IN-SITU FTIR STUDY OF THE ELECTROCATALYTIC OXIDATION OF ETHANOL AT IRIDIUM AND RHODIUM ELECTRODES

In-situ Fourier transform IR (FTIR) reflectance spectroscopy has been used to study the electroadsorption and oxidation of ethanol at polycr ystalline Ir and Rh electrodes in HClO4 solutions. The formation of su rface and solution species has been followed optically during slow vol tammetric scans. Ethanol electroadsorption leads to the formation of l inearly bonded and bridge-bonded CO on Rh surfaces but only to linearl y bonded CO on Ir. In the oxidation potential region, Ir electrodes sh ow different catalytic properties from Rh electrodes, with Ir being a more selective catalyst than Rh. Oxidized states at early potentials p lay an activating role in ethanol electro-oxidation. Acetaldehyde is p robably an intermediate product, but the major product on Ir electrode s is acetic acid whereas CO2 is the main product at Rh electrodes.