Hydrogen production coupled with biomass upgrading is vital for future sustainable energy developments. However, most biomass electrooxidation reactions suffer from high working voltage and low ...current density, which substantially hinder large-scale industrial applications. Herein, we report an acidic hydrogen production system that combined anodic ascorbic acid electrooxidation with cathodic hydrogen evolution. Unlike C-H and O-H bonds cleavage with slow kinetics in conventional organic oxidation, the highly active enol structure in ascorbic acid allows for an ultralow overpotential of only 12 mV@10 mA/cm
using Fe single-atom catalysts, and reaches 1 A/cm
at only 0.75 V (versus reversible hydrogen electrode) with approximately 100% Faraday efficiency for hydrogen production. Furthermore, the fabricated two-electrode membrane-free electrolyser delivers an industrial current density of 2 A/cm
@1.1 V at 60 °C (2.63 kWh/Nm
H
), which requires half of the electricity consumption in conventional water electrolysis (~5 kWh/Nm
H
). This work provides a new avenue for achieving industrial-scale hydrogen production from biomass.
A spontaneous exchange bias (SEB) discovered by Wang et al. Phys. Rev. Lett. 106 (2011) 077203. after zero-field cooling (ZFC) has attracted recent attention due to its interesting physics. In this ...letter, we report a giant SEB tuned by Sb-doping in Ni50Mn38Ga12-xSbx Heusler alloys. Such an SEB was switched on below the blocking temperature of approximately 50 K. The maximum exchange bias HE can arrive at 2930 Oe in a Ni50Mn38Ga10Sb2 sample after ZFC to 2 K. Further studies showed that this SEB was attributable to interaction of superspin glass (SSG) and antiferromagnetic matix, which was triggered by the crossover of SSG from canonical spin glass to a cluster spin glass. Our results not only explain the underlying physics of SEB, but also provide a way to tune and control the SEB performance.
Metal oxide and nanocarbon heterostructures provide a powerful strategy to materials innovation because judicious combination of different materials may afford collective properties that are ...otherwise unattainable. However, design and fabrication of spatially patterned heterostructures has been still challenging. Here, we develop a facile approach to synthesize a CuO and carbon nanotube necklace-like heterostructure in solution for enhanced lithium storage performance. Observations confirm that propagative sidewall alkylcarboxylation of carbon nanotubes in liquid ammonia allows the CuO nanospheres to grow on the functional defect sites introduced by the functionalization. Such a method does not require surfactants and is highly scalable. The resulting materials show high lithium ion storage capacities (stable at 500 mAh g–1) and enhanced cycling performance as a lithium-ion battery anode. The improved performance is attributed to the necklace-like nanostructure, which provides an electrical channel as well as excess room to accommodate the volume changes of CuO during electrochemical cycling.
A lithium-assisted approach has been developed for the exfoliation of pristine graphite, which allows the large-scale preparation of few-layer graphene nanosheets. The process involves an unexpected ...physical insertion and exfoliafion, and the graphene nanosheets prepared by this method reveal undisturbed sp2-hybridized structures. A possible two-step mechanism, which involves the negative charge being trapped around the edges of the graphite layers and a subsequent lithiation process, is proposed to explain the insertion of lithium inside the graphite interlayers. If necessary, the present exfoliation can be repeated and thinner （single or 2-3 layer） graphene can be achieved on a large scale. This simple process provides an efficient process for the exfoliation of pristine graphite, which might promote the future applications of graphene.
► The ultrafine CuO nanowires were controlled synthesized by a simple solution route. ► CuO nanowires exhibit high capacity, superior cyclability and improved rate capability. ► Voltage–capacity ...curves show larger extra reversible reactions at low potentials in CuO nanowires. ► CV curves show lower over-potential in CuO nanowires.
A simple solution route is used to synthesize ultrafine Cu(OH)
2 nanowires by restraining the morphology transformation of early formed 1D nanostructure. The obtained ultrafine nanowires can be well preserved at a low temperature structure transformation in solid state. As anode material for lithium-ion batteries, the ultrafine CuO nanowires exhibit high reversible capacity, superior cycling performance and improved rate capability. The improved electrochemical properties of CuO nanowires are ascribed to their ultrafine size which lead to the reduced over-potential, extra reversible reactions at low potentials and improved interface performance between the electrode and electrolyte.
► Composite-hydroxide-mediated synthesis of hierarchical Co
3O
4 nanostructure. ► Hierarchical Co
3O
4 nanostructure is assembled by extremely thin nanosheets. ► Hierarchical Co
3O
4 anode exhibits ...good cycle performance and high rate capability.
Hierarchical Co
3O
4 nanostructure is synthesized via a self-assembled process in molten hydroxides. The morphologies, crystal structures and the phase transformation processes are analyzed by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. As an anode material for lithium ion batteries, the hierarchical Co
3O
4 exhibit an initial capacity of 1336
mAh
g
−1 and a stable capacity of 680
mAh
g
−1 over 50 cycles. More importantly, high rate capability is obtained at different current densities between 140 and 1120
mA
g
−1. The improved electrochemical performance of Co
3O
4 could be attributed to the unique hierarchical nanostructure.
Natural phenolic compounds are rich in cereal and pulse seeds and their dietary functions tend to improve dramatically during germination. This article reviews recent research on the transformation ...of phenolic compounds during seed germination. In particular, it highlights the classification of crude phenolic compounds that can be divided into extractable and non-extractable phenolic compounds based on the biosynthesis process and extraction method. It also recommends grouping resorcinol lipids in the category of extractable phenolic compounds as non-polar solvent extractable phenolic compounds. Moreover, it discusses the variation of the different form of phenolic compounds and proposes a possible metabolic model of these phenolic compounds for seeds germination. This article is crucial for phenolic compounds research, cereal and pulse seeds germination, and food ingredients industry.
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•GC–MS and GC–O profiles of aromatic components in chickpea, lentil, and yellow pea flours.•Olfactometry identifies low olfactory threshold odor components.•Longer germination ...increases beany flavor in lentil and yellow pea flours.•Germination decreases the beany flavor in chickpea flours.•Markers predict the development of beany flavor during germination.
In this study, volatile component changes of germinated chickpea, lentil, and yellow pea flours over the course of 6 days germination were characterized by HS-SPME-GC–MS/O. In total, 124 volatile components were identified involving 19 odor active components being recorded by GC-O exclusively. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed that lentil and yellow pea flours had the similar aromatic attributes, while the decrease of beany flavor compounds along with the occurrence of unpleasant flavors was detected in chickpea flours upon germination. Six beany flavor markers, including hexanal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 3-methyl-1-butanol, 1-hexanol, and 2-pentyl-furan, were employed to quantify beany flavor formation in the flours over the course of germination. The results suggested that no significant beany flavor formation or mitigation was appeared after 1 day of germination. The findings are crucial for tailing pulse germination process to enhance the macronutrients without increasing undesirable beany flavor.
•Odor profiles of protein isolates from chickpea, lentil, yellow pea were examined.•Odor profiles of protein isolates evolved during the extraction procedure.•Only seven beany-related compounds ...identified in pulse protein isolates.•Germination increases overall beany-related odor of pulse protein isolates.•Free radicals and LOX activity affect the flavor attributes during pulse germination.
In this study, pulse protein isolates (PPIs) were extracted from 0, 1, 3, and 5 days germinated chickpea, lentil, and yellow pea flours by alkaline extraction–isoelectric precipitation method. The germination time had negligible impact on the proximate composition of PPIs. In total, 67 volatiles in PPIs were identified via HS-SPME–GC–MS/O. Among all the identified volatile components, seven of them, including hexanal (11), (E)-2-octen-1-ol (7), (E,Z)-2,6-nonadienal (17), 3-octen-2-one (33), 3,5-octadien-2-one (34), 2-methoxy-3-isopropylpyrazine (56), and 2-methoxy-3-(1-methylpropyl)pyrazine (57), contributed to the beany-related odor of PPIs but much less than that in raw flours. However, the overall beany-related odor of PPIs increased when the germination time exceeded 1 day. Both the activity of lipoxygenase and the free radical populations in PPIs were positively related to the overall beany-related odor. Our findings are crucial for the preparation of germinated pulse proteins with improved functionality but without increasing undesirable odor.
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