Enthalpy and entropy of oxygen electroadsorption on RuO₂(110) in alkaline media

We report the temperature influence of the OH_ad and O_ad electroadsorption on RuO₂(110) films grown on TiO₂(110) crystals in alkaline media. From the temperature effect, we evaluate the enthalpy and entropy of the OH_ad and O_ad electroadsorption, including the adsorbate-adsorbate interactions that we analyze using the interaction parameters of the Frumkin-isotherm model. We found that the adsorbates repel each other enthalpically but attract each other entropically. Our result suggests that an entropy analysis is necessary to capture the electroadsorption behavior on RuO₂ since the enthalpy-entropy competition strongly influences the electroadsorption behavior. Our observation of an entropic force is consistent with the view that water may be a mediator for adsorbate-adsorbate interactions.