One-step synthesis of Ni@Pd/NH_(2)-Fe_(3)O_(4)nanoparticles as affordable catalyst for formic acid dehydrogenation

Currently,one of the critical issues in the world is finding an appropriate green alternative to fossil fuels due to the concerns about global warming.As a hydrogen source,formic acid has been given particular attention owing to the attractive features such as highenergy density,no toxicity,high stability at ambient temperature and high hydrogen content.Introducing an affordable and highly efficient catalyst with easy recovery from the reaction mixture for selective dehydrogenation of formic acid is still demanding.In this report,we used a simple onestep process to synthesize Ni@Pd core shell nanoparticles on 3aminopropyltriethoxysilane modified Fe3O4 nanoparticles.The existence of Ni and Pd results in a synergic effect on the catalytic activity.The—NH2 groups play an important role for obtaining welldispersed ultrafine particles with high surface area and active sites.In addition,Fe3O4 lead to convenient magnetic recovery of the catalyst from reaction mixture.Our results indicate that the asprepared catalyst give the superb turnover frequency of 5367.8 h 1 with no additive,which is higher than most of the previously reported catalysts.

Ex situ aging effect on sulfonated poly(ether ether ketone) membrane:Hydration-dehydration cycling and hydrothermal treatment

Prolonged hydrothermal treatment for sulfonated poly(ether ether ketone) membranes induces mechanical degradation and developing hydrophilic-hydrophobic phase separation, simultaneously. The enhanced phase separation provides incremental proton conductivity to the membranes, whereas mechanical degradation drastically reduces device stability. On this basis, we describe here the effects of two different ex situ aging processes on sulfonated poly(ether ether ketone) membranes: hydrationdehydration cycling and prolonged hydrothermal treatment. Both aged membranes exhibited enhanced phase separation under the hydrated conditions, as characterized by small angle X-ray scattering.However, when the aged membranes were dried again, the nanostructure of the membranes aged via the hydration-dehydration cycling was recoverable, whereas that of the membranes aged via prolonged hydrothermal treatment was irreversible. Furthermore, the two differently aged membranes showed clear differences in thermal, mechanical, and electrochemical properties. Finally, we implemented both aged membranes in fuel cell application. The sample aged via hydration-dehydration cycling maintained its improved cell performance, whereas the sample aged via hydrothermal treatment showed drastically reduced cell performance after durability test for 50 h.

In Situ Etching for Total Control Over Axial and Radial Nanowire Growth

We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway,independent of other growth parameters.Thereby a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial growth.We demonstrate the method using etching by HCl during InP nanowire growth.The improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.

A Comparative Study of the Effect of Gold Seed Particle Preparation Method on Nanowire Growth

Highly controlled particle-assisted growth of semiconductor nanowires has been performed for many years,and a number of novel nanowire-based devices have been demonstrated.Full control of the epitaxial growth is required to optimize the performance of devices,and gold seed particles are known to provide the most controlled growth.Successful nanowire growth from gold particles generated and deposited by various different methods has been reported,but no investigation has yet been performed to compare the effects of gold particle generation and deposition methods on nanowire growth.In this article we present a direct comparative study of the effect of the gold particle creation and deposition methods on nanowire growth characteristics and nanowire crystal structure,and investigate the limitations of the different generation and deposition methods used.