Benzyl alcohol oxidation and hydrogen generation over MoS2/ZnIn2S4 composite photocatalyst

Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived...     

Synthesis and characterization of three co-crystals of bis(benzimidazole) derivatives with aromatic dicarboxylic acids

Research on Chemical Intermediates - Combination of three aromatic carboxylic acids (5-nitroisophthalic acid (H2nip), 2,6-naphthalenedicarboxylic acid (H2ndc), tetrabromoterephthalic acid (H2tbta))...     

Two near-infrared highly sensitive cyanine fluorescent probes for pH monitoring

Two near-infrared(NIR) p H-activated heptamethine indocyanine probes with quaternary ammonium unit were designed and synthesized. The absorption and emission titrations indicate that cationic structure improves the cyanine dye's aqueous solubility and these two probes exhibit highly sensitive response to p H in acid condition. Their fluorescence intensities both gradually increase about 25-fold from p H 7.60 to 3.00 with p Ka values of 4.72 and 4.45 respectively, which are suitable for studying acidic organelles in living cells. Moreover, their fluorescence intensities are linearly proportional to p H values in the range of 5.50–4.00. These results are probably attributed to the protonation of the indole nitrogen atoms, which are verified by 1H NMR spectra. Furthermore, these two probes can achieve real-time imaging of cellular p H and detection of p H in situ in living He La cells due to their excellent properties,including good reversibility, desirable photostability, high selectivity, low cytotoxicity and remarkable membrane permeability.     

具有光控氧空缺的钼掺杂Bi5O7Br纳米片用于光催化氮气合成氨

氨(NH3)作为合成燃料、化肥和潜在能源载体的重要前体,是现代化学工业中最重要的化学品之一.工业中主要通过高能耗的Haber-Bosch工艺在高温高压下将氮气和氢气转化为NH3,而原料氢气由天然气蒸汽获得,因而不仅消耗大量能源,而且导致温室气体二氧化碳的大量排放,对环境造成危害.光催化固氮以光能为驱动力,以水为质子源,为合成NH3提供了一种温和、绿色和可持续的方法.然而,传统固氮催化剂具有与N2结合弱、成键难以及电子转移效率低的缺点.为了克服上述问题,在催化剂中引入氧空缺和过渡金属作为给电子中心和活性位点的策略被广泛研究.本文以半导体Bi5O7Br纳米片作为研究对象,通过在水热合成过程中添加Na2MoO4前驱盐在Bi5O7Br中掺杂钼元素,合成了不同摩尔含量的钼掺杂Bi5O7Br(Mo-Bi5O7Br)纳米片,并将其应用于光催化N2还原反应,发现Mo-Bi5O7Br的光催化固氮性能显著优于空白Bi5O7Br的催化性能.扫描电镜、透射电镜、能量色散X射线元素映射以及X射线光电子能谱的结果表明,掺杂过程不会影响Bi5O7Br纳米片的晶相和形貌,掺杂后钼元素均匀地分布在Bi5O7Br纳米片晶格中.采用紫外可见漫反射光谱、电子自旋共振光谱、氮气程序升温脱附谱以及光电化学测试等方法研究了Mo-Bi5O7Br相较于空白Bi5O7Br纳米片在光催化N2还原反应中催化性能提升的原因.UV-vis DRS结果表明,钼掺杂对Bi5O7Br可见光吸收能力具有增强作用.以催化NH3产率最高的Mo-Bi5O7Br-1(Mo摩尔百分含量为1％)为研究样本,EPR结果表明,在黑暗条件下,只有Mo-Bi5O7Br-1样品可以检测到明显的表面氧空位(OVs)信号;在光照条件下,Bi5O7Br和Mo-Bi5O7Br-1两种样品都出现OVs的信号峰,但同等光照时间下的Mo-Bi5O7Br-1具有更高的信号强度.此外,OVs信号会随着光照时间的延长逐渐增强;当移除光源后,信号强度逐渐降低.这表明Mo-Bi5O7Br-1在光照下会产生更高浓度的表面光控OVs.N2-TPD结果表明,光控OVs作为活性位点促进催化剂对N2的吸附.关闭光源后,OVs被环境中的水或氧气中的氧原子重新填充,避免了OVs易被氧化而导致反应失活的缺点,有助于保持Mo-Bi5O7Br-1催化N2还原反应的活性和稳定性.光电化学表征结果表明,Mo-Bi5O7Br-1中的光生载流子的分离和迁移效率明显提高.以上结果表明,掺杂过渡金属钼有助于Bi5O7Br纳米片表面光控OVs的生成,光控OVs作为活性位点提升了Bi5O7Br吸附和活化N2的能力,钼掺杂和光控OVs协同提高Bi5O7Br内部光生载流子的分离迁移效率,增强Bi5O7Br光催化固氮合成氨的反应性能.     

Two silver(I) complexes based on dicarboxylate and flexible bis(benzimidazole) ligands: synthesis,crystal structures,sensing and photocatalytic properties

Transition Metal Chemistry - Two Ag(I) complexes, namely [Ag2(L1)2(HMIP)2·H2O]n (1) and [Ag2(L2)2(HPA)2]n (2) (L1?=?1,6-bis(2-methylbenzimidazol-1-yl)hexane,...     

β-环糊精增敏荧光光谱法对柔红霉素的定量测定

采用荧光光谱法对β-环糊精（β-CD）与柔红霉素（DNR）包结物溶液进行表征。研究了β-CD与DNR之间的超分子包结作用机理,讨论了时间、温度和β-CD浓度对包结反应的影响,建立了新的定量检测微量DNR的方法。研究结果表明,DNR本身具有天然荧光,与β-CD形成1：1的超分子包结络合物后,荧光强度增大,β-CD对DNR有较强的荧光增敏作用。在25℃,pH7.0时,包结常数K=1.26×106L/mol。β-CD增敏荧光定量测定DNR的线性回归方程为y=1.78×107x＋312.76,相关系数为r=0.9953,检测下限为3.77×10-6mol/L。     

HBF4溶液中全铅液流电池

报道了一种HBF₄水溶液中的全铅液流电池,正、负电极电解液均采用Pb（BF₄）₂的HBF₄水溶液.在酸性的四氟硼酸铅电解液中考察了石墨电极和玻碳电极作为工作电极的循环伏安性能,石墨电极较适于用作全铅液流电池的正、负电极.采用石墨电极作为电池的正、负电极并在四氟硼酸铅酸性电解液中进行充放电实验,其中Pb（BF₄）₂浓度分别为0.5、1.0和1.5 mol·L^-1,且保持游离的HBF₄浓度为1.0 mol·L^-1.该电池为单液流电池,不需要隔膜分隔正、负极的电解液,电流密度为10、20和40 mA.cm^-2,当限定充电容量为7.0 mAh.cm^-2,放电电压截止到1.0 V时,平均库仑效率大于87%,平均能量效率大于68%;当电解液采用1.0或1.5 mol·L^-1 Pb（BF₄）₂+1.0 mol·L^-1HBF₄水溶液时,在10及20 mA.cm^-2电流下的能量效率最高可超过74%.     

One-pot synthesis of peony-like Bi2S3/BiVO4(040) with high photocatalytic activity for glyphosate degradation under visible light irradiation

In this work, samples consisting of BiVO₄ with exposed (040) facets coupled with Bi₂S₃ (Bi₂S₃/BiVO₄) were prepared through a one-pot hydrothermal method, using ethylenediaminetetraacetic acid as directing agent and L-cysteine as sulfur source and soft template. X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy measurements indicated that the Bi₂S₃ content had a significant influence on the growth of (040) and (121) facets as well as on the morphology of the Bi₂S₃/BiVO₄ samples. When the Bi₂S₃ content reached 1 mmol, the Bi₂S₃/BiVO₄ samples exhibited a peony-like morphology. The results of transient photocurrent tests and electrochemical impedance spectroscopy measurements confirmed that a more effective charge separation and a faster interfacial charge transfer occurred in Bi₂S₃/BiVO₄ than BiVO₄. The enhanced photocatalytic activity of the Bi₂S₃/BiVO₄ samples could be attributed to the improved absorption capability in the visible light region and the enhanced electron-hole pair separation efficiency due to the formation of the Bi₂S₃/BiVO₄ heterostructure. In addition, the Bi₂S₃/BiVO₄ samples showed relative stability and reusability. The simple method presented in this work could be used to fabricate composite photocatalysts with high activity for different applications, such as photocatalytic degradation of organic pollutants, photocatalytic splitting of water, and photocatalytic reduction of carbon dioxide.     

基体对流动锌酸钾碱液中锌电沉积的影响

在流动的高浓度锌酸钾碱液中研究了镍箔和镀镍冲孔钢带基体电极对锌沉积/溶解电化学行为的影响. 结果表明, 在流动电解液中电极表面浓度梯度变化不大, 不同基体上均未出现锌沉积的阴极峰; 扫描速度超过10 mV/s, 循环伏安曲线基本不随扫速变化, 说明锌的沉积/溶解峰电流不仅与扫描速度有关, 还取决于锌沉积的时间. 采用镀镍冲孔钢带基体兼有析氢过电位大和稳定性好的特点, 又由于其特殊的冲孔结构, 改变了传质方式, 锌沉积的极化降低, 孔的周围形成紧密堆积的沉积锌, 锌沉积的电流和电量大, 沉积效率高, 经 4次充放电循环后, 库仑效率即达95％以上, 是性能较佳的基体电极.     

罗丹明类荧光探针的合成及对铜离子的检测

合成了罗丹明类Cu2+荧光增强型分子探针3',6'-双(二乙氨基)-2-(N-乙叉基氨基)螺[异吲哚-1,9'-占吨]-3-酮（RA）,并研究了它的光谱性能及对铜离子的识别作用.在乙腈/水（体积比1/1）的介质中,当加入Cu2+后探针RA显玫瑰红色,最大吸收波长为548 nm,最大发射波长为571 nm,且荧光强度显著增强,但是,其它常见离子如Na+, K+, Mg2+, Ca2+, Mn2+, Cd2+, Cr3+, Co2+, Ni2+, Ag+, Pb2+, Zn2+, Fe3+, Hg2+不引起或引起很小的紫外/可见或荧光光谱变化.RA的选择性荧光增强主要是由于Cu2+诱导分子中的酰胺闭环结构发生开环,导致分子结构的共轭程度增大.在6.5×10-8～2.9×10-6 mol?L-1范围内RA可以有效检测Cu2+,检测限为5.0×10-8 mol?L-1.RA对Cu2+的识别不可逆,而且探针RA对pH值不敏感,可以在比较宽的范围内（pH=4.1～10.5）高灵敏、高选择性检测Cu2+.