DIFFERENTIAL ELECTROCHEMICAL MASS-SPECTROMETRY USING SMOOTH ELECTRODES - ADSORPTION AND H/D-EXCHANGE REACTIONS OF BENZENE ON PT

While previously a porous electrode fixed to a hydrophobic membrane had to be used as the inlet system for differential electrochemical mass spectrometry, a newly designed thin-layer cell allows for the first time processes to be studied that occur on a smooth electrode. The feasibility of the new cell is demonstrated for the cathodic desorption of benzene adsorbed on annealed Pt in 0.5 M H2SO4. Partial desorption occurs in the H region. Complete desorption is only achieved under hydrogenation to cyclohexane at more negative potentials, where the hydrogen evolution reaction takes place. No partially hydrogenated products are formed. Experments in which C6D6 was used show that no C-D bond rupture occurs upon adsorption. Various degrees of H/D exchange occur in the adsorbate. © 1990 American Chemical Society.