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Sodium zirconate (sodium zirconium oxide; Na2ZrO3) is a widely investigated carbon dioxide (CO2) sorbent. Since it was first discussed in the 1960s, Na2ZrO3 has been reported to adopt monoclinic, hexagonal, and cubic structures, and it is widely believed that the CO2 capture performance of Na2ZrO3 is related to its crystal structure. Researchers have relied on the differences in the relative intensities of two peaks (2 ∼16.2° and 38.7°) in the powder X-ray diffraction (PXRD) pattern to determine the phase of this compound. However, to date, a defined crystal structure of hexagonal Na2ZrO3 has remained elusive. Our findings show that the current literature discussion on the structure of Na2ZrO3 is misleading. With the use of 3D electron diffraction (3D ED), and PXRD, we prove that hexagonal Na2ZrO3 does not exist. The so-called hexagonal Na2ZrO3 is actually Na2ZrO3 with three different types of disorder. Furthermore, the two PXRD peaks (2 ∼16.2° and 38.7°) cannot be used to distinguish the different phases of Na2ZrO3, as the change in the PXRD pattern is related to the extent of structure disorder. Finally, we also show that the CO2 uptake properties of Na2ZrO3 are not related to the differences in crystal structures, but rather to the Na+ site occupancy differences in different Na2ZrO3 samples. In order to further develop applications of Na2ZrO3, as well as other mixed-metal oxides, their structures, and the existence of any disorder, need be understood using the methods shown in this study. [ABSTRACT FROM AUTHOR]

Maximizing products of high value and minimizing incineration of side-streams is key to realize future biorefineries. In current textile production from forestry, hemicellulose is removed by prehydrolysis before delignification. The resulting prehydrolysis liquor is incinerated in the recovery boiler at low efficiency. This additional burden on the limiting recovery boiler reduces the pulp production. In this study, we demonstrate that prehydrolysis liquor can be upgraded, in 5 steps, to yield aviation fuels. Prehydrolysis liquors were dehydrated to furfural by zeolite catalysis. Furfural was selectively reduced to furfuryl alcohol by Au@NC. Rhenium-catalysed Achmatowicz rearrangement gave a C5 intermediate susceptible to self [2 + 2] cycloaddition to give the C10 oxygenated precursor. By using a combination of Ru/C and zeolites, full hydrodeoxygenation was achieved. The overall transformation from furfural to hydrocarbons resulted in a 48% carbon yield. The resulting hydrocarbons, containing an anticipated strained four-membered ring, are preferred aviation fuel components. This is an important step to show that aviation fuels can be produced sustainably from existing industrial side-streams. A comparative life cycle assessment was applied to evaluate the environmental impact of the proposed valorization approach, demonstrating benefits in the climate change impact category when implementing this technology in a pulp mill compared to the incineration of pre-hydrolysis liquor scenario. [ABSTRACT FROM AUTHOR]

Encapsulating and protecting dopamine from oxidation is a difficult challenge. We propose to use SU-101 BioMOF as a dopamine host, where we study different adsorption scenarios by a robust computational approach. Our results show that dopamine encapsulation is feasible with the formation of non-covalent interactions within the SU-101 pores. These computational results have been corroborated experimentally. [ABSTRACT FROM AUTHOR]

Multifunctional, biobased materials processed by means of additive manufacturing technology can be highly applicable within the water treatment industry. This work summarizes a scalable and sustainable method of anchoring a green metal–organic framework (MOF) SU-101 onto the surface of 3D printed, biobased matrices built of polylactic acid (PLA)-based composites reinforced with TEMPO-oxidized cellulose nanofibers (TCNFs). The two tested anchoring methods were hydrolysis via either concentrated hydrochloric acid treatment or via a photooxidation reaction using UV–ozone treatment. Stable deposition of SU-101 distributed homogenously over the filter surface was achieved and confirmed by FT-IR, XPS and SEM measurements. The obtained 3D printed and functionalized MOF@PLA and MOF@TCNF/PLA (aka MOF@Cell) filters exhibit high efficiency in removing heavy metal ions from mine effluent and methylene blue from contaminated water, as demonstrated through batch adsorption experiments. In addition to their potential for removal of contaminants from water, the MOF@Cell filters also exhibit excellent mechanical properties with a Young's modulus value of about 1200 MPa, demonstrating their potential for use in practical water treatment applications. The MOF@Cell filters were able to maintain their structural integrity and filtration performance even after multiple cycles of use and regeneration. This study highlights the potential of multifunctional, biobased materials processed by additive manufacturing technology as a cost-effective alternative to traditional water treatment methods. The MOF@Cell filters presented in this study demonstrate high efficiency, durability, and reusability, making them promising candidates for practical applications in the modern water treatment industry. [ABSTRACT FROM AUTHOR]

The CO2 sorption properties of sodium hafnium oxide (Na2HfO3) were investigated in this study. Na2HfO3 was synthesized by solid-state synthesis using Na2CO3 and HfO2 as starting materials. The solid-state synthesized Na2HfO3 appeared structurally similar to other mixed metal oxides such as Na2ZrO3, but stacking disorder appeared to be common in Na2HfO3. The synthesis conditions, including the Na : Hf ratio (between 0.5 and 1.5 : 1), synthesis temperature, time and heating rate, were investigated to optimize CO2 sorption properties of Na2HfO3. The Na2HfO3 sorbent showed comparable CO2 uptake capacity, reaction rate and excellent cycling stability compared to other metal oxide sorbents. Na2HfO3 with Na : Hf = 1 : 1 and 1.25 : 1 showed the highest CO2 uptake among all Na2HfO3 samples obtained, with a CO2 uptake capacity of around 15 wt% (at 650–800 °C). The CO2 uptake rate of NHO-1 and NHO-1.25 was fast with over 80% of the equilibrium uptake reached within 250 s. Na2HfO3 remained stable even after 100 cycles with less than 3% difference in the CO2 uptake capacity between the 1st and 100th cycles. We performed kinetic analysis on the CO2 sorption data and found that the Avrami–Erofeev model fitted the kinetic data best among the kinetic models used. Apart from sorbent optimization, we showed that 3D-printing of Na2HfO3 : HfO2 mixtures can be used to produce structured Na2HfO3 sorbents with a slightly improved CO2 uptake rate and the same CO2 uptake capacity as the powder-based solid-state synthesized Na2HfO3 sorbent. [ABSTRACT FROM AUTHOR]

Mono- and a di-protonated pyridine type cations have been used for the synthesis of two bis(oxalato) cuprate(II) salts, namely, (C5H7N2O)2[Cu(C2O4)2] (C5H7N2O = 2-amino-3-hydroxypyridinium) 1 and C13H16-N2[Cu(C2O4)2] (C13H16N2 = 4,4'-trimethylenedipyridinium) 2. In the crystal structures, C2O42- adopts different coordination modes: the common bidentate chelating oxalate in 1 and the relatively scarce µ-oxalato-?³O¹,O²:O¹' in 2. X-ray diffraction also revealed that [Cu(C2O4)2]2- anions do not polymerize in 1 (a phenomenon hardly observed in such salts), while in 2, the polymerization of [Cu(C2O4)2]2- units occurs via the Cu-Oaxial contact forming a zigzag Cu(II) chain. In complex 1, the emerging building blocks are linked into 2D supramolecular layers via N-H···O and O-H···O hydrogen bonds and weaker C-H···O interaction to form a 3D net. In contrast to 2, the emerging building blocks are linked into 1D chains via N-H···O hydrogen bonds, which further extend to form a 3D supramolecular framework through Cu-Oaxial and other C-H···O interactions. The structural diversities show that iminium counterions play key roles in the construction of various architectures. Thermal analyses showed no weight loss for either system in the temperature range of 20-180 °C, which indicates that none of these complexes possess solvation water molecules. Magnetic studies indicate the presence of antiferromagnetic coupling between the spin centres in 1 and 2. [ABSTRACT FROM AUTHOR]

The effect of solvent has been investigated for the synthesis of bismuth gallate compounds, of which the water-based bismuth subgallate has been used as an active pharmaceutical ingredient (API) for over a century. Using methanol as a solvent, two new bismuth gallates were acquired: first a flexible 3-periodic metal–organic framework (MOF) forms, which transforms upon extended synthesis times into a layered 2-periodic coordination polymer of the same bismuth-to-gallate ratio. The structures were determined by three-dimensional electron diffraction. Synthesis in ethanol resulted in the formation of the MOF phase, but not the layered phase. The layered material of the methanol-based synthesis was used as a Lewis acid catalyst due to its higher stability, showing a comparatively quick and regiospecific conversion of styrene oxide to 2-methoxy-2-phenylethanol, indicating the presence of open metal sites in the material. The acquisition of bismuth gallate structures of varying periodicity highlights the prospect of acquiring novel MOFs and coordination polymers from the same components of APIs. [ABSTRACT FROM AUTHOR]

Bibrocathol is an active pharmaceutical ingredient that has been used to treat eyelid diseases for over a century, yet its structure has remained unknown. 3D electron diffraction on crystals from a commercial ointment revealed two structures. These results highlight the technique's potential in structure elucidation from microcrystalline mixtures. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) metal–organic frameworks (MOFs) have become a hot topic recently due to their high surface area, larger number of exposed active sites, and improved conductivity. Combining different 2D MOFs could introduce new physical and chemical properties. Here, we have synthesized a heteroepitaxially grown 2D zeolitic imidazolate framework with a leaf-like morphology (ZIF-L). ZIF-L has a layer-by-layer dense structure, which possesses a high content of N and metal ions as active sites. ZIF-L-Co is heteroepitaxially grown on ZIF-L-Zn, while ZIF-L-Zn@ZIF-Co has been successfully prepared. After pyrolysis, the heteroepitaxially grown MOF derived ultra-small Co nanoparticle immobilized nitrogen doped carbon (NC) material (HM-Co@NC) exhibits superior oxygen reduction reaction (ORR) activity (Eonset = 0.998 V, E1/2 = 0.905 V) and better stability than Pt/C, achieving well-qualified assemblies for use in rechargeable Zn–air batteries. [ABSTRACT FROM AUTHOR]

Bismuth-based coordination polymers (CPs) have recently attracted attention as catalyst precursors for the electrocatalytic CO2 reduction reaction (eCO2RR). We present a comparative study by investigating six bismuth-based compounds in-depth to elucidate the correlation between their structures and their catalytic CO2-to-formate conversion. Thereby, we identify structural indicators of the pristine CPs resulting in optimized catalytic performance, paving the way for future design of CP derived catalysts. The structural properties of the six pristine materials vary in terms of porosity (from non-porous to 495 m2 g−1), linker type (carboxylate- or phenolate-based), thermal- and chemical stability, and metal content. Herein, electrochemical studies are combined with comprehensive structural investigations using electron microscopy, powder X-ray diffraction, and X-ray absorption spectroscopy. Our study reveals that low chemical stability of the pristine CPs is crucial for the conversion of the precursors into active Bi2O2CO3 and of paramount importance for the eCO2RR activity, while the nature of the pristine material mostly influence the catalyst morphology and transport properties. Of the six investigated CPs, the best performing compounds selectively convert CO2 to formate with faradaic efficiencies in the range 80(3)–95(3)% and current densities of 5(1)–8(1) mA cm−2 at −0.97 VRHE. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is an efficient means of producing energy carriers, such as H2. The hydrogen evolution reaction (HER) requires high-efficiency electrocatalysts. Understanding the active site structures of the HER electrocatalysts is essential for the rational design and development of water splitting devices. In this study, porous CoW sulfides were employed as model electrocatalysts for pH-universal HER. Multiple characterization studies, such as X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and operando X-ray diffraction, were systematically used to investigate the reconstruction of the active species at the surface and in the bulk. The results show that during the HER, the structural transformation of the species CoW sulfides is strongly dependent on the pH of the electrolyte. Electrolytes of varying pH lead to varied reconstruction and influence the true catalytically active species responsible for the HER. The surface and the bulk of the electrocatalysts transform to different oxides/hydroxides when subjected to the HER. This is the first time that the pH-dependent bulk and surface structural evolution in the HER has been revealed. This study reveals the reconstruction and potential active site evolution of mixed-metal sulfides for the HER. We believe that the present study not only provides an idealized "pre-catalyst" for pH-universal highly-efficient HER, but also provides a thorough understanding about the identification of the real active sites and the mechanism of the structural evolution of the electrocatalysts during hydrogen evolution. [ABSTRACT FROM AUTHOR]

Electron and powder diffraction were combined to elucidate the structure of the new coordination polymer [Sc2(FcDC)3] based on 1,1′-ferrocenedicarboxylate (FcDC2−), denoted as CAU-50. Remarkably, three different conformers of the very same linker molecule are observed, two of which serve as connectors for the scandium cations while one conformer acts as capping agent. [ABSTRACT FROM AUTHOR]

Two novel dopant-free hole-transport materials (HTMs) with spiro[dibenzo[c,h]xanthene-7,9′-fluorene] (SDBXF) skeletons were prepared via facile synthesis routes. A power conversion efficiency of 15.9% in perovskite solar cells is attained by using one HTM without dopants, which is much higher than undoped Spiro-OMeTAD-based devices (10.8%). The crystal structures of both new HTMs were systematically investigated to reveal the reasons behind such differences in performance and to indicate the design principles of more advanced HTMs. [ABSTRACT FROM AUTHOR]

Three new In-MOFs with –NH2 and/or –NO2 functionalities are reported using 2-amino- (H2BDC-NH2), 2-nitro- (H2BDC-NO2) and 2-amino-5-nitroterephthalic acid (H2BDC-NH2/NO2). Their structures were determined from single crystal X-ray diffraction data. The structure of the first In-MOF of composition [In(BDC-NH3)(BDC-NH2)]·1.6DMF·1.9H2O (In-BDC-NH2; DMF is dimethylformamide; the space group is P6222, a = b = 14.738(2) Å and c = 12.257(3) Å) is built up by two interpenetrating nets of InO8 polyhedra interconnected by BDC-NH22− ions to form a framework with qtz topology. Charge balance is accomplished by partial protonation of the amino group, which was confirmed by IR spectroscopy. The interpenetration leads to a decrease of the pore dimension (4.4 Å in diameter). Thermogravimetric analysis revealed stability up to 300 °C. Replacement of H2BDC-NH2 by H2BDC-NO2 in the reaction mixture led to the isoreticular MOF containing no –NO2 groups but exclusively un- and amino-functionalized linkers. Hence an indium mediated reduction of the H2BDC-NO2 linker molecule during solvothermal synthesis has occurred. The use of H2BDC-NH2/NO2 under exactly the same reaction conditions did not result in the formation of a MOF, but by changing the synthesis parameters, a new –NH2/–NO2 bifunctionalised In-MOF of composition (DMA)2[In3(μ3-O)(BDC-NH2/NO2)4.5]·DMF (DMA is dimethylammonium), denoted In-BDC-NH2/NO2, was obtained. The crystal morphology can be altered from cubic to truncated octahedral crystals by varying the DMF/ethanol volume ratio during synthesis. The compound crystallises in the cubic space group I4̅3m, a = 24.8947(1) Å, and the framework contains trinuclear {In3(μ3-O)} clusters which are interlinked by the BDC-NH2/NO22− ions to form super-tetrahedra. Four face-sharing super-tetrahedra form ultra-tetrahedra which are connected to form the final cubic framework with an ncb topology and isolated inaccessible pores. [ABSTRACT FROM AUTHOR]

Bismuth subgallate has been used in wound and gastrointestinal therapy for over a century. The combination of continuous rotation electron diffraction and sample cooling finally revealed its structure as a coordination polymer. The structure provides insight regarding its formula, poor solubility, acid resistance and previously unreported gas sorption properties. [ABSTRACT FROM AUTHOR]

The effect of solvent has been investigated for the synthesis of bismuth gallate compounds, of which the water-based bismuth subgallate has been used as an active pharmaceutical ingredient (API) for over a century. Using methanol as a solvent, two new bismuth gallates were acquired: first a flexible 3-periodic metal-organic framework (MOF) forms, which transforms upon extended synthesis times into a layered 2-periodic coordination polymer of the same bismuth-to-gallate ratio. The structures were determined by three-dimensional electron diffraction. Synthesis in ethanol resulted in the formation of the MOF phase, but not the layered phase. The layered material of the methanol-based synthesis was used as a Lewis acid catalyst due to its higher stability, showing a comparatively quick and regiospecific conversion of styrene oxide to 2-methoxy-2-phenylethanol, indicating the presence of open metal sites in the material. The acquisition of bismuth gallate structures of varying periodicity highlights the prospect of acquiring novel MOFs and coordination polymers from the same components of APIs.

A disordered open-framework germanate, denoted as SU-75, was synthesized under hydrothermal conditions using diethylenetriamine (dien) or alternatively 1,4-diaminobutane (dab) as the structure directing agent (SDA). SU-75 crystallizes in a tetragonal space group I42d (No. 122) with a = 18.145(3) Å and c = 41.701(9) Å. The three-dimensional (3D) framework is built from Ge(10)(O,OH)(28) (Ge(10)) clusters that are connected following the pcu (primitive cubic) net topology. SU-75 has 10-, 11- and 12-ring channels along the a- and b-axes and channels with alternating 8-, 10-, 12-, 10-ring openings along the c-axis. The framework exhibits a serious disorder, resulted from two possible connectivities between the units of four Ge(10) clusters (4Ge(10) unit). The chemical formula of SU-75 is |(H(2)SDA)(2)(H(2)O)(n)|[Ge(10)O(21)(OH)(2)] (SDA = dien or dab, n = 5-6), determined by combining single crystal synchrotron X-ray diffraction, thermogravimetric analysis (TGA) and CHN elemental analysis. A superoctahedron is introduced to simplify the description of the connectivity of the Ge(10) clusters and to illustrate the disorder. This is also used to compare the structure of SU-75 with those of related Ge(10) germanates.