Phase synchronization and suppression of chaos through intermittency in forcing of an electrochemical oscillator

External periodic forcing was applied to a chaotic chemical oscillator in experiments on the electrodissolution of Ni in sulfuric acid solution. The amplitude and the frequency $\left(\Omega \right)$ of the forcing signal were varied in a region around $\Omega ={\omega }_0,$ where ${\omega }_0$ is the frequency of the unforced signal. Phase synchronization occurred with increase in the amplitude of the forcing. For $\Omega /{\omega }_0$ near 1 the signal remained chaotic after the transition to the phase-locked state; for $\Omega /{\omega }_0$ somewhat farther from 1 the transition was to a periodic state via intermittency. The experimental results are supported by numerical simulations using a general model for electrochemical oscillations.