A SIMPLIFIED SET-UP FOR ELECTROCHEMICAL MASS-SPECTROMETRY AND THE USEOF A GOLD SUBSTRATE FOR THE INVESTIGATION OF POROUS-ELECTRODE MATERIALS

A cell for use in electrochemical mass spectrometry (EMS) using silico n rubber membranes and a gold substrate is described. The silicon rubb er membrane used has a time constant and sensitivity for small molecul es comparable with that of the microporous PTFE membranes used traditi onally, but eliminates the need for a special prevacuum chamber and ex tra turbomolecular pump in the mass spectrometer. To investigate porou s electrode materials a microporous electronically conducting film is formed on the silicon rubber membrane by evaporation. Below the potent ial of oxide formation the gold film behaves as an electrochemically i nert substrate for the oxidation of methanol on different porous elect rode materials. The applicability of the set-up has been demonstrated by mass spectrometric cyclic voltammetry (MSCV) on the oxidation of me thanol on platinum black.