The flower-like silver nanoparticles have been synthesized by reducing silver nitrate （AgNO3） with ascorbic acid （AA） as the reductant and polyvinyl pyrrolidone （PVP） as the capping agent under vigorous stirring...The flower-like silver nanoparticles have been synthesized by reducing silver nitrate （AgNO3） with ascorbic acid （AA） as the reductant and polyvinyl pyrrolidone （PVP） as the capping agent under vigorous stirring. Such flower-like nanoparticles are aggregates of small nanoplates and nanorods. They were tested as substrates for the surface-enhanced Raman scattering （SERS）, showing high sensitivity for detecting Rhodamine 6G （RBG） at a concentration as low as 10 7 mol/L. It has been found that replacing mechanical stirring with ultrasound sonication would drastically change the particle morphology, from flower-like nanoparticles to well-dispersed smaller nanoparticles. Furthermore, when trace amounts of NaC1 were added into the reagents, well-dispersed Ag nanoparticles formed even in vigorous stirring. These phenomena can be explained with the diffusion and reactant supply during nucleation and growth of Ag nanoparticles.展开更多
Formic acid oxidation is an important electrocatalytic reaction in proton- exchange membrane （PEM） fuel cells, in which both active sites and species adsorption/activation play key roles. In this study, we have deve...Formic acid oxidation is an important electrocatalytic reaction in proton- exchange membrane （PEM） fuel cells, in which both active sites and species adsorption/activation play key roles. In this study, we have developed hollow Pd-Ag alloy nanostructures with high active surface areas for application to electrocatalytic formic acid oxidation. When a certain amount of Ag is incorporated into a Pd lattice, which is already a highly active material for formic acid oxidation, the electrocatalytic activity can be significantly boosted. As indicated by theoretical simulations, coupling between Pd and Ag induces polarization charges on Pd catalytic sites, which can enhance the adsorption of HCO0＊ species. As a result, the designed electrocatalysts can achieve reduced Pd usage and enhanced catalytic properties at the same time. This study represents an approach that simultaneously fabricates hollow structures to increase the number of active sites and utilizes interatomic interactions to tune species adsorption/ activation towards improved electrocatalytic performance.展开更多
A facile hydrothermal approach is used to synthesize hollow silver nanoparticles, labeled as hAgNPs, involving an initial formation of metal complexes from Ag＋ ion precursors and dodecylamine in a water]ethanol mixtu...A facile hydrothermal approach is used to synthesize hollow silver nanoparticles, labeled as hAgNPs, involving an initial formation of metal complexes from Ag＋ ion precursors and dodecylamine in a water]ethanol mixture at room temperature and a subsequent reduction in an autoclave at elevated temperature. A number of characterization techniques are used to characterize the structure and chem- ical composition of the as-formed hAgNPs, and to understand the mechanism behind the formation, The notable simplicity renders this synthetic approach promising for creating hAgNPs on a large scale for a given technological application, and the mechanistic understanding may provide new opportunities to design and fabricate other hollow nanostructures.展开更多
基金financial support for this work from the Natural Science Foundation for Young Scientists of Shanxi Province of China (No. 2015021078)International Cooperation of Science and Technology Project in Shanxi Province of China (No. 2014081006-2)
文摘The flower-like silver nanoparticles have been synthesized by reducing silver nitrate （AgNO3） with ascorbic acid （AA） as the reductant and polyvinyl pyrrolidone （PVP） as the capping agent under vigorous stirring. Such flower-like nanoparticles are aggregates of small nanoplates and nanorods. They were tested as substrates for the surface-enhanced Raman scattering （SERS）, showing high sensitivity for detecting Rhodamine 6G （RBG） at a concentration as low as 10 7 mol/L. It has been found that replacing mechanical stirring with ultrasound sonication would drastically change the particle morphology, from flower-like nanoparticles to well-dispersed smaller nanoparticles. Furthermore, when trace amounts of NaC1 were added into the reagents, well-dispersed Ag nanoparticles formed even in vigorous stirring. These phenomena can be explained with the diffusion and reactant supply during nucleation and growth of Ag nanoparticles.
文摘Formic acid oxidation is an important electrocatalytic reaction in proton- exchange membrane （PEM） fuel cells, in which both active sites and species adsorption/activation play key roles. In this study, we have developed hollow Pd-Ag alloy nanostructures with high active surface areas for application to electrocatalytic formic acid oxidation. When a certain amount of Ag is incorporated into a Pd lattice, which is already a highly active material for formic acid oxidation, the electrocatalytic activity can be significantly boosted. As indicated by theoretical simulations, coupling between Pd and Ag induces polarization charges on Pd catalytic sites, which can enhance the adsorption of HCO0＊ species. As a result, the designed electrocatalysts can achieve reduced Pd usage and enhanced catalytic properties at the same time. This study represents an approach that simultaneously fabricates hollow structures to increase the number of active sites and utilizes interatomic interactions to tune species adsorption/ activation towards improved electrocatalytic performance.
文摘A facile hydrothermal approach is used to synthesize hollow silver nanoparticles, labeled as hAgNPs, involving an initial formation of metal complexes from Ag＋ ion precursors and dodecylamine in a water]ethanol mixture at room temperature and a subsequent reduction in an autoclave at elevated temperature. A number of characterization techniques are used to characterize the structure and chem- ical composition of the as-formed hAgNPs, and to understand the mechanism behind the formation, The notable simplicity renders this synthetic approach promising for creating hAgNPs on a large scale for a given technological application, and the mechanistic understanding may provide new opportunities to design and fabricate other hollow nanostructures.
