Investigations of the anodic oxidation of ethanol under forced convection and ambient conditions

The electro-oxidation of ethanol was investigated in alkaline solution (0.5 M ethanol and 0.1 M NaOH) on a polycrystalline platinum electrode. The electrode was positioned in a flow channel (channel electrode) which ensures controllable and defined convection conditions in the electrode surrounding. Moreover, a flow through UV-Vis absorbance cell was used for intermediate (acetaldehyde) detection and its quantification. It was experimentally observed that the intermediate current efficiency is a function of flow rate. Furthermore, the intermediate current efficiency increases with increasing surface poisoning during ethanol oxidation. From the experimental results it can be estimated that the intrinsic current efficiency for the pathway to acetaldehyde is at least 73(3)%. Hence, the current efficiency for pathways leading directly via surface reactions to other reaction products is at most 27(3)% (both are integral values over 15 min of oxidation at 0.6 V vs. RHE).