Search for multi-functional catalysts: The electrooxidation of acetaldehyde on Platinum–Ruthenium–Rhodium electrodeposits

Preliminary studies on the influence of Platinum–Rhodium electrodeposits upon the rate of acetaldehyde electrooxidation showed that Rhodium plays a dual role during electrooxidation, because it favors the break of C–C bonds whilst prevents the deliverance of oxygen-containing species, thus inhibiting the oxidation steps. Based on these results, in this work Platinum–Ruthenium and Platinum–Ruthenium–Rhodium electrodeposits were prepared and characterized by electrochemical and spectroscopic methods (FTIR in situ). The addition of Ruthenium is justified by its ability to promote a facile oxidation of adsorbed species by activation of water molecules. The results indicate a compromise between the existence of superficial sites able to break carbon chains (provoked by Rhodium) and responsible by the oxidation of adsorbed species (provoked by Ruthenium). Among the atomic compositions investigated, PtRuRh (73:23:04) shows the maximum activity towards acetaldehyde electrooxidation, but the production of acetic acid seems to be the main responsible for this activity.