la0501132_si_001.pdf (1.41 MB)
Modeling of the Hysteresis Phenomena in Finite-Sized Slitlike Nanopores. Revision of the Recent Results by Rigorous Numerical Analysis
journal contribution
posted on 2005-07-05, 00:00 authored by Piotr Kowalczyk, Katsumi Kaneko, Lech Solarz, Artur P. Terzyk, Hideki Tanaka, Robert HołystThe systematic investigation of the hysteresis phenomena in finite-sized slitlike nanopores via the
Aranovich−Donohue (AD) lattice density functional theory (LDFT) is presented. The new reliable
quantitative modeling of the adsorption and desorption branch of the hysteresis loop, through the formation
and movement of the curved meniscus, is formulated. As a result, we find that our proposal, which closely
mimics the experimental findings, can reproduce a rounded shape of the desorption branch of the hysteresis
loop. On the basis of the exhausted commutations, we proved that the hysteresis loop obtained in the
considered finite-sized slitlike geometry is of the H1 type of the IUPAC classification. This fundamental
result and the other most important results do not confirm the results of the recent studies of Sangwichien
et al., whereas they fully agree with the recent lattice studies due to Monson et al. We recognize that the
nature of the hysteresis loops (i.e. position, width, shape, and the multiple steps) mainly depends on the
value of the energy of both the adsorbate−adsorbate and adsorbate−adsorbent interactions; however, the
first one is critical for the appearance of hysteresis. Thus, for relatively small adsorbate−adsorbate
interactions, the adsorption−desorption process is fully reversible in the whole region of the bulk density.
We show that the strong adsorbate−adsorbent interactions produce (also observed experimentally) multiple
steps within hysteresis loops. Contrary to the other studies of the hysteresis phenomena in confined
geometry via the LDFT formalism, we constructed both ascending and descending scanning curves, which
are known from the experimental observations. Additionally, we consider the problem of the stability of
both the obtained adsorption and desorption branches of the computed hysteresis loop in finite-sized
slitlike nanopores.