Electrochemical cyclovoltammetry experiments were carried out on the platinum surface of a platinum–silicon thin-film device in sulfuric acid. The internal electronic barrier of the device allows the separation of ground state and excited state charge transfer events released by the electrochemical surface reaction. The traces of the device current show similar features as the cyclovoltammogram and can be discussed in terms of small deviations from the equilibrium state of the thin platinum film. The device current plotted as a function of the electrode potential shows a well-defined shift of the baseline when hydrogen is adsorbed. This baseline shift may be originated by an adsorbate-induced change of the chemical potential of the platinum film, thus influencing the internal field in the device (up to values of 23 mV).
Plot of the electrochemical current and the device current as functions of the electrode potential.