ZnFe2O4/CNFs钛网基对电极膜厚对染料敏化太阳能电池性能的影响

通过静电纺丝和简单的一步水热法合成了碳纳米纤维（CNFs）负载的ZnFe₂O₄纳米颗粒（ZnFe₂O₄/CNFs）,并将其刮涂在钛网基底上作为染料敏化太阳能电池（DSSCs）的对电极进行组装测试,电池表现出优异的电化学性能。我们着重研究了不同膜厚对电极对DSSCs光电性能的影响。经过反复测试结果表明,当ZnFe₂O₄/CNFs复合电极材料膜厚为12 μm时存在最高的光电转换效率8.60%。     

Enantiomeric separation of oxybutynin by recycling high‐speed counter‐current chromatography with hydroxypropyl‐β‐cyclodextrin as chiral selector

Recycling high‐speed counter‐current chromatography was successfully applied to the preparative separation of oxybutynin enantiomers. The two‐phase solvent system consisted of n‐hexane, methyl tert‐butyl ether, and 0.1 mol/L phosphate buffer solution (pH = 5.0) with the volume ratio of 6:4:10. Hydroxypropyl‐β‐cyclodextrin was employed as the chiral selector. The influence of factors on the chiral separation process, including the concentration of chiral selector, the equilibrium temperature, the pH value of the aqueous phase were investigated. Under optimum separation conditions, 15 mg of oxybutynin racemate was separated with the purities of both the enantiomers over 96.5% determined by high‐performance liquid chromatography. Recovery for the target compounds reached 80–82% yielding 6.00 mg of (R)‐oxybutynin and 6.15 mg of (S)‐oxybutynin. Technical details for recycling elution mode were discussed.     

Homoisoflavonoids profiling of Ophiopogon japonicus by off‐line coupling high‐speed countercurrent chromatography with high‐performance liquid chromatography–diode array detector‒quadrupole time‐of‐flight tandem mass spectrometry

Roots of Ophiopogon japonicus have been used as a functional food ingredient and traditional Chinese medicine for a long time in China. Homoisoflavonoids are one of the major kinds of bioactive compounds in O. japonicus; however, literature data about its homoisoflavonoids profile are scarce because of the complex ingredients with low abundance. Here, homoisoflavonoid fraction was prepared by petroleum ether extraction. Then, a high‐speed countercurrent chromatography off‐line coupling with high‐performance liquid chromatography–diode array detector?quadrupole time‐of‐flight tandem mass spectrometry was developed for systematic identification of homoisoflavonoids. After that, 39 homoisoflavonoids, including 29 homoisoflavanone and 10 homoisoflavone, were unambiguously or tentatively identified, while 12 of them were reported in O. japonicus for the first time. Finally, eight available homoisoflavonoids were sensitively, precisely, and accurately determined by standard calibration curves, with limit of detection and limit of quantification in the range of 0.05–0.30 μg/mL and 0.12–0.66 μg/mL, relative standard deviation less than 7.3% for intra‐ and interday variations, and recovery at 94.5–105.2%. Collectively, our developed method is efficient, reliable, and valuable to profile chemical components of complex natural products.     

An efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment,separation, and purification of alkaloids and organic Acids from natural products

This study presents an efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment, separation, and purification of alkaloids and organic acids from natural products. First, an acid or base modified two‐phase solvent system with maximum or minimum partition coefficient was developed for the liquid‐liquid extraction of the crude extract. As a result, alkaloids or organic acids could be selectively enriched in the upper or lower phase. Then pH‐zone‐refining counter‐current chromatography was employed to separate and purify the selectively enriched alkaloids or organic acids efficiently. The selective enrichment and separation of five bufadienolide from toad venom of Bufo marinus was used as an example to show the advantage of this strategy. As a result, 759 mg of selectively enriched bufadienolide was obtained from 2 g of crude extract and the total content of five targets was increased from 14.64 to 83%. A total of 31 mg of marinobufagin‐3‐adipoyl‐l ‐arginine, 42 mg of telocinobufagin‐3‐pimeloyl‐l ‐arginine, 51 mg of telocinobufagin‐3‐suberoyl‐l ‐arginine, 132 mg of marinobufagin‐3‐suberoyl‐l ‐arginine, and 57 mg of bufalin‐3‐suberoyl‐l ‐arginine were all simultaneously separated from 500 mg of selectively enriched sample, with the purity of 92.4, 97.5, 90.3, 92.1, and 92.8%, respectively.     

Well‐Dispersed CoS Nanoparticles on a Functionalized Graphene Nanosheet Surface: A Counter Electrode of Dye‐Sensitized Solar Cells

With a facile electrophoretic deposition and chemical bath process, CoS nanoparticles have been uniformly dispersed on the surface of the functionalized graphene nanosheets (FGNS). The composite was employed as a counter electrode of dye‐sensitized solar cells (DSSCs), which yielded a power conversion efficiency of 5.54 %. It is found that this efficiency is higher than those of DSSCs based on the non‐uniform CoS nanoparticles on FGNS (4.45 %) and built on the naked CoS nanoparticles (4.79 %). The achieved efficiency of our cost‐effective DSSC is also comparable to that of noble metal Pt‐based DSSC (5.90 %). Our studies have revealed that both the exceptional electrical conductivity of the FGNS and the excellent catalytic activity of the CoS nanoparticles improve the conversion efficiency of the uniformly FGNS‐CoS composite counter electrode. The electrochemical impedance spectra, cyclic voltammetry, and Tafel polarization have evidenced the best catalytic activity and the fastest electron transport. Additionally, the dispersion condition of CoS nanoparticles on FGNS plays an important role for catalytic reduction of I₃^?.     

Platinum‐Free Binary Co‐Ni Alloy Counter Electrodes for Efficient Dye‐Sensitized Solar Cells

Dye‐sensitized solar cells (DSSCs) have attracted growing interest because of their application in renewable energy technologies in developing modern low‐carbon economies. However, the commercial application of DSSCs has been hindered by the high expenses of platinum (Pt) counter electrodes (CEs). Here we use Pt‐free binary Co‐Ni alloys synthesized by a mild hydrothermal strategy as CE materials in efficient DSSCs. As a result of the rapid charge transfer, good electrical conduction, and reasonable electrocatalysis, the power conversion efficiencies of Co‐Ni‐based DSSCs are higher than those of Pt‐only CEs, and the fabrication expense is markedly reduced. The DSSCs based on a CoNi_0.25 alloy CE displays an impressive power conversion efficiency of 8.39 %, fast start‐up, multiple start/stop cycling, and good stability under extended irradiation.     

Separation and purification of hydrolyzable tannin from Geranium wilfordii Maxim by reversed‐phase and normal‐phase high‐speed counter‐current chromatography

Three hydrolyzable tannins, geraniin, corilagin and gallic acid, main active components of Geranium wilfordii Maxim, have been separated and purified in one‐step by both reversed‐phase and normal‐phase high‐speed counter‐current chromatography. Gallic acid, corilagin and geraniin were purified from 70% aqueous acetone extract of G. wilfordii Maxim with solvent system n‐hexane–ethyl acetate–methanol–acetic acid–water (1:10:0.2:0.2:20) by reversed‐phase high‐speed counter‐current chromatography at purities of 94.2, 91.0 and 91.3%, at yields of 89.3, 82.9 and 91.7%, respectively. Gallic acid, corilagin and geraniin were purified with solvent system n‐hexane–ethyl acetate–methanol–acetic acid–water (0.2:10:2:1:5) by normal‐phase high‐speed counter‐current chromatography at purities of 85.9, 92.2 and 87.6%, at yields of 87.4, 94.6 and 94.3%, respectively. It was successful for both reversed‐phase and normal‐phase high‐speed counter‐current chromatography to separate high‐polarity of low‐molecular‐weight substances.     

Retention parameters of some isomeric 2-benzoylbenzoic acids in reversed-phase ion-pair high performance thin-layer and column chromatography

Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by log k and R_M values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated.     

Online extraction and isolation of highly polar chemical constituents from Brassica napus L. pollen by high shear technique coupled with high-performance counter-current chromatography

High shear technique coupled with high-performance counter-current chromatography was successfully used for the extraction and online isolation of seven highly polar chemical constituents from the Brassica napus L. The lower phase of ethyl acetate-n-butanol-water (1:4:5, v:v:v) was used as both the high shear technique solvent and high-performance counter-current chromatography mobile phase. Seven compounds of 14.2 mg of uridine, 4.6 mg of xanthosine, 7.8 mg of guanosine, 5.3 mg of adenosine, 19.5 mg of kaempferol-3,4'-di-O-β-D-glucopyranoside, 17.7 mg of kaempferol-3-O-(2-O-β-D-glucopyranosy1)-β-D-glucopyranoside, and 25.7 mg of an unknown compound, with a high-performance liquid chromatography (HPLC) purity over 95.0%, were obtained in a one-step extraction-separation process within 130 min from 20.0 g of raw material of pollen of Brassica napus L. Moreover, the mode of elution-extrusion was employed for the separation of the last one compound. The isolated compounds were analyzed by HPLC, and the chemical structures of the compounds mentioned above were identified by UV and NMR. It is the first time to combine the high shear technique and high-performance counter-current chromatography for the online isolation of the nature products.     

Isolation of bioactive components from Flaveria bidentis (L.) Kuntze using high-speed counter-current chromatography and time-controlled collection method

Semipreparative high-speed counter-current chromatography (HSCCC) by time-controlled collection method was successfully applied for isolation and purification of α-terthienyl, 5-(3-buten-1-ynyl)-2,2'-bithienyl, and 5-(3-penten-1-ynyl)-2,2'-bithienyl from Flaveria bidentis (L.) Kuntze for the first time. The two-phase solvent system composed of n-hexane and acetonitrile at the volume ratio of 1:1 (v/v) was used for the semipreparative HSCCC. The 5.2 mg α-terthienyl, 2.2 mg 5-(3-buten-1-ynyl)-2,2'-bithienyl, and 4.3 mg 5-(3-penten-1-ynyl)-2,2'-bithienyl with the purity of 99.9, 90.2, and 92.1% were produced from 265.6 mg crude extract, respectively, and 5-(3-penten-1-ynyl)-2,2'-bithienyl was first isolated from Flaveria bidentis (L.) Kuntze. The structures of the separated compounds were identified by electrospray-ionization mass spectrometry and proton and carbon nuclear magnetic resonance ((1)H- and (13)C-NMR).