HPLC Fluorescence Method for Eugenols in Basil Products Derivatized with DIBI.

Eugenols (Eugs) such as eugenol (Eug), methyleugenol (MeEug), and linalool (Lin) in basil product are the main bioactive components of basil products and have a terminal double-bond. A sensitive HPLC-fluorescence method for Eugs derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIBI) was developed. Good separation of DIB-Eugs was achieved within 20 min on an Atlantis T3 column (50 × 2.1 mm i.d., 3 µm) with a mobile phase of methanol-water. The calibration curves obtained with Eug standards showed good linearities in the range of 0.1-50 µM (r ≥ 0.999). The limits of detection at a signal-to-noise ratio (S/N) = 3 for Eug, MeEug, and Lin were 1.0, 6.0, and 4.8 nM, respectively. The limits of quantitation (S/N = 10) of the Eugs were lower than 19.9 nM. The accuracies for the Eugs were within 96.8-104.6%. The intra- and inter-day precisions as relative standard deviations for the Eugs were less than 1.2 and 9.6% (n = 3). The recoveries of Eug, MeEug, and Lin were 99.0 ± 0.1, 98.0 ± 0.2, and 96.0 ± 0.4% (n = 3), respectively. The DIB-Eugs were confirmed to be stable for 2 h (>90%) at room temperature and 24 h (>95%) at 4 °C. These parameters of the proposed method were useful for the simultaneous determination of Eugs in basil products. Therefore, the developed method may be a powerful tool for the quality evaluation of dried commercially available basil products.

Zirconia nanocolloids having a nanospace of poly(cyclodextrin): preparation and application to liquid crystal devices.

Poly(gamma-cyclodextrin) (PgammaCyD)-protected ZrO2 nanocolloids were prepared by using a microwave reactor equipped with ultrasonic nozzle mixing at 240 degrees C for 30 min in a tetraethylene glycol solution of zirconium (IV) ethoxide in the presence of poly(gamma-cyclodextrin). Particles in PgammaCyD-protected ZrO2 nanocolloids have an average diameter of 7.2 nm and mainly distribute within the range of about 3 to 10 nm. The nanocolloids were dispersed in 4'-pentylbiphenyl-4-carbonitrile (5CB) and practical liquid crystal to construct novel twisted nematic liquid crystal devices (TN-LCDs). The response time of this TN-LCDs in the presence of PgammaCyD-protected ZrO2 nanocolloids was faster than that in the absence. The threshold voltage of TN-LCDs by doping PgammaCyD-protected ZrO2 nanocolloids decreased. The decrease of threshold voltage can reduce power consumption, which may meet the demands of future power-saving LCDs.

One-pot synthesis of PdPtAg porous nanospheres with enhanced electrocatalytic activity toward polyalcohol electrooxidation.

Porous nanospheres (PNSs) have great development prospects in the electrocatalysis field because of their structural characteristics, such as a large specific surface area. However, it is still a challenge to find a simple and energy-saving method for the controllable synthesis of PNS nanocatalysts. In this paper, a one-pot CTAC-assisted strategy was developed for the successful formation of PdPtAg PNSs with high porosity at room temperature. Benefitting from the unique structures, optimized composition, acceleration of charge transfer and enhanced resistance to CO poisoning, the PdPtAg PNSs displayed considerably improved electrocatalytic performance with high mass activity and stability toward the ethylene glycol oxidation reaction (EGOR) and glycerol oxidation reaction (GOR). The EGOR and GOR mass activities of PdPtAg were 5.00 A mgmetal-1 and 3.06 A mgmetal-1, which are 6.22 and 1.91 times that of commercial Pd/C, respectively. This work is expected to offer a new path for improving catalytic performance by simple design and adjustment of morphology.

Photoelectrocatalytic oxidation of ethylene glycol on trimetallic PdAgCu nanospheres enhanced by surface plasmon resonance.

The notable surface plasmon resonance (SPR) effect of some metals has been applied to improve the efficiency of alcohol oxidation reactions, whereas the comprehensive investigation of Cu-assisted photoelectrocatalysis remains challenging. We herein successfully prepared trimetallic PdAgCu nanospheres (NSs) with abundant surface bulges for the advanced ethylene glycol oxidation reaction (EGOR) and compared them with bimetallic PdAg NSs to investigate the performance enhancement mechanism. Impressively, the as-optimized PdAgCu NSs exhibited superb mass activity and electrochemical stability. Moreover, under visible light illumination, the mass activity of PdAgCu NSs increased to 1.62 times compared to that in the dark, and in contrast, the mass activity of PdAg NSs only increased to 1.48 times that in the dark. A mechanistic study indicated that the incorporation of Cu not only strengthens the whole SPR effect of PdAgCu NSs but also further modifies the electronic structure of Pd. This work highlighted that the incorporation of Cu into PdAg NSs further enhanced the photoelectrocatalytic performance and increased noble metal atom utilization, which may provide guidance to fabricate novel and promising nanocatalysts in the field of photoelectrocatalysis.

Heterostructure engineering and ultralow Pt-loaded multicomponent nanocage for efficient electrocatalytic oxygen evolution.

Developing highly efficient electrocatalysts based on appropriate heterojunction engineering and electronic structure modification for the oxygen evolution reaction (OER) has been extensively recognized as an effective approach to increase the efficiency of water splitting. Herein, ultralow Pt-loaded (1 %) NiCoFeP@NiCoFe-PBA hollow nanocages with well-defined heterointerfaces and modified electronic environment are successfully fabricated. As expected, the obtained Pt-NiCoFeP@NiCoFe-PBA exhibits outstanding performance with a low overpotential of 255 mV at 10 mA cm-2 and a small Tafel slope of 57.2 mV dec-1. More specifically, the highly open three-dimensional structure, exquisite interior voids and abundant surface defects endow Pt-NiCoFeP@NiCoFe-PBA nanocages with more electrochemical active sites. Meanwhile, experimental results and mechanism studies also reveal that the construction of heterogeneous interfaces as well as incorporation of noble metals could readily induce strong synergistic effects and significantly tailor electronic configurations to optimize the binding energy of the intermediates, thereby achieving prominent OER performance.

Construction and electro-optic properties of liquid-crystal display doped by rhodium nanoparticles.

We prepared 4'-pentylbiphenyl-4-carbonitrile (5CB)-stabilized rhodium (5CB-Rh) nanoparticles and poly(cyclodextrin) (PCyD)-stabilized rhodium (PCyD-Rh) nanoparticles. The average diameter of Rh nanoparticles stabilized by 5CB, PalphaCyD, PbetaCyD, and PgammaCyD are 1.2, 5.4, 6.8, and 5.2 nm, respectively. The nanoparticles were dispersed in liquid crystal 5CB to construct novel twisted nematic liquid crystal device (TN-LCD). Voltage holding ratio was measured for TN-LCD fabricated by doping PbetaCyD-Rh nanoparticles. The decrement of the voltage was very much reduced for that doped with PbetaCyD-Rh. The response time of this TN-LCD in the presence of PbetaCyD-Rh nanoparticles was faster than that in the absence.

In situ nanopores enrichment of Mesh-like palladium nanoplates for bifunctional fuel cell reactions: A joint etching strategy.

Two-dimensional (2D) nanomaterials with nanopore display an enhancement effect on electrocatalysis behavior, whereas the nanopore engineering for 2D nanocatalysts remains an insurmountable challenge. We advance the synthesis of multilayer Pd nanoplates (Pd NPs) and two types of meshy nanoplates (Pd LMNPs/MNPs) with escalating nanopores from none and sparse to porous. Specially, an in situ nanopore enrichment on these Pd nanoplates hinges on a joint etching strategy with integrated manipulation of reaction kinetics. The optimized Pd MNPs exhibit exceptional oxygen reduction reaction performance, owing to the enhanced intermediates protonation on Pd site neighboring nanopore, which has been elucidated by density functional theory calculations. In addition, Pd MNPs also deliver excellent performances in fuel cell anodic reactions, including ethanol oxidation reaction and formic acid oxidation reaction. This study highlights a new strategy for in situ nanopores engineering, providing a prospect for designing superior nanocatalysts.

Size-controlled synthesis of polymer hollow nanoparticles using emulsion templates prepared by tandem acoustic emulsification.

We have developed a new emulsion template method for the synthesis of poly(methylmethacrylate) (PMMA) hollow nanoparticles with different sizes. This synthetic method involves sequential ultrasonic irradiation (20 kHz → 500 kHz → 1.6 MHz → 2.4 MHz → 5.0 MHz) for acoustic emulsification of a water-insoluble fluorous solvent such as perfluoromethylcyclohexane (PFMCH) in an aqueous medium, followed by monomer (methylmethacrylate (MMA)) adsorption on the surface of the PFMCH emulsion droplets and photopolymerization of the adsorbed MMA in the obtained emulsion solution. Since the size of the PFMCH droplet templates can be tuned according to the number of steps of tandem acoustic emulsification, the obtained PMMA particle size can also be controlled. The subsequent removal of the core fluorous solvent by the heat treatment yielded size-controlled PMMA hollow nanoparticles and monodisperse PMMA hollow nanoparticles of different sizes. Furthermore, we confirmed that the substances could go in or go out of the hollow particles through the shells. Such a nice permeability is important for applications such as nanoreactors and drug delivery systems.

Engineering Spiny PtFePd@PtFe/Pt Core@Multishell Nanowires with Enhanced Performance for Alcohol Electrooxidation.

Engineering robust electrocatalysts is always a key point in direct alcohol fuel cells. Catalysts with a one-dimension (1D) structure are well studied and considered as promising candidates among various catalysts in the past decades; however, the precise regulation on the surface structure of 1D nanomaterials is still a worthy subject. By creatively introducing a trimetallic nanoalloy, core@multishell structure, and 1D nanowire (NW) morphology, we have constructed a kind of novel spiny PtFePd@PtFe/Pt core@multishell 1D NW catalysts with PtFePd as the core and PtFe/Pt as the multishell on the basis of improving catalytic property. The composition-optimized Pt5FePd2 1D NWs display remarkable catalytic properties for ethanol oxidation reaction and methanol oxidation reaction, in which mass activities are 4.965 and 4.038 A mg-1, 4.6 and 5.0 and 4.0 and 9.2-fold higher than Pt/C and Pd/C catalysts. Furthermore, the obtained Pt5FePd2 NWs can also retain favorable stability after durability tests. The unique core@multishell structure, spiny 1D NWs with many steps and kinks, and interior electronic and synergistic effect all contribute to the advanced catalytic performance. The present work has rationally designed the novel 1D PtFePd@PtFe/Pt core@multishell NW catalysts and offered a meaningful guideline for the designing of high-performance electrocatalysts.

Microfluidic Paper-based Analytical Device for the Determination of Hexavalent Chromium by Photolithographic Fabrication Using a Photomask Printed with 3D Printer.

This article describes a simple and inexpensive microfluidic paper-based analytical device (µPAD) for the determination of hexavalent chromium (CrVI) in water samples. The µPADs were fabricated on paper by photolithography using a photomask printed with a 3D printer and functionalized with reagents for a colorimetric assay. In the µPAD, CrVI reacts with 1,5-diphenylcarbazide to form a violet-colored complex. Images of µPADs were captured with a digital camera; then the red, green, and blue color intensity of each detection zone were measured using images processing software. The green intensity analysis was the best sensitive among the RGB color. A linear working range (40 - 400 ppm; R2 = 0.981) between the CrVI and green intensity was obtained with a detection limit of 30 ppm. All of the recoveries were between 94 and 109% in recovery studies on water samples, and good results were obtained.

Hierarchical NiMo Phosphide Nanosheets Strongly Anchored on Carbon Nanotubes as Robust Electrocatalysts for Overall Water Splitting.

Although a great achievement has been made in the field of electrochemistry, the exploration of high-efficiency catalysts for the generation of hydrogen and oxygen via overall water splitting is still a grand challenge. We herein report the successful construction of a new class of hierarchical catalysts with defect-enriched nickel-molybdenum phosphide nanosheets anchored on the surface of carbon nanotubes for efficient water splitting. Via the construction of a hierarchical nanostructure, more efficient electron mobility and mass transfer occurrence were achieved, resulting in a substantial enhancement of electrocatalytic performances. Interestingly, overpotentials of only 255 and 135 mV are required for the optimized Ni1Mo1P NSs@MCNTs to afford a current of 10 mA cm-2 for oxygen evolution reaction and hydrogen evolution reaction, respectively. More significantly, the introduction of molybdenum and phosphorus is also significant for exposing surface active sites and modifying the bonding energy between hydrogen and metals; all of these advantages have endowed the Ni1Mo1P NSs@MCNTs//Ni1Mo1P NSs@MCNTs couple to display highly efficient water electrocatalysis property with a relatively low overall potential of 1.601 V at 10 mA cm-2, shedding bright light for large-scale overall water electrocatalysis.

Hierarchical branched platinum-copper tripods as highly active and stable catalysts.

Designing and manipulating the structure of nanomaterials can efficiently tailor their catalytic properties, enabling the promotion of both their activity and stability. We herein report the shape-controlled synthesis of advanced Pt-Cu hierarchical tripod nanocrystals (HTNCs) by controlling the amount of KI and reaction time. The as-prepared nanocrystals (NCs) look like a typical tripod on the whole, consisting of similar branch structural units. In addition, the structure of the HTNCs could also be obtained with a narrow Pt/Cu feeding ratio. Owing to the unique HTNC structure and exposed high-index facets, as well as probable electronic effects between Cu and Pt, the as-obtained Pt-Cu HTNCs can exhibit greatly enhanced electrocatalytic activity toward ethylene glycol oxidation reaction (EGOR) and glycerol oxidation (GOR), which are 5.1 and 6.5 times higher in mass activity, as well as 5.6 and 7.3 times higher in specific activity relative to commercial Pt/C, showing that they are a class of promising electrocatalyst for fuel cells. This work presents huge opportunities for optimizing the electrocatalytic oxidation reaction by designing the structure of nanocatalysts.

Heterogeneous Co(OH)2 nanoplates/Co3O4 nanocubes enriched with oxygen vacancies enable efficient oxygen evolution reaction electrocatalysis.

Heterogeneous Co(OH)2 nanoplate/Co3O4 nanocube hybrids with rich oxygen vacancies have been constructed through a controllable approach. The high surface areas of such unique nanohybrids together with abundant oxygen vacancies provide more surface active sites, which can facilitate the charge transfer and boost the exchange of intermediates. Specifically, the resultant Co(OH)2 nanoplate/Co3O4 nanocube hybrids display outstanding oxygen evolution reaction (OER) performances with a low overpotential of 281 mV at 10 mA cm-2 and excellent durability after continuous CV of 3000 cycles, shedding light for large-scale applications in practical water splitting.

Self-supported nickel-cobalt nanowires as highly efficient and stable electrocatalysts for overall water splitting.

The development and design of highly active and stable electrocatalysts based on cheap and Earth-abundant materials is critically important to enable water splitting as a desirable renewable energy source. Herein, we fulfill the significant electrochemical water splitting enhancement in both electrocatalytic activity and durability by constructing self-supported nickel-cobalt nanowire catalysts with abundant oxygen vacancies. Specifically, the rich oxygen vacancies can largely promote the oxygen evolution reaction (OER) activity of optimal Ni1Co1O2 NWs with a relatively low overpotential of 248 mV to drive a current density of 10 mA cm-2. More significantly, after the phosphorization of Ni1Co1O2 NWs, the resultant Ni1Co1P NWs can also display excellent electrocatalytic hydrogen evolution reaction (HER) performances with an overpotential of only 101 mV to achieve a current density of 10 mA cm-2. Furthermore, benefiting from the unique 1D nanowire structure, the synergistic effect, and the optimal Gibbs free energy for hydrogen evolution evolved from the phosphorization, the Ni1Co1O2 NWs//Ni1Co1P NWs couple is thus highly active and stable for overall water electrolysis with a low voltage of 1.58 V at 10 mA cm-2, showing extraordinary promise for practical overall water splitting electrolysis.

Pt Islands on 3 D Nut-like PtAg Nanocrystals for Efficient Formic Acid Oxidation Electrocatalysis.

Precise control of structures offers a great opportunity to efficiently tune the catalytic performance of nanomaterials, enhacing both their activity and durability. Herein, we achieve a new class of Pt islands on 3 D nut-like PtAg nanocrystals by exploiting the lower electronegativity of Ag in conjunction with the galvanic replacement of catalytically active Pt to Ag. Such nanostructures coated with Pt nanoparticles, exhibiting exposed facets, and active surface composition enhance formic acid oxidation electrocatalysis with optimized PtAg1 nut-like catalysts and achieved a factor of 4.0 and 2.4 in mass and specific activities (1728.3 mA mg-1 and 3.31 mA cm-2 ) relative to those of the commercial Pt/C (431.2 mA mg-1 and 1.41 mA cm-2 ), respectively. Moreover, such 3 D PtAg1 nut-like catalysts also display great enhancement in durability with less decay for at last 500 cycles, showing a great potential to serve as promising catalysts for fuel cells and other applications. Our work provides a fundamental insight on the effect of the morphology toward liquid fuel electrooxidation, which may pave a new way for the fabrication of highly efficient electrocatalysts for fuel cells.

Ethylene Glycol Electrooxidation Based on Pentangle-Like PtCu Nanocatalysts.

The research of active and stable electrocatalysts toward liquid-fuel oxidation reaction is of great significance for the large-scale commercialization of fuel cells. Although extensive efforts have been devoted to pursuing high-performance nanocatalysts for fuel cells, both the high cost and sluggish reaction kinetics have been two major drawbacks that limited its commercial development. In this regard, we demonstrated a facile solvothermal method for the syntheses of an advanced class of PtCu nanocatalysts with a unique pentangle-like shape. By combining the merits of a highly active surface area as well as the synergistic and electronic effects, the as-prepared pentangle-like Pt3 Cu nanocatalysts showed superior electrocatalytic activity towards ethylene glycol oxidation with a mass and specific activities of 5162.6 mA mg-1 and 9.7 mA cm-2 , approximately 5.0 and 5.1 times higher than the commercial Pt/C, respectively. More significantly, the Pt3 Cu pentangle also showed excellent long-term stability with less activity decay and negligible changes in structure after 500 cycles, indicating another class of anode catalysts for fuel cells and beyond.

1D alloy ultrafine Pt-Fe nanowires as efficient electrocatalysts for alcohol electrooxidation in alkaline media.

Fuel cells have been gaining much interest due to their advantages of high energy conversion efficiency, easy handling, etc., whereas some drawbacks of anode catalysts regarding limited performances have seriously restricted their practical applications. Therefore, the development of anode nanocatalysts with higher activity and stability has become an urgent need. In view of this, we have developed a facile wet-chemical approach to synthesize 1D alloy ultrafine Pt-Fe NWs, and we have also revealed the formation mechanism of the ultrafine Pt-Fe NWs using time-dependent studies. More importantly, 1D ultrafine nanowires with anisotropy, superior flexibility, high surface area and excellent conductivity are promising candidates for the improvement of nanocatalytic activity and stability enhancement. Therefore, the electrocatalytic activities of ultrafine Pt3Fe NWs in the oxidation of ethylene glycol and glycerol are 3.9 and 2.5 times greater than that of commercial Pt/C, respectively. Moreover, they provide excellent long-term stability. Our efforts may potentially promote the commercialization of fuel cells to some extent.

Sophisticated Construction of Binary PdPb Alloy Nanocubes as Robust Electrocatalysts toward Ethylene Glycol and Glycerol Oxidation.

The design of nanocatalysts by controlling pore size and particle characteristics is crucial to enhance the selectivity and activity of the catalysts. Thus, we have successfully demonstrated the synthesis of binary PdPb alloy nanocubes (PdPb NCs) by controlling pore size and particle characteristics. In addition, the as-obtained binary PdPb NCs exhibited superior electrocatalytic activity of 4.06 A mg-1 and 16.8 mA cm-2 toward ethylene glycol oxidation reaction and 2.22 A mg-1 and 9.2 mA cm-2 toward glycerol oxidation reaction when compared to the commercial Pd/C. These astonishing characteristics are attributed to the attractive nanocube structures as well as the large number of exposed active areas. Furthermore, the bifunctional effects originated from Pd and Pb interactions help to display high endurance with less activity decay after 500 cycles, showing a great potential in fuel cell applications.

Thermostability of Hybrid Thermoelectric Materials Consisting of Poly(Ni-ethenetetrathiolate), Polyimide and Carbon Nanotubes.

Three-component organic/inorganic hybrid films were fabricated by drop-casting the mixed dispersion of nanodispersed-poly(nickel 1,1,2,2-ethenetetrathiolate) (nano-PETT), polyimide (PI) and super growth carbon nanotubes (SG-CNTs) in N-methylpyrrolidone (NMP) at the designed ratio on a substrate. The dried nano-PETT/PI/SG-CNT hybrid films were prepared by the stepwise cleaning of NMP and methanol, and were dried once more. The thermoelectric properties of Seebeck coefficient S and electrical conductivity σ were measured by a thin-film thermoelectric measurement system ADVANCE RIKO ZEM-3M8 at 330-380 K. The electrical conductivity of nano-PETT/PI/SG-CNT hybrid films increased by 1.9 times for solvent treatment by clearing insulated of polymer. In addition, the density of nano-PETT/PI/SG-CNT hybrid films decreased 1.31 to 0.85 g·cm-3 with a decrease in thermal conductivity from 0.18 to 0.12 W·m-1·K-1. To evaluate the thermostability of nano-PETT/PI/SG-CNT hybrid films, the samples were kept at high temperature and the temporal change of thermoelectric properties was measured. The nano-PETT/PI/SG-CNT hybrid films were rather stable at 353 K and kept their power factor even after 4 weeks.

Hollow AuxAg/Au core/shell nanospheres as efficient catalysts for electrooxidation of liquid fuels.

One plausible approach to endow nanocrystals with both enhanced catalytic activity and stability for the electrooxidation of liquid fuels is to chemically control the crystal structures of nanoparticles. To date, core-shell and alloy structures have been demonstrated to offer generally two precious opportunities to design highly efficient nanocatalysts for the electrooxidation reaction of organic molecules. We herein combine these two advantages and develop a general method to successfully synthesize hollow AuxAg/Au core/shell nanospheres with a high yield approaching 100% via a combined seed mediated and galvanic replacement method. The results from the electrochemical measurements have revealed that this as-obtained hollow AuxAg/Au core/shell nanosphere exhibited considerably high electrocatalytic performance towards ethylene glycol and glycerol oxidation with mass activity of 4585 and 3486 mA mgAu-1, which were 5.3- and 5.8-fold higher than that of pure Au. We trust this strategy may be extended to the syntheses of other multimetallic nanocatalysts with such fascinating nanostructures and the as-obtained hollow AuxAg/Au core/shell nanospheres can be well applied to serve as highly desirable anode catalysts for the electrooxidation of ethylene glycol and glycerol.