一种刺松藻来源的硫酸阿拉伯聚糖的制备及特征结构表征

刺松藻(Codium fragile)经水提-醇沉获得粗多糖, 进一步将刺松藻粗多糖(CFP) 通过Q-Sepharose Fast Flow(QFF) 阴离子交换柱纯化得到6个多糖组分CFP1CFP6, 其中, 在CFP6中发现纯度较高的阿拉伯聚糖. 采用高效凝胶渗透色谱与十八角激光散射仪联用法和1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生高效液相色谱法对CFP6的分子量及单糖组成进行了分析. 结果表明, CFP6是一种分子量为79290的多糖, 由阿拉伯糖(Ara)和半乳糖(Gal)组成, 二者摩尔比为14.8:1.0. 通过多维核磁共振波谱、 液相色谱-质谱联用及二级质谱等方法对CFP6的糖苷键连接方式及其寡糖序列结构进行表征, 进一步阐明了该复杂多糖的特征结构. 经判断, CFP6主链由Ara组成, 通过 β-(1→3)糖苷键连接, 在Ara的C2位存在分支结构, 硫酸基位于Ara的C4或C2位.     

气相色谱-质谱法测定纺织品中喹啉与异喹啉

建立了纺织品中喹啉和异喹啉的气相色谱-质谱检测方法。采用乙酸乙酯为溶剂,超声提取,经蒸发浓缩和定容后,以GC-MS测定。结果表明,喹啉和异喹啉在0.05～10.0 mg/L范围内线性良好(r0.999 0),回收率为82.0%～99.8%,相对标准偏差(n=6)为0.9%～3.8%;方法的定量下限为0.05 mg/kg。该方法灵敏度高、简便、高效、准确,可以满足纺织品中喹啉和异喹啉的检测需求。     

A Diffusion‐‐Reaction Competition Mechanism to Tailor Lithium Deposition for Lithium‐Metal Batteries

Lithium metal is recognized as one of the most promising anode materials owing to its ultrahigh theoretical specific capacity and low electrochemical potential. Nonetheless, dendritic Li growth has dramatically hindered the practical applications of Li metal anodes. Realizing spherical Li deposition is an effective approach to avoid Li dendrite growth, but the mechanism of spherical deposition is unknown. Herein, a diffusion‐reaction competition mechanism is proposed to reveal the rationale of different Li deposition morphologies. By controlling the rate‐determining step (diffusion or reaction) of Li deposition, various Li deposition scenarios are realized, in which the diffusion‐controlled process tends to lead to dendritic Li deposition while the reaction‐controlled process leads to spherical Li deposition. This study sheds fresh light on the dendrite‐free Li metal anode and guides to achieve safe batteries to benefit future wireless and fossil‐fuel‐free world.     

Lithium Bonds in Lithium Batteries

Lithium bonds are analogous to hydrogen bonds and are therefore expected to exhibit similar characteristics and functions. Additionally, the metallic nature and large atomic radius of Li bestow the Li bond with special features. As one of the most important applications of the element, Li batteries afford emerging opportunities for the exploration of Li bond chemistry. Herein, the historical development and concept of the Li bond are reviewed, in addition to the application of Li bonds in Li batteries. In this way, a comprehensive understanding of the Li bond in Li batteries and an outlook on its future developments is presented.     

Achieving Superior Electrocatalytic Performance by Surface Copper Vacancy Defects during Electrochemical Etching Process

Vacancy defects of catalysts have been extensively studied and proven to be beneficial to various electrocatalytic reactions. Herein, an ultra‐stable three‐dimensional PtCu nanowire network (NNW) with ultrafine size, self‐supporting rigid structure, and Cu vacancy defects has been developed. The vacancy defect‐rich PtCu NNW exhibits an outstanding performance for the oxygen reduction reaction (ORR), with a mass activity 14.1 times higher than for the commercial Pt/C catalyst (20 %.wt, JM), which is currently the best performance. The mass activity of the PtCu NNW for methanol oxidation reaction (MOR) is 17.8 times higher than for the commercial Pt/C catalyst. Density‐functional theory (DFT) calculations indicate that the introduction of Cu vacancies enhances the adsorption capacity of Pt atoms to the HO* intermediate and simultaneously weakens the adsorption for the O* intermediate. This work presents a facile strategy to assemble efficient electrocatalysts with abundant vacancy defects, at the same time, provides an insight into the ORR mechanism in acidic solution.     

广西合山石村矿超高有机硫煤饱和烃特征分析

以合山石村矿超高有机硫煤为研究对象,利用带能谱的扫描电镜(SEM-EDX)及气相色谱(GC)和色谱-质谱联用(GC-MS)分析技术,综合分析探讨了研究区样品中有机质来源、沉积环境及物源输入。结果表明,研究区样品镜质体反射率均值1.76%,全硫含量均值6.01%,其中有机硫含量占比达94.3%,为高成熟度的超高有机硫煤。饱和烃色谱图中未分辨的复杂混合物(UCM)鼓包明显,前峰及双峰型均有分布,前峰型主峰碳为C_(16)、C_(18)、C_(21),双峰型主峰碳为C_(18)、C_(27),化合物降姥鲛烷、脱氢松香烷、咔达烯均有发现,规则甾烷C_(27)、C_(28)、C_(29)均呈"V"型分布,说明沉积母质受藻类等低等水生生物与高等植物双重输入的影响。姥植比参数、C_(31-35)藿烷呈阶梯式递减的分布特征表明在海相碳酸盐台地成煤带中存在一定的氧化条件。扫描电镜中拍摄到的铁含氧硫酸盐、细胞充填环状黄铁矿说明在沉积质晚期成岩阶段受到一定程度热液作用影响。     

A Fluorescent Sensor for Dual‐Channel Discrimination between Phosgene and a Nerve‐Gas Mimic

The ability to analyze highly toxic chemical warfare agents (CWAs) and related chemicals in a rapid and precise manner is essential in order to alleviate serious threats to humankind and public security caused by unexpected terrorist attacks and industrial accidents. In this investigation, we designed a o‐phenylenediamine‐pyronin linked dye that is capable of both fluorogenic and colorimetric discrimination between phosgene and the prototypical nerve‐agent mimic, diethyl chlorophosphate (DCP) in the solution or gas phase. Moreover, this dye has been used to construct a portable kit that can be employed for real‐time monitoring of DCP and phosgene in the field, both in a discriminatory manner, and in a simple and safe way.     

乙二胺三乙酸与锌(Ⅱ)、钴(Ⅱ)相互作用的固体和溶液化学特性

在水热和弱酸性反应条件下,螯合型表面活性剂前驱体乙二胺三乙酸分别与氯化锌、氯化钴反应,形成水合乙二胺三乙酸金属配合物[M(H₂O)₆][M(ED3A)(H₂O)]₂·2H₂O[M=Zn(1),Co(2);H₃ED3A=乙二胺三乙酸,C₈H₁₄N₂O₆]。 产物经元素分析、红外、热重、液体核磁共振和X射线单晶衍射结构表征。 乙二胺三乙酸和锌(Ⅱ)、钴(Ⅱ)五配位,并与水一起形成典型的[MN₂O₄]或[MO₆]八面体结构。 ¹³C核磁共振实验结果表明,溶液中乙二胺三乙酸与锌形成配合物在弱酸性条件下(pH值3~7)稳定存在,在酸性溶液中完全解离,乙二胺三乙酸进一步经分子内成环反应生成3-酮哌嗪二乙酸(H₂kpda=C₈H₁₂N₂O₅)。     

高分散Ru/FeOx催化剂在二氧化碳选择加氢反应中的应用及其催化活性的调控

由于化石能源的大量开采和利用造成CO2过度排放,从而导致严重的温室效应和气候环境问题,给人类生存带来极大威胁.CO2选择加氢反应可以将CO2催化加氢生成高附加值的CO产物.与其他的CO2转化反应策略相比,该过程中H2的消耗更少,成为可有效处理及转化CO2的手段之一.同时,应尽可能抑制CO2深度加氢以及甲烷的产生,研制及设计具有高CO选择性的新型高效催化剂及其构效关系的分析仍十分重要.据报道,负载型贵金属基催化剂的使用有利于H2分子的活化,具有优异的催化活性,因而广泛应用于多种催化反应中.然而,贵金属催化剂实现工业应用的最大挑战是资源的限制及其高额的成本.近年来,由贵金属制备的负载型亚纳米团簇受到广泛关注,主要包括如Au,Pt,Pd,Ru等贵金属,可有效应用于多相催化反应.人们还致力于提高负载型亚纳米团簇的分散度,促进催化剂活性位点的有效暴露,有利于大幅度提高催化剂的有效利用率.本文采用共沉淀法成功制备了超高分散的负载型Ru基催化剂,通过CO2选择加氢-程序升温表面反应(TPSR)和质谱联用技术测试了催化剂性能,发现CO2加氢反应生成CO选择性达100%.采用XRD,BET和TEM等方法对催化剂结构进行表征,并结合H2-TPR,H2-TPD和XPS等表征结果深入探讨了催化剂构效关系,并提出了针对该催化剂体系较为合理的反应模型.在CO2选择加氢反应的催化性能测试中,2.50%Ru/FeOx催化剂对目标产物CO选择性仅为41%; 随着Ru负载量降低至0.25%和0.1%时,CO选择性明显提高至80%; 当进一步降低Ru含量至0.01%时,CO选择性接近100%,且表现出优异的反应速率.在360 oC时,0.01%Ru/FeOx催化剂的相对反应速率为7.71 molCO2molRu-1 min-1,是2.50%Ru/FeOx催化剂相对反应速率的154倍.H2-TPR结果表明,贵金属Ru可以明显促进载体FeOx的还原,并产生丰富的氧空位,进而促进CO2的吸附、活化.而且CO2选择加氢TPSR结果显示,目标产物CO的起始生成温度总是滞后于原料H2的初始活化温度,与H2-TPR结果及文献报道的CO2选择加氢反应机理一致.通过H2-TPD深入理解H2在催化剂表面的活化和氢溢流现象,以及Hads与不同催化剂之间的相互作用力,0.01%Ru/FeOx催化剂相对较高的H2脱附峰温度表明,该样品中Ru与Hads具有极强的相互作用力,相对抑制了Hads与COads深入加氢生成CH4,从而提高了CO选择性,而2.50%Ru/FeOx催化剂的情况则与此相反.本文提出了从Hads吸附作用力强弱来考虑CO2选择加氢反应选择性的新思路,同时为设计CO2选择加氢制高附加值CO的高催化反应速率、高CO选择性的高分散Ru基催化剂提供了一种经济简易的催化剂设计思路.     

Enhanced electrochemical performance of SnS nanoparticles/CNTs composite as anode material for sodium-ion battery

SnS/CNTs composite as anode for SIBs exhibits high reversible capacity, good cyclability as well as rate performance, which is superior to that of pure SnS. The enhanced electrochemical performance can be attributed to the adding of CNTs as a flexible and conductive structure supporter and the formation of SnS nanoparticles with small diameter.