#CORE SHELL NANOPARTICLE APPLICATIONS ISO#

Once adsorbed, the molecule dissociates to liberate an ion and electron, alongside an adsorbed atom, which is further dissociated in a fast charge-transfer process. It is generally accepted that the reaction proceeds along a three-step pathway, firstly involving adsorption of molecular hydrogen onto the catalyst surface. The mechanism of this is shown below, Figure 1. At the anode, hydrogen fuel is dissociated in contact with the catalyst layer to produce two hydrogen (H +) ions, and two electrons (e −) in the hydrogen evolution reaction (HER). A PEFC consists of an anode and cathode separated by a polymer membrane, typically composed of a fluorinated polymer such as Nafion ®. These fuel cells utilise hydrogen fuel to generate electricity with water as the only by-product or emission, and may find applications in sectors including transportation and consumer electronics. One particular application of nanoparticulate electrocatalysts is in catalysing the reactions required for the operation of low temperature fuel cells, such as the polymer electrolyte fuel cell (PEFC). With this in mind, nanoparticle (electro)catalysts have been the subject of significant research endeavour in recent years. This is an intrinsic property of nanoparticles due to their nanoscale dimensions, a greater proportion of their mass is exposed to the surface than an equivalent macroscale bulk material. One strategy towards doing so is the use of nanoparticulate catalysts, which by definition will have a greater number of active sites gram for gram compared to a bulk material, due to their high surface area to mass ratio. In their work, the authors refer to one of the key lines of development in electrocatalysis being work to increase the number of (catalytically) active sites on a given electrode. highlighted the crucial role for electrocatalysis in securing a ‘clean energy’ future. Another key application for nanoparticles is in catalysis, and particularly in electrocatalysis. Indeed, nanoparticles now find applications as diverse as in drug delivery, chemical sensing, and in protective ‘self-cleaning’ coatings.

These unique properties have inspired significant scientific interest and research effort in a range of fields of human endeavour.

#CORE SHELL NANOPARTICLE APPLICATIONS ISO#

The ISO standard goes on to elaborate that materials in the nanoscale ‘often have properties that are not simple extrapolations of the properties of their larger form.’ That is to say, such nanomaterials exhibit physical and chemical properties not otherwise observed for macroscale objects of the same material. Nanoparticles are defined by the International Organization for Standardization (ISO) technical standard 80004-2 as materials for which all three of their external dimensions are in the nanoscale (1–100 nm).

Core shell nanoparticle applications