Title: Destructive Impact of Molecular Noise on Nanoscale Electrochemical Oscillators,
Abstract: We study the loss of coherence of electrochemical oscillations on meso- and
nanosized electrodes with numeric simulations of the electrochemical master
equation for a prototypical electrochemical oscillator, the hydrogen peroxide
reduction on Pt electrodes in the presence of halides. On nanoelectrodes, the
electrode potential changes whenever a stochastic electron-transfer event takes
place. Electrochemical reaction rate coefficients depend exponentially on the
electrode potential and become thus fluctuating quantities as well. Therefore,
also the transition rates between system states become time-dependent which
constitutes a fundamental difference to purely chemical nanoscale oscillators.
Three implications are demonstrated: (a) oscillations and steady states shift
in phase space with decreasing system size, thereby also decreasing
considerably the oscillating parameter regions; (b) the minimal number of
molecules necessary to support correlated oscillations is more than 10 times as
large as for nanoscale chemical oscillators; (c) the relation between
correlation time and variance of the period of the oscillations predicted for
chemical oscillators in the weak noise limit is only fulfilled in a very
restricted parameter range for the electrochemical nano-oscillator.