resistance and barrier properties.

Smart Drug Delivery Systems Based on Single-Wall Carbon Nanotubes Loaded with Nanocurcumin Extract for Cancer Therapy and Toxicity

The main objective of the study is to prepare smart drug delivery systems based on single-wall carbon nanotubes. In this study, nanocurcumin (N.Cur) was loaded onto SWCNTs containing polyethylene glycol (PEG) and polyethyleneimine (PEI), which includes amino groups — this led to the successful production of PEG-PEI-SWCNTs. XRD, UV-Vis, and TEM techniques were employed to investigate the spectral and structural properties of (PEG-PEI-SWCNTs-N.Cur). The PEG-PEI-SWCNTs showed distinct crystalline structures and flaws, as well as a larger interlayer spacing, as evidenced by XRD patterns. After loading N. Cur, TEM analysis confirmed the presence of curcumin extract. UV-Vis absorbance peaks at 289, 300.98, (282,425), and (273,431) nm appear to be linked to SWCNTs, PEG-PEI-SWCNTs, N. Curcumin extract, and PEG-PEI-SWCNTs-N, respectively. After exposure to a variety of produced SWNTs and PEG-PEI-SWCNTs at concentrations ranging from 6.25 to 100 g/ml for 72 hours, the rate of growth inhibition in cancer cells including the liver cancer HepG2 cell line—was assessed. The cancer cells were found to be very dangerous by the cytotoxicity testing.

Synthesis of nano-TiO2 assisted by glycols and submitted to hydrothermal or conventional heat treatment with promising photocatalytic activity

TiO2 nanoparticles were successfully synthesized by the sol-gel method employing different glycols (ethylene glycol, diethylene glycol or polyethylene glycol 300), which were heat-treated in conventional oven or by hydrothermal via, obtaining photocatalysts with particle sizes and distinct crystalline structures. HRTEM analyses showed that the oxides submitted to hydrothermal treatment featured spherical morphology, being formed by partially aggregated particles with sizes varying between 2 and 5 nm. X-ray diffractograms and Raman spectroscopy confirm that anatase was predominant in all synthesized compounds, with presence of brookite phase for samples that received hydrothermal treatment or were synthesized in the presence of polyethylene glycol with heat treatment in conventional oven. The amount of brookite as well as the cell volume, deformation, network parameters and crystallinity were estimated by Rietveld refinement. The surface area and porosity of the materials were higher when the synthesis involved the use of hydrothermal treatment. These oxides are mesoporous with porosity between 14 and 31%. The oxide synthesized in the presence of ethylene glycol with hydrothermal thermal treatment (TiO2G1HT) exhibited the highest photocatalytic activity in terms of mineralization of azo-dye Ponceau 4R (C.I. 16255), under UV-Vis irradiation. This higher photocatalytic activity can be attributed to the formation of binary oxides composed by anatase and brookite and by its optimized morphological and electronic properties.

Ultrahigh Electrocatalytic Activity of an Iron-Based Bimetallic Oxide for Oxygen Evolution Reaction in Alkaline

The present environmental issue has been drawn the demand on a breakthrough in efficient energy conversion and storage systems. Solar and wind energies are expected as attractive renewable energy resources, which can be inexhaustibly used to generate electricity, but their intermittency and isolated locations from consuming sites prevent their practical application. Hence, these natural energies are required to be converted into energy carriers to store and transport them to consuming sites. One of promising candidates as such energy carriers is hydrogen. Hydrogen is a clean fuel which does not discharge CO2 and other poisonous emissions and possesses high energy density. To efficiently and sustainably produce hydrogen, alkaline electrolyzers have recently received much interest. Alkaline electrolyzers can produce pure hydrogen from abundant water using electricity and have been considered to be a cost-effective mode for energy conversion, because alkaline conditions allow to employ nonprecious metals as electrocatalysts. However, the sluggish anodic oxygen evolution reaction (OER) (4OH− → O2 + 2H2O + 4e−) of water splitting with a large overpotential is the main concern [1]. Ruthenium oxide (RuO2) and iridium oxide (IrO2) are well-known as state-of-the-art electrocatalysts for OER [2–4], but the high costs of these precious metals limit widespread use. Hence, cost-effective electrocatalysts that possess excellent OER activity are highly desirable.As alternative OER electrocatalysts, iron (Fe)-based materials have recently attracted much attention [5], because Fe is the most abundant 3d transition metal in the earth's crust [6] which is found to be the fourth place in the Clarke numbers. Although simple Fe oxides are intrinsically inactive for electrochemical OER, its OER activity can be dramatically enhanced by doping and substitution with other metals. Most of previous works studied the OER activities on spinel [7] and perovskite [8]-type oxides due to their good electrochemical activities and facile synthesis, whereas very few reports have investigated other classes of Fe-based metal composite oxides consisting of. e.g., edge- and face-shared polyhedral networks.We herein present a Fe-based bimetallic oxide with prominent OER activity, comprising a distinct crystalline structure from normal spinel- and perovskite-type oxides. The crucial factor of the excellent OER activity of the Fe-based bimetallic oxide was elucidated through comparison with similar Fe-based bimetallic oxide analog containing alkaline-earth metals as second metal components. It is noteworthy that the OER specific activity per surface areas of the Fe-based oxide particles overcame those of previously reported Fe-based bimetallic oxides comprising alkaline-earth and rare-earth metals as well as even benchmark IrO2. Furthermore, a durability test by potential cycles at OER potential region caused the only negligible loss of OER current, and its crystalline structure and metal compositions were thoroughly retained, demonstrating high stability of the oxide in alkaline OER. Moreover, the prominent OER activity of the Fe-based oxide was elucidated by DFT calculations, suggesting that the OER activity of the oxide was boosted by its balanced structural and electronic effects. Since this Fe-based oxide has many advantages, such as simple synthesis, high abundance, cost effectiveness and environmental friendliness, it is a quite promising OER electrocatalyst for water splitting and can open a new way for development of energy conversion devices.

Mn–Ni binary metal oxide for high-performance supercapacitor and electro-catalyst for oxygen evolution reaction

Manganese-nickel (Mn–Ni) binary metal oxides are prepared using a hydrothermal technique followed by calcination. X-ray diffraction analysis confirms the formation of two distinct crystalline structures, NiMnO3 and NiMn2O4. The Transmission electron microscope analysis reveals that the as-prepared NiMnO3 exhibits an average size in the range of 50–100 nm. X-ray photoelectron microscope results show that the metal oxides (Mn and Ni) exhibit different oxidation states in the composite. The NiMnO3 exhibits higher electrochemical performance than NiMn2O4 owing to the higher surface area. In a three-electrode configuration, NiMnO3 delivers a capacitance of 230 F g−1 at 1.0 A g−1 and withstands 67% of its initial charge storage capability up to 2000 cycles. The asymmetric aqueous two-electrode (NiMnO3/RGO) set-up delivers a capacitance of 33 F g−1 with an energy density of 8.4 Wh Kg−1 and power density of 675 W Kg−1 at 1 A g−1. Besides, the NiMnO3 is a good electro-catalyst for oxygen evolution reaction with a low over-potential of 256 mV vs RHE at 10 mA cm−2 and stable up to 20 h.

Binding Energy as Driving Force for Controllable Reconstruction of Hydrogen Bonds with Molecular Scissors

Hydrogen bonds are one of the most important directional intermolecular interactions and play key roles in chemical and biochemical systems, but there is still a lack of prediction and understanding of their control. Herein, hydrogen-binding energy (EHB) acted as a driving force for controllably reconstructing hydrogen bonds with molecular scissors. We related hydrogen-binding energies of the donor-acceptor couple (EHB,2) and the donor itself (EHB,1) and ΔG based on ΔG = a1EHB,1 + a2EHB,2 + a3. When EHB,1 and EHB,2 satisfy the condition ΔG < 0, the acceptor is predicted as molecular scissors with sufficient reconstruction capacity in breaking the initial hydrogen bonds and forming new ones. Remarkably, we developed an experimental method to determine the EHB values by a linear equation as a function of chemical shifts (δ) ([Formula: see text]), which is innovational since in the former research EHB can only be deduced from empirical formulas and DFT calculation. On that basis, the hydrogen bonds of α-cellulose were broken and re-formed in molecular scissors-consisting deep eutectic solvents, leading to the white powder transforming into a hydrogel and colorless and transparent thin film materials with distinct crystalline structure, surface flatness, and morphology.

Crystal structures and pressure-induced phase transformations of LiAlH4: A first-principles study

Given the fact that lithium aluminum hydride (LiAlH4) can exist in distinct crystalline structures under different conditions, in this study, we aim to theoretically investigate the structural properties and the pressure-induced phase transformations of its 13 closely related crystal structures by means of the density functional theory (DFT). The present study reveals that the phase transformation of LiAlH4 from the most stable form (α-phase) to the second most stable form (β-phase) occurs at approximately 3.3 GPa, corresponding to a volume collapse of ∼14% and a reduction of 22% in the crystal volume. Due to the relatively higher hydrogen weight content, β-LiAlH4 becomes a potentially attractive candidate for solid-state hydrogen storage at moderate pressures. The two most stable forms, i.e., the structures with the (i) P21/c (α-LiAlH4) and (ii) I41/a (β-LiAlH4) space groups, have been selected so that their structural and electronic properties can be discussed in greater detail. Our study also shows that the numerical results are greatly influenced by the choice of the DFT methods used, such as the exchange-correlation functionals and optimization schemes.

Crystallization behavior of glasses from the system CdO-B2O3 with varying CdO contents (30–90 mol%)

A novel study on the crystallization behavior of extended cadmium borate glasses with varying CdO contents (30–90 mol%), has been carried out. Collective structural FTIR spectral measurements were made for the parent cadmium borate glasses and their glass-ceramic derivatives to identify the structural building groups within the prepared glasses and their crystalline derivatives. X-ray diffraction together with scanning electronic microscopic analysis of the prepared glass-ceramic were done to find out the formed crystalline phases upon thermal heat treatment with two-step regime and identifying the morphological features of the formed crystalline phases. FTIR spectral data reveal the appearance of both the vibrational bands due to triangular and tetrahedral borate groups irrespective of the high CdO content but with varying intensities. The tetrahedral borate (BO4) groups are identified to possess their vibrational modes within the wavenumber 800-1200 cm-1 while the triangular borate (BO3) groups are vibrating within the range 1200–1600 cm-1. The glass-ceramics reveal similar FTIR spectra but with distinct sharpness and the generation of a further IR band at 1060 cm-1 due to formed distinct crystalline tetrahedral structures (such as triborate, pentaborate, diborate). X-ray diffraction patterns indicate the formation of main crystalline phases of cadmium borates with increasing the ratio of CdO to B2O3 by increasing the CdO content (CdO·2B2O3 → CdO·B2O3 → 3CdO·2B2O3→ 2CdO·1B2O3). The ease of crystallization of the studied binary CdO-B2O3 glassy system is assumed to be related to the presence of phase separation in this divalent borate glassy system as other related divalent borate glasses and hence thermal heat-treatment of the parent glasses leads to voluminous crystallization.