Adsorption of camphor at Bi(111) electrode

Abstract

Impedance spectroscopy and in situ STM methods have been used for investigation of the camphor adsorption at the electrochemically polished Bi(111) electrode from weakly acidified Na2SO4 base electrolyte aqueous solution. The influence of the electrode potential on the adsorption kinetics and camphor adsorption layer structure on Bi(111) has been demonstrated. In the region of the capacitance pit in the differential capacitance vs. electrode potential curve the so- called heterogeneous adsorption step is the rate determining stage for camphor adsorption at the electrochemically polished Bi(111) electrode, but not diffusion as usually assumed. It was found that the stable adsorbate adlayer detectable by using the in situ STM method has been observed only at the positively charged electrode surface, where the weak co-adsorption of SO42- anions and camphor molecules is possible. At the weakly negatively charged Bi(111) electrode surface there are only physically adsorbed camphor molecules forming the compact adsorption layer.