The experimental system was a three-electrode electrochemical cell set up to study the potentiostatic electrodissolution of copper in an acetate buffer electrolyte solution of sodium acetate and acetic acid. The experimental setup and the general electrochemical behavior of the system is described in some detail by Dewald, Parmananda, and Rollins[8,9]. Figure 1 is a schematic diagram of the system.
Figure: Schematic representation of the three-electrode
electrochemical cell. V is the anodic potential and I is
the anodic current. The potentiostat adjusts the emf to hold
V at the desired set value.
The anode was
a rotating copper
disk (5 mm diameter) shrouded in a cylinder of Teflon.
The supporting electrolyte solution was a
mixture of 60 parts glacial acetic acid
to 35 parts 2M sodium acetate.
The potential of the anode was measured relative to a
saturated calomel reference electrode (SCE) and the cathode was a
2.5 cm
platinum foil disk. The emf of the circuit was
continuously adjusted by a potentiostat to maintain the desired
set value of the anodic potential (the potential between the anode
and the reference electrode). The anodic potential was used
as our control parameter. Time series data was collected by measuring
the anodic current at 20 ms intervals using a
12 bit A/D converter interfaced
to a computer. The period for the current oscillations in the
chaotic states used in these experiments ranged from 2 to 4 sec so that
the time between data points in the time series is small compared
to the typical period
of the oscillations. The set point for the anodic potential was controlled
by the computer through a D/A converter with the smallest increment of the
control voltage being 0.1 mV.