Investigation of "Current Doubling" Mechanism of Organic Compounds by the Rotating Ring Disk Electrode Technique

The photo‐oxidation mechanisms of methanol, formaldehyde, and formic acid, which are potentially "current‐doubling agents," were investigated using the RRDE technique. The disk electrode was and was illuminated by a xenon lamp while the ring electrode was Pt. Hydrogen ion, generated at the disk during the oxidation of water or the organic solute, was observed by its reduction near −1V vs.. SCE at the ring. Formic acid was also reduced to hydrogen at the ring electrode in this potential region. , produced by decomposition while in transit from the disk, was reduced at −0.4V vs. SCE at the ring. The experimental results are consistent with initial production of hydroxyl radicals by photogenerated holes, followed by oxidation of the organic solute. One pathway involves injection of an electron into the conduction band resulting in increased photocurrents. Although true current‐doubling (100% increase) was not observed, photocurrent increases of ∼50% were observed.