Metallic nanoparticles cell separation

Summing up this section, we would like to note that understanding size effects in electrocatalysis requires the application of appropriate model systems that on the one hand represent the intrinsic properties of supported metal nanoparticles, such as small size and interaction with their support, and on the other allow straightforward separation between kinetic, ohmic, and mass transport (internal and external) losses and control of readsorption effects. This requirement is met, for example, by metal particles and nanoparticle arrays on flat nonporous supports. Their investigation allows unambiguous access to reaction kinetics and control of catalyst structure. However, in order to understand how catalysts will behave in the fuel cell environment, these studies must be complemented with GDE and MEA tests to account for the presence of aqueous electrolyte in model experiments. 

Although metal nanoparticles experience strong radiation pressure and scattering forces due to their high absorption and polarizability, stable trapping of such particles has been demonstrated in both two and three dimensions [74, 85, 86]. As for cells and dielectric particles, a NIR laser is usually used to trap metal nanoparticles while a separate laser, or the trapping laser itself, excites the... 

In the case of Au, nanoparticles are stable both under light irradiation and in the dark. Therefore, the charge separation system is applied to photovoltaic cells and photocatalysis. Photovoltaic cells may be a wet type or solid state. In the wet-type cell, a photoanode such as electrode/nSC/MNP (nSC = n-type semiconductor MNP = metal nanoparticle) [8] or a photocathode such as electrode/MNP/nSC [9] is used with an electrolyte containing a redox couple. Structures of solid-state cells are electrode/ nSC/MNP/HTM/electrode (HTM = hole transport material or p-type semiccmductor) [11] and electrode/nSC/MNP/electrode [12],... 

PEBBLEs are water-soluble nanoparticles based on biologically inert matrices of cross-linked polymers, typically poly(acrylamide), poly(decylmethacrylate), silica, or organically modified silicates (ORMOSILs), which encapsulate a fluorescent chemo-sensor and, often, a reference dye. These matrices have been used to make sensors for pH, metal ions, as well as for some nonionic species. The small size of the PEBBLE sensors (from 20 to 600 nm) enables their noninvasive insertion into a living cell, minimizing physical interference. The semipermeable and transparent nature of the matrix allows the analyte to interact with the indicator dye that reports the interaction via a change in the emitted fluorescence. Moreover, when compared to naked chemosensors, nanoparticles can protect the indicator from chemical interferences and minimize its toxicity. Another important feature of PEBBLEs, particularly valuable in intracellular sensing applications, is that the polymer matrix creates a separate... 

Exploring various phenomena at metal/solution interfaces relates directly to heterogeneous catalysis and its applications to fuel cell catalysis. By the late 1980s, electrochemical nuclear magnetic resonance spectroscopy (EC-NMR) was introduced as a new technique for electrochemical smface science. (See also recent reviews and some representative references covering NMR efforts in gas phase surface science. ) It has been demonstrated that electrochemical nuclear magnetic resonance (EC-NMR) is a local surface and bulk nanoparticle probe that combines solid-state, or frequently metal NMR with electrochemistry. Experiments can be performed either under direct in situ potentiostatic control, or with samples prepared in a separate electrochemical cell, where the potential is both known and constant. Among several virtues, EC-NMR provides an electron-density level description of electrochemical interfaces based on the Eermi level local densities of states (Ef-LDOS). Work to date has been predominantly conducted with C and PtNMR, since these nuclei... 

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