A STUDY OF THE ELECTROOXIDATION OF METHANOL ON PLATINUM IN 1 M NA2SO4 BY ELECTROCHEMICAL AND INSITU FTIR TECHNIQUES

The electrochemical oxidation of methanol in unbuffered 1 M Na2SO4 has been studied in order to shed light on the oxidation mechanism. Results from RDE and RRDE measurements suggest that surface poisoning by adsorbed carbonyl species plays an important role, as in acidic solutions, and in situ FTIR studies reveal a rich surface chemistry involving a variety of carbonyl intermediates. The electrochemistry in 1 M Na2SO4 is complicated by pH swings during both oxidation and reduction cycles, and the release of protons can be detected both at the platinum ring and by in situ FTIR. Both stationary electrode and FTIR studies indicate the presence of a substantial cathodic current on sweeping the electrode back from positive potentials where CO2 formation has taken place. This cathodic process disappears if the electrode is rotated. If methanol is not present, no analogous process takes place, and FTIR data suggest that it may be due to incorporation of surface-bound CO2 onto a poisoned surface with concomitant reorganisation of adsorbed CO. © 1990.