The metallic 1T-WS2 can function as a noble-metal-free co-catalyst for photocatalytic hydrogen evolution for its excellent conductivity and high density of active sites on the basal plane and edge.
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•The metallic 1T-WS2 is synthesized through solvothermal method.•1T-WS2 exhibits higher activity than 2H-WS2 as co-catalyst in photocatalytic HER.•Enhanced conductivity and extra active sites contribute to the improvement.
To date, despite significant achievements in noble-metal co-catalysts, it is still challenging to develop high-performance noble-metal-alternative co-catalysts for economic hydrogen production. In this work, we demonstrate that the metallic 1T-WS2 obtained through a facile solvothermal method can function as co-catalyst for boosting the photocatalytic hydrogen production with the merits below: (i) noble-metal-free; (ii) excellent electrical conductivity; (iii) extra active sites on basal plane rather than edge sites for H2 generation. As demonstrated in photocatalytic hydrogen evolution, the designed composite using two-dimensional carbon nitride (2D-C3N4) as semiconductor and 1T-WS2 as co-catalyst (1T-WS2/2D-C3N4) exhibits giant enhancement, in comparison with the bare 2D-C3N4 and 2H-WS2/2D-C3N4. This work highlights the surface engineering strategy of co-catalysts such as phase engineering for promoting the photocatalytic performance.
The NiMoV LDH/NF electrode realizes high-efficiency catalysis for UOR in view of the rapid kinetics, high intrinsic activity and robust durability in variable urea concentration and pH values ...conditions.
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•Mo and V dopants in NiMoV LDH optimizes the electronic structure to facilitate thein-situconversion of Ni3+species.•Co-doping of Mo and V atoms in NiMoV LDH enhances the adsorption energy of Ni site to urea molecule during UOR process.•1.40 V is required to achieve 100 mA cm−2in urea oxidation for NiMoV LDH in alkaline.•The NiMoV LDH electrode is suitable for a wide range of urea concentrations and pH changes.
Fabrication of advance electrocatalysts for urea oxidation reaction (UOR) is of great significance for purifying urea-enriched wastewater and producing hydrogen. Here, a doping engineering strategy is adopted to obtain a ternary NiMoV layered double hydroxide (LDH) nanosheet array supported on the three-dimensional (3D) nickel foam substrate. The synergistic effect brought by the unique 2D/3D hierarchical structure could expose more active sites and accelerate charge and mass transfer. In addition, experimental and theoretical results confirm that Mo and V dopants are capable of modifying the local electronic structure of Ni sites to optimize the adsorption energy for urea molecules. Therefore, the as-prepared NiMoV LDH/NF electrode realizes high-efficiency catalysis for UOR in view of the rapid kinetics, high intrinsic activity and robust durability. Specifically, NiMoV LDH/NF electrode presents a low potential of 1.40 V to deliver 100 mA cm−2 for UOR, which is about 260 mV less for its urea-free counterpart in alkaline electrolyte. When anodic NiMoV LDH/NF electrode and cathodic Pt/C electrode are integrated into a two-electrode system for water electrolysis in variable urea concentration and pH values conditions, urea-assisted electrolysis water system exhibit the lower potential (≤1.63 V) than that of conventional water electrolysis at 100 mA cm−2. This work shows that the local electronic structure adjustment of the active site caused by the heteroatom doping effect could improve the electrocatalytic oxidation performance of some small molecules.
Three grinding stones from Shizitan Locality 14 (ca. 23,000-19,500 calendar years before present) in the middle Yellow River region were subjected to usewear and residue analyses to investigate human ...adaptation during the last glacial maximum (LGM) period, when resources were generally scarce and plant foods may have become increasingly important in the human diet. The results show that these tools were used to process various plants, including Triticeae and Paniceae grasses, Vigna beans, Dioscorea opposita yam, and Trichosanthes kirilowii snakegourd roots. Tubers were important food resources for Paleolithic hunter-gatherers, and Paniceae grasses were exploited about 12,000 y before their domestication. The long tradition of intensive exploitation of certain types of flora helped Paleolithic people understand the properties of these plants, including their medicinal uses, and eventually led to the plants' domestication. This study sheds light on the deep history of the broad spectrum subsistence strategy characteristic of late Pleistocene north China before the origins of agriculture in this region.
g-C3N4 is a promising visible-light-driven photocatalyst for H2 evolution reaction; however, the achievement of the high photocatalytic performance is primarily limited by the low separation ...efficiency of the photogenerated charge carriers and partly restricted by the slow kinetics of charge transfer. 2D g-C3N4 can significantly improve the charge generation, transfer, and separation efficiencies. The 2D g-C3N4-based Z-scheme heterostructure can further enhance the charge-carrier separation and simultaneously increase the redox ability, thereby further boosting the photocatalytic performance. Here we report a transition-metal-oxide (TMO)-mediated subtractive manufacturing process toward the large-scale synthesis of 2D g-C3N4 and the simultaneous formation of a 2D/2D TMO/g-C3N4 Z-scheme heterojunction. The TMOs serve as catalysts to facilitate the hydrolysis reaction of the bulk g-C3N4 in the presence of moist air, forming 2D g-C3N4. The resulting 2D/2D TMO/g-C3N4 catalysts, in particular, 2D/2D Co3O4/g-C3N4, exhibit high-efficiency and high-yield photocatalytic H2 evolution due to the suppression of electron–hole pair recombination and enhanced redox ability. The 2D/2D Co3O4/g-C3N4 photocatalyzes the H2 evolution with a rate of ∼370 μmol h–1 within λ > 400 nm. The external quantum efficiency of 2D/2D Co3O4/g-C3N4 at λ = 405 nm reaches 53.6%, which is among the highest values for g-C3N4-based catalysts.
In 2011, porcine epidemic diarrhea virus (PEDV) infection rates rose substantially in vaccinated swine herds. To determine the distribution profile of PEDV outbreak strains, we sequenced the ...full-length spike gene from samples from 9 farms where animals exhibited severe diarrhea and mortality rates were high. Three new PEDV variants were identified.
The lithic assemblage from Shizitan 29, a late Upper Paleolithic open-air site in Shanxi, China, provides evidence for the earliest, well-dated microblade production in East Asia, ca. 26/24 Ka cal ...BP. To pursue a behavioral rather than traditional typological understanding of this key adaptive technology, we apply a techno-functional approach that enables us to reconstruct the entire operational sequence in behavioral terms through the derivation of technical objectives. This methodology can serve as a model to be applied to other assemblages for greater understanding of the origins and spread of the broadly distributed eastern Asian Late Pleistocene microblade industries. Within the eight cultural layers at Shizitan 29, microblade production abruptly appears at the top of Layer 7 following earlier core-and-flake production, supporting hypotheses of microblade technology arising within adaptive strategies to worsening Late Glacial Maximum environments. Significantly, reconstruction of the operational sequence supports microblade technology being introduced into the North China Loess Plateau from regions further north. It also allows us to re-think microblades' relationship in behavioral terms with earlier limited examples of East Asian blade production and the evolution and spread of microblade technology, providing new insights into the adaptive relationships between subsequent microblade productions.
In the electrospinning process, a modified parallel electrode method (MPEM), conducted by placing a positively charged ring between the needle and the parallel electrode collector, was used to ...fabricate highly aligned carbon nanotubes/polyacrylonitrile (CNTs/PAN) composite nanofibers. Characterizations of the samples-such as morphology, the degree of alignment, and mechanical and conductive properties-were investigated by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), universal testing machine, high-resistance meter, and other methods. The results showed the MPEM could improve the alignment and uniformity of electrospun CNTs/PAN composite nanofibers, and enhance their mechanical and conductive properties. This meant the successful preparation of highly aligned CNT-reinforced PAN nanofibers with enhanced physical properties, suggesting their potential application in appliances and communication areas.
Toxic organic pollutants in the aquatic environment cause severe threats to both humans and the global environment. Thus, the development of robust strategies for detection and removal of these ...organic pollutants is essential. For this purpose, a multifunctional and recyclable membrane by intercalating gold nanoparticles and graphitic carbon nitride into graphene oxide (GNPs/g‐C3N4/GO) is fabricated. The membranes exhibit not only superior surface enhanced Raman scattering (SERS) activity attributed to high preconcentration ability to analytes through π–π and electrostatic interactions, but also excellent catalytic activity due to the enhanced electron–hole separation efficiency. These outstanding properties allow the membrane to be used for highly sensitive detection of rhodamine 6G with a limit of detection of 5.0 × 10−14m and self‐cleaning by photocatalytic degradation of the adsorbed analytes into inorganic small molecules, thus achieving recyclable SERS application. Furthermore, the excellent SERS activity of the membrane is demonstrated by detection of 4‐chlorophenol at less than nanomolar level and no significant SERS or catalytic activity loss was observed when reusability is tested. These results suggest that the GNPs/g‐C3N4/GO membrane provides a new strategy for eliminating traditional, single‐use SERS substrates, and expands practical SERS application to simultaneous detection and removal of environmental pollutants.
A multifunctional membrane including superior surface enhanced Raman scattering (SERS) and photocatalytic activity by intercalating gold nanoparticles and graphic carbon nitride into graphene oxide nanosheets is developed. The membrane exhibits the extraordinary ability for use in removal, SERS detection, and degradation of organic pollutants, holding great promise for environmental pollutants removal and monitoring.
Well-shaped Y2O3:Eu hollow microspheres have been successfully prepared on a large scale via a urea-based homogeneous precipitation technique in the presence of colloidal carbon spheres as hard ...templates followed by a subsequent heat treatment process. XRD results demonstrate that all the diffraction peaks of the samples can be well indexed to the pure cubic phase of Y2O3. TEM and SEM images indicate that the shell of the uniform hollow spheres, whose diameters are about 250 nm, is composed of many uniform nanoparticles with diameters of about 20 nm, basically consistent with the estimation of XRD results. Furthermore, the main process in this method was carried out in aqueous condition, without the use of organic solvents or etching agents. The as-prepared hollow Y2O3:Eu microspheres show a strong red emission corresponding to the 5D0−7F2 transition of the Eu3+ ions under ultraviolet or low voltage excitation, which might find potential applications in fields such as light phosphor powders, advanced flat panel displays, field emission display devices, and biological labeling.
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