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Highly efficient asymmetric hydrogenation of dibenzo[b,f][1,4]oxazepine, dibenzo[b,f][1,4]thiazepine and dibenzo[b,e]azepine derivatives with chiral cationic ruthenium diamine catalysts has been developed, giving diverse chiral seven-membered N-heterocycles with excellent results (up to 99% yield and 99% ee). Moreover, it was found that the catalyst counteranion regulated the enantioselectivity obviously in the hydrogenation of dibenzo[b,f][1,4]thiazepine and dibenzo[b,e]azepine derivatives. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical combination of mixed graphene oxide builds ideal ion transfer routes. • One-pot hydrothermal reaction constructs compact and flexible backbone. • Ice-template method helps to obtain orientated filled graphene oxide aerogel. • Novel recapture mechanism let the device activate on charging or deformation cycle. This work demonstrates a hierarchical structure design with mixed holey graphene oxide (HGO) and Ni(OH) 2 active material layer made by one-pot hydrothermal reaction clinging to Nickel foam as backbone and ice-template oriented graphene oxide (GO) aerogel as filling, aiming to create an asymmetric solid supercapacitor (ASC) device with compliable flexibility and high electrochemical performance. The effects of hydrothermal treatment and ice-template freezing parameters on electrochemical stability under repeated exterior deformation are discussed, the optimal parameters result in a high areal capacitance of 479.8 mF/cm2 in asymmetric supercapacitor device setup. The use of porous HGO and oriented GO aerogel synergistically contribute to the high energy and power density up to 1.69 Wh/m2 and 9 W/m2 as well as excellent electrochemical performance retention under repeated curving deformation which reaches 102% thanks to a novel activation process. The electrode assembly including metal foam and the buffering GO aerogel should be instructive for future supercapacitor design. [ABSTRACT FROM AUTHOR]

The lone pair electrons in the electronic structure of molecules have been a prominent research focus in chemistry for more than a century. Stable s2 lone pair electrons significantly influence material properties, including thermoelectric properties, nonlinear optical properties, ferroelectricity, and electro(photo)catalysis. While major advances have been achieved in understanding the influence of lone pair electrons on material characteristics, research on this effect in organic‐inorganic hybrid materials is in its initial stage. In this work, we successfully obtained a novel organic‐inorganic hybrid multifunctional material incorporating Ge with 4s2 lone pair electrons, (MeHDabco)2[GeBr3]4‐H2O (MeHDabco=N‐methyl‐1,4‐diazabicyclo[2.2.2]octane) (1). Driven by the stereochemically active lone pair electrons on the Ge2+, 1 crystallizes in the noncentrosymmetric space group P21 at room temperature and exhibits good second harmonic generation (SHG) responses. Interestingly, 1 also shows electrocatalytic activity for the hydrogen evolution reaction (HER) due to the existence of lone pair electrons on Ge2+ cations. The electrochemical experiment combined with the density functional theory (DFT) calculations revealed that the lone pair electrons act as both an active site for proton adsorption and facilitate the ionization of water. This work not only emphasizes the important role of lone pair electrons in material properties and functions but also provides new insight for designing novel Ge‐based multifunctional hybrid materials. [ABSTRACT FROM AUTHOR]

[Display omitted] To address the problem that capacitor electrode being low in capacitance and reliant on binder to retain shape, a binder-free, self-supporting supercapacitor electrode is made via pyrolysis of porous polyacrylonitrile (PAN) formed by phase separation, supported by hydrothermally treated nickel foam backbone. The role of hydrothermal reaction time and PAN solution concentration on electrochemical properties was thoroughly studied, and the results indicate a generally peaked capacitance at 4 h of hydrothermal reaction time, but after a certain threshold, a supposed micro-domain buffering mechanism would take over and enhance the pseudocapacitance from NiO to reach a specific capacitance as high as 152 F/g at a high active material mass load of 14.98 mg/cm2, providing the area specific capacitance up to 1.98 F/cm2. The use of temperature-controlled phase separation and incorporation of nickel oxide together guarantees the electrode sufficient ion and electron transportation pathway while improving its capacitance by redox electrochemical reactions. [ABSTRACT FROM AUTHOR]

A flexible nickel foam (NF) based reduced Holey Graphene Oxide (rHGO) wrapping on NiO@NF hybrid supercapacitor electrode is fabricated using facile hydrothermal reaction followed by HGO dispersion dipping to achieve an efficient, bendable and scalable supercapacitor with high capacitance for wearable smart device usage. The sample electrode reveals a typical wrapping morphology of porous rHGO spreading on uniform nickel oxide crystal layer while exposing crystals through recurrent rHGO slits. Benefiting from this morphology and optimization of fabrication parameters, the sample electrode gains better electrochemical performance from higher electric double layer capacitance incorporation and more efficient electrolyte ion transportation, with less than 0.1 Ω equivalent series resistance (ESR), 752.9 F/g of capacitance, and 90% capacitance retention under 10 A/g current density. The sample electrode is then made into an all-solid-state supercapacitor device possessing 0.267 Wh/m2 energy density at a power density of 8.14 W/m2, and the bendable fact of the device endows it 97% capacitance retention after 500 times of curving, making it especially suitable as flexible energy provider. This simple fabrication method should shed light on flexible hybrid supercapacitor development. [ABSTRACT FROM AUTHOR]

A hierarchical structure is proved to be important for the improvement of electrochemical performances of MnO 2 -based electrode materials used in supercapacitors. However, the rational design of materials' structure and its real performance served as electrode materials are still facing challenges. Herein, hierarchical porous carbon nanofibers using ZIF-8 nanoparticles as pore templates are designed to provide one-dimensional hollow frameworks for the growth of ultrathin MnO 2 nanosheets (referred as HPCNF/MnO 2). The as-prepared HPCNF/MnO 2 samples have a hierarchical coaxial core-shell structure, with HPCNFs as the core and MnO 2 sheets as the shell. The novel nanostructure of this hybrid provides abundant electrochemical active sites for Faradic reactions and short diffusion channels for ions/electron transport. The utilization of HPCNF/MnO 2 active material with such a structure can be significantly enhanced, especially at the high current density. When evaluated as electrode materials, HPCNF/MnO 2 exhibits a specific capacitance of 269 F g−1 at 0.5 A g−1 (308 F g−1 for MnO 2), a high capacitive retention of 98% even after 5000 cycles at 50 mV s−1 by cyclic voltammetry (86.7% capacitance retention at 1 A g−1 after 2000 cycles) and a rate capability of 58% from 0.5 to 10 A g−1. Especially at the current density of 10 A g−1, the specific capacitance of HPCNF/MnO 2 has increased by 133% compared with that of non-porous carbon fiber/MnO 2 composites, demonstrating a great superiority of hierarchical porous carbon nanofibers as frameworks to support pseudocapacitive materials. [ABSTRACT FROM AUTHOR]

We reported a novel and effective strategy to achieve higher continuity at a lower volume fraction of interphase by using compatibilizers in ternary blend consisting of PVDF, PS and HDPE. PVDF-g-PS was synthesized by electron beam radiation induced free radical graft copolymerization reaction and PVDF-g-PS was characterized by FTIR, DSC and 1 H NMR. PVDF-g-PS showed effective compatibilization in PVDF/PS binary blend. The phase size of PVDF/PS binary blend was decreased at addition of PVDF-g-PS. For phase morphology development, morphology of uncompatibilized PVDF/PS/HDPE (52/6/42 vol%) ternary blend revealed a part of PS droplets situated in PVDF/HDPE interface, the other part was located inside HDPE phase. Whereas, compatibilized blend showed more and more PS migrate to PVDF/HDPE interface. When adding 7% PVDF-g-PS, PS droplets formed into uniform layer self-assembly arrayed at interface, then tri-continuous morphology was formed and continuity of PS phase increased by 32%, ultralow percolation threshold ternary blend was successfully achieved. [ABSTRACT FROM AUTHOR]

High-performance supercapacitors are widely studied, but few works have paid attention to the optimization of conductive bonding networks in the electrode to improve its electrochemical performance. Herein, a rationally designed three-dimensional (3D) conductive bonding network consisting of one-dimensional carboxylated carbon nanotubes (CNT-COOH) and two-dimensional reduced holey graphene oxide (rHGO) is introduced to porous carbon nanofiber/ultra-thin MnO 2 nanosheets (PCNF/U-MnO 2) electrode through vacuum filtration. The CNT-COOH/rHGO network endows the electrode with desired electron transport and ion diffusion properties for its advantages in 3D structures, conductivity and electrolyte wettability, which promote efficient use of PCNF/U-MnO 2 active materials. Thus, PCNF/U-MnO 2 in the electrode with CNT-COOH/rHGO network shows better capacitive performance than that of traditionally fabricated electrode with PTFE and acetylene black. Besides, CNT-COOH/rHGO network is conducive to structural stability of PCNF/U-MnO 2 electrode, and it obtains a capacitance retention of 87% even after 4500 cycles. Then, an asymmetric supercapacitor with PCNF/U-MnO 2 cathode and N, B-doped PCNFs anode has been assembled, which exhibits good flexibility using LiCl/PVA hydrogel as electrolyte and has a high energy density of 45 Wh kg−1 at a power density of 540.8 W kg−1. The strategy of CNT-COOH/rHGO network construction can be an effective and promising way beneficial to high-performance supercapacitor fabrication. [Display omitted] [ABSTRACT FROM AUTHOR]