Growth of High‐Quality,Thickness‐Reduced Zeolite Membranes towards N2/CH4 Separation Using High‐Aspect‐Ratio Seeds

Greatly improved zeolite membranes were prepared by using high‐aspect‐ratio zeolite seeds. Slice‐shaped seeds with a high aspect ratio (AR) facilitated growth of thinner continuous SAPO‐34 membranes of much higher quality. These membranes showed N₂ permeances as high as (2.87±0.15)×10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ at 22 °C while maintaining a decent N₂/CH₄ selectivity (9–11.2 for equimolar mixture). On the basis of these thinner high‐quality SAPO‐34 membranes, fine‐tuning the local crystal structure by incorporating more silicon further increased the N₂ permeance by 1.4 times without sacrificing the N₂/CH₄ selectivity. We expect that application of large AR zeolite seeds might be a viable strategy to grow thin high‐quality zeolite membranes. In addition, fine‐tuning of the crystal structure by changing the crystal composition might be a feasible way for further improving the separating performance of high‐quality zeolite membranes.     

Organic–Inorganic Copolymerization for a Homogenous Composite without an Interphase Boundary

Ionic oligomers and their crosslinking implies a possibility to produce novel organic–inorganic composites by copolymerization. Using organic acrylamide monomers and inorganic calcium phosphate oligomers as precursors, uniformly structured polyacrylamide (PAM)-calcium phosphate copolymer is prepared by an organic–inorganic copolymerization. In contrast to the previous PAM-based composites by mixing inorganic components into polymers, the copolymerized material has no interphase boundary owing to the homogenous incorporation of the organic and inorganic units at molecular level, resulting in a complete and continuous hybrid network. The participation of the ionic binding effect in the crosslinking process can substantially improve the mechanical strength; the copolymer can reach a modulus and hardness of 35.14±1.91 GPa and 1.34±0.09 GPa, respectively, which are far superior to any other PAM-based composites.     

Alkyl-Chain-Regulated Charge Transfer in Fluorescent Inorganic CsPbBr3 Perovskite Solar Cells

Improved charge extraction and wide spectral absorption promote power conversion efficiency of perovskite solar cells (PSCs). The state-of-the-art carbon-based CsPbBr₃ PSCs have an inferior power output capacity because of the large optical band gap of the perovskite film and the high energy barrier at perovskite/carbon interface. Herein, we use alkyl-chain regulated quantum dots as hole-conductors to reduce charge recombination. By precisely controlling alkyl-chain length of ligands, a balance between the surface dipole induced charge coulomb repulsive force and quantum tunneling distance is achieved to maximize charge extraction. A fluorescent carbon electrode is used as a cathode to harvest the unabsorbed incident light and to emit fluorescent light at 516 nm for re-absorption by the perovskite film. The optimized PSC free of encapsulation achieves a maximum power conversion efficiency up to 10.85 % with nearly unchanged photovoltaic performances under 80 %RH, 80 °C, or light irradiation in air.     

Safe,Low‐Cost,Fast‐Kinetics and Low‐Strain Inorganic‐Open‐Framework Anode for Potassium‐Ion Batteries

A key challenge for potassium‐ion batteries is to explore low‐cost electrode materials that allow fast and reversible insertion of large‐ionic‐size K⁺. Here, we report an inorganic‐open‐framework anode (KTiOPO₄), which achieves a reversible capacity of up to 102 mAh g^?1 (307 mAh cm^?3), flat voltage plateaus at a safe average potential of 0.82 V (vs. K/K⁺), a long lifespan of over 200 cycles, and K⁺‐transport kinetics ≈10 times faster than those of Na‐superionic conductors. Combined experimental analysis and first‐principles calculations reveal a charge storage mechanism involving biphasic and solid solution reactions and a cell volume change (9.5 %) even smaller than that for Li⁺‐insertion into graphite (≈10 %). KTiOPO₄ exhibits quasi‐3D lattice expansion on K⁺ intercalation, enabling the disintegration of small lattice strain and thus high structural stability. The inorganic open‐frameworks may open a new avenue for exploring low‐cost, stable and fast‐kinetic battery chemistry.     

Chemical Vapor Deposition of Phase‐Pure Uranium Dioxide Thin Films from Uranium(IV) Amidate Precursors

Homoleptic uranium(IV) amidate complexes have been synthesized and applied as single‐source molecular precursors for the chemical vapor deposition of UO₂ thin films. These precursors decompose by alkene elimination to give highly crystalline phase‐pure UO₂ films with an unusual branched heterostructure.     

Understanding Hydrogen Bonding Interactions in Crosslinked Methylammonium Lead Iodide Crystals: Towards Reducing Moisture and Light Degradation Pathways

Methylammonium lead halide perovskite‐based solar cells have demonstrated efficiencies as high as 24.2 %, highlighting their potential as inexpensive and solution‐processable alternatives to silicon solar cell technologies. Poor stability towards moisture, ultraviolet irradiation, heat, and a bias voltage of the perovskite layer and its various device interfaces limits the commercial feasibility of this material for outdoor applications. Herein, we investigate the role of hydrogen bonding interactions induced when metal halide perovskite crystals are crosslinked with alkyl or π‐conjugated boronic acid small molecules (‐B(OH)₂). The crosslinked perovskite crystals are investigated under continuous light irradiation and moisture exposure. These studies demonstrate that the origin of the interaction between the alkyl or π‐conjugated crosslinking molecules is due to hydrogen bonding between the ‐B(OH)₂ terminal group of the crosslinker and the I of the [PbI₆]^4? octahedra of the perovskite layer. Also, this interaction influences the stability of the perovskite layer towards moisture and ultraviolet light irradiation. Morphology and structural analyses, as well as IR studies as a function of aging under both dark and light conditions show that π‐conjugated boronic acid molecules are more effective crosslinkers of the perovskite crystals than their alkyl counterparts thus imparting better stability towards light and moisture degradation.     

Carbon-13 nuclear magnetic resonance studies of some phosphonium,arsonium, sulfonium and pyridinium keto-stabilized salts,and ylides and of their palladium(II) complexes

The ¹³C chemical shifts, the ¹³C³¹P coupling constants, and some one-bond ¹³C¹H coupling constants were measured for the title compounds. For the ylides of phosphorus, arsenic and sulfur, the data are consistent with an sp²-hybridized ylidic carbon with a strong, localized negative charge, while for the pyridinium ylide this charge is much more delocalized. in the homologous series of salts the electron-withdrawing ability of the groups studied varies in the order: Ph₃P⁺ < Ph₃As⁺ « Me₂S⁺ « Me₂C₅H₃N⁺. The differences in the carbonyl chemical shift between the ylides and the corresponding salts are a measure of the resonance stabilization of the negative charge in the form X⁺CCO^?; this stabilization varies with the groups studied in the order: Ph₃P⁺ < Ph₃As⁺ ≈ Me₂S⁺ « Me₂C₅H₃N⁺. The ylide—palladium(II) complexes contain a bond between the ylidic carbon and the metal: the ylidic carbon is shifted upfield in the complex with respect to the free ligand, while the adjacent carbonyl is shifted strongly downfield. These data suggest that the PdC(1) bond is strongly polarized with a high electron density on the C(1) atom which cannot be delocalized through resonance as in the free ligands.     

Crystal structures and phase transition of Rb2TeBr6 (300-12.5 K)

Using 298 and 160(3) K diffractometer intensity data the structure of Rb₂TeBr₆ has been determined by single crystal X-ray technique and refined to a final R_w of 0.041 and 0.037, respectively (K₂PtCl₆ type structure, space group Fm3m, Z = 4 with a₂₉₈ = 10.773(4) Å and a₁₆₀ = 10.713(6) Å). The powder diffraction pattern from 300 to 12.5 K was recorded by a low-temperature Guinier diffractometer and camera. Below 45(5) K a second-order phase transition leads to a tetragonally distorted structure corresponding to a softening of the T_1g(Γ) rotary phonon. The powder pattern measured with the diffractometer at 12.5 K was used for structural refinement (R = 0.092). This low-temperature phase shows a ferrorotative displacement of the TeBr₆-octahedra with a tilt angle of 4.7(1) deg. (space group $\text{I4}\text{m}\text{, Z = 2, a = 7.4726(3)}$ Å and c = 10.7008(5) Å). The structural results indicate that there is no stereochemical activity of the lone pair electrons at Te(IV) even at very low temperatures. Phase transitions of Rb₂TeBr₆ and Rb₂TeI₆ (A_2g(X)-condensation) are compared. The results of a lattice dynamic calculation shows that only the T_1g(Γ) condensation can be explained with a rigid ion model.