  We propose a new, cyclic-voltammetry based experimental technique that can
not only differentiate between discontinuous and continuous phase transitions
in an adsorbate layer, but also quite accurately recover equilibrium behavior
from dynamic analysis of systems with a continuous phase transition. The
Electrochemical first-order reversal curve (EC-FORC) diagram for a
discontinuous phase transition (nucleation and growth), such as occurs in
underpotential deposition, is characterized by a negative region, while such a
region does not exist for a continuous phase transition, such as occurs in the
electrosorption of Br on Ag(100). Moreover, for systems with a continuous phase
transition, the minima of the individual EC-FORCs trace the equilibrium curve,
even at very high scan rates. Since obtaining experimental data for the EC-FORC
method would require only a simple reprogramming of the potentiostat used in
conventional cyclic-voltammetry experiments, we believe that this method has
significant potential for easy, rapid, in-situ analysis of systems undergoing
electrochemical deposition.
