Figure 6. Experiments with coupled electrochemical reactions.

(a) Schematic of the experimental setup containing the reference (RE), counter (CE) and two Ni working electrodes (WE) in an electrochemical cell with 50 ml 3 mol L⁻¹ sulfuric acid at a temperature of 10 ^oC. (b) Establishing AD with α=1 and regaining oscillations with α=0. Without control, the oscillations phase drift (t<40.13 s, K=0). With direct feedback control AD is observed (40.13 s<t<127.1 s, K=−1.0 V mA⁻¹, τ=1.09 s and α=1). With α=0, the oscillations are anti-phase synchronized. (t>127.1 s, K=−1.0 V mA⁻¹, τ=1.09 s and α=0). (c) Current time series with several values of α=0, 0.1, 0.2, 0.3 and 0.4. (d) AD domains for α=1 and 0.8 in the parameter space for K versus τ. The set of discrete data points are approximated by a cubic spline interpolation, which indicates the border between AD and oscillatory states.