Detection of Intermediates and Products of Electrochemical Processes-a DEMS Study

Abstract

The presentation describes an on-line connection of electrochemical cell and mass spectrometer used for detection, identification and observation in time of volatile and semivolatile species during electrochemical polarisation of working electrode (DEMS - Differential Electrochemical Mass Spectrometry). DEMS is a type of experimental technique, which makes possible an investigation of electrosorption, electrooxidation and electrohydrogenation processes of molecules like aromatic hydrocarbons, some other small organic molecules and reaction intermediates. The experimental set-up consists of a mass spectrometer connected with an electrochemical cell separated by hydrophobic membrane. Standard three-electrode electrochemical arrangement is applied. As test system we studied the process of electrochemical hydrogenation of naphthalene and benzene and processes of electrochemical oxidation of formic acid and dimethylformamide in 0,5 M H2SO4 on polycrystalline Pt electrode.