Oxygen Vacancies in Bismuth Tantalum Oxide to Anchor Polysulfide and Accelerate the Sulfur Evolution Reaction in Lithium-Sulfur Batteries.

The shuttling effect of soluble lithium polysulfides (LiPSs) and the sluggish conversion kinetics of polysulfides into insoluble Li2S2/Li2S severely hinders the practical application of Li-S batteries. Advanced catalysts can capture and accelerate the liquid-solid conversion of polysulfides. Herein, we try to make use of bismuth tantalum oxide with oxygen vacancies as an electrocatalyst to catalyze the conversion of LiPSs by reducing the sulfur reduction reaction (SRR) nucleation energy barrier. Oxygen vacancies in Bi4TaO7 nanoparticles alter the electron band structure to improve instinct electronic conductivity and catalytic activity. In addition, the defective surface could provide unsaturated bonds around the vacancies to enhance the chemisorption capability with LiPSs. Hence, a multidimensional carbon (super P/CNT/Graphene) standing sulfur cathode is prepared by coating oxygen vacancies Bi4TaO7-x nanoparticles, in which the multidimensional carbon (MC) with micropores structure can host sulfur and provide a fast electron/ion pathway, while the outer-coated oxygen vacancies with Bi4TaO7-x with improved electronic conductivity and strong affinities for polysulfides can work as an adsorptive and conductive protective layer to achieve the physical restriction and chemical immobilization of lithium polysulfides as well as speed up their catalytic conversion. Benefiting from the synergistic effects of different components, the S/C@Bi3TaO7-x coin cell cathode shows superior cycling and rate performance. Even under a high level of sulfur loading of 9.6 mg cm-2, a relatively high initial areal capacity of 10.20 mAh cm-2 and a specific energy density of 300 Wh kg-1 are achieved with a low electrolyte/sulfur ratio of 3.3 µL mg-1. Combined with experimental results and theoretical calculations, the mechanism by which the Bi4TaO7 with oxygen vacancies promotes the kinetics of polysulfide conversion reactions has been revealed. The design of the multiple confined cathode structure provides physical and chemical adsorption, fast charge transfer, and catalytic conversion for polysulfides.

Synergistic Adsorption-Catalytic Sites TiN/Ta2O5 with Multidimensional Carbon Structure to Enable High-Performance Li-S Batteries.

Lithium-sulfur (Li-S) batteries are deemed to be one of the most optimal solutions for the next generation of high-energy-density and low-cost energy storage systems. However, the low volumetric energy density and short cycle life are a bottleneck for their commercial application. To achieve high energy density for lithium-sulfur batteries, the concept of synergistic adsorptive-catalytic sites is proposed. Base on this concept, the TiN@C/S/Ta2O5 sulfur electrode with about 90 wt% sulfur content is prepared. TiN contributes its high intrinsic electron conductivity to improve the redox reaction of polysulfides, while Ta2O5 provides strong adsorption capability toward lithium polysulfides (LiPSs). Moreover, the multidimensional carbon structure facilitates the infiltration of electrolytes and the motion of ions and electrons throughout the framework. As a result, the coin Li-S cells with TiN@C/S/Ta2O5 cathode exhibit superior cycle stability with a decent capacity retention of 56.1% over 300 cycles and low capacity fading rate of 0.192% per cycle at 0.5 C. Furthermore, the pouch cells at sulfur loading of 5.3 mg cm-2 deliver a high areal capacity of 5.8 mAh cm-2 at low electrolyte/sulfur ratio (E/S, 3.3 µL mg-1), implying a high sulfur utilization even under high sulfur loading and lean electrolyte operation.

Fast polysulfide catalytic conversion and self-repairing ability for high loading lithium-sulfur batteries using a permselective coating layer modified separator.

Li-S batteries are considered as one of the most promising battery systems because of their large theoretical capacity and high energy density. However, the "shuttle effect" of soluble polysulfides and sluggish electrochemical redox kinetics of Li-S batteries could cause a broken electrode structure and poor electrochemical performance. Herein, a high-performance and stable Li-S battery has been demonstrated by employing organo-polysulfide chain modified acetylene black (ABPS) as the coating layer on the separator. In addition to the traditional advantages of fast electron transport and polysulfide-interception ability of the carbon coating layer, the grafted organo-polysulfide chain endows the ABPS coating layer with permselectivity for lithium ion against polysulfides, electrocatalytic ability for the sluggish redox kinetics and self-repairing ability for the broken electrode. Hence, the battery prepared using an ABPS-coated separator delivers the best cycling performance (970 mA h g-1 at 0.2 C after 100 cycles) and rate performance (805 mA h g-1 at 2 C) as compared to the cells using acetylene black (AB)-coated or Celgard separators. Moreover, the Li-S battery prepared using an ABPS-coated separator exhibits a stable cycling performance at 1 C over 500 cycles with a low degradation of 0.04% per cycle, and a high coulombic efficiency (near 100%). Furthermore, as the sulfur loading was increased to 6.8 mg cm-2, the Li-S battery using the ABPS-coated separator still could deliver a high areal capacity of 6.03 mA h cm-2 with a low electrolyte/sulfur ratio (E/S = 4, µLelectrolyte mgS-1) after 170 cycles. Significantly, ABPS is an effective coating layer material for improving and stabilizing Li-S batteries.

[Assessment of enhancement release of Oncorhynchus keta in Suifen River, Northeast China]. / 绥芬河大麻哈鱼增殖放流效果评估.

To evaluate the effects of enhancement release of Chum salmon (Oncorhynchus keta) in Suifen River, the homing Chum salmon was monitored in Dongning section of Suifen River from 2012 to 2017. A total of 462 samples were collected, 41 samples out of which were tagged indivi-duals which were cut off adipose fin before they were released. The recapture rate and the effects of Chum salmon enhancement release were analyzed and evaluated based on the releasing information. The results showed that the entire recapture rate of Chum salmon from 2010 to 2012 was 0.295%, and the input-output ratio of enhancement release was 1:2.87. Both the tagged and non-tagged groups were composed of 1+ to 5+ age individuals, with the average age being 3.93 and 3.63 years, respectively. The fork length at 50% individuals reached sexual maturity (L50) was estimated using a logistic moderating function, which was 53.13 cm and 49.89 cm for tagged and non-tagged groups, respectively. Results from ARSS analysis showed that there was no significant difference in fork length growth between tagged and non-tagged groups, but a significant difference in sexual maturity ratio. Our results confirmed the positive effects of enhancement release on recovery of Chum salmon resource and provided suggestions for the enhancement release efforts.

A tristable [2]rotaxane that is doubly gated by foldamer and azobenzene kinetic barriers.

A hydrogen bonded foldamer unit and an azobenzene unit have been incorporated into the linear component of a tristable [2]rotaxane to give rise to a doubly gated switching system tuned by the folding-defolding of the foldamer unit and the photo-initiated trans-cis isomerization of the azobenzene unit.

Efficient one-pot synthesis of trans-Pt(II)(salicylaldimine)(4-picoline)Cl complexes: effective agents for enhanced expression of p53 tumor suppressor genes.

A series of trans-Pt(II)(salicylaldimine)(4-picoline)Cl complexes were synthesized in 78-87% yield using a one-pot procedure from commercially available precursors. The structures of these complexes were characterized by (1)H, (19)F and (13)C NMR spectroscopy, HRMS (ESI) as well as single crystal X-ray analysis. Bioactivity investigations including bio-assay, time- and dose-dependent, cell cycle progression study, caspase 3 and 9 apoptosis marker assay and DNA interaction using pBR322 plasmid DNA by gel electrophoresis were performed. The results indicated that the complexes showed promising in vitro cytotoxicity in MCF-7 and A549 cancer cell lines. Moreover these complexes enhanced the expression of p53 tumor suppressor gene family members such as p63 and p73.

Hydrogen-bonding-driven aromatic foldamers: their structural and functional evolution.

This Personal Account summarizes the development of the design of hydrogen-bonding-driven aromatic foldamers and their applications in supramolecular chemistry. This account begins with a short, non-exhaustive description of the background in the study of hydrogen-bonded aromatic foldamers. The construction of foldamers from discrete aromatic residues, including amide, urea, hydrazide and 1,2,3-triazole units, is then described. In the following parts, the applications of such compact aromatic oligomers in supramolecular chemistry, including the development of acyclic receptors, the construction of hybrid helical sequences through intramolecular stacking, the promotion of the formation of covalently and noncovalently bonded macrocycles, the tuning of the mechanical properties of copolymers, and the regulation of the shuttling behavior of [2]rotaxanes and the controlled release of dye from reverse vesicles formed from them, are described. In the final part, the binding-induced folding of conformationally flexible aromatic amide oligomers and their self-binding are described.

Tetrathiafulvalene-based macrocycles formed by radical cation dimerization: the role of intramolecular hydrogen bonding and solvent.

Compounds 1 a and 1 b were prepared by appending two tetrathiafulvalene (TTF) units to an aromatic amide segment that is driven by six or two intramolecular N-H⋅⋅⋅O hydrogen bonds to adopt a folded conformation. UV/Vis absorption experiments revealed that if the TTF units were oxidized to TTF(·+) radical cations, the two compounds could form a stable single molecular noncovalent macrocycle in less polar dichloromethane or dichloroethane or a bimolecular noncovalent macrocycle in a binary mixture of dichloromethane with a more polar solvent owing to remarkably enhanced dimerization of the TTF(·+) units. The stability of the (TTF(·+))2 dimer was evaluated through UV/Vis absorption, electron paramagnetic resonance, and cyclic voltammetry experiments and also by comparing the results with those of control compound 2. The results showed that introduction of the intramolecular hydrogen bonds played a crucial role in promoting the stability of the (TTF(·+))2 dimer and thus the noncovalent macrocyclization of the two backbones in both uni- and bimolecular manners.