Anisotropic Crystallographic Engineering of α-MoO.

The α-phase molybdenum trioxide (α-MoO), a biaxial hyperbolic van der Waals (vdW) crystal, supports highly confined and anisotropic phonon polaritons (PhPs), positioning it as a superior platform for mid-infrared light manipulation. The performance of PhP-based devices critically depends on the properties of α-MoO flakes, including their thickness, roughness, and pattern geometry. However, conventional patterning techniques, such as ion beam milling and plasma etching, often introduce doping artifacts and surface damage, resulting in high PhP losses.

Oxygen hole states facilitated cleavage of Ni-O bonds in the rock-salt phase of a conversion-type anode.

This work studies the influence of oxygen chemistry on the reduction potential in conversion-type NiO anodes in lithium-ion batteries and reveals that the hole states on oxygen are highly polarized and serve as a bridge that facilitates the reduction of Ni, representing a higher potential plateau associated with Ni-O bond cleavage.

High-Temperature Polymorphism and Band-Gap Evolution in BaZrS.

Barium zirconium trisulfide (BZS) is a three-dimensional (3D) perovskite with optoelectronic properties suitable for photovoltaic (PV) and light-emitting diode (LED) applications that is conventionally reported in the orthorhombic (62) symmetry. Synchrotron X-ray diffraction, thermal analysis, and Raman and absorption spectroscopy revealed three high-temperature polymorphs that appear when BZS is heated in air prior to complete oxidation (BaZrS + 5O → BaSO + ZrO + 2SO↑) at 700 °C with the approximate stability ranges: BaZrS IV (62)T < 400 °CBaZrS III (63)400 °C ≤ T ≤ 500 °CBaZrS II14/ (140)500 °C ≤ T ≤ 700 °CDifferential scanning calorimetry (DSC) revealed exothermic features accompanying the IV → III and III → II phase changes. Furthermore, the direct band gap varied inversely with temperature with distinct energies for each polymorph (1.

Hydrogen-Bond-Regulated Mechanochemical Synthesis of Covalent Organic Frameworks: Cocrystal Precursor Strategy for Confined Assembly.

Two-dimensional imine covalent organic frameworks (2D imine-COFs) are crystalline porous materials with broad application prospects. Despite the efforts into their design and synthesis, the mechanisms of their formation are still not fully understood. Herein, a one-pot two-step mechanochemical cocrystal precursor synthetic strategy is developed for efficient construction of 2D imine-COFs.

Ultra-high Performance Thermochromic Polymers via a Solid-solid Phase Transition Mechanism and Their Applications.

Thermochromic materials are substances that change color in response to temperature variations. Today, sustainability concerns are the main drivers of thermochromic research, with smart, energy-efficient windows being one of the primary applications. While vanadium oxides and leuco dyes are traditionally the main thermochromic materials, hydrogels operating based on change of solvation have risen as some of the most promising materials due to their high optical transparency and good solar modulating abilities.

Bio-Polyethylene and Polyethylene Biocomposites: An Alternative toward a Sustainable Future.

Polyethylene (PE), a highly prevalent non-biodegradable polymer in the field of plastics, presents a waste management issue. To alleviate this issue, bio-based PE (bio-PE), derived from renewable resources like corn and sugarcane, offers an environmentally friendly alternative. This review discusses various production methods of bio-PE, including fermentation, gasification, and catalytic conversion of biomass.

Hydrolytic degradation and biodegradation of polylactic acid electrospun fibers.

Increased use of bioplastics, such as polylactic acid (PLA), helps in reducing greenhouse gas emissions, decreases energy consumption and lowers pollution, but its degradation efficiency has much room for improvement. The degradation rate of electrospun PLA fibers of varying diameters ranging from 0.15 to 1.

Chiral Two-Dimensional Hybrid Organic-Inorganic Perovskites for Piezoelectric Ultrasound Detection.

Hybrid organic-inorganic perovskites (HOIPs) have exhibited striking application potential in piezoelectric energy harvesting and sensing due to their high piezoelectricity, light weight, and solution processability. However, to date, the application of piezoelectric HOIPs in ultrasound detection has not yet been explored. Here, we report the synthesis of a pair of chiral two-dimensional piezoelectric HOIPs, -(4-bromo-2-butylammonium)PbBr and -(4-bromo-2-butylammonium)PbBr [-(BrBA)PbBr and -(BrBA)PbBr], which show low mechanical strength and significant piezoelectric strain coefficients that are advantageous for mechanoelectrical energy conversion.

Closed-Loop Multi-Objective Optimization for Cu-Sb-S Photo-Electrocatalytic Materials' Discovery.

Copper antimony sulfides are regarded as promising catalysts for photo-electrochemical water splitting because of their earth abundance and broad light absorption. The unique photoactivity of copper antimony sulfides is dependent on their various crystalline structures and atomic compositions. Here, a closed-loop workflow is built, which explores Cu-Sb-S compositional space to optimize its photo-electrocatalytic hydrogen evolution from water, by integrating a high-throughput robotic platform, characterization techniques, and machine learning (ML) optimization workflow.

Nanoengineering Metal-Organic Frameworks and Derivatives for Electrosynthesis of Ammonia.

Electrocatalytic synthesis under mild conditions has become increasingly important as one of the practical alternatives for industrial applications, especially for the green ammonia (NH) industry. A properly engineered electrocatalyst plays a vital role in the realization of superior catalytic performance. Among various types of promising nanomaterials, metal-organic frameworks (MOFs) are competitive candidates for developing efficient electrocatalytic NH synthesis from simple nitrogen-containing molecules or ions, such as N and NO.

As-Grown Miniaturized True Zero-Order Waveplates Based on Low-Dimensional Ferrocene Crystals.

As basic optical elements, waveplates with anisotropic electromagnetic responses are imperative for manipulating light polarization. Conventional waveplates are manufactured from bulk crystals (e.g.

Noncryogenic Air Separation Using Aluminum Formate Al(HCOO) (ALF).

Separating oxygen from air to create oxygen-enriched gas streams is a process that is significant in both industrial and medical fields. However, the prominent technologies for creating oxygen-enriched gas streams are both energy and infrastructure intensive as they use cryogenic temperatures or materials that adsorb N from air. The latter method is less efficient than the methods that adsorb O directly.

Variable Temperature Behaviour of the Hybrid Double Perovskite MAKBiCl.

Perovskite-related materials show very promising properties in many fields. Pb-free perovskites are particularly interesting, because of the toxicity of Pb. In this study, hybrid double perovskite MAKBiCl (MA = methylammonium cation) was found to have interesting variable temperature behaviours.

Valorization of Spent coffee Grounds: A sustainable resource for Bio-based phase change materials for thermal energy storage.

Spent coffee grounds (SCGs) are waste residues arising from the process of coffee brewing and are usually sent to landfills, causing environmental concerns. SCGs contain a considerable amount of fatty acids and is therefore a promising green alternative bio-based phase change material (PCMs) compared to conventional organic and inorganic PCMs. In this study, the extraction of coffee oil from SCGs was conducted using three different organic solvents-ethanol, acetone, and hexane.

Cu(I)/Cu(II) Creutz-Taube Mixed-Valence 2D Coordination Polymers.

Graphene-like 2D coordination polymers (GCPs) have been of central research interest in recent decades with significant impact in many fields. According to classical coordination chemistry, Cu(II) can adopt the dsp hybridization to form square planar coordination geometry, but not Cu(I); this is why so far, there has been few 2D layered structures synthesized from Cu(I) precursors. Herein a pair of isostructural GCPs synthesized by the coordination of benzenehexathiol (BHT) ligands with Cu(I) and Cu(II) ions, respectively, is reported.

Aluminum formate, Al(HCOO): An earth-abundant, scalable, and highly selective material for CO capture.

A combination of gas adsorption and gas breakthrough measurements show that the metal-organic framework, Al(HCOO) (ALF), which can be made inexpensively from commodity chemicals, exhibits excellent CO adsorption capacities and outstanding CO/N selectivity that enable it to remove CO from dried CO-containing gas streams at elevated temperatures (323 kelvin). Notably, ALF is scalable, readily pelletized, stable to SO and NO, and simple to regenerate. Density functional theory calculations and in situ neutron diffraction studies reveal that the preferential adsorption of CO is a size-selective separation that depends on the subtle difference between the kinetic diameters of CO and N.

Understanding the Structural and Electronic Properties of Bismuth Trihalides and Related Compounds.

Bismuth trihalides, BiX (X = F, Cl, Br, and I), have been thrust into prominence recently because of their close chemical relationship to the halide perovskites of lead, which exhibit remarkable performance as active layers in photovoltaic cells and other optoelectronic devices. In the present work, we have used calculations based on density functional theory to explore the energetics and electronic properties of BiX in a variety of known and hypothetical structure types. The results for BiX are compared with those obtained for the halides of the later rare earths, represented by YX and LuX.

Enhanced visible light absorption for lead-free double perovskite CsAgSbBr.

In a search for Pb-free photovoltaic materials, a double perovskite Cs2AgSbBr6 with an indirect optical bandgap of 1.64 eV has been synthesized. Single crystal X-ray diffraction determined the space group as Fm3[combining macron]m with a = 11.

Unraveling the Interfacial Structure-Performance Correlation of Flexible Metal-Organic Framework Membranes on Polymeric Substrates.

Pure metal-organic framework (MOF) layers deposited on porous supports are important candidates for molecular sieving membranes, but their performance usually deviates from theoretical estimations. Here, we combine step-wise scanning electron microscopy imaging, time-resolved synchrotron X-ray scattering, terahertz infrared spectroscopy, and density functional theory calculation to investigate the ZIF-8 membrane formation on two types (polydopamine and TiO) of functionalized porous supports. Though molecular sieving of ZIF-8 membranes for smaller gases (He, H, and CO) can be achieved with both types of functionalized supports, we unravel that the strong interaction between MOF and polydopamine can disrupt the formation of "perfect" MOF crystals at the interface, leading to a "contracted" MOF structure with partially uncoordinated imidazolate ligands.

Synthesis and Characterization of the Rare-Earth Hybrid Double Perovskites: (CHNH)KGdCl and (CHNH)KYCl.

Two hybrid rare-earth double perovskites, (CHNH)KGdCl and (CHNH)KYCl, have been synthesized by a solution evaporation method and their structures determined by variable temperature single-crystal X-ray diffraction. The diffraction results show that at room temperature both perovskites adopt a rhombohedral structure with R3̅m symmetry, as found previously for (MA)KBiCl, and lattice parameters of a = 7.7704(5) Å and c = 20.

Factors Influencing the Mechanical Properties of Formamidinium Lead Halides and Related Hybrid Perovskites.

The mechanical properties of formamidinium lead halide perovskites (FAPbX , X=Br or I) grown by inverse-temperature crystallization have been studied by nanoindentation. The measured Young's moduli (9.7-12.

Variable temperature and high-pressure crystal chemistry of perovskite formamidinium lead iodide: a single crystal X-ray diffraction and computational study.

We investigate the variable temperature (100-450 K) and high-pressure (p = ambient - 0.74 GPa) crystal chemistry of the black perovskite formamidinium lead iodide, [(NH)CH]PbI, using single crystal X-ray diffraction. In both cases we find a phase transition to a tetragonal phase.