固体电解质电解池一氧化碳电催化还原反应研究

以α-Zr(HPO4)H2O为质子固体电解质设计电解池, 于常温常压实现了CO电催化加氢还原反应, 反应产物与电极材料、 电流密度密切相关. Cu/ZrP电极表面反应主要产物是甲醛, 电流密度100 mA/cm2时, 甲醛的Faradic效率达到29.0 %, Fe/ZrP电极表面反应主要产物是乙烯, 电流密度100 mA/cm2-时, 乙烯的Faradic效率达到15.0%.     

The Zintl Phase Cs7NaSi8 – From NMR Signal Line Shape Analysis and Quantum Mechanical Calculations to Chemical Bonding

Powder samples as well as red and transparent single crystals of the Zintl phase Cs₇NaSi₈ were synthesized and characterized by means of X‐ray diffraction and differential thermal analysis. Cs₇NaSi₈ was found to be isotypic to the recently reported phase Rb₇NaSi₈. It crystallizes in the Rb₇NaGe₈ structure type forming trigonal pyramidal Si₄^4– anions. Two unique environments of the cations are observed, a linear arrangement [Na(Si₄)₂]^7– with short Na–Si distances of 3.0 Å and a Cs2 atom coordinated by six Si₄^4– anions with long Cs–Si distances of 4.2 Å. The bonding situation was investigated by a combined application of ²⁹Si, ²³Na, and ¹³³Cs solid‐state NMR spectroscopy and quantum mechanical calculations of the NMR coupling parameters. In addition the electronic density of states (DOS), the electron localizability indicator (ELI) and the atomic charges using the QTAIM approach were studied. Good agreement of the calculated and experimental values of the NMR coupling parameters was obtained. An anisotropic bonding situation of the silicon atoms is indicated by the chemical shift anisotropy being similar to Rb₇NaSi₈. Confirmation is given by the observation of one lone‐pair‐like feature for each silicon atom and two types of two‐center Si–Si bonds using the ELI. Calculation and NMR spectroscopic determination of the ²³Na and ¹³³Cs electric field gradients prove anisotropies of the charge distribution around the cations. Due to the similar values for the Na atoms in M₇NaSi₈ (M = Rb, Cs) equal bonding situations can be concluded. The much larger anisotropy of the charge distribution of the Cs atoms can be addressed as the main difference to Rb₇NaSi₈.     

Control of Co content and SOFC cathode performance in Y1−ySr2+yCu3−xCoxO7+δ

The electrochemical performance of the layered perovskite YSr₂Cu_3−xCo_xO_7+δ, a potential solid oxide fuel cell (SOFC) cathode, is improved by increasing the Co content from x = 1.00 to a maximum of x = 1.30. Single phase samples with x > 1.00 are obtained by tuning the Y/Sr ratio, yielding the composition Y_1−ySr_2+yCu_3−xCo_xO_7+δ (where y ≤ 0.05). The high temperature structure of Y_0.95Sr_2.05Cu_1.7Co_1.3O_7+δ at 740 °C is characterised by powder neutron diffraction and the potential of this Co-enriched material as a SOFC cathode is investigated by combining AC impedance spectroscopy, four-probe DC conductivity and powder XRD measurements to determine its electrochemical properties along with its thermal stability and compatibility with a range of commercially available electrolytes. The material is shown to be compatible with doped ceria electrolytes at 900 °C.     

固相微萃取-气相色谱/三重四级质谱法测定土壤中氯代苯胺类残留

建立了固相微萃取-气相色谱/三重四级质谱法( SPME-GC/QQQ)同时测定土壤中多种氯代苯胺的方法。优化了多反应监测( MRM)的仪器条件,研究了土壤取样量、加水量、萃取温度、萃取时间对SPME富集效果的影响,确定最佳实验条件为：取8 g土壤样品加入4 mL纯净水中,80℃下萃取40 min。方法的检出限为1~10 pg/g,线性范围为5~1000 pg/g。200 pg/g加标土壤的回收率在96.8%~144.2%,相对标准偏差在13.4%~27.8%(n=5)。方法综合了SPME简便快捷和MRM高选择性的优点,尤其适合于土壤中痕量氯代苯胺类污染物的大量快速筛查分析。     

中空纤维膜萃取电喷雾电离质谱测定水中的全氟化合物

采用中空纤维膜( HF)做固相微萃取( SPME)材料,与常压离子化质谱( AMS)联用,分析水中全氟庚酸(PFHpA)、全氟辛酸(PFOA)、全氟壬酸(PFNA)、全氟癸酸(PFDA)、全氟辛烷磺酸(PFOS)、全氟十一酸(PFuDA)和全氟十二酸(PFDoA)7种全氟化合物(Perfluorinated compounds, PFCs)。对萃取时间和萃取溶液pH值进行了优化,质谱在负模式下使用选择反应监测扫描( SRM),并使用同位素内标13 C4-PFOS和13 C4-PFOA进行定量分析。结果表明,本方法对7种PFCs均有良好的线性(R2>0.99);除了PFHpA外,其它6种PFCs化合物的检出限为0.8~2.7 ng/L,定量限为2.7~8.9 ng/L;其中5种PFCs的富集倍数超过200倍。实际水样中(自来水和珠江水)7种PFCs均未检出,PFCs加标浓度在40和400 ng/L时,自来水的回收率范围分别为88.5%~108.3%和94.2%~116.7%,珠江水的回收率范围分别为75.0%~102.6%和82.1%~97.6%。     

Studies on Mechanochemistry: Solid Coordination Compounds from Primary Aromatic Amines and Cobalt(II) Chloride Hexahydrate

Cobalt(II) chloride hexahydrate and primary aromatic amines were reacted by co‐grinding in 1:2 metal salt to ligand ratio under solvent‐free environment at room temperature. Out of 16 solid state reactions, seven cobalt‐amine complexes could be established as solid coordination compounds by elemental analysis, TGA, IR, PXRD, magnetic susceptibility etc., in addition to visual observation of the color change of reaction mixture. Based on investigation of reaction and analysis of products, conclusions with outlook could be made as follows: On top of the —NH₂ group on primary aromatic amines an additional substituent group should better be at para or meta positions and not at ortho position in order to realize the solid coordination compounds. On the other hand, an electron withdrawing substituent or an extra aromatic ring is negative towards formation of the solid coordination compounds. The solid coordination Co(II)‐compounds are labile in solution.     

Polythiophene/hexagonally ordered silica nanocomposite coating as a solid‐phase microextraction fiber for the determination of polycyclic aromatic hydrocarbons in water

A highly porous fiber coated with polythiophene/hexagonally ordered silica nanocomposite was prepared for solid‐phase microextraction (SPME). The prepared nanomaterial was immobilized onto a stainless‐steel wire for the fabrication of the SPME fiber. Polythiophene/hexagonally ordered silica nanocomposite fibers were used for the extraction of some polycyclic aromatic hydrocarbons from water samples. The extracted analytes were transferred to the injection port of a gas chromatograph using a laboratory‐designed SPME device. The results obtained prove the ability of the polythiophene/hexagonally ordered silica material as a new fiber for the sampling of organic compounds from water samples. This behavior is due most probably to the increased surface area of the polythiophene/hexagonally ordered silica nanocomposite. A one‐at‐a‐time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, and desorption temperature and time. Under the optimum conditions, the LOD of the proposed method is 0.1–3 pg/mL for analysis of polycyclic aromatic hydrocarbons from aqueous samples, and the calibration graphs were linear in a concentration range of 0.001–20 ng/mL (R² > 0.990) for most of the polycyclic aromatic hydrocarbons. The single fiber repeatability and fiber‐to‐fiber reproducibility were less than 8.6 and 19.1% (n = 5), respectively.     

Determination of aminophenols and phenol in hair colorants by ultrasound‐assisted solid‐phase dispersion extraction coupled with ion chromatography

A simple and reliable ultrasound‐assisted solid‐phase dispersion extraction coupled with ion chromatography was developed for the determination of aminophenols and phenol. The highly viscous hair colorant was dispersed in solvents using anhydrous sodium sulfite having dual functions of dispersant and antioxidant. The use of anhydrous sodium sulfite did not change the sample volume because it could completely dissolve in solution after matrix dispersion. The extraction and cleanup were combined in one single step for simplifying operation. The extraction process could be rapidly accomplished within 9 min with high sample throughput under the synergistic effects of vibration, ultrasound, and heating. Satisfactory linearity was observed with correlation coefficients higher than 0.9992, and the limits of detection varied from 0.02 to 0.09 mg/L. The applicability of the proposed method was demonstrated by measuring the concentrations of aminophenols and phenol in 32 different commercial hair color products. The recoveries ranged from 86.4–101.2% with the relative standard deviations in the range of 0.52–4.3%. The method offers an attractive alternative for the analysis of trace phenols in complex matrices.     

Sensitive determination of polychlorinated biphenyls in environmental water samples by headspace solid‐phase microextraction with bamboo charcoal@iron oxide black fibers prior to gas chromatography with tandem mass spectrometry

We have investigated the feasibility of bamboo charcoal@iron oxide black for the headspace solid‐phase microextraction of polychlorinated biphenyls in environmental water samples. Bamboo charcoal@iron oxide black was prepared and used as a solid‐phase microextraction coating material, and gas chromatography with tandem mass spectrometry was used for detection. Several important factors affecting the extraction efficiency were systematically investigated and optimized. Under the optimum conditions, the experimental data exhibited wide linear range over the range 0.2–1000 ng/L and low limits of detection in the range of 4.7–22.2 pg/L. The novel coating was successfully used for the enrichment and determination of polychlorinated biphenyls in real environmental water samples. All these results indicated that bamboo charcoal@iron oxide black‐based headspace solid‐phase microextraction coupled to gas chromatography with tandem mass spectrometry was an excellent alternative for the sensitive analysis of polychlorinated biphenyls at ultratrace levels in the environment.     

On‐line determination of 4‐nitrophenol by combining molecularly imprinted solid‐phase extraction and fiber‐optic spectrophotometry

In the present paper, we describe a new on‐line SPE system where molecular imprinting, fiber‐optic detection and flow injection analysis were combined for the first time. This new system has been applied for the on line detection of 4‐nitrophenol (4‐NP). Initially, molecularly imprinted polymers (MIP) have been prepared for the selective extraction of 4‐NP using 4‐vinylpyridine and ethylene glycol dimethacrylate as functional and cross‐linking monomers, respectively. Selective extraction was achieved using the designed MIP with 97% of recovery on imprinted polymer and 10% on control polymer. The system provided a high degree of accuracy, with RSDs varying between 0.7 and 1.39%. In respect of accuracy, reproducibility, and rapidity, this system is comparable with HPLC. In short, the system allows simple, fast, and accurate analyte determination with the possibility of future automation.