Electrocatalytic activity of Pt nanoparticles on bamboo shaped carbon nanotubes for ethanol oxidation

Silver nanoparticles assessment in moisturizing creams by ultrasound assisted extraction followed by sp-ICP-MS

Advances on nanometrology require reliable sample pre-treatment methods for extracting/isolating nanomaterials from complex samples. The current development deals with a discontinuous ultrasonication (60% amplitude, 15 cycles of ultrasound treatment for 59 s plus relaxing stage for 59 s, 20 mL of methanol) method for a fast and quantitative extraction of silver nanoparticles (Ag NPs) from moisturizing creams. Possibilities offered by modern inductively coupled plasma mass spectrometry (ICP-MS) which allow 'single particle' assessment (sp-ICP-MS) have been used for Ag NPs assessment (Ag NPs concentration and Ag size distribution). The relative standard deviation (RSD) of the over-all procedure (Ag NPs concentration in eleven extracts from a same cream) was found to be 5%; whereas, the analytical recovery for spiking experiments with Ag NPs of 20, 40, and 60 nm was found to be within the 90-109% range. The limit of quantification in Ag NPs concentration was established at 8.25 × 10⁵ Ag NPs g^-1; whereas, the limit of detection in size was found to be within the 5-13 nm (several equations were used for calculation). Finally, moisturizing creams prescribed for atopic dermatitis and also regular moisturizing creams were analyzed for total Ag, and for Ag NPs characterization (Ag NPs concentration and Ag NPs size distribution) by sp-ICP-MS. Electronic microscopy was also used for comparative (qualitative) purposes.

Highly Active and Stable Pt-Pd Alloy Catalysts Synthesized by Room-Temperature Electron Reduction for Oxygen Reduction Reaction

Carbon-supported platinum (Pt) and palladium (Pd) alloy catalyst has become a promising alternative electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. In this work, the synthesis of highly active and stable carbon-supported Pt-Pd alloy catalysts is reported with a room-temperature electron reduction method. The alloy nanoparticles thus prepared show a particle size around 2.6 nm and a core-shell structure with Pt as the shell. With this structure, the breaking of O-O bands and desorption of OH are both promoted in electrocatalysis of ORR. In comparison with the commercial Pt/C catalyst prepared by conventional method, the mass activity of the Pt-Pd/C catalyst for ORR is shown to increase by a factor of ≈4. After 10 000-cycle durability test, the Pt-Pd/C catalyst is shown to retain 96.5% of the mass activity, which is much more stable than that of the commercial Pt/C catalyst.