Search

Rechargeable sodium/chlorine (Na/Cl2) batteries are emerging candidates for sustainable energy storage owing to their superior energy densities and the high abundance of Na and Cl elements. However, their practical applications have been plagued by the poor rate performance (e.g., a maximum discharge current density of 150 mA g−1), as the widely used carbon nanosphere cathodes show both sluggish electron‐ion transport and reaction kinetics. Here, by mimicking the sufficient mass and energy transport in a sponge, we report a bicontinuous‐structured carbon cubosome with heteroatomic doping, which allows efficient Na+ and electron transport and promotes Cl2 adsorption and conversion, thus unlocking ultrahigh‐rate Na/Cl2 batteries, e.g., a maximum discharge current density of 16,000 mA g−1 that is more than two orders of magnitude higher than previous reports. The optimized solid–liquid–gas (carbon–electrolyte–Cl2) triple interfaces further contribute to a maximum reversible capacity and cycle life of 2,000 mAh g−1 and 250 cycles, respectively. This study establishes a universal approach for improving the sluggish kinetics of conversion‐type battery reactions, and provides a new paradigm to resolve the long‐standing dilemma between high energy and power densities in energy storage devices. [ABSTRACT FROM AUTHOR]

Maximizing hole‐transfer kinetics—usually a rate‐determining step in semiconductor‐based artificial photosynthesis—is pivotal for simultaneously enabling high‐efficiency solar hydrogen production and hole utilization. However, this remains elusive yet as efforts are largely focused on optimizing the electron‐involved half‐reactions only by empirically employing sacrificial electron donors (SEDs) to consume the wasted holes. Using high‐quality ZnSe quantum wires as models, we show that how hole‐transfer processes in different SEDs affect their photocatalytic performances. We found that larger driving forces of SEDs monotonically enhance hole‐transfer rates and photocatalytic performances by almost three orders of magnitude, a result conforming well with the Auger‐assisted hole‐transfer model in quantum‐confined systems. Intriguingly, further loading Pt cocatalyts can yield either an Auger‐assisted model or a Marcus inverted region for electron transfer, depending on the competing hole‐transfer kinetics in SEDs. [ABSTRACT FROM AUTHOR]

The development of novel polymerization capable of yielding polymers with low molecular weight distribution (Đ) is essential and significant in polymer chemistry, where monofunctional initiator contains only one initiation site in these polymerizations generally. Here, ketyl radical anion species is introduced to develop a novel Ketyl Mediated Polymerization (KMP), which enables radical polymerization at carbon radical site and anionic ring‐opening polymerization at oxygen anion site, respectively. Meanwhile, polymerization and corresponding organic synthesis generally couldn't be performed simultaneously in one pot. Through KMP, organic synthesis and polymerization are achieved in one pot, where small molecules (cyclopentane derivates) and polymers with low Đ are successfully prepared under mild condition simultaneously. At the initiation step, both organic synthesis and polymerization are initiated by single electron transfer reaction with ketyl radical anion formation. Cyclopentane derivates are synthesized through 3–3 coupling reaction and cyclization. Polystyrene and polycaprolactone with low Đ and a full monomer conversion are prepared by KMP via radical polymerization and anionic ring‐opening polymerization, respectively. This work therefore enables both organic synthesis and two different polymerizations from same initiation system, which saves time, labour, resource and energy and expands the reaction mode and method libraries of organic chemistry and polymer chemistry. [ABSTRACT FROM AUTHOR]

Trifluoromethyl‐bearing 5‐membered rings are prevalent in bioactive molecules, but modular approaches to these compounds by functionalization of robust C(sp3)−H bonds in a direct and selective manner are extremely challenging. Herein we report the rhodium‐catalyzed α‐CF3‐α‐alkyl carbene insertion into C(sp3)−H bonds of a broad range of substrates to access 7 types of CF3‐bearing saturated 5‐membered carbo‐ and heterocycles. The reaction is particularly effective for benzylic C−H insertion exerting good site‐, diastereo‐ and enantiocontrol, and applicable to the synthesis of chiral CF3 analogues of bioactive molecules. Ruthenium α‐CF3‐α‐alkyl carbene complexes underwent stoichiometric reactions to give C−H insertion products, lending evidence for the involvement of metal α‐CF3‐α‐alkyl carbene species in the catalytic cycle. DFT calculations revealed that the π⋅⋅⋅π attraction and intra‐carbene C−H⋅⋅⋅F hydrogen bond elucidate the origin of selectivity of the benzylic C−H insertion reactions. [ABSTRACT FROM AUTHOR]

The McMurry coupling is a facile, gentle and low‐cost chemical reaction for synthesizing. Here, for the first time, we employed the McMurry coupling reaction to prepare π‐conjugated anion exchange membranes (AEMs). The inter‐chain π‐π stacking between adjacent benzene rings induces directional self‐assembly aggregation and enables highly ordered ion‐conductive channels. The resulting structure was characterized through UV/VIS spectrum, X‐ray diffraction (XRD) pattern, small‐angle X‐ray scattering (SAXS), transmission electron microscopy (TEM) and density functional theory (DFT) calculations, leading to high OH− conductivity of 135.5 mS cm−1 at 80 °C. Furthermore, the double bonds in the π‐conjugated system also trigger in situ self‐crosslinking of the AEMs to enhance dimensional and alkaline stability. Benefiting from this advantage, the as‐obtained Cr‐QPPV‐2.51 AEM exhibits superior alkaline stability (95 % conductivity retention after 3000 hrs in 1 M KOH at 80 °C) and high mechanical strength of 34.8 MPa. Moreover, the fuel cell using Cr‐QPPV‐2.51 shows a maximum peak power density of 1.27 W cm−2 at 80 °C. [ABSTRACT FROM AUTHOR]

Metal‐free and metal‐containing molecular trefoil knots are fascinating ensembles that are usually covalently assembled, the latter requiring the rational design of di‐ or multidentate/multipodal ligands as connectors. In this work, we describe the self‐assembly of pentadecanuclear AuI trefoil knots [Au15(C≡CR)15] from monoalkynes HC≡CR (R=9,9‐X2‐fluorenyl with X=nBu, n‐hexyl) and [AuI(THT)Cl]. Hetero‐bimetallic counterparts [Au9M6(C≡CR)15] (M=Cu/Ag) were self‐assembled by reactions of [Au15(C≡CR)15] with [Cu(MeCN)4]+/AgNO3 and HC≡CR. The type of pentadecanuclear trefoil knots described herein is characterized by X‐ray crystallography, 2D NMR and HR‐ESI‐MS. [Au9Cu6(C≡CR)15] is relatively stable in hexane; its excited state properties were investigated. DFT calculations revealed that non‐covalent metal–metal and metal–ligand interactions, together with longer alkyl chain‐strengthened inter‐ligand dispersion interactions, govern the stability of the trefoil knot structures. [ABSTRACT FROM AUTHOR]

In anion exchange membrane fuel cells, catalytic reactions occur at a well‐defined three‐phase interface, wherein conventional heterogeneous catalyst layer structures exacerbate problems, such as low catalyst utilization and limited mass transfer. We developed a structural engineering strategy to immobilize a molecular catalyst tetrakis(4‐methoxyphenyl)porphyrin cobalt(II) (TMPPCo) on the side chains of an ionomer (polyfluorene, PF) to obtain a composite material (PF‐TMPPCo), thereby achieving a homogeneous catalysis environment inside ion‐flow channels, with greatly improved mass transfer and turnover frequency as a result of 100 % utilization of the catalyst molecules. The unique structure of the homogeneous catalysis system comprising interconnected nanoreactors exhibits advantages of low overpotential and high fuel‐cell power density. This strategy of reshaping of the catalyst layer structure may serve as a new platform for applications of many molecular catalysts in fuel cells. [ABSTRACT FROM AUTHOR]

A transition‐metal‐free C(sp2)−C(sp2) bond formation reaction by the cross‐coupling of diazo quinones with catechol boronic esters was developed. With this protocol, a variety of biaryls and alkenyl phenols were obtained in good to high yields under mild conditions. The reaction tolerates various functionalities and is applicable to the derivatization of pharmaceuticals and natural products. The synthetic utility of the method was demonstrated by the short synthesis of multi‐substituted triphenylenes and three bioactive natural products, honokiol, moracin M, and stemofuran A. Mechanistic studies and density functional theory (DFT) calculations revealed that the reaction involves attack of the boronic ester by a singlet quinone carbene followed by a 1,2‐rearrangement through a stepwise mechanism. [ABSTRACT FROM AUTHOR]

All-inorganic cesium lead-halide perovskite nanocrystals have emerged as attractive optoelectronic nanomaterials owing to their stabilities and highly efficient photoluminescence. Herein we report a new type of highly luminescent perovskite-related CsPb2Br5 nanoplatelets synthesized by a facile precipitation reaction. The layered crystal structure of CsPb2Br5 promoted an anisotropic two-dimensional (2D) crystal growth during the precipitation process, thus enabling the large-scale synthesis of CsPb2Br5 nanoplatelets. Fast anion exchange has also been demonstrated in as-synthesized CsPb2Br5 nanoplatelets to extend their photoluminescence spectra to the entire visible spectral region. The large-scale synthesis and optical tunability of CsPb2Br5 nanoplatelets will be advantageous in future applications of optoelectronic devices. [ABSTRACT FROM AUTHOR]

In ihrem Forschungsartikel (e202200748) berichten Jie-Sheng Huang, Chi-Ming Che und Mitarbeiter über die Verwendung von Monoalkinen und einer einkernigen Au SP I sp -Verbindung für die Selbstorganisation von Au-C-verknüpften B Au b SB B 15 b sb -Kleeblattknoten, die nichtkovalente Au SP I sp -Au SP I sp -Wechselwirkungen aufweisen. Die Strukturen, das Lösungsverhalten und die Photolumineszenzeigenschaften der B Au b SB B 15 b sb - und B Au b SB B 9 b sb B M b SB B 6 b sb -Kleeblattknoten (M=Cu/Ag) wurden untersucht. Innenrücktitelbild: Self-Assembly of Molecular Trefoil Knots Featuring Pentadecanuclear Homoleptic AuI-, AuI/AgI-, or AuI/CuI-Alkynyl Coordination (Angew. [Extracted from the article]