Electrochemical characteristics of boron-doped, undoped and nitrogen-doped diamond films

Boron-doped, undoped and nitrogen-doped diamond films were synthesized by microwave plasma assisted chemical vapor deposition (MP-CVD). Raman spectroscopy, XPS, EPMA and UV-Vis were used to characterize the properties of the synthesized films. Electrochemical characteristics for several redox systems on the three kinds of diamond films were examined. For Li+/Li (E0=−3.05 V) and H+/H2 (E0=0.00 V) redox couples, the marked differences in cyclic voltammetric (CV) behaviors were observed on the nitrogen-doped diamond films, whereas for Fe(CN)3−/4− (E0=0.36), Au/AuCl4− (E0=1.00) and O2/H2O (E0=1.23 V) couples, the CV behaviors on the nitrogen-doped films were similar to those on the boron-doped or undoped diamond films. The significant differences of CV behaviors could be explained by hypothesizing that the electron transfers of the redox species in the solution on diamond electrodes happened at the top of valence band together with the surface doping model suggested by F. Maier and colleagues [F. Maier, M. Riedel, B. Mantel, J. Ristein, L. Ley, Phys. Rev. Lett. 85 (2000) 3472].