Remarkable Enhancement of the Rate of Cathodic Reduction of Hydrocarbonate Anions at Palladium in the Presence of Caesium Cations

Steady-state polarization curves, representative of the electrochemical reduction of HCO ions at a smooth palladium cathode, obtained in CsHCO₃ and NaHCO₃ solutions, are compared. The net current densities, associated with the electroreduction of HCO anions, measured in 1M CsHCO₃ solution are shown to be up to 9 times larger than those observed in 1M NaHCO₃ solution. This result is interpreted in terms of a direct involvement of the Cs⁺ cations in the reaction at the cathode through the formation of ion pairs with the HCO anions.