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Direct ethanol fuel cell (DEFC) has attracted wide attention due to its wide range of fuel sources, cleanliness, and high efficiency. However, the problems of low catalytic efficiency and poor catalyst stability still exist in DEFC catalysts, which restrict its rapid development. With chloroplatinic acid (H2PtCl6·6H2O) as the precursor, Polyvinylpyrrolidone (PVP) plays the role of surfactant, stabilizer, and reducing agent in the experiment. Glycine is the surface control agent and co-reducing agent. Pt high-index facets nanocatalyst was prepared with the one-pot hydrothermal method by adjusting the amount of PVP and glycine. X-Ray Diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM) were used to characterize the micro-structure of the nanocatalyst, and the influence of PVP and glycine on the synthesis of high-index facets catalyst was studied. The electrocatalytic performance of the catalyst was tested with an electrochemical workstation, and it was found that the performance of the prepared catalyst was better than that of the commercial catalyst. When the mass ratio of PVP and Pt was 50:1 and the molar ratio of glycine and Pt was 24:1, Pt nanocatalysts with {310}, {520} and {830} high exponential facets were prepared. The electrochemical test results showed that the peak current density of ethanol oxidation was 2.194 m2/g, and the steady-state current density was 0.241 mA/cm2, which was 5.7 times higher than that of commercial catalyst. The results of this paper show that due to the defects such as steps and kinks on the surface of the high-index facets, the active sites are increased, thus showing excellent electrocatalytic performance. This study provides a theoretical basis for the development and commercial application of high index facets nanocatalysts. [ABSTRACT FROM AUTHOR]

Controllable synthesis and rational design of ordered nanostructures are crucial for their renewable energy applications. In this work, a mesoporous CoP/Fe2P doped with 5 % Ce by a simple nanocasting method is designed as a superior electrocatalyst for the oxygen evolution reaction (OER). The well‐designed composite delivers an efficient electrocatalytic activity with a low overpotential of 250 mV at 10 mA cm−2 and excellent long‐term stability with no degradation after 10 h of electrochemical OER test, superior to that of the state‐of‐the‐art RuO2 electrocatalyst in alkaline electrolyte. A comprehensive analysis demonstrates that the outstanding OER performance is due to the desirable combination of the highly exposed active centers in the Ce‐doped bimetallic phosphides, efficient mass transfer, and effective electron conduction owing to the hierarchically mesoporous hybridization. Furthermore, the synergistic effect between Ce and CoP/Fe2P accelerates the migration rate of electrons/ions and increases the electrochemical active area. This excellent OER performance observed by Ce doping of CoP/Fe2P makes them possible candidates toward OER in alkaline electrolytes. [ABSTRACT FROM AUTHOR]

Accurate and sensitive detection of dopamine (DA) is fundamental to monitor and diagnose certain neurological diseases. Herein, highly ordered mesoporous ZnFe 2 O 4 (OM-ZnFe 2 O 4) is prepared via a facile nanocasting method and shows the highly sensitive in the electrochemical detection of DA. The optimized OM-ZnFe 2 O 4 -40 shows the most excellent activity for DA oxidation in a wide linear range from 2 to 600 nM with a quick response time of 5 s, high sensitivity of 0.094 nA nM−1 and a lower detection limit of 0.4 nM (S/N = 3). The electrode modified with OM-ZnFe 2 O 4 is further successfully used to monitor the increase of DA concentration induced by K+-stimulation of living PC12 cells in a neurological environment. This work offers a simple and powerful strategy for designing electrodes for detecting DA in biological systems. Image 1 • Mesoporous ZnFe 2 O 4 prepared successfully via a facial nanocasting method. • Mesoporous Fe 3 O 4 showed excellent detection of DA with a quick response time of 5 s, high sensitivity of 0.094 nA nM−1 and a lower detection limit of 0.4 nM (S/N = 3). • Practical application of the sensor was demonstrated in PC12 cells. • Mesoporous materials possess large specific surface area, which facilitate the mass transport and electron transfer for detection. [ABSTRACT FROM AUTHOR]

Core–shell architecture coupled with rational surface engineering constitutes an efficient strategy for promoting electrocatalysis on multimetallic nanocrystals via the optimization of composition, facets and coordination environment. Here, by leveraging controlled surface segregation, we realize core–shell formation with systematic tuning of surface composition on well-defined PdCuRu nanocrystals. When applied for the hydrogen evolution reaction (HER), we established a direct correlation between surface composition and activity. In particular, PdCuRu catalysts with a Pd-rich surface achieved an overpotential of 31 mV at a current density of 10 mA cm−2 and a low Tafel slope of 52 mV dec−1 in an alkaline electrolyte, considerably enhanced relative to control PdCuRu/C catalysts with other surface compositions and even exceeding those of state-of-the-art Pt/C. Similar trends were also observed in both neutral and acid electrolytes. We deduce that, in this catalytic system, the enhanced electrocatalysis originates from the strain effect rather than the bifunctional mechanism. The present study builds a bridge between surface engineering and HER performance, and opens up new material designs for surface Pd-rich core–shell nanostructures for the purpose of improving HER catalytic activity and stability at all pH values. [ABSTRACT FROM AUTHOR]

2-Methylbutanal (2-MB) and 3-methylbutanal (3-MB) are highly volatile compounds and typical beer aging compounds. The development of a kinetic model of the formation of 2- and 3-MB is useful to estimate the wort flavor during the wort boiling and the flavor stability of beer. A model experiment was performed, using d-glucose/ d-maltose and l-leucine/isoleucine to study Maillard reaction in a buffer solution of a pH value of 5.2. The simulated solution was heated at different time (0-360 min) and temperature (90-130 °C). The concentrations of d-glucose/ d-maltose, l-leucine/isoleucine and 2- and 3-MB were determined by HPLC and GC. This kinetic model is based on the correlation between the concentration of 2- and 3-MB and the concentration of l-leucine/isoleucine. In this paper, the multistep formation method of 2-MB/3-MB is simplified to a three-step reaction. The kinetic parameters Ea, A and k were calculated for each reaction step. It was found that the formation of 2- and 3-MB has a sequence like this: GL > ML > GI > MI. The total activation energies for the formation of 2- and 3-MB are ranging from 107.87 to 178.88 kJ/mol. The developed kinetic model gives a good fit with the experimental data. This study is useful for the control of the wort quality during the boiling process and could also be interesting for food and beverage industries. Practical Applications Maillard reactions are responsible for the formation of most wort flavors. In addition to this there exist intermediates, which lead to the development of off-flavors during shelf life. The 2- and 3-MB are the Strecker aldehydes and have typical wort flavors. Wort boiling is not only the midpoint of the brewhouse, it is also one of the most important steps in producing an excellent beer. The kinetic study of the formation of 2- and 3-MB is very useful for the control of wort boiling parameters. This result is helpful to calculate a suitable wort boiling time for different raw materials under brewing process conditions. [ABSTRACT FROM AUTHOR]

Dimethyl sulfide ( DMS), which has a characteristic taste and aroma of cooked celery, is one of the most studied off-flavors in wort and beer. Although there have been many kinetic studies conducted with different wort boiling systems under isothermal conditions, the results are difficult to apply to the heating up process, in which the decomposition of the DMS precursor ( DMS- P), S-methylmethionine ( SMM) also takes place. And it is not easy to define the time of the beginning of wort boiling ( t = 0) under isothermal conditions. In this study, the kinetics of thermal decomposition of SMM was studied using multiple dynamic measurements under non-isothermal conditions. Wort was heated to 140C in sealed test tubes with different heating rates (1-6 K/min). The activation energies ( Ea) and the pre-exponential factors ( A) for the decomposition of SMM were investigated using Coats- Redfern, Kissinger and Flynn- Wall- Ozawa method, respectively. The reaction mechanism follows first-order kinetics. The kinetic triple ( Ea, A, G( α)) obtained from the non-isothermal method is compared with the results from isothermal method. In order to predict the formation of DMS and provide a better control during brewing process, a kinetic model was developed, which is applied to the heating up process and boiling process. Practical Applications The assessment of a wort boiling system and the improvement of a brewing recipe should be based on chemical kinetic perceptions. Dimethylsulfide ( DMS) is a typical leader substance and evaporation factor and also an off-flavor in wort. The knowledge about kinetic analysis on the formation of DMS is one of the important keys in order to control the brewing process and to guarantee the final beer quality. The results in this study can be used to calculate the optimal wort boiling to achieve the desired wort quality and final beer taste under atmospheric boiling conditions. In addition, the results can be used to improve the control of other heating parameters during heating and boiling of the wort. [ABSTRACT FROM AUTHOR]

[Display omitted] • Indium sulfide with indium defects and hydrophobic surface is prepared. • Defect is important for the induction of CTAB. • The hydrophobic indium sulfide enhances the adsorption of lignin and oxygen. • In x S 3 -C exhibits good activity under low visible light (80 mW⋅cm−2, 5 W LED). • The degradation pathway of lignosulfonate was proposed by HPLC-MS. Lignin is difficult to be degraded due to its complex structure and hydrophobicity. Herein, we report an effective strategy to degrade lignin by defective indium sulfide with the hydrophobic surface (In x S 3 -C). In x S 3 -C is synthesized by a one-pot hydrothermal method with the assistance of CTAB. The optimal photocatalyst (In 0.75 S 3 -C) exhibits great adsorption capacity and degradation efficiency for lignosulfonate. The degradation rate of lignosulfonate achieves 90% after irradiating by visible light for 30 min, representing nearly 80 times higher activity than the commercial photocatalyst (P25). The great photocatalytic performance of In 0.75 S 3 -C is ascribed to the enhanced adsorption of lignosulfonate and oxygen, which facilitates intimate contact and mass transfer. Furthermore, TG-DSC, FTIR, UV–vis DRS and TRPL demonstrate that the defects are important for the introduction of CTA+, as well as enhance visible light absorption and the separation of photogenerated carriers. Combined with HPLC-MS analysis, a possible degradation pathway of lignosulfonate is proposed. [ABSTRACT FROM AUTHOR]

In recent years, nickel based nanomaterials have attracted much attraction owing to their low cost and the unique catalytic properties in some special reactions. Uniform diameter polymethyl methacrylate (PMMA) nanofibers and β-cyclodextrin (β-CD) functionalized PMMA nanofibers were obtained through electrospinning. Nickel-loaded nanofibers (Ni/β-CD/PMMA) were prepared by a reductive impregnation method. With increasing addition of β-CD, the diameter of the composite nanofibers became larger. The images by scanning electron microscopy (SEM) suggested that the morphology for different β-CD loadings of the β-CD/PMMA nanofibers was uniform until the loading of β-CD was 8 wt.%; the morphology of the nanofibers then became nonuniform and nodes appeared. Energy dispersive spectrometry (EDS) revealed that the Ni nanoparticles were loaded on the surface of nanofibers successfully. [ABSTRACT FROM PUBLISHER]

In the study, PAN/β-cyclodextrin (β-CD) one dimensional composite nanofibers were synthesized with sol-gel method and electrospinning, and then, we dipped the composite nanofibers into NaBH4aqueous solution acted as reducing agent to fabricate PAN/β-CD/Cu composite nanofibers. We got the PAN/β-CD/Cu composite nanofibers with different concentration of β-CD, and Cu nanoparticles formed on its surface. The final products were characterized using scanning electronic microscope (SEM), fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). The results of characterization showed that the Cu nanoparticles with small size were well-distributed on the composite nanofibers. [ABSTRACT FROM PUBLISHER]

A novel adsorption material of α-, β- and γ-cyclodextrin (CD)/ Poly(acrylonitrile) (PAN) composite nanofibers was prepared via electrospinning. The PAN composite nanofibers were applied to Cu (II) ion adsorption, which is suitable for Cu (II) ion adsorption due to their high adsorption affinity for metal ions. The amounts of the metal ions adsorbed onto α-, β- and γ-CD/PAN composite nanofibers mats were influenced by α-, β- and γ-CD concentration and the contact time. The physicochemical properties and adsorption performance of α-, β- and γ-CD/PAN composite nanofibers were characterized. [ABSTRACT FROM PUBLISHER]

nanoparticles ( NPs) embedded carbon nanofibers (CNFs) were prepared by a new route which included chemical reaction process, electrospinning and calcination technique. The morphology and structure of the composite nanofibers were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction. It indicated that NPs were uniformly distributed in the CNFs. This effective synthesis method can be used to prepare other composite nanofibers with functionality. The NPs/CNFs that served as supported catalysts were used in the styrene epoxidation by TBHP. The NPs/CNFs catalyst showed its highly catalytic activity for the epoxidation of styrene (conversion: 40.6%, SO selectivity: 35.9%). This kind of composite nanofiber membrane was proved effectively catalytic activity and recycled easily in the styrene epoxidation. The composite nanofibers that silver nanoparticles supported on CNFs materials were successfully prepared by using chemical reaction process, electrospinning technology and high-temperature calcination technology. Ag NPs were monodispersed and uniformly distributed in the carbon nanofibers. The Ag NPs/CNFs served as supported catalysts were used in the styrene epoxidation by TBHP. This composite nanofiber membrane was proven to have effective catalytic activity, and recycled easily in the styrene epoxidation. These new supported catalysts in the styrene epoxidation have potential practical value. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile (PAN) and PAN/β-cyclodextrin (β-CD) microspheres were prepared via an electrospinning method. The PAN microspheres could be successfully obtained in a suitable range of concentrations of electrospun PAN solutions. When β-CD was added to the PAN solutions, electrospun PAN/β-CD composite spheres were prepared. The morphology of the spheres was characterized by scanning electron microscopy (SEM); it showed that the spheres had uniform diameter and a smooth surface. The composition of the composite microspheres was studied by Fourier transform infrared spectroscopy (FTIR). The results showed that the β-CD was incorporated in the polymer microspheres. [ABSTRACT FROM AUTHOR]

By regulating the phosphorization conditions, the optimized Fe-doped Ni 2 P nanosheets arrays with slightly rough surface exhibit high-efficiently electrocatalytic oxygen and hydrogen evolution activities, as well as excellent overall-water-splitting performance. • By regulating the phosphorization conditions, the Fe-doped Ni 2 P nanosheets arrays with different surface roughness can be obtained. • The as-prepared Fe-doped Ni 2 P nanosheets arrays with slightly rough surface exhibit low overpotentials (η 100) of 213 and 210 mV for OER and HER. • The designed principle is to increase the electrochemical active sites by combining the control of surface structural conditions and the incorporation of Fe atoms, thus inducing the enhanced bifunctional electrocatalytic activity. • The assembled water electrolyzer using this bifunctional electrocatalysts only needs a low cell voltage. The 3D nanosheets arrays architecture, coupled with the modulation of surface structure and the incorporation of foreign atoms, constructs an anticipated method to boost the electrocatalytic performance on the transition metal compounds-based non-precious catalysts. Herein, we report a structural engineering strategy of Fe-doped Ni 2 P nanosheets arrays supported on Ni foam for enhancing electrocatalytic performance of both oxygen evolution (OER) and hydrogen evolution (HER) reactions. Benefitting from the increased electrochemical active sites caused by structural engineering and the strong electronic effect derived from Fe-doping, the Fe-doped Ni 2 P nanosheets arrays with slightly rough surface can achieve the highest OER activity with a low overpotential of 213 mV at a current density of 100 mA cm−2 and a Tafel slope of 50.7 mV dec–1, better than the other catalysts with different surface structures. Moreover, the enhanced HER performance can also be obtained based on this distinct structure. Finally, a two-electrode alkaline electrolyzer, applying this optimized bifunctional catalyst as both the cathode and anode, can be driven with a low cell voltage of 1.54 V to afford a current density of 10 mA cm−2, as well as excellent stability. The present study bridges the gap between structural engineering and bifunctional electrocatalytic activity towards overall water splitting, and opens up a new avenue for the material designs of high-performance nanoarrays electrocatalysts. [ABSTRACT FROM AUTHOR]

The materials of Ni nanoparticles/carbon nanofibers (Ni NPs/CNFs) and carbon nanofibers (CNFs) were prepared by electrospinning the Ni doped precursor solutions. The Ni doped nanofibers with the diameter of 200-300 nm possess the uniform morphology and smooth surface. These nanofibers were carbonized at 600 degrees C for 2 h. The Ni NPs/CNFs composite was characterized with SEM (scanning electro microscope), XRD (X-ray diffraction) and FT-IR (Infrared spectroscopy). The Ni NPs/CNFs electrode was investigated through the cyclic voltammetry measurement. The average specific capacity was calculated to be 113 F x g(-1) at the scan rate of 2 mV x s(-1). The high specific capacity was larger than the CNFs owing to the Ni NPs. The specific capacity retention also maintains 72% after 5 cycles, suggesting that the electrode possess good reversibility. The Ni NPs/CNFs composite material with excellent electrochemical properties will be a promising material which can be used for energy storage.