EPFL doctorate Award 2009 - Kapalka Agnieszka

"For her experimental and theoretical work on Boron-Doped diamond electrochemistry and specifically for the activation of dioxygen via electrogenerated hydroxyl radicals"

Reactivity of electrogenerated free hydroxyl radicals and activation of dioxygen on boron-doped diamond electrodes

Synthetic boron-doped diamond (BDD) thin film is an electrode material with outstanding electrochemical properties such as high chemical and dimensional stability, low background current and a very wide potential window of water stability. Upon anodic polarization, BDD generates hydroxyl radicals (HO) that mediate oxidation processes in the vicinity of the electrode surface. In this thesis, the theoretical aspect of electrogeneration of free hydroxyl radicals is discussed and the model describing HO concentration profile at the BDD surface is presented. The theoretical and the experimental studies showed that HO are involved in both oxygen evolution and organics oxidation on BDD. In the presence of organics, electrogenerated HO initiate chain reaction resulting in implication (activation) of molecular oxygen dissolved in aerated solution. This non-faradaic enhancement of the electro-oxidation processes opens the possibilities for designing a less energy consuming oxidation processes on diamond electrodes. Ideally, current would be supplied mainly to initiate formation of hydroxyl radicals whereas complete oxidation of organics would proceed via activation of molecular oxygen.