A polymer containing aldehyde active groups (PVB) was synthesized by atom transfer radical polymerization (ATRP), acting as a polymer precursor to graft a functional moiety via nucleophilic addition reaction. DHI (2-(1,5-dimethyl-hexyl)-6-hydrazino-benzo[de]isoquinoline-1,3-dione) and NPH (nitrophenyl hydrazine) groups, which contain naphthalimides that act as narrow traps and nitro groups that act as deep traps, were anchored onto the PVB at different ratios. A series of graft polymers were obtained and named PVB-DHI, PVB-DHI4 -NPH, PVB-DHI-NPH4 , and PVB-NPH. The chemical composition of the polymers was analyzed by (1) H-NMR spectroscopy and X-ray photoelectron spectroscopy (XPS). Memory devices were prepared from the polymers, and I-V characteristics were measured to determine the performance. By adjusting the ratio of different electron acceptors (DHI and NPH) to 4:1, ternary memory behavior was achieved. The relationship between memory behavior of PVB-DHIx NPHy and acceptor groups as well as their conduction mechanism were studied in detail.
In article number 1900788, Zhiwei Zhang, Longwei Yin, and co-workers demonstrate a 3D hierarchical NiCo2S4@NiO heterostructure array on carbon paper for Li-O2 battery cathodes. A built-in interfacial potential between NiCo2S4 and NiO can drastically enhance interfacial charge transfer kinetics. Furthermore, intrinsic LiO2-affinity characteristics of NiCo2S4 and NiO play a synergistic role in constructing a low-impedance Li2O2/cathode contact interface. The resulting hybrids exhibit superior electrocatalytic activity toward both ORR and OER.
High sensitivity plays a crucial role in the development of wearable electronic devices. For fiber-based wearable sensors, the sensitivity mainly depends on the conductive properties and surface structure of the fibers. Researchers have made great progress in exploring novel structures and sensing mechanisms for flexible sensors so far. However, the development of convenient and rapid methods to prepare conductive fibers with high conductivity and sensitivity still requires unremitting efforts. In this work, PEDOT: PSS fibers were firstly prepared by wet spinning, which were subsequently placed in Tollens' reagent with the addition of hydroxyurea for a specific silver mirror reaction, achieving three-layer core-shell Ag/AgCl/PEDOT: PSS composite fibers with an optimal conductivity up to 5.2×104 S·cm-1. The resultant composite fibers have extremely fast response time (32 ms) and high sensitivity (5.12 kPa-1), while revealing a pressure-dependent feature. It is worth mentioning that the surface of these composite fibers is not a smooth silver layer, but a layer made of tightly stacked Ag nanoparticles, which contribute to a fast response time, ultra-low detection limit, and bidirectional resistance change. Benefiting from the excellent performance, these fibers have been demonstrated to be used as a flexible sensor in wearable e-textiles. Meanwhile, it is expected to be prepared into next-generation flexible electronics such as bionic arms or artificial intelligence.
Alkali- und Erdalkalimetalltetraeder in Kombination mit einem diamantähnlichen Strukturtemplat (DLS) lieferten das erste nichtlinear-optische (NLO) Material Li4MgGe2S7 mit Alkali- und Erdalkalimetallen. Diese Arbeit erweitert die Vielfalt der DLS-Verbindungen und eröffnet einen Weg für die Entwicklung und Erforschung neuer Infrarot-NLO-Materialien mit hervorragenden NLO-Eigenschaften, wie Shilie Pan, Junjie Li et al. in ihrem Forschungsartikel auf S. 24333 darlegen.
Lithium–sulfur batteries are attracting significant attention due to their high specific capacity, reaching 1672 mAh g–1, but their practical applications are hindered by the inherent insulation of sulfur and slow electrochemical kinetics. To overcome these challenges, an in situ method to chemically attach graphene oxide to the surface of sulfur-rich copolymers is developed in this study. Herein, novel conductive sulfur-rich copolymer composites, cp(S-r-DIB)-Cy-rGO (cpSDG), with a high sulfur copolymerization degree of ca. 52 at % and excellent capacity rates of 1227 mAh g–1 at 0.1 C and 950 mAh g–1 at 1 C, have been obtained by covalently bonding cysteamine-functionalized reduced graphene oxide (Cy-rGO) to the surface of the sulfur-rich polymer matrix (cp(S-r-DIB)). Compared to a copolymer without Cy-rGO loading and pure sulfur cathodes, the composites display significant enhancements of lithium-ion diffusion coefficients and a higher cycling stability, with a capacity decay of only 0.06% per cycle.
Lithium-sulfur (Li-S) batteries with high theoretical energy density are considered as the most promising devices for rechargeable energy-storage systems. However, their actual applications are rather limited by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish redox kinetics. Here, the boron nitride nanosheets are homodispersedly embedded into N-doping porous carbon fibers (BNNSs/CHFs) by an electrospinning technique and a subsequent in situ pyrolysis process. The hybridized BNNSs/CHFs can be smartly designed as a multifunctional separation coating onto the commercial PP membrane to enhance the electrochemical performance of Li-S batteries. As a result, the Li-S batteries with extra BNNSs/CHF modification deliver a highly reversible discharge capacity of 830.4 mA h g-1 at a current density of 1 C. Even under 4 C, the discharge specific capacity can reach up to 609.9 mA h g-1 and maintain at 553.9 mA h g-1 after 500 cycles, showing a low capacity decay of 0.01836% per cycle. It is considered that the excellent performance is attributed to the synergistic effect of adsorption and catalysis of the BNNSs/CHF coating used. First, this coating can efficiently reduce the charge transfer resistance and enhance Li-ion diffusion, due to increased catalytic activity from strong electronic interactions between BNNSs and N-doping CHFs. Second, the combination of polar BNNSs and abundant pore structures within the hybridized BNNSs/CHF networks can highly facilitate an adsorption for LiPSs. Here, we believed that this work would provide a promising strategy to increase the Li-S batteries' performance by introducing hybridized BNNSs/N-doping carbon networks, which could efficiently suppress the LiPSs' shuttle effect and improve the electrochemical kinetics of Li-S batteries.
A new fulvene-based ligand L was synthesized and its coordination chemistry with Ag(i) ion has been investigated. Two novel Ag(i) polymeric complexes, [Ag2L2∙5.5(C6H6)]SbF6 (1) and [AgL∙2.5(C6H6)]SbF6 (2), were obtained by combination of L with AgSbF6 in one-pot reaction. X-Ray single-crystal analysis revealed that both 1 and 2 crystallize in triclinic system P1. In 1 and 2, the ligand L adopts a trans-conformation to bind the Ag(i) centres into a one-dimensional twin-chain structure through either Ag–O coordination or π–π interactions.
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