ZIF-8 derived bimetallic Fe–Ni-Nanoporous carbon for enhanced oxygen reduction reaction

The development of highly efficient nοn-nοble meta? catalysts for (ОRR) in PEMFCs is at the heart of the research, yet their performance is not satisfactory. The Fe–N active sites enclosed in carbon matrix are generally agreed to be the most promising active sites for ORR. In view of this, further effort is made to increase the Fe–N active sites. Here we present the fabrication of novel FeNi bimetallic electrоcatalyst obtained from ZIF, which consists of FeNi nanоallоys incorporated in N-doped carbon (FeNi-NC) featuring carbon nanotubes and porous carbon demonstrates outstanding results for ОRR. The Fe–N and Ni–N active sites synergistically enhance the ORR activity of FeNi-NC catalyst. The FeNi-NC showed remarkable performance in KОH with the half-wave and onset potential of 0.89 V and 0.99 V vs RHE, respectively. This catalyst shows exceptional stability in methanol equivalent to Pt/C commercial. The FeNi-NC retained 71%, while Pt/C commercial retained only 59% of its original current density. The exceptional stability and activity might be associated with the interplay among FeNi active sites and N-doped carbon, the distinct nanо-structure made up of porous carbon and carbon nanotubes with a high graphitization degree.     

Preparation and characterization of highly stable protic-ionic-liquid membranes

A highly durable proton exchange membranes (PEM)s based on covalently supported ionic liquid (IL) bearing sulfonic acid imidazolium groups were successfully fabricated. The membrane preparation involved radiation induced grafting of 1-vinyl imidazole (1-VIm) onto poly(ethylene-co-tetraflouroethene) (ETFE) film, followed by covalent immobilization of 3-sulfopropyl and subsequent treatment with trifluoromethanesulfonic acid. The ionic conductivity of the supported IL membranes was increased with the increase in the concentration of IL and reached a maximum value of 138 mS cm⁻¹ in a fully hydrated state with an ion exchange capacity of 4.82 mmol g⁻¹ that is higher than Nafion with a similar thickness. The membranes displayed excellent chemical and mechanical stability. In addition, the dimensional and thermal stability of supported IL-membranes were significantly higher than commercial Nafion membranes.     

Synthesis,thermal properties,conductivity and lifetime of proton conductors based on nanocrystalline cellulose surface-functionalized with triazole and imidazole

A new proton conductor based on 1H-1,2,3-triazole doped nanocrystalline cellulose (2.66 CNC-Tri) has been synthesized for possible use as an electrolyte in proton exchange membrane (PEM) cells. The physicochemical properties of 2.66 CNC-Tri were determined and compared with those of imidazole-doped nanocrystalline (1.17 CNC-Im) and pure nanocrystalline cellulose (CNC). The composites were obtained in the form of a film and their synthesis proceeded under vacuum. The maximum conductivity of 2.66 CNC-Tri was measured to be 0.1 × 10⁻⁴ S/m at 175 °C and that of 1.17 CNC-Im to be 1.6 × 10⁻² S/m at 155 °C, in the anhydrous state. The composite 2.66 CNC-Tri, compared to 1.17 CNC-Im, has much better thermal properties manifested as stability of the matrix and durability of the heterocyclic molecule. The lifetimes of 2.66 CNC-Tri fulfills the requirements of the U.S. Department of Energy for the minimum lifetimes of a PEM based fuel cell for cars.     

毛细管区带电泳-间接紫外检测法测定婴儿配方奶粉中的胆碱

目的建立毛细管区带电泳-间接紫外检测法测定婴儿配方奶粉中胆碱含量的新方法。方法用5 mmol/L乙酸提取婴儿配方奶粉样品中的胆碱,涡旋混匀、9000 r/min离心,上清液经0.45μm醋酸纤维素滤膜过滤后进样。用未涂覆熔融石英毛细管75μm×70 cm(有效长度:60 cm)作为分离柱。以10 mmol/L磷酸二氢钠+20 mmol/L磷酸+7 mmol/L 4-甲基咪唑为分离缓冲体系。分离电压为28 k V,进样压力及时间为0.5 psi、10 s,检测波长为214 nm。结果胆碱的校正峰面积与质量浓度在8.7~86.8 mg/L范围内间线性关系良好,相关系数为0.9997、检出限为2.6 mg/L、定量限为8.7 mg/L,方法的日内和日间精密度分别为1.9%和3.9%(n=7)。3个质量浓度添加水平的平均加标回收率分别为98.8%、95.2%及97.6%,相应RSD分别为0.8%、0.9%及0.6%(n=5)。用本法分析了10件婴儿配方奶粉样品,均获满意结果。结论本方法简单、无需有机溶剂,适用于婴儿配方奶粉中胆碱的常规检测。     

Imidazole polymerized ionic liquid as a precursor for an iron-nitrogen-doped carbon electrocatalyst used in the oxygen reduction reaction

A class of non-precious metal and highly efficient catalysts (Fe–N(PIL)/C) for the oxygen reduction reaction (ORR)were prepared by a two-step reaction involving polymerization and one-pot high-temperature pyrolysis reaction. The characteristics of Fe–N(PIL)/C electrocatalyst samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). Additionally, the electrocatalytic properties were tested by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Under alkaline conditions, the Fe–N(PIL)/C catalyst exhibited a 2D-mesoporous structure with prominent catalytic activity. The E_on and E_1/2 reached 1.08 V and 0.93 V (vs. a reversible hydrogen electrode), respectively. The catalyst showed excellent ORR catalytic performance and stability and is superior to a 20 wt% Pt/C catalyst. This could be attributed to its mesoporous structure and the high content of Fe–N activity sites that enable it to carry out a nearly 4e⁻ reaction pathway for the ORR.     

Microwave-assisted synthesis of tetrasubstituted aryl imidazole based polymers via cascade polycondensation process

Poly(Tetrasubstituted Aryl Imidazole)s (PTAIs), a new class of poly(heteroaromatic) polymers was prepared via a cascade polycondensation process, under microwave irradiation. These polymers were obtained by the tetrasubstituted aryl imidazole ring formation involving bis(aryl α-diketone)s, bis(arylaldehyde)s, mono(arylamine)s and ammonium acetate. The polymerization performed under microwave irradiation allowed to get high molecular weight PTAIs in very short reaction times. The chemical structure of these PTAIs was confirmed by NMR spectroscopy. Thermogravimetric analyses (TGA) showed a very good grade of thermal stability of these polymers. Glass transition temperatures (T_g) of PTAIs ranging from 155 °C to 265 °C were determined by Differential Scanning Calorimetry (DSC).     

1-咪唑基异喹啉衍生物的合成与表征

以2-炔基苯甲醛肟和咪唑类化合物为原料,利用串联反应合成两种未曾报道的1-咪唑基异喹啉化合物,所得目标产物均经1HNMR、13CNMR、HRMS确认。     

生物碱类化合物的研究进展

生物碱作为一类广泛存在于自然界中的碱性含氮有机化合物,数目众多,结构类型复杂。依据化学结构不同可分为异喹啉类、喹啉类、咪唑类、哌啶类、莨菪烷类、吲哚类、咔唑类、海洋多环胍类、萜类、manzamine型生物碱等。文章就部分生物碱类化合物结构研究进展进行综述。     

双氰胺/环氧粉末涂料的研究

以E-12环氧树脂为基础树脂、双氰胺(Dicy)为固化剂、2-甲基咪唑(2-MI)为促进剂,并配以其他助剂,经熔融共混制备出双氰胺/环氧粉末涂料。考察双氰胺、2-甲基咪唑用量对固化反应、涂膜附着力及耐冲击性的影响,并确定了两者的较佳用量。利用非等温差示扫描量热法研究了环氧/双氰胺/2-甲基咪唑体系的固化反应,并通过动力学分析得出了理论固化温度等固化动力学参数。在此基础上,根据实验得到了较好的固化时间和固化温度。另外,根据Kissinger和Crane方程拟合了固化反应动力学方程。结果表明,涂膜附着力及耐冲击性随着双氰胺及2-甲基咪唑用量增加先提高后减小。双氰胺、2-甲基咪唑用量分别为环氧树脂用量的4.00%、0.40%时,体系固化温度较低,130.00°C下固化30 min所得涂膜综合性能最好。     

咪唑封闭水性聚氨酯复鞣剂的制备及表征

通过分子设计,以咪唑为封闭剂,1,6-己二异氰酸酯（HDI）、二羟甲基丙酸（DMPA）、2,2-二（4-羟基苯基）丙烷、聚酯二醇为原料制备出咪唑封闭水性聚氨酯复鞣剂（BPU）。用FT-IR、动态激光光散射（DLS）、TEM、TGA、DSC分别对BPU分子结构、乳胶粒形态及热性能进行了表征,分析了BPU复鞣剂的分子作用基础。结果表明产物分子结构中出现了羧基、咪唑环和聚氨酯结构;乳胶粒呈较为规则的、具有核壳结构的球形,粒径的多分散性是BPU具有良好选择填充性的微观原因。TGA和DSC分析显示BPU耐热性较高并随封闭率增加而略有降低;BPU解封温度范围为107.5～124.5℃,峰值为115.1℃;应用过程中BPU解封程度极低,利于助染性能的提高。