RESUMO
An understanding of solid-liquid interfaces is of great importance for fundamental research as well as industrial applications. However, it has been very challenging to directly image solid-liquid interfaces with high resolution, thus their structure and properties are often unknown. Here, we report a quasi-liquid phase between metal (In, Sn) nanoparticle surfaces and an aqueous solution observed using liquid cell transmission electron microscopy. Our real-time high-resolution imaging reveals a thin layer of liquid-like materials at the interfaces with the frequent appearance of small In nanoclusters. Such a quasi-liquid phase serves as an intermediate for the mass transport from the metal nanoparticle to the liquid. Density functional theory-molecular dynamics simulations demonstrate that the positive charges of In ions greatly contribute to the stabilization of the quasi-liquid phase on the metal surface.
RESUMO
Excavated cubic Pt93Ir7 alloy nanocrystals enclosed by high-index {710} facets exhibit excellent electrocatalytic properties for the nitrogen reduction reaction (NRR) with a high faradaic efficiency (40.8%) and NH3 production rate (28 µg h-1 cm-2). The presence of Ir on the Pt stepped surface suppresses the hydrogen evolution reaction (HER) and accelerates the NRR.
RESUMO
We have reported, for the first time, in situ growth of high-index {hk0} faceted concave Pt nanocubes on multi-walled carbon nanotubes (CNTs) via an electrochemical method in choline chloride-urea (ChCl-U) based deep eutectic solvents (DESs). Mechanistic studies indicate that a urea hydrogen bond donor (HBD) plays a key role in the formation of concave Pt nanocubes, in which the urea HBD preferentially adsorbs onto the {100} faces and blocks the growth of nanocrystals along the ã100ã axis. The as-prepared concave Pt nanocubes are characterized to be enclosed mainly with high-index {710}, {610} and {510} facets. It has been determined that the concave cubic Pt/CNT exhibits higher catalytic activity and stability than the flower-like Pt/CNT and commercial Pt/C catalysts, and this is ascribed to its high density of surface atomic steps and the synergistic effect between the CNT and Pt nanocubes.