The electrochemical oxidation and detection of ascorbic acid at hydrogen- and oxygen-terminated boron-doped diamond thin film electrodes

This work studied the effects of electrochemical polarization in different acidic media on the oxidation kinetics for ascorbic acid at polycrystalline diamond electrodes. The polarization introduced oxygen functionalities onto the surface of the electrode, which increased the Epox and decreased the ipox for the oxidation of ascorbic acid.; Raman and AFM spectroscopy were used to show that anodic polarization had no effect on the bulk structure of the diamond electrodes. There was very little change in the reaction kinetics for Ru(NH3)6 +2/+3, which also indicates that the anodic polarization only added oxygen to the surface of the electrode.; The DeltaEp for Fe(CN)6-3/-4, which is very sensitive to surface oxygen functionalities, also increased after anodic polarization.; Rehydrogenation of the diamond electrode removed the surface oxygen and returned the ascorbic acid electron-transfer kinetics to the pre-polarized state.