A unique approach based on the colloidal route allowing the synthesis of monodisperse bimetallic, trimetallic, tetrametallic and pentametallic nanoparticles with diameters around 5 nm as solid solutions.
We report a new and versatile colloidal route towards the synthesis of nanoalloys with controlled size and chemical composition in the solid solution phase (without such phases segregations as core-shell...
Biotemplated
syntheses have emerged as an efficient strategy
to
control the assembly of metal nanoparticles (NPs) and generate promising
plasmonic properties for sensing or biomedical applications. However,
understanding the nucleation and growth mechanisms of metallic nanostructures
on biotemplate is an essential prerequisite to developing well-controlled
nanotechnologies. Here, we used liquid cell Transmission Electron
Microscopy (TEM) to reveal how the formation kinetics of gold NPs
affects their size and density on Tobacco Mosaic Virus (TMV). These in situ insights are used as a guideline to optimize bench-scale
synthesis with the possibility to homogenize the coverage and tune
the density of gold NPs on TMV. In line with in situ TEM observations, fluorescence spectroscopy confirms that the nucleation
of NPs occurs on the virus capsid rather than in solution. The proximity
of gold NPs on TMV allows shifting the plasmonic resonance of the
assembly in the biological window.
The development of synthesis methods with enhanced control over the composition, size and atomic structure of High Entropy Nano-Alloys (HENA) could give rise to a new repertoire of nanomaterials with...
The aim of the present work is to valorise the brewing industry’s waste, i.e., brewer’s spent grain (BSG), into functional biocarbon for environmental catalysis applications. In this context, cost-effective and environmentally friendly biochar support coated with in-situ-generated Ag-Cu nanocrystals, was developed via the wet impregnation of BSG biomass powder with copper (II) nitrate trihydrate and silver nitrate aqueous solution prior to pyrolysis at moderate temperature (500 °C). Small-size homogenously distributed Ag-Cu nanocrystals (≤80 nm) on the surface of the biochar (Biochar@Ag-Cu) were observed by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Elemental compositions were determined by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX). The crystalline nature of the nanoparticles was confirmed by X-ray powder diffraction (XRD). Information about the thermal stability of the materials and quality were obtained by thermogravimetric analysis (TGA) and Raman, respectively. The potentiality of the Biochar@Ag-Cu catalyst in the field of pollutant removal is demonstrated by taking methyl orange and methylene blue as model dyes. A kinetics study was performed and analyzed by UV–vis spectroscopy. Its highly active catalytic nature is proved by the complete mineralization of the methyl orange dye (100%) through oxidative degradation. The reusability of the catalyst has shown 96% removal efficiency after 3 cycles. The linear plot of −Ln (CA/C0) vs time (R2 = 0.9892) reveals that the mineralization of the methyl orange dye follows pseudo-first-order kinetics (k = 0.603 × 10−2 min−1). A methyl orange + methylene blue dye mixture degradation study has revealed the faster kinetics of the present catalyst towards methylene blue degradation. The current study suggests that BSG Biochar@Ag-Cu can be a potential candidate in contribution towards SDG 6.
This manuscript describes a new process for the synthesis of very high quality 2D Covalent Organic Frameworks (COFs), such a C2N and CN carbon nitrides. The structure/quality of these materials is demonstrated by extensive cross-characterisations at different scales. The availability of such very large, high quality layers of these materials opens interesting perspectives, for example in photochemistry and electronics (intrinsic transport properties, high gap substrate for graphene, etc...). We thus consider that this work could be of interest to a broad readership, considering that this topic is among the current hottest ones.
The surfactant used during a colloidal synthesis is known
to control
the size and shape of metallic nanoparticles. However, its influence
on the nanoparticle (NP) structure is still not well understood. In
this study, we show that the surfactant can significantly modify the
lattice parameter of a crystalline particle. First, our electron diffraction
measurements reveals that NiPt nanoparticles around 4 nm in diameter
covered by a mixture of oleylamine and oleic acid (50:50) display
a lattice parameter expansion around 2% when compared to the same
particles without surfactant. Using high-resolution transmission electron
microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive
X-ray spectroscopy (EDX) techniques, we show that this expansion can
not be explained by crystal defects, twinning, oxidation, or atoms
insertion. Then, using covered NPs in the 4–22 nm size range,
we show that the lattice parameter evolves linearly with the inverse
of the NP size, as it is expected when a surface stress is present.
Finally, the study is extended to pure nickel and pure platinum NPs,
with different sizes, coated by different surfactants (oleylamine,
trioctylphosphine, polyvinylpyrrolidone). The surfactants induce
lattice parameter variations, whose magnitude could be related to
the charge transfer between the surfactant and the particle surface.
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