Surface structure and electrochemical characteristics of boron-doped diamond exposed to rf N 2-plasma

Abstract

Epitaxial (100)-oriented diamond layer with boron doping above 10 20 cm −3 was exposed to an RF N 2 plasma, the resulting surface structure and electrochemical characteristics were investigated. The N 2 plasma treatment was combined with in vacuo pre-heating to remove adsorbates and with surface shielding to reduce plasma-induced corrosion. X-ray photoemission spectroscopy revealed full nitrogenation of the surface with the presence of C N and C N bond structures. Anodic treatment in 0.1 M KOH in the oxygen evolution range generated nitrogen–oxygen bonds and carbon–oxygen functionalities which partially substitute the initial nitrogen-termination. The nitrogenated and electrochemically polarised diamond electrode exhibited higher catalytic activity to [Fe(CN) 6] 3−/4− but slower to [Ru(NH 3) 6] 3+/2+ redox reactions, as compared to an identical diamond electrode with fully oxygen-terminated surface.