Nanopore model

An obvious approach in evaluating the nanopore model would involve a measurement of the proton conductivity of a nanoporous layer with charged metallic walls as a function of the applied voltage. Proton concentration in a conductive nanoporous membrane is a function of (pP . Assuming bulk-like proton transport, the variation of... 

An initial evaluation of the nanopore model can be conducted by comparison with electrochemical performance data for MEAs that utilize UTCLs on the cathode side. The two types of experimental materials considered are nanoporous gold leafs plated with varying amounts of Pt (Pt-NPGL) (Zeis et al., 2007) and Pt NSTF layers of 3M (Pt-NSTF) (Debe et al., 2006). 

FIGURE 3.29 A comparison of nanopore model and experimental polarization data for Pt-NPGL layers. (Reprinted from Chan, K., and Eikerling, M. 2011. J. Electrochem. Soc., 158(1), B18-B28, Figures 1,2,3,4,5,6. Copyright (2011), the Electrochemical Society. With permission.)... 

RPM model, but theories for the SPM model electrolyte inside a nanopore have not been reported. It is noticed that everywhere in the pore, the concentration of counterion is higher than the bulk concentration, also predicted by the PB solution. However, neutrality is assumed in the PB solution but is violated in the single-ion GCMC simulation, since the simulation result of the counterion in the RPM model is everywhere below the PB result. There is exclusion of coion, for its concentration is below the bulk value throughout the pore. Only the solvent profile in the SPM model has the bulk value in the center of the pore. 

FIG. 17 Diffusion coefficients of the counterions and coions of a 1 1 RPM model electrolyte in a cylindrical nanopore of i = lOd. The circles and triangles represent the results of coions and counterions, respectively. 

Figure 2.52 2-D model of a counter-current heat-exchanger reactor with a nanoporous catalyst layer deposited on the channel wall.

In the light of the findings illustrated so far, the disagreement between expected and observed nanopores diameter, cannot be defined but significant and this datum reveals that the TCS model needs further testing. 

In order to see how the electrode thickness might be optimized in order to provide the lowest electrode resistivity, we have developed a theoretical model to describe the charge/discharge processes in porous carbon electrodes. As a first approximation, let us consider an electrode having two sets of cylindrical pores, namely, nanopores (NP) of less than 3 nm in diameter and transport channels (TC) of more than 20 nm in diameter, with each nanopore having an exit to only one TC. ... 

Figure 1. Model presentation of a few nanopore tiers facing a transport channel.

From this, the velocities of particles flowing near the wall can be characterized. However, the absorption parameter a must be determined empirically. Sokhan et al. [48, 63] used this model in nonequilibrium molecular dynamics simulations to describe boundary conditions for fluid flow in carbon nanopores and nanotubes under Poiseuille flow. The authors found slip length of 3nm for the nanopores [48] and 4-8 nm for the nanotubes [63]. However, in the first case, a single factor [4] was used to model fluid-solid interactions, whereas in the second, a many-body potential was used, which, while it may be more accurate, is significantly more computationally intensive. 

Two kernels of theoretical isotherms in cylindrical channels have been constructed corresponding to the adsorption and desorption branches. For a series of samples [2-4], we show that the pore size distributions calculated from the experimental desorption branches by means of the desorption kernel satisfactory coincide with those calculated from the experimental adsorption branches by means of the adsorption kernel This provides a convincing argument in favor of using the NLDFT model for pore size characterization of nanoporous materials provided that the adsorption and desorption data are processed consistently,... 

Figure 4 Model of the nanopore structure (cut through a (001) plane), evolution of the inter pore distances with treatment at 620 K, involving shrinkage in the direction normal to the substrate surface.

Dubbeldam, D. and Snurr, R.Q. (2007) Recent developments in the molecular modeling of diffusion in nanoporous materials. Molec. Sim., 33, 305. 

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