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A one-step preparation of alginate-stabilized gold nanoparticles (Au NPs) using the microwave-induced plasma-in-liquid process (MWPLP) was reported. Effects of alginate with various concentrations on the preparation and properties of the synthesized Au NPs, including reaction rate, morphology, size, and optical absorption property, were studied. The introduction of alginate (1) accelerated the reaction rate, (2) prevented aggregation and precipitation due to long time discharge in MWPLP, and (3) provided long-term colloidal stability. An abnormal size change (from large to small) of Au NPs during particle growth, which was opposite to the typical change in bottom-up chemical reduction, was observed and a possible mechanism was proposed based on the dynamical and thermodynamical instability of particles during growth. The strategy of drying and redispersion of Au NPs in alginate solution was also studied. The drying and redispersion process had an imperceptible effect on the Au NPs. As a consequence, this strategy might be an effective technique for the long-term storage of Au NPs and other metal NPs. The alginate-stabilized Au NPs without the addition of toxic reducing or stabilizing agents can be appropriate to biomedical applications.

This article provides a detailed discussion of 1-hexanoic-acid-stabilised copper nanoparticles with an average diameter of similar to 80 nm prepared from cupric oxide micro-powders for low-temperature sintering applications. The obtained fine particles were dispersed in dipropylene glycol using a bead mill to obtain a stable paste containing 50 wt% copper. Sintering experiments at temperatures in the range of 120-250 degrees C were performed under a nitrogen or 3%H-2-N-2 gas flow. The lowest resistivity, approximately three times that of bulk copper, was obtained at 250 degrees C. These particles exhibited good conductivity upon sintering under nitrogen only. 1-Hexanoic acid contributed to the acceleration of sintering by removing the Cu64O oxide layer of the particles and activating the surface. The dispersed copper paste and the copper layer after sintering were observed using SEM.

Anisotropic growth to form Cu particles of rod and wire shapes has been obtained typically in a complex system that involves both organic capping agents and Cl- ions. However, the sole effect of Cl- ions on the formation of Cu wires has yet to be fully understood, especially in an organic system. This present work determines the effect of Cl- ions on the morphologies of Cu particles in an organic phase without any capping agents. The results revealed that anisotropic Cu rods could be grown with the sole presence of Cl- ions. The rods have the (011 facets as the long axis, the (111) facets as the tip, and the (100) facets as the side surface. By increasing the Cr ion concentration, more Cu atoms contributed to the formation of Cu rods and the kinetic growth of the length and the diameter of the rods varied. This suggests that Cl- ions have preferential adsorption on the (100) Cu surfaces to promote the anisotropic growth of Cu. Meanwhile, the adsorption of CI to the (111) and (100) surfaces at high Cl- concentrations regulates the relative growth of the particle length and diameter.

Eutectic gallium indium (EGaIn) has drawn considerable research interest in potential liquid catalysis. Herein, we report that EGaIn liquid metal acts as a catalyst for the growth of a graphitic carbon layer from ethanol under ultrasonication. High-speed imaging demonstrated the formation of ultrasonic cavitation bubbles at the liquid metal/ethanol interface, which facilitated the pyrolysis of ethanol into graphitic carbon on the liquid metal surface.