The room temperature stability of nanometer-sized silver clusters in silica matrices has been investigated by following the temporal evolution of their surface plasmon absorption. Ag clusters in SiO2 were prepared by either annealing silica samples doped with atomic silver or by co-deposition of pre-formed clusters of defined size. Clusters were found to be unstable at ambient conditions on a t...

The effect of a localized SiO2 codoping on the conversion of polycrystalline, MgO-doped Al2O3 tubes to single-crystal sapphire was investigated. Codoping with SiO2 before sintering intentionally triggered abnormal grain growth, which resulted in the full conversion of tube surfaces to single crystal without adversely affecting densification to a almost pore-free, translucent state. The degree o...

Si-based Er-doped Si nanostructures were fabricated for exploring efficient light emission from Er ions and Si nanocrystallites. High-resolution transmission electron microscopy observations reveal that Si nanocrystallites are spherically embedded in the SiO2 matrix. Energy-dispersive x-ray analysis indicates that the Er centers are distributed at the surfaces of nanocrystallites surrounded by ...

The thermal decomposition of Nafion N117 membrane, a typical perfluorosulfonic acid membrane that is widely used in various chemical technologies, was investigated in this study. Structural identification of thermolysis products in water and methanol was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). The fluoride release was studied using ...

A facile one-pot microemulsion method has been developed for the synthesis of spherical silver core-silica shell (Ag@SiO2) nanoparticles with europium chelates doped in the shell through a silane agent. The method is significantly more straightforward than other extant methods. Measurements of the luminescent emissions from the Ag@SiO2 nanoparticles, in comparison with control silica nanopartic...

Ascorbic acid (AA) is the principle interferent present in brain extracellular fluid that can inhibit the ability of electrochemical sensors to selectively detect a particular analyte of interest. Considerable efforts have been made in recent times to develop highly selective membrane coatings to counteract the drawbacks associated with AA interference during in vivo monitoring. The primary obj...

The performance and stability of a direct methanol fuel cell (DMFC) with membrane electrode assemblies (MEA) using different Nafion contents (30, 50 and 70 wt % or MEA30, MEA50 and MEA70, respectively) and graphitized carbon nanofiber (GNF) supported PtRu catalyst at the anode was investigated by a constant current measurement of 9 days (230 h) in a DMFC and characterization with various techni...

Although proton-exchange membrane fuel cells (PEMFC) are considered as a safe and clean energy technology, aging phenomena of the membrane-electrode assembly (MEA), more particularly membrane, still restrict PEMFC lifetime. In this paper, ex-situ accelerated chemical degradation – via Fenton's reagents exposure reinforced Nafion™ XL is performed in order to investigate impact on structure prope...

An electrochemiluminescence (ECL) approach for methamphetamine determination was developed based on a glassy carbon electrode modified with a Ru(bpy)₃ (2+)-doped silica nanoparticles/Nafion composite film. The monodispersed nanoparticles, which were about 50 nm in size, were synthesized using the water-in-oil microemulsion method. The ECL results revealed that Ru(bpy)₃ (2+) doped in silica nano...

Operating temperature can be a limiting factor in reliable applications of Proton Exchange Membrane (PEM) fuel cells. Nanoindentation tests were performed on perfluorosulfonic acid (PFSA) membranes (Nafion® 117) in order to study the influence of the temperature condition on their mechanical properties. The hardness and reduced modulus of Nafion® 117 were measured within a certain temperature r...