Biomedical Engineering Reference
In-Depth Information
approximation of thermodynamics of the irreversible processes
(in a somewhat novel version). These methods have been used to
critically and constructively analyze and systematize a large body of
experimental data on hydrogen sorption by graphite and new carbon
nanomaterials (with sp
2
hybridization). The aim of this analysis
is the indirect experimental determination of thermodynamic,
transport, and diffusion that are the fundamental characteristics of
the relevant sorption processes. In particular, for the interpretation
of the obtained characteristics, we used the well-known results [36]
of the first-principle calculations by
molecular orbit (MO)
theory of the chemisorption energies of atomic hydrogen by graphite
and carbon nanostructures.
This approach has been successfully used [43-50] to solve a
number of related pressing problems involving gas-solid interactions.
For instance, the approach described in Ref. [47] for processing
appropriate experimental data allowed us to do the following:
(i) expose some new fundamental aspects regarding the
micromechanisms giving hydride-like nanosegregations on
dislocations in palladium;
(ii) modify substantially (for effects ranging from two to seven
orders of magnitude) the widely used Lifshits-Slezov and
Wagner theories of internal oxidation and coagulation of
depositions in metals.
In the subsequent paragraphs, we examine the concepts and
methods developed [10, 17-25], and the procedures and results
of their application to the analysis and systematization of a most
reliable experimental data set on hydrogen sorption by carbon
materials. In particular, the following paragraph describes a new
method [18] used in thermal-desorption studies (temperature-
programmed desorption, or TPD, TPD peaks, and TPD spectra)
to determine experimentally the thermodynamic, diffusion, and
transport characteristics of sorption processes and to establish
their nature. This method is used to analyze the experimental data.
In what follows, the numbering of process I-IV corresponds to that
adopted in Refs. [10, 17].
ab initio
2.2.2.2
Dissociative Chemisorption of Hydrogen
2.2.2.2.a
Process III
One of the processes similar to process I in Ref. [27] is the
dissociative chemical adsorption of hydrogen (H
gas
) (process III in
2
