Photochemical Modification of a Boron-doped Diamond Electrode Surface with Vinylferrocene

Boron-doped diamond (BDD) surfaces were photochemically modified with vinylferrocene (VFC), and the modified surfaces were analyzed both qualitatively and quantitatively by electrochemical techniques. VFC-modified BDD (VFC-BDD) was prepared by ultraviolet (254 nm) irradiation of hydrogen-terminated BDD in mesitylene, acetonitrile, or n-alkane solutions of VFC. Cyclic voltammetry (CV) results indicated facile electron transfer between ferrocenyl groups and the BDD substrate. The surface coverage of VFC-modified polycrystalline and single-crystal (100) BDD was also estimated by CV and was found to reach saturation at a value possibly corresponding to monolayer coverage by ferrocenyl groups. The electrochemical stability of VFC-BDD to successive potential cycling in acetonitrile was found to be much higher than that of a self-assembled ferrocenylalkanethiol monolayer on an Au electrode surface. This study is the first to show that appropriate solutions of a terminal alkene can be used in the photochemical modification of diamond, yielding monolayer coverage of the surface.