P. Nikitas, DIFFUSE LAYER EFFECT AND EFFECT OF CURVATURE ON THE MECHANISM AND THEPROPERTIES OF PHASE-TRANSITIONS AT ELECTRIFIED INTERFACES, Journal of electroanalytical chemistry [1992], 446(1-2), 1998, pp. 165-175
The criteria for an adsorbed layer to undergo a reversible phase trans
ition on an electrode surface are examined by means of classical therm
odynamics. It is shown that, although this process takes place always
at a constant value of the potential drop across the adsorbed layer, i
t may occur at either a constant value of the applied potential or ove
r a certain range of applied potentials. The first possibility can be
realised when the concentration of ions in the diffuse layer is high e
nough to produce an approximately equipotential plane just beyond the
adsorbed layer or when the diffuse layer is imposed to undergo a kind
of phase transition characterised by its separation into two parts wit
h different total electrical charge but the same potential drop or the
transition extends throughout the interface. If neither of the above
processes can be realised, then the second possibility is very likely
due to a diffuse layer effect. For the examination of the diffuse laye
r effect in more detail, the classical supersaturation theory is exten
ded to two-dimensional phase transitions on electrode surfaces and an
attempt is made to explain the existence and extent of metastable stat
es as well as the mechanism and the properties of irreversible transit
ions. The results obtained are compared with current views on two-dime
nsional phase transitions. (C) 1998 Elsevier Science S.A. All rights r
eserved.