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Ge-containing Lewis acidic zeolites are typically synthesized using a conventional hydrothermal strategy from amorphous silica sources, through a long time- and energy-consuming approach limiting their wide applications. This study reports a rapid synthesis strategy for a series of IWV aluminogermanosilicate zeolites (T-x-Al) with a wide range of Si/Ge molar ratios (5–15) by interzeolite transformation of dealuminated FAU (DA-FAU). Notably, Ge-rich IWV could be obtained with crystallization time as short as one day by the equimolecular Si/Ge ratio gel. The effect of synthetic parameters was investigated and the obtained T-x-Al samples were characterized by XRD, SEM, EDS, ICP, 29Si and 27Al MAS NMR, FTIR, and N2 physisorption analyses. Compared with a previously reported IWV germanosilicate (H-3), T-x-Al displayed a better catalytic activity in Baeyer-Villiger (BV) oxidation, attributed to the presence of the active framework Ge sites with the assistance of the extra-framework Al species. The cyclic catalysis tests revealed that the presence of framework Al species contributed to the stability of the T-x-Al. Specifically, T-x-Al, with 14-membered ring (MR) supercages, outperformed the typical 12-MR Sn-beta catalyst in the BV oxidation of large ketone-like 2-admantanone, indicating a promising potential application in the macromolecular catalytic process. [ABSTRACT FROM AUTHOR]

This paper is concerned with event-triggered H∞ control of sampled-data systems. Its novelties lie in three aspects: (i) A novel accumulated-state-error-based event-triggered scheme is introduced by comparing the integral of the state error from tk to t with the system state sampled at tk. This condition works well due to the fact that the so-called Zeno behaviour does not occur. (ii) A novel Lyapunov functional is constructed to establish a criterion to ensure some certain H∞ performance of the closed-loop system. This Lyapunov functional is dependent on the integral of the state error involved in the event-triggered scheme. (iii) Under the event-triggered sampling scheme, suitable state-feedback controllers can be designed rather than be given a priori. Moreover, a self-triggered implementation of the proposed event-triggered sampling scheme is presented as well. Finally, a batch reactor model and an inverted pendulum system are given to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Elemental Te is important for semiconductor applications including thermoelectric energy conversion. Introducing dopants such as As, Sb, and Bi has been proven critical for improving its thermoelectric performance. However, the remarkably low solubility of these elements in Te raises questions about the mechanism with which these dopants can improve the thermoelectric properties. Indeed, these dopants overwhelmingly form precipitates rather than dissolve in the Te lattice. To distinguish the role of doping and precipitation on the properties, we have developed a correlative method to locally determine the structure-property relationship for an individual matrix or precipitate. We reveal that the conspicuous enhancement of electrical conductivity and power factor of bulk Te stems from the dopant-induced metavalently bonded telluride precipitates. These precipitates form electrically beneficial interfaces with the Te matrix. A quantum-mechanical-derived map uncovers more candidates for advancing Te thermoelectrics. This unconventional doping scenario adds another recipe to the design options for thermoelectrics and opens interesting pathways for microstructure design. Doping is a common strategy to improve thermoelectric performance yet limited to the solid solubility of dopants. Here, the authors find that forming metavalently bonded precipitates is key to property enhancement in Te rather than modifying the matrix lattice. [ABSTRACT FROM AUTHOR]

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By tactically integrating two different kinds of proton donors and acceptors into one supramolecular tecton, a new crystalline hydrogen-bonded organic framework (HOF-SXU-1) has been developed. HOF-SXU-1 features a remarkable proton conductivity as high as 6.32 mS cm−1 and an extremely low activation energy of 0.16 eV at 160 °C under anhydrous N2 conditions. By contrast, under identical conditions, the organic precursors of HOF-SXU-1 only exhibit negligible proton conduction performance, demonstrating that the formation of HOF is crucial for excellent proton conduction performance. [ABSTRACT FROM AUTHOR]

NiFe composites have been regarded as promising candidates to replace commercial noble-based electrocatalysts for the oxygen evolution reaction (OER). However, their practical applications still suffer from poor conductivity, limited activity, and durability. To address these issues, herein, by utilizing three-dimensional covalent organic framework (3D-COF) with porous confined structures and abundant coordinate N sites as the precursor, the partially oxidized Ni3Fe nanoalloys wrapped by N-doped carbon (N-C) layers are constructed via simple pyrolysis and subsequent oxidization. Benefiting from the 3D curved hierarchical structure, high-conductivity of Ni3Fe and N-C layers, and well-distributed active sites, the as-synthesized O-Ni3Fe-N-C catalyst demonstrates excellent activity and durability for catalyzing OER. Experimental and theoretical analyses disclose that both high-temperature oxidization and the OER process greatly promote the formation and exposure of the Ni(Fe)OOH active species as well as lower charge transfer resistance, inducing its optimized OER activity. The robust graphitized N-C layers with superior conductivity and their couplings with oxidized Ni3Fe nanoalloys are beneficial for stabilizing catalytic centers, thereby imparting O-Ni3Fe-N-C with such outstanding stability. This work not only provides a rational guidance for enriching and stabilizing high-activity catalytic sites towards OER but also offers more insights into the structural evolution of NiFe-based OER catalysts. [ABSTRACT FROM AUTHOR]

A partial ligand exchange strategy for fabricating catalytically active single palladium site immobilized on zeolitic imidazolate framework-8 (ZIF-8, Pd1/ZIF-8) is proposed in this work. The one-step synthesis simply involves reacting Na2PdCl4 with ZIF-8 in solvent. The Cl ligands of Na2PdCl4 exchanged with 2-methylimidazole (2-MeIm) of the framework, resulting in the anchoring Pd on the framework and dissociation of Zn into the solution. The whole synthesis is performed at ambient conditions and the crystalline integrity of ZIF-8 is well retained. The resulting Pd1/ZIF-8 is extensively characterized by different techniques which confirm the proposed mechanism. Pd1/ZIF-8 is also successfully applied in the size-selective semi-hydrogenation of alkynes. [ABSTRACT FROM AUTHOR]

Metal halide perovskites based on MX6 (M is metal and X is halogen) octahedra have developed into significant materials, extensively used in many fields, such as solid-state lighting, semiconductor, and nonlinear optics. However, the MX5 square pyramid-based hybrid metal halides beyond zero-dimensional (0D) polyhedrons and clusters are rarely reported. Herein, we reported two new isostructural hybrid antimony halides, namely (2cepyH)SbCl4 (1-Cl) and (2cepyH)SbBr4 (2-Br) (2cepy = 1-(2-chloroethyl)pyrrolidine), characterized by 1D polar polyanionic chains formed by corner-sharing SbX5 tetragonal pyramid units. Upon photoexcitation at 340 nm, 1-Cl shows broad, yellow phosphorescence emissions stemming from triplet self-trapped excitons, as proved by its long lifetime (6.85 μs) and the temperature dependences of broadband emission. To our knowledge, this should be the first observation on the broadband emissive properties in the 1D hybrid metal halide constructed by MX5 tetragonal pyramid units. Moreover, second harmonic generation measurements show that the nonlinear optical properties of 2-Br (∼3.2 × KDP) are superior to that of 1-Cl (∼1.8 × KDP). Experimental and calculated data indicate that the bandgap of 1-Cl is larger than that of 2-Br and that the polar inorganic moieties determine their band structures. Our work opens up a new way for constructing broadband emission materials with novel polar frameworks. [ABSTRACT FROM AUTHOR]

A correction to this paper has been published: https://doi.org/10.1007/s00280-021-04287-1 [ABSTRACT FROM AUTHOR]