Electrochemical synthesis of diamondlike carbon films

Electrodeposition of diamondlike carbon films through oxidation of acetylides (prepared both in situ and ex situ) dissolved in dimethylsulfoxide (DMSO) was carried out at room temperature by potentiodynamic, potentiostatic, and galvanostatic methods onto gold substrates. Diamondlike carbon films (and nanoinclusions of diamond, graphite, and lonsdaleite phases) were prepared from acetylene-saturated liquid ammonia at a temperature of -33 degrees C by potentiodynamic, potentiostatic, galvanostatic, and pulsed deposition methods. The films were characterized in situ by electrochemical methods and ex situ by Raman spectroscopy, optical microscopy, transmission electron microscopy, profilometry, and electron diffraction. Films were successfully deposited by both methods. The fastest growth rate was achieved with acetylides prepared ex situ and oxidized in the presence of NaBH4 in DMSO solution. Film thickness was found to increase either by processing at higher values of potential or for longer deposition times. Films of the highest quality and greatest uniformity were prepared by pulsed deposition from acetylene-saturated liquid ammonia. Nanodiamond and lonsdaleite inclusions were obtained by potentiostatic deposition from the same medium. (C) 2008 The Electrochemical Society.