Hydroxyl groups on boron-doped diamond electrodes and their modification with a silane coupling agent

Oxygen-containing functional groups can be introduced onto the surface of p olycrystalline boron-doped diamond (BDD) electrodes by either anodic polari zation or oxygen plasma treatment. Of these, the hydroxyl groups are of par ticular interest and can be studied specifically by means of specific chemi cal modification with 3-aminopropyltriethoxysilane (APTES). The modificatio n of the surface hydroxyl groups with APTES accelerates the [Fe(CN)(6)](3-/ 4-) redox reaction, compared to the retardation by the oxidized surface. Th ese changes can be explained in terms of changes in the electrostatic inter action between the surface functional groups and the [Fe(CN)(6)](3-/4-) ani on. In particular, electrostatic attraction between [Fe(CN)(6)](3-/4-) and protonated amino groups at the APTES-treated surfaces should be responsible for the acceleration. These results, as well as those obtained in contact angle measurements and X-ray photoelectron measurements, indicate that hydr oxyl groups are generated on the oxidized BDD surfaces and that they can be modified with silane coupling agents for introduction of various functiona lities onto the BDD electrode surface. (C) 2001 The Electrochemical Society .