Simultaneous Stabilization of Potassium Metal and Superoxide in K–O2 Batteries on the Basis of Electrolyte Reactivity

In superoxide batteries based on O₂/O₂^? redox chemistry, identifying an electrolyte to stabilize both the alkali metal and its superoxide remains challenging owing to their reactivity towards the electrolyte components. Bis(fluorosulfonyl)imide (FSI^?) has been recognized as a “magic anion” for passivating alkali metals. The KFSI–dimethoxyethane electrolyte passivates the potassium metal anode by cleavage of S?F bonds and the formation of a KF‐rich solid–electrolyte interphase (SEI). However, the KFSI salt is chemically unstable owing to nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable to KO₂, but results in mossy potassium deposits and irreversible plating and stripping. To circumvent this dilemma, we developed an artificial SEI for the metal anode and thus long‐cycle‐life K–O₂ batteries. This study will guide the development of stable electrolytes and artificial SEIs for metal–O₂ batteries.     

Ni/TPC催化剂的制备、表征及在秸秆热解燃气重整中的应用

以废弃汽车外轮胎热解后的副产物轮胎热解焦（Tyre pyrolysis char,TPC）为原料,利用均匀沉淀法制备以轮胎焦为载体的负载型Ni/TPC催化剂,采用EDX、SEM、XRD、TG、BET手段对催化剂进行了表征与分析,同时使用管式炉测试了Ni/TPC催化剂在秸秆热解燃气重整中的催化性能,并考察了热解温度、保温时间、镍负载量及催化时间对秸秆热解燃气重整效果的影响。研究结果表明,TPC富含焦和金属,Ni/TPC催化剂分散均匀,热稳定性好,比表面积为62 m²/g。催化剂活性测试显示,Ni/TPC催化剂用于作物秸秆热解燃气重整具有很强的催化活性,可显著提高燃气中可燃气体含量;热解温度在750℃、保温时间10 min、30%的Ni负载量时Ni/TPC催化剂的催化效率最高,连续使用850 min后,燃气中的H₂含量仍相对提高到50%以上,长时间使用后活性结构由Ni₃ZnC_0.7转变成FeNi₃,催化活性依然较强且趋于稳定,TPC可以作为良好的新型镍基催化剂载体。     

Syndiospecific polymerization of styrene with BzCpTiCl3 and methylaluminoxane as cocatalysts

Benzyl cyclopentadienyl titanium trichloride (BzCpTiCl₃) was synthesized from benzyl bromide, cyclopentadienyl lithium, and titanium tetrachloride and used in combination with methylaluminoxane (MAO) for the syndiospecific polymerization of styrene. Kinetic measurements of the polymerization were carried out at different temperatures. The polymerization with BzCpTiCl₃/MAO differs from the polymerization with cyclopentadienyl titanium trichloride in its behavior toward the Al/Ti ratio. In addition, high activities are observed at high Al/Ti ratios. By analyzing the polymerization runs and the physical properties of the polymers with differential scanning calorimetry, ¹³C NMR spectroscopy, wide‐angle X‐ray scattering measurements, and gel permeation chromatography, we found that the phenyl ring coordinates to the titanium atom during polymerization. Other known substitutions of the cyclopentadienyl ring (V. Scholz, Dissertation, University of Hamburg, 1998) in principle influence the polymerization activity. The physical properties of the polymers produced by the catalysts already known are nearly identical. BzCpTiCl₃ is the first catalyst that leads to polystyrene obviously different from the polystyrene produced by other highly active catalysts. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2805–2812, 2001     

Theoretical investigation of half‐metallicity in Co/Ni substituted AlN

Results of Co and Ni substituted AlN in the zinc blende phase are presented. For spin up states, the hybridized N‐2p and Co/Ni‐3d states form the valance bands with a bandgap around the Fermi level for both materials, while in the case of the spin down states, the hybridized states cross the Fermi level and hence show metallic nature. It is found that, Al_0.75Co_0.25N and Al_0.75Ni_0.25N are ferromagnetic materials with magnetic moments of 4 μ_B and 3 μ_B, respectively. The integer magnetic moments and the full spin polarization at the Fermi level make these compounds half‐metallic semiconductors. Furthermore it is also found that the interaction with the N‐2p state splits the 5‐fold degenerate Co/Ni‐3d states into t_2g and e_g states. The t_2g states are located at higher energies than the e_g states caused by the tetrahedral symmetry of these compounds. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Remarkable improvement of cyclic stability in Li–O2 batteries using ruthenocene as a redox mediator

Nonaqueous Li–O₂ batteries attract attention for their theoretical specific energy density. However, due to the difficulty of decomposition of Li₂O₂, Li–O₂ batteries have high charge overpotential and poor cycling life. So all kinds of catalysts have been studied on the cathode. Compared to heterogeneous solid catalysts, soluble catalysts achieve faster and more effective transport of electrons by reversible redox pairs. Here, we first report ruthenocene (Ruc) as a mobile redox mediator in a Li–O₂ battery. 0.01 mol/L Ruc in the electrolyte effectively reduces the charging voltage by 610 mV. Additionally, Ruc greatly increases the cycling life by four-fold (up to 83 cycles) with a simple ketjen black (KB) cathode. The results of SEM, XPS and XRD confirm that less discharge product residue accumulated after recharge. To verify the reaction mechanisms of the mediator, free energy profiles of the possible reaction pathways based on DFT are provided.     

Improved RP‐HPLC method for determination of bovine lactoferrin and its proteolytic degradation in simulated gastrointestinal fluids

The objective of this study was to qualitatively and quantitatively evaluate bovine lactoferrin (bLf) and its stability using a rapid RP‐HPLC method. bLf could be rapidly detected within 20 min and quantitated at levels down to 5 µg/mL, and the equation of linearity was y = 86.10x + 178.31 with the correlation coefficient (r²) 0.9997. Quantitative data obtained in the present study proved the improved RP‐HPLC method to be a sensitive and accurate analytical tool for bLf determination. The proteolytic cleavage of bLf in simulated human gastrointestinal fluids was further analyzed by RP‐HPLC, and found to follow pseudo‐first‐order kinetics. The typical equation obtained by pepsin was log₁₀ [A_t]/[A₀] = ?0.03x (r² = 0.85), and log₁₀ [A_t]/[A₀] = ?0.01x (r² = 0.81) for trypsin and chymotrypsin combination. Pepsinolysis of bLf in simulated gastric fluid was relatively fast with the half‐life t_1/2 23.1 min. The digestion of bLf in simulated intestinal fluid was slower with about a 3‐fold increase in half‐life (69.3 min). After the complete proteolysis of bLf, small cleaved peptide fragments were fully separated and identified by RP‐HPLC. The proteolytic study indicated that this validated RP‐HPLC was able to evaluate bLf stability though monitoring the derivatization products. Copyright © 2012 John Wiley & Sons, Ltd.     

Lysosome‐targeted potent half‐sandwich iridium(III) α‐diimine antitumor complexes

Fifteen organometallic Ir(III) half‐sandwich complexes ( 1A – 5C ) having the general formula [(η⁵‐Cp^x)Ir(N^N)Cl]PF₆ (Cp^x = Cp*, tetramethyl(phenyl)cyclopentadienyl (Cp^xph) or tetramethyl(biphenyl)cyclopentadienyl (Cp^xbiph); N^N = diamine) have been synthesized and characterized. The molecular structure of 1A was determined using single‐crystal X‐ray diffraction analysis. The hydrolysis of 1A – 5C was monitored using UV–visible spectra. Complexes 3A – 3C showed catalytic activity for the oxidation of NADH to NAD⁺, where 3C showed the highest turnover number of 29.9 within 450 min. Cytotoxicity examination by MTT assay was carried out against two human cancer cell lines (HeLa and A549) after 24 or 48 h drug treatment. The complexes showed high potency, where the most potent complex ( 3C ; IC₅₀ = 3.4 μM) was six times more active than cisplatin against A549 cells after 24 h drug exposure. Cytotoxic potency towards A549 cells increased with phenyl substitution on Cp ring: Cp^xbiph > Cp^xph > Cp*. In addition, the biological studies showed that 3C caused cell apoptosis and cell cycle arrest at G₁ phase in A549 cancer cells. Moreover, 3C increased the level of reactive oxygen species markedly after 24 h, which may provide an important basis for killing cancer cells. Confocal laser scanning microscopy was used to track 3C in A549 cells. The cellular localization experiment showed that 3C targeted lysosomes and caused lysosomal damage.     

Modeling study of non-line-narrowed hole-burned spectra in weakly coupled dimers and multi-chromophoric molecular assemblies

Several different models have been proposed to explain the origin of the complex anti-hole features observed in hole-burned (HB) spectra of excitonically coupled systems such as photosynthetic complexes. This lack of consensus presents a serious constraint on the interpretation of HB spectra and the underlying electronic structures of these systems. To resolve this problem we present results of modeling studies of non-resonant HB spectra taking uncorrelated excitation energy transfer and excitonic interactions into account. Simplified analytical results are compared with Monte Carlo simulations in which excitonic interactions are explicitly taken into account in order to disentangle a number of distinct effects. It is shown that these effects can accurately account for both hole shapes and the broad anti-hole structure observed in excitonically coupled systems. We argue that these models will provide a necessary framework for probing the electronic structure of these systems via HB spectroscopy.