Oleylamine-Mediated Hydrothermal Growth of Millimeter-Long Cu Nanowires and Their Electrocatalytic Activity for Reduction of Nitrate

Fabrication of Cu Micromembrane as a Flexible Electrode

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and PEI provides adhesive, wetting, and reducing functionalities that facilitate subsequent Ag activation and Cu electroless plating. Scanning electron microscopy reveals conformal deposition of Cu on individual PP fibers. Porometer analysis indicates that the porous nature of PPMM is properly maintained. The Cu micromembrane demonstrates impressive electrical conductivities in both the X direction (1.04 ± 0.21 S/cm) and Z direction (2.99 ± 0.54 × 10^-3 S/cm). In addition, its tensile strength and strain are better than those of pristine PPMM. The Cu micromembrane is flexible and mechanically robust enough to sustain 10,000 bending cycles with moderate deterioration. Thermogravimetric analysis shows a thermal stability of 400 °C and an effective Cu loading of 5.36 mg/cm². Cyclic voltammetric measurements reveal that the Cu micromembrane has an electrochemical surface area of 277.8 cm² in a 1 cm² geometric area (a roughness factor of 227.81), a value that is 45 times greater than that of planar Cu foil.

A combined TEM and SAXS study of the growth and self-assembly of ultrathin Pt nanowires

Ultrathin Pt nanowires possess high activity for various electrocatalytic applications. However, little work has focused on understanding their growth mechanisms. Herein, we utilize a combination of time-dependent,ex situtransmission electron microscopy (TEM) and small angle x-ray scattering (SAXS) techniques to observe the growth process in addition to associated surfactant-based interactions. TEM images indicate that initially nanoparticles are formed within 30 s; these small 'seed' particles quickly elongate to form ultrathin nanowires after 2 min. These motifs remain relatively unchanged in size and shape up to 480 min of reaction. Complementary SAXS data suggests that the initial nanoparticles, which are coated by a surfactant bilayer, arrange into abccsuperlattice. With increasing reaction time, thebcclattice disappears as the nanoparticles grow into nanowires, which then self-assemble into a columnar hexagonal structure in which the individual nanowires are covered by a CTAB monolayer. The hexagonal structure eventually degrades, thereby leading to the formation of lamellar stacking phases comprised of surfactant bilayers. To the best of our knowledge, this is the first time that SAXS has been used to monitor the growth and self-assembly of Pt nanowires. These insights can be used to better understand and rationally control the formation of anisotropic motifs of other metallic nanostructures.

Combustion Products of Calcium Carbide Reused by Cu-Based Catalysts for Acetylene Carbonylation

Sustainable development is a worldwide concern. This work mainly focuses on the reuse of the combustion products of calcium carbide and the influence of different kinds of copper on the acetylene carbonylation reaction. A series of catalysts were prepared by heating the precursors under various atmospheres (air, hydrogen, and nitrogen). The X-ray diffraction and the X-ray photoelectron spectroscopy have been analyzed regarding copper species composition and content in catalysts. The result of the Cu⁺-promoted reaction was in good agreement with the conducted density functional theory analysis, and we speculate that Cu⁺ promotes the transfer of electrons in the reaction. Transmission electron microscopy and elemental mapping evaluation confirmed the difference in Cu dispersion. Characterization of catalysts using temperature programmed desorption and pyridine Fourier-transform infrared revealed differences in their acidity. Acidity was found to be favorable for acetylene carbonylation. Selectivity and yield of the CuAlZn-LDO(N) catalyst at 225 °C were 73 and 70%, respectively, and the catalyst showed good stability over two consecutive cycles of reuse.

Aqueous Phase Synthesis of Cu2-x S Nanostructures and Their Photothermal Generation Study

Size- and shape-dependent features of plasmonic nanocrystals govern the development of their applications. In the past decades, gold nanostructures, such as gold nanorods and nanoshells, have been well studied and applied for sensing, bioimaging, and photothermal generation. However, knowledge of copper chalcogenide, a new generation of plasmonic nanomaterials, is limited, especially about their preparation and size- and shape-dependent photothermal properties. In this work, controllable size and shape Cu_2-x S nanocrystals (NCs) are synthesized by a facile aqueous route. Using low-molecular-weight polyethylenimine (PEI) as the reducing and capping agents, the size and shape of Cu_2-x S NCs can be controlled with lengths from 6.5 to 46.5 nm and the aspect ratio from 2.2 to 7.5 by adjusting the concentration of PEI. The plasmonic peak of Cu_2-x S experiences a redshift (from 1145 to 1369 nm) when the length increases from 6.5 to 44.5 nm. Under the irradiation of 1064 nm laser with 1.33 W/cm², an excellent photothermal conversion rate (from 34.9 to 49.0%) is obtained. The characterization of Cu_2-x S NCs is conducted with a UV-vis spectrometer, transmission electron microscopy, powder X-ray diffraction measurements, and 1064 nm laser.